Science method

Filtration - Science method

A process of separating particulate matter from a fluid, such as air or a liquid, by passing the fluid carrier through a medium that will not pass the particulates.
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I prepare a chitosan solution in acetic acid (0.5 M). Some of the small threads are remained in the solution. In literature it is reported that solution is filtered before using. I want to know which filter is suitable for the filtration of chitosan solution?
Thanks
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For filtering chitosan solutions, it is recommended to use a filter with a pore size of 0.2 µm or smaller
One suitable filter for this purpose is a syringe filter with a 0.2 µm pore size, made of materials such as nylon, PVDF, or PTFE. These filters can effectively remove particles and aggregates from chitosan solutions without causing clogging or loss of chitosan
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using KOH (10%) and incubation for 48 Hrs. was not enough because the slime of the snails was not degrade and it was effect the filtration process ...Shall i increase the concentration ? or better to have alternatives let us say Nitric Acid ?
please let me know your ideas ..
Muna
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Would someone please help? I have carried out Fenton pretreatment and that has left out a lot of ferric precipitates on my filter paper. So, i have added 50 to 60 % of sulphuric acid onto my GF filters to dissolve the ferric precipitates. Then, I could see that the precipitates were dissolved immediately and then I have washed the filter paper with plenty of millipore water. But, I would like to know whether this process (less than one min of contact between filter paper and 55 % sulphuric acid solution) would affect the chemical nature of my microplastics? Observation in microscope suggests that discolouration has occurred. But I would like to know does any of you has encountered similar situation? What is your recommendation? Thank you so much.
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My CNF membrane cannot be transferred well after suction filtration. It will stick together after drying on the filter paper and make the filter paper brittle. What is the reason for this phenomenon?
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The sticking together of the CNF membrane after drying on the filter paper and making the paper brittle may be due to insufficient wetting or poor adhesion of the CNF to the filter paper during the suction filtration process. This can result in a weak interface between the CNF membrane and the filter paper, leading to poor transfer of the membrane and sticking together of the fibers upon drying.
To improve the transfer of the CNF membrane and prevent sticking, it is important to ensure that the CNF is evenly distributed on the filter paper and well-wetted during the suction filtration process. This can be achieved by using a proper dispersion method to uniformly disperse the CNF in the solvent, such as sonication or homogenization, and by carefully controlling the filtration parameters, such as the vacuum pressure and filtration time.
Another possible reason for the sticking together of the CNF membrane is the use of low-quality filter paper that is not compatible with the CNF or is too thin to support the membrane. It is important to choose a filter paper that is compatible with the CNF and has sufficient strength to support the membrane during transfer.
In addition, it is recommended to use a transfer membrane, such as a hydrophilic membrane or a PDMS stamp, to transfer the CNF membrane from the filter paper to the desired substrate. This can prevent damage to the CNF membrane during transfer and ensure its uniform and complete transfer to the substrate.
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I'm concentrating my AAV preparation using Amicon Ultra 100KDa and I observed that sometimes I need really long time to concentrate.
The point is that I have the longest centrifugation times when I start from a low concentration.
How is this possible? Is it correct or I am doing something wrong?
Thanks for all the answer!
Giulia
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I equilibrate with one wash with PBS before I apply the AAV.
After the iodixanol gradient I purify my AAVs on sepharose colums, so I dont have much of iodixanol left and the AAV is in gradient buffer.
I will try to equilibrate with gradient buffer (that has much more salts) instead of PBS.
Thanks for your feedback
Best
Giulia
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How can I calibrate my GF column with MW protein markers?
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Thank You.
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My FBS upon thawing was full of aggregates and posing the great hindrance in imaging of my cells. I centrifuged it and use it but it did not work. when i filter it with 0.2 micron filter it works. Is it right to use a smaller size filter or any other pore size can also be used.
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In my experience, I easily filter around 100mL clear / without any precipitate FBS using a 0.2-micron filter. I have not used a 0.45-micron syringe filter for FBS.
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Hi,
I'm in the process of setting our lab up for lipids analysis and I would love to hear some of your insights on filtration methods.
My background is in DNA/RNA, so I've been using columns and centrifugation, but I keep seeing people using vacuum manifolds when working on lipids. It's a very similar process, using silica-based filter columns to separate cell components, but somehow it seems both sides use their own method.
Now, my understanding is that we simply need to make our liquid sample pass through the filter, I can't see how it would make a difference whether it's pushed through by centrifugation or pulled through by a vacuum. The difference might simply be a custom in the different fields, but am I missing something?
PS.: This community's Q and A section has been a huge help during my studies (still is), I thank you all for your contributions here and with others!
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I would also favour the use of a vacuum manifold. Firstly, you can readily process many samples in parallel but most importantly you can actively monitor the chromatographic process (some samples may run faster than others and it is generally not a good idea to allow columns to run dry) without the inevitable delays inherent in the the use of a centrifuge.
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Yes, I am looking for low-cost ways. Some ideas are- centrifugation, flocculation-straining, and filtration. But which one of these will have the lowest cost?
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One way to remove light sludge from light oil without using distillation is to use a filtration method. This can be done by passing the light oil through a filter medium to remove the sludge particles. The filter medium can be anything from a paper filter to a more advanced system such as a centrifuge. This method is usually quick and cost-effective and can be used to remove a wide range of contaminants.
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I'm currently working on the synthesis of mixed ligands metal complexes. One of the ligands is a carboxylic acid. Is it possible to get colourless filtrate for the metal complexes?
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If a complex absorbs light in vis-range, you can't make it colorless without destroying it.
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Does anyone know what type of bacteria/fungi? it could be?
These were in my filtrate after filtration of the culture through an 80um mesh size filter cloth. The "brush" form orientation was quite common all over the slide.
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Is this a pure culture?
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am trying to purify a human DNA binding protein (normally localized in nucleus and mitochondria). I am currently optimizing the conditions I tried 2 different approaches:
1. HisTrap-> TEV --> HisTrap--> Gel filtration.
2. HisTrap --> TEV--> HiTrap --> Gel filtration
The expression was performed in BL21 (DE3) E.coli, 2YT media at OD600 = 0.8 induction was performed with either 0.5 or 0.1 mM IPTG at 16oC for 12 Hrs.
In all the conditions my protein wasn't pure, after doing mass spectroscopy I figured out that the additional bands are from E.coli (the host).
Can you please suggest me how to get rid of the contaminants?
I have attached the gel for more information, the protein of interest is in red rectangle
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The His-tag itself is not really suited for the purest results. Therefore one usually performs an SEC afterward if high levels of purity are required.
What I can also recommend you is not to use His-tag. It is Nickel based (nothing wrong with that).
But Nickel-based beads lie on the High-yield-less purity side even inside the already kinda impure His-tag purifications.
What you can do is use Co-NTA instead. Same protocols, only the Ion is different.
Co-NTA tends to have lower yields than Ni-NTA but noticeably higher levels of purity. That is just the usual trade-off in protein purifications.
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I am using hemp fibers to make a CNF solution; how much should be the concentration to vacuum filter and get a transparent nanopaper?
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What is the diameter of the nanopaper that you want to produce? What will your end purpose be? How do you plan on retaining the CNC fibers? Sorry for all of the questions, but would be helpful to understand what your goal is in producing the hemp nano-paper. If you simply want to produce a transparent film for testing purposes. Here is a good article to read. CNC by themselves tend to be somewhat brittle, so producing a composite film is a good method for assessing their strength.
"Mechanical enhancement of cellulose nanofibril (CNF) films through the addition of water-soluble polymers". E.S. Forti, Cellulose (2021)
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I am working on Analytical 3D fabricated Honeycomb shape memory structure for grey waste water treatment. The flow simulation of this research will depend on the interaction between solid and water.
#simulation #dynamics #wastewater
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Kindly go through this research article on Grey water which may help you a lot.
Article Biomass Production Through Grey Water Fertigation in Eucalyp...
Article Grey water pollutant loads in residential colony and its eco...
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Hi everyone,
Thank you very much for your time to look at my question!
On the IHSS (international humic substances society) website, filtration over a 0.2µm filter to remove the remaining mineral fraction/clays is suggested to be a replacement for the HF/HCl, but I could not really find anything about it in the literature.
Do you perhaps know any reference regarding using filtration to replace HF-HCl to remove clays when extracting humic acid from the soil?
Thank you very much in advance!
Best,
Jiaoyi
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Hi all,
Thanks a lot for the answers. That is very kind of you all.
But I might not make myself clear. I am not that interested in the effect of HF/HCl treatment. I am actually looking for some reference to support the replacement of HF/HCl application by filtration to remove minerals during the process of extracting HA from soil (this replacement is suggested on IHSS website (https://humic-substances.org/isolation-of-ihss-soil-fulvic-and-humic-acids/) but I couldn't find the evidence in papers.)
If you have any information you could offer on my question, that would be much appreciated. Thank you very much in advance!
Best,
Jiaoyi
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I want to separate the bacterial/fungal cells from the growth medium loaded with ointment/cream. Please, anyone, share the techniques to separate cells alone after treatment with drug
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Is this an anhydrous ointment?
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Hi folks/researchers,
While doing filtration of solution routinely facing the filter choke issue.
The density of solution quite closer to water density.
The particles obtained in bulk are evaluated for ≥ 10 micron particles (No such observation).
Is there any other causes or is it linked with molecular weight of active?
Please suggest/comment your innovative ideas!!
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Hello Senthamil
Thank you for your answers, but I am not clear on some of them. We're getting into a level of detail where we should continue the discussion privately. Please send me an email (alan.gabelman@gabelmanps.com).
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Dear Scientists,
I would like to consult you about the issue that I recently faced with that. I am planning to do 0.2 µm filtration of silica nanoparticles in water with a size of around 50 nm. I tried different filter types (cellulose, PTFE, PES, Nylon, hydrophilic, etc), but unfortunately, non of them worked out. Could you please recommend to me which filter type (material) I have to select to easily pass the sample through it without issue?
Best regards,
Ali
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Hanieyeh Etezadi Thanks for your kind reply. I would like to pass a sample very well dispersed in water through 200 nm filter and centrifugal filter doesn't work as I don't want to purify it. Regarding the nylon syringe filter, I tried that as well and didn't work out :(
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Hi everyone,
I have get this chromatogram in sephadex G25 column while purifying extracellular polysaccharide. I collected fractions 10 mL/ tube. I get both higher OD and activity (flocculation) at very first tube itself. After that the OD was gradually flatted but activity was little bit raised after some fractions.
Here my questions are:
1) whether the separation has taken place properly?
2) Why does the flocculation rate raise even though there polysaccharide content is absent?
3) what would be the molecular weight of EPS?
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No, not unless you can prove that the material eluting in tube 1 corresponds to the excluded volume of the column. This is determined by loading a very large molecule (often colored) and measuring the volume that passes before the material elutes. For example, let’s say your column is 100ml packed volume. You add a colored molecule >>10kDa in say 5ml volume and IMMEDIATELY start to collect the fluid eluding from the column in fractions (let’s say 5ml fractions for example). You then add further buffer to ‘push’ the material down the column and eventually it will elute, let’s say in tube 6. Excluded volume is therefore 30ml. In other words, the earliest that any molecule can appear, no matter how big, is after 30ml volume has passed through the column.
In your case, you say the material elutes in tube 1. While you do not give your column dimensions, this does not seem plausible. What is the packed volume of the column? I am assuming it is quite large otherwise you would not collect 10ml fractions. Unless you know the excluded volume of the column and unless you have demonstrated with markers that excluded molecules would be expected to emerge in what you describe as ‘tube 1’ you cannot say anything about molecular weight.
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I am trying to wash reduced graphene oxide with water through centrifugation process at 10000 rpm for 10 min. However, a lot of rGO particles are also lost while removing supernatant, albeit rGO apparently seems to be separated from water at the end of centrifugation. Kindly suggest some suitable alternative except filtration (chances of product loss) and freeze drying (not available in my institute).
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I have reduced graphene oxide using ascorbic acid under alkaline conditions in the presence of ammonia solution, so washing was mainly done to remove the acid and ammonia to promote dispersion stability of rGO. However, I think the use of organic solvent won't facilitate the separation of rGO by centrifugation.
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I am using (emulsification solvent diffusion) techniques to prepare polymer nanoparticle. according to the procedure, I have to use cross-flow filtration techniques using Minitan device (Millipore, USA-Bedford, MD), which is not available in my lab., my question is: is there any alternative method to eliminate the solvent? in the other word is it possible to use rotary evaporator for this reason?
regards
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Also check please the following useful RG link:
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Hi
How can I do filtration for RCT studies in Google Scholar for a systematic review?
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Hi Jumanah
You should include RCT in your search terms. I mean you should add RCT (with AND) to your search terms. Because as I know there is not any filtering tool in the Google scholar. You can also use Advanced search in Google scholar.
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I am considering using duckweed for research projects. Does anyone have any technical papers that explain culturing and maintaining duckweed that they have used and works?
I am imagining that I can grow it in a small aquarium with a light source. But what about aeration, nutrients, temperature, and filtration?
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In my experience, I did not use aeration to grow duckweed. I used small plastic containers with Hoagland's medium for the nutrient source. For lighting instead of sunlight, I used white LED lights. What must be considered is the surface area of ​​the cultivation space, because duckweed lives on the surface. Make sure there is enough room for multiplication in the surface. Maybe some of my works could help you.
📷
📷
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Is it mandatory to use RO + UV-treated double distilled water or MilliQ water? Or is it sufficient to use double-distilled water after autoclaving it?
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25 years ago, it used to work. We were feeding our quartz distillation machine with bulk RO water (in-house supply) which had been prepared from Munich's municipal water. Media then were filter sterilized into autoclaved bottles. No UV treatment was involved.
Depending on the price for off the shelf liquid media, you might want to calculate the efficiency and cost of the whole process, though
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I have collected exome data from a few literature articles. I got a thousand variants and would like to proceed in the next step which is variant filtration to determine the gene of interest. How does an automated variant filtration pipeline narrow down my gene of interest? Does anyone have an idea about this? I am new to bioinformatics tools.
Thank you
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Mohamed-Mourad Lafifi Thank you for your reply
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My procedure which did not work was:
1. Cell lysis with 0.2% Triton X-100
2. Protein precipitation with TCA
3. SPE (I have tried without this step but results were the same)
4. Filtration through a 0.2 um membrane
5. HPLC analysis
I am trying to analyse the lysate for itaconic acid. The chromatogram did not have any major peaks exept one giant asimetrical peak (which can be triton x-100 judging by the size but not the uv absorbtion spectrum).
I am trying to find out which other cell lysis protocols do scientists use for HPLC? Thank you in advance!
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@Grant Simpson Thank you for replying! I have found that for metabolite extraction cold methanol works best. Also hplc with pda detector is not ideal for detecting metabolites in a cell lysate therefore i am trying to incorporate gc-ms for metabolite quantitation.
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Hi,
I am looking for approaches to grab short peptides (5-10 mers) other than a 1000 or 3000 MWCO spin filter, do you have any suggestion?
Thanks
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I suggest using Superdex 30 Increase SEC columns from Cytive which are designed for high resolution, small-scale purification, and analysis of small biomolecules with Mr ~ 100 to ~ 7000, such as peptides...
Good luck...
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We all are aware that metro water is contaminated due to its pipeline.so water from reverse osmosis filtration of metro water the health benefits of reverse osmosis filtration water and the content of its mineralisation.
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The membrane used in reverse osmosis retains minerals like Ca, Fe, etc., and can affect bone density in healthy individuals. The final verdict is to use R.O water only in a case when the bone density isn't reducing otherwise mineral water is fine until the ppm exceeds.
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Does anyone work with expression in S2 cells? How efficient is the transfection using Lipofectamine 2000? Everytime I try to transfect using CaCl2 I get a cloudy media, and it seems that the culture is infected with a small bacteria, even filtrating all reagents with a 0.1 filter.
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I usually use Lipofectamine 2000 to transfect S2 cells, and it works
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Having known that in a real field scenario, shale is characterized by its average dispersive fracturing, how will you correlate the differences in filtration and inhibition properties with shale (clay content and size) and with drilling fluids
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Dear Dr. Bhola Kumar
Shales are anisotropic to the propagation of seismic waves, please look at the following Open Acess Research Article to see if it has some answers to your question, I guess it does not include dispersion, which is a hard issue to address:
James G. Berryman, Seismic waves in rocks with fluids and fractures, Geophysical Journal International, Volume 171, Issue 2, November 2007, Pages 954–974, https://doi.org/10.1111/j.1365-246X.2007.03563.x
Best Regards.
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I tried to filter only water through a standard 25mm 0.2 um syringe filter. Of course, it's easy to do this manually with the syringe, but I have several litters to pass. So I connected a peristaltic pump. To my surprise, the pump was unable to push the water through the filter. This is a very powerful pump that develops high pressure. What's wrong with it? Are we providing more pressure with our hand and syringe than the pump?
Has anyone tried pump assisted filtration through 25mm / 0.2um filters successfully?
Thanks
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in a 2 ml syringe, a pressure of more than 10 atmospheres is created by hand, if your pump gives a higher pressure and the filtration is slower, then the filter is clogged. Or the liquid is too viscous.
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Hello everyone,
We need suggestions for a situation that has arisen in our laboratory. We are conducting catalytic photodegradation studies of Rhodamine-B. To monitor the degradation, we use conventional techniques (UV-visible spectroscopy). When we take aliquots at different irradiation times, we filter them to remove the catalyst, using 0.45 micron acrodisc filters, attached to a syringe. We have found that these filters retain the dye, so follow-up measurements by spectroscopy have meaningless fluctuations. We have used various types of filters (PTFE, nylon, cellulose, polyethersulfone) from different suppliers and pore sizes (even 0.2 microns), but the effect is repeated. We have tried other options, such vacuum filtration, or centrifugation, but these processes are not very efficient. I'd appreciate if anyone suggests any realistic alternatives.
Best,
Fran
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Dear Adam,
Thanks for your recommendations.
We haven't tried aluminum filters, but we're going to try it. We have also tried centrifugation (4,000 rpm/10 min), but what we observe are inconsistencies: the absorbance does not stabilize... However, we will try to centrifuge at a higher speed. Thanks again.
Best,
Fran
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We are doing gel filtration in our lab and encountering issues related to column length, we are not getting expected results from our process. We previously used a 24ml column with appropriate elution buffer but could not elute the desired protein fraction. We are having issues in deciding the bed volume. How do we decide column length or bed volume?
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It is important to calculate the bed volume of your column using the formula pi (r square) h , value of pi is 22/7 column length h and its internal diameter ( radius r is half of diameter).
Can use simple scale to measure the length and diameter of your column.
Elute with 1.5 to 2 bed volumes of the elution buffer with elute all the proteins from gel filtration column .
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I used DMAP for the polymerization of L-Lactide. I want to completely remove DMAP from my product. I tried filtration, Soxhlet and precipitation (Diethyl ether) but none of them worked well. I only want to completely remove DMAP irrespective of percentage yield, if it is more than 30%.
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Dear all, if the MW of PLLA is high enough, you can eliminate it by membrane dialysis, just choose the one with the right MW cut-off. My Regards
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I am a new researcher currently doing experiments on perovskite solar cells.
Since I haven't got much experience in this area, I confront some questions regarding the experimental techniques.
I read the experimental sections from papers, but they usually only summarize the steps.
My questions are
1. For ETL, I use SnO2 dispered nanoparticles.
What is the difference between using IPA+DI water and using DI water only for dilution?
Do I need to stir to get rid of particles, or just sonication is enough?
Is filtration required after sonication?
2. As for the perovskite layer, I normally use FAPbI3 with small amount of MAPbr3 added.
Do I need a higher temperature or room temperature when I stir the mixture? and why?
3. For HTL, do I need to stir the mixture of spiro and chlorobenzene before adding additives and again after adding additives?
4. Lastly, does the thickness of film depend on the amount of solution dropped? What I read was it mainly depends on the rotation speed and time.
These may seem stupid questions, but I still look forward to answers..
Thank you!
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Dear Jh Kim ,
welcome!
And here some additional advises:
You have to make your fabrication in a clean dry environment.
You must be sure that every layer is deposited and formed properly before depositing the next layer by testing and inspection.
It is better to measure the optical and electrical properties of the layers to be sure that they satisfy the requirements of good working solar cells.
If you make this testing routinely you will grantee good functioning solar cells systematically.
Best wishes
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Dear Colleagues,
For Exosomes/Extracellular vesicles (EVs) labelling by PKH26 stain, and studying their cellular uptake.
Is there anyone who tried to mix conditioned medium with PKH26 to stain Exosomes/Extracellular vesicles (EVs) before isolation with targeted filtration?
I am using the kit "101 PureExo" for targeted filtration and isolation of EVs.
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Hi,
It won't be an appropriate way of labeling exosomes. As explained by Malcolm Nobre by doing so you will label other cells components. For Pkh26 Exo labeling first, dilute Exo and Pkh26 dye in the diluent C available in the kit, combine them and keep for some minutes at RT, stop the reaction by adding serum and PBS wash by ultracentrifuge to remove unbound dye, and you are good to use them for cellular uptake studies.
Good luck.
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I have done hot filtration test for the catalyst to show leaching and I found no reaction after filtration. So, is it still necessary to perform ICP analysis of the catalyst??
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Dear Loveneesh Kumar thanks for sharing this very interesting technical question with the RG community. According to the relevant literature reference cited below, a "hot filtration test alone cannot prove that the reaction occurs heterogeneously":
Synthesis, catalytic activity, and leaching studies of a heterogeneous Pd-catalyst including an immobilized bis(oxazoline) ligand
Fortunately this article has been posted by the authors as public full text on RG, so that you can freely download it as pdf file.
It might also be worth a try to check the answers given to the following closely related questions which have been asked earlier on RG:
How might I measure the leaching of heterogeneous catalyst using simple techniques?
(4 answers)
and
What is the best technique to test the heterogeneity of a reaction in catalysis?
(58 answers)
Good luck with your work and please stay safe and healthy!
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Hello, I had purchased MS2 (freeze-dried) from ATCC: 15597-B1 (https://www.atcc.org/products/15597-b1). I revived the culture according to the method given in the product sheet. For propagation, I have used E. coli BL21 instead of the recommended strain. Also, the revival was done past the 30 day time period that was mentioned. I have separated the E.coli by centrifugation at 15000 rpm. Is it possible that the MS2 remained in the E. coli cell? Or is it that I stored the freeze-dried culture for too long before reviving it? Or is it because I have used the wrong strain of E. coli? I still have half o the free dried pellet but before using it I want to make sure that the method I am following is correct.
Is there some other way apart from plaque assay and PCR to ensure that the MS2 is present in the filtrate?
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MS2 is a male-specific phage that adsorbs to sex pili, such as those encoded by the F episome. BL21 does not harbour such episome (it is F-), thus it is not able to propagate MS2. I would try again infecting with an F+ strain.
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Hello everyone,
I'm working in my doctoral thesis in the purification of a lipolytic enzyme from an halophile archea. Currently, I'm trying to purificate the recombinant enzyme using Haloferax volcanii as an expression system. The problem is that suddenly when filtering my crude extract through a 0.45 um nitrocellulose membrane I lose 90 % of the enzymatic activity, when that did not happen before and at most I lost 20 % of the activity.
Has the same thing happened to someone else? Or do you have any ideas that could help me? Thanks!
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Yep, nitrocellulose is a poor choice
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Hi everyone.
I am studying and culturing marine diatom Phaeodactylum tricornutum for my PhD project.
To harvest microalgal biomass after culturing it I currently centrifuge it, even if I am about to try the filtration through GF/C filters.
In order to wash all salts (since it is a marine species) what should I use? I have read about an ammonium formate solution 0,65 M. Do you have other suggestions?
Hope someone can help.
Thank you all
Regards
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Ciao Caterina,
Usually with marine protist i rinse the pellet with some clean freshwater, avoiding the distilled water that could damage the cells!
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I want to prepare microfiltration flat membranes with PVDF or polysulfone. I did the process by solving various concentrations of the polymers (from 13 to 15%) to NMP to produce the casting solution base on the other articles using non-solvent induced phase separation method with a fixed height of 100 μm. However, the surface of the as-prepared membranes are dense in SEM images and no obvious pores (larger than 100 nm) can be seen. I would be very appreciated if someone help me.
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PVDF is OK, not only inside-outside but also outside-inside operation mode, there are lots of successful operation projects around China and all over the world. Du-pont\ KOCH, and many other famous company have their own PVDF flat membrane production, it is widly used around the world.
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I am making kosaric media using artificial seawater in various salinity for microalgae cultivation. At first, I tried to filter the seawater and then add chemicals. After autoclaving, there was some deposits at the bottom of the media. I also tried to autoclave the artificial seawater and media separately, and then let both solutions cooled down and added together in laminar flow. However, once I added the kosaric media into seawater, precipitation was observed and large amount of white crystalline substance at the bottom. Is there any other way to make it?
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hello dear,
i think you can first filter your seawater, then add your desired chemicals might be these chemicals react with each other i am not sure but i heard from my friend, he face such this type of problem.
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I've been synthesizing bulk hBN powder from boric acid and urea precursors in a tube furnace. However, when I mass the finished powder into water with a stir bar (so I can run reactions with the material), the pH shoots up as the material seems to fall apart in the water. Why is that? How can I synthesize a water-stable boron nitride? (not hydrophilic, just stable)
Synthesis approach:
I've been using a high molar ratio of urea: boric acid for precursors, so I've been doing 30:1 (though I've also tried lower). I add ~150 mg boric acid and ~4.5g urea to a beaker with 20 mL DI H2O + 20 mL methanol (based on:
), then leave it in a 65C oven overnight to evaporate and recrystallize. In the morning, I grind it to a fine powder using a mortar and pestle, then load the powder into a quartz boat and load that into the quartz tube. I attach the N2 gas line and I run the gas for 30 min, then turn on the instrument. I heat up at 5C/min until 1200C, the max for my furnace, holding at 1200C for a few hours. When it's cool, I use vacuum filtration to wash with water and ethanol, then dry in a 65C oven. I then grind this into a fine white powder and try my reactions.
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I think you should check out are there some nanoparticles in your solution. What are the physical methods did you use to prove quality of your product?
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We collected the plasma filtrate from the plasma exchange of the patients and stored it in -80℃. Now we attempt to obtain the IgG from the filtrate, however, we worry that the IgG may be degraded and inactive since the filtrate has been frozen for 2 years. Generally, how long can such IgG be stored, and whether extra preprocess is needed for the storage?
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Storage of IgG in its plasma at -80C or below is great.
Just avoid -18 or -20 storages.
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During RNA extraction I used preheated wash 1 solution( about 40C) "by mistake", discarded the filtrate, used wash2 and then the preheated elution buffer (the only buffer that should be heated according to instructions) ...
Does the heated wash solution make the RNA dissolve & go to the filtrate???
Note: we don't have the technics and materials for RNA electrophoresis
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It's possible that some RNA was lost because of this, but probably not very much. The wash buffers contain around 75% ethanol, and they wash away salts (which will dissolve in 75% ethanol) but not RNA (which won't). Most substances are more soluble in any given solvent when the temperature is increased, but given that the solubility of RNA in 75% ethanol is really poor, I doubt it will have made much difference. Was the concentration of RNA around what you expected? If so, I don't think there's any reason to worry about the RNA quality or integrity.
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For the synthesis of MOFs many have reported purification only by filtration and washing with water/solvent. How do you make sure the MOFs are free of unreacted metal compounds/ligands by washing with water/solvents? Is there a way to confirm the complete removal of unreacted material?
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Dear Bing Wei Chua this is a very interesting technical question for all researchers who work on the synthesis and characterization of MOFs. The purification of MOFs is an issue which can sometimes not be easily solved. Most MOFs are prepared using hydrothermal / solvothermal synthesis methods. Thus they normally crystallize upon slow cooling of the reaction mixtures. The key to success here is to choose the right molar ratios of starting materials so that as little by-products as possible are formed. Normally the resulting MOFs cannot be purified by recrystallization. Thus it is a safe get to first wash the product with water to remove unreacted metal salts and then wash with a universal organic solvent such as acetone to remove unreacted organic linkers.
Good luck with your work!
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Hello everyone,
I am new to hydro-chemistry and planning to analyze freshwater (pristine environment) water samples for trace element analysis using ICP-MS. I have gone through literature for identification of suitable filter type for in-situ sample filtration and found that people have used a variety of filter types Cellulose Nitrate/PES Filter/Millipore filters/Polytetrafluoroethylene/Ester cellulose millipore/Polycarbonate, etc.
I was wondering which could be the most suitable filter choice for freshwater sample filtration?
I request you to give your valuable suggestions in this respect.
Thanking you all.
Regards
Rajat
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Make sure before you purchase too many sample containers etc, that the supplies are appropriately metal-free. This applies to filters as well, and the acids you will need to stabilize the trace elements in the sampled water. Check the lids too: liners may be treated with something that might look like field contamination, but was in the flexible disc inside the screw-on lid.
As you say you are new to hydrochemistry , I would recommend you speak to a local expert (university researchers or government environment office etc), see what equipment they use etc and get an idea of what you need for your purposes.
Also speak to the analytical laboratory that will be doing your analysis and find out what they need in a sample: they may have done this work before and will have some suggestions that could save you a lot of time, travel, and plastic containers if you haven't thought of some important details.
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I was unsuccessful to find anything in the literature about proteins that are not reabsorbed (efficiently) in the renal tubule. Maybe it was the way I searched or it doesn't occur or no one has looked for it. Sure, it's unlikely and I assume the uptake mechanisms are so "generic" that any protein/peptide will be fished out of the filtrate and taken up by tubular cells. But maybe there are some proteins that escape this?
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سؤال قيم كنت اتمنى الإجابة
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I am planning to run a column test in a constant head permeameter setup. I plan on reducing the hydraulic conductivity of the soil and would like to monitor any change in effective porosity. I have read a paper where this methodology is utilized, however they do not explain how or reference the technique they used, except that it was done in Hydrus. They injected a salt tracer and then routinely measured the effluent to plot specific conductance vs time, this somehow was used to calculate porosity
Does anyone perhaps know how they managed to do this or know of a reference I can refer to and read up on?
I have tried some searches, but no luck. I think the terminology I am using is not sufficient to return any decent results.
Any direction or information would be greatly appreciated.
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Dear Stenzl, I advise you to obtain the residence time distribution curves using the salt tracer. You can use pulse or step-by-step injection to estimate the mean hydraulic detention time (HDT) using curves C, F, and E. Briefly, curve C is its conductivity versus time, curve F is the normalization of curve C using the ratio Ci / Cmax (Ci: conductivity at time i; cmax: measured maximum conductivity). Curve E is the first point-to-point derivative of curve F (dF / dt) and then HDT is the area under curve E or the integral from 0 to infinity of curve E. Once you have your HDT, you can estimate the empty volume of your "packed column" by multiplying your HDT by your flow. So, since you might know the volume of your column without the soil, you can calculate your porosity by the ratio between the void volume of your "packed column" and the volume of your column without the soil.
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I want to synthesis a molecule based on a published paper, in the experimental section, the author said "......5 g silica and 2 drops of dibutyltindilaurate were added, and the mixture was heated at 60 C for 1 h. The silica was removed by filtration and the chloroform in resulting solution was removed in vacuo......". So, which kind of silica should I choose for this reaction? the silica gel for column chromatography? fumed silica? or other.
Thanks in advance!
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Dear Yang Zhou many thanks for sharing this interesting technical question with the RG community. Apparently in this reaction the silica acts as a catalyst. Thus my suggestion would be to use just the common silica which is normally employed for column chromatography. This will be easily removed by filtration after the reaction. Good luck with your work and best wishes!
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I have extracted polyclonal antibodies with PEG 6000 in PH (5.2, using HCL to adjust PH). Using dialysis membrane (12000 cutoff), the PEG was successfully separated from the polyclonal antibodies and I purified my product.
Currently, I am trying to establish product in industrial scale. But, I do not know what can be used instead of dialysis membrane in industry scale???? What is your suggestion? Could you please kindly help me regarding to the separation of PEG from polyclonal antibodies (180 KDa) in industry scale??????
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I have done that by an ammonium sulphate precipitation, PEG is insoluble in AS solutions and forms an organic layer on top after centrifugation. You remove first that, then the aqueous phase and retain the protein pellet. Quick, simple and cheap.
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Hello dear researchers,
I would like to know if there is a possibility to purify antibodies using ionique exchange chromatography or gel filtration with basic equipment.
If yes, i would like to have some tips to make it possible.
Thank you in advance.
Best regards,
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Yes all you need is a glass tube or plastic syringe of appropriate length. Glass tube can be elongated with a gas flame to constrict the exit. Then pack down a blocking amount of glass wool ( I used aquarium filter plastic cotton wool). Pour the slurry of matrix into the tube and add more as the column flows and packs down under gravity until there is about 2cm above the gel matrix. You can then add sample and collect samples into tubes for protein measurement. Large molecules will flow round the beads and elute in the void volume of the column and small salts elute in the total volume of the column and between those two extremes your proteins will elute. With ion exchange it will be easier to manage as there will be fewer eluted samples to test...just the binding process and the elution but probably not the wash steps. You could try emailing colleagues to see if anyone uses disposable desalting columns because these can be washed and refilled many times
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Slurries generally consists of some heavier particles which should remain suspended in solution for best coating results. Kindly suggest best way to maintain viscosity of alumina slurries. Thank you:)
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Hi,
I'd like to compare between mass spec. results of 2 samples that I have (each sample has 3 biological replicates).
Following several filtration steps- I have a list of proteins that were identified in 1 sample (in all of the 3 replicates), but were not identified in the second sample... (and vice versa).
How should I consider these proteins in my statistical analysis? Can I consider them significant by default? Should I include them in one list with the other proteins that were (differentialy) identified in both samples and have values to compare?
Thanks!
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Nakachew Minuye , you can calulate iBAQ or NSAF for label free quantification. Then you can calculate fold change (treated/control) and p-value (t-test) to identify the target proteins of interest.
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In bacterial filtration efficiency assay, staphylococcus aureus is used as challenging microbe in the aerosol form. can we use other microorganisms for the test.
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Yes after the first run. It's something S. aureus cannot produce innately and must synthesize using ambient resources as with the case of many other vitamins added to the media. Exhaustion of vitamins would force the cells to enter a phase of low carbon availability which apart from hindering cellular growth also affects the extracellular polymer secretion, this in turn would directly impact nutrient acquisition by the cells or the colonies.
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I have a high density product contains 30% Oxytetracycline dihydrate dissolved in pyrrolidone, it is very difficult to filter with vacuum filtration method ( 0.2 or 0.45 micron nylon filter paper) is there any other way for filtration with 0.2 micron filter paper?
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It looks like your filtration is difficult because the high value of the viscosity of the fluid (not quite density). If you can increase temperature the viscosity will decrease.
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The proteins that I label always have a His-tag so I normally perform Ni-NTA purification after maleimide labeling, but it doesn't get rid of all the excess dye. Hence, I'm looking for alternate methods and gel filtration seems to be widely used. We have SEC gel filtration columns (Biorad version of Superdex) in the lab and we never use them for this application as we fear that free dye might stick to the column during runs and affect other protein purification studies. Does anyone have any experience regarding this?
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It takes a long time to get all the free dye off the gel filtration column. I suggest instead that you use a disposable desalting column such as a PD-10 column. This is a prepacked gel filtration column. It can be used either by gravity or by centrifugation.
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Join Date: Aug 2021
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Dear Scholars
I am trying to simulate molecular filtration of fluid like Reverse osmosis of water. I am new to Ansys and I am in need to succeed it.
Is it possible to do filtration by pore size of porous material and fluid molecules size?
If yes, kindly share with me. I will be thankful to you.
Kindly provide the email id for further communication.
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CFD Simulation
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hIAPP monomer which is of 4 kDa. I want to do buffer exchange. is it fine to do with 3 kDa centricon filtration falcon?
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As per my knowledge, one thumb rule for selecting ultrafiltration membrane molecular weight cutoff is that the MWCO of membrane should be 1/3 to 1/6 size of the targeted retentate particles. Otherwise the rejection will be more.
Hope this is useful
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And ¿Is it better to use natural or artificial seawater?
Thank U!
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@Jordan: The autoclaving of sea water will lead to the precipitation of many salts (elements) containing in sea water. This may decrease the viability of bacteria you are interested in. So, I would recommend you to use two steps filtration for the sterilization: 1) you should use a trivial Watman paper to separate the debris; 2) to filtrate water through 0.22 um filter. Good luck. IB
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I am doing lignocellulosic extraction from biomass. After treatment with acid solution, I filtered the mixture with the help of G3 sintered frits bucchner funnel. I can see that later filtration is slow and stain over frits. Please help
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Dear all, one simple tip is the backflow introduction of any available digestion solution, such as diluted HF and Piranha. My Regards
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I need to know the specific column and HPLC conditions required to standardize the protocol.
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Here are some articles for your reference:
Removal of B. cereus cereulide toxin from monoclonal antibody bioprocess feed via two-step Protein A affinity and multimodal chromatography
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I'm trying to prepare R2B/R2A media with seawater to cultivate marine bacteria after autoclaving (110°C) my media. I systematically observe a important precipitate. Despite many tests (in particular at different percentage of seawater and different types of filtration, I did not succeded to find the solution. Do you have any idea to help me ?
Thank for you help !
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Ah~ You trying not easy process! If you will not cultivate all marine microorganisms, prepare media only with NaCl is a way. Actually many marine microorganisms require salts such as Mg, K, or Ca as well as Na. Hence, another way is prepare medium with Na, K, Mg and trace elements solution (If possible to neglect strains require Calcium).
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Do we get a trifluoroacetic acid (TFA) peak during gel filtration (desalting) of the synthesised peptide after RP-HPLC purification (0.1% TFA in buffers)? The molecular weight of my peptide is 2545.9 Da. And if no, how could we confirm that the peptide is TFA free now.
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Thank you so much for the reply. Should There be any peak for TFA also.
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I am looking for the exact recipe to make urine filtrate for analysis.
Can anyone help me along with the references, please?
Many thanks
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Hi Nabeel,
Please see my page, we have some work on urine and kidney stones
Good luck
Safia
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I am preparing nanoparticles using alginate polymer. Before, I used syringe filter 0.45 um for alginate solution to be clean before adding CaCl2. Now I going to produce a big amount of alginate nanoparticles, so can I centerfuge alginate solution compensate to filtration
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Dear Hazem, sorry I missed your question. No problem to me if you ask questions. If this is still relevant, I can add this:
I used a filtration cascade connecting the unfiltered liquid first to a 5 micron filter to remove the largest particles, next in line was a 1 micron filter and the third filter was an 0.45 micron filter. Depending on the load one of these will clogg first (I used pressure sensors to see which filter has the highest deltaP), in my case it was the 1 micron filter which needed replacing once every 24 hours, the 5 micron filter I later replaced by a glass filter as it fouled very irregularly. The 0.45 micron filter I changed (as a precaution) every 48 hours.
Kind regards, Leo
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the team I am working with and I are having a problem. It is a project in which we have to eliminate the bacteria that exist in a water supply. It is a must to remove them all because we do not want to face following problems like biofilm formation in Reverse Osmsis system. it is impossible to use heat, and filtration is not preferred. ozone was tested and did not work properly. chlorine is been using and it can remove all bacteria, but it needs more than 10 hours time. this bacterium we are facing can tolerate chlorine, ozone, and can pass 0.2 micrometer fliter. can anyone help us to meet this problem?
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Mohammad Hossein Abbaspour interesting question and there are many ways of quick and best ways to treat water and avoid polluted water but again it depends on the economics as well as the size of the plant or amount of water to be treated on a daily basis so one can come to a conclusion with the amount of water to be treated and for what purpose is also to make an economical feasibility option to select the best possible available technology.
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I have been searching for the most compatible syringe filter to reach maximum protein recovery after filtration. However, I have found contradicting data which confused me. MCE syringe filters have been suggested for their very low protein binding and maximum protein recovery. PES and PVDF syringe filters have also been recommended for their low protein binding capabilities. I have a buffer solution that contains human plasma proteins, and I don't want to lose any of them during the filtration process.
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You can try centrifuging your sample at 10,000rpm for 10mins. However, to answer your question, you can use a .22µm PES membrane (33mm) syringe filter.
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I want to know about theory of the upward continuation and why do we use upward continuation and down ward continuation? Other thing is what is the relationship between the filtration and up/downward continuation?  
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Just to add to the answers already provided, upward continuation enhances deep structures. So, if your interest is to investigate deep regional structures, then upward contunuation should be your choice of enhancement technique.
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We find these structures in the urine filtrates of humans/canines exhibiting a similar host of symptoms, of unknown etiology. They can be highlighted using a variety of stains and are along the scale of 250-500 um. We greatly appreciate any thoughts or suggestions you might have as to what may be creating these structures, or a more specific name/identify for them.
microscopy
cytology
infection
bacterial nets
fungal nets
fruiting body
myxamoebae
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Pics do not look like the typical urine cast
maybe artifacts
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While purifying the exosomes, after ultracentrifugation, we are passing the exosomes thru a 0.2um filter. The product before and after filtration seems the same when we look at the particle size profile. Either the filtration did not work, or the exosomes aggregated after coming thru the filter. Would like to get opinions from experts. The exosomes are in PBS.
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Thanks so much. This is very helpful
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Is it necessary to filtrate S.aureus supernatant for further analysis (e.g. cytotoxic assay) - or is it possible to use it without filtration?
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For cytotoxicity its good if you filter your S. auerus supernatant.
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Hi,
During a buffer exchange in a concentrator for a protein, I needed to measure the protein concentration through Nanodrop OD 280 nm. I want to know which one of the following I should use as the blanking Buffer?
1. The initial buffer ( Of course it doesn't make sense to use this, as the protein is not in the initial buffer anymore) but is it possible that traces of this buffer may still be present in the protein?
2. The final buffer to which the protein is exchanged , but then it is not 100% the environment of the protein? (when you switch buffer, there is likelihood of some amount of protein loss into degradation)
3. The filtrate through the concentrator in the bottom chamber as this represents 100% the present background of the protein?
4. or a combination of two or more of the above please?
Thanks for any logical explanation please.
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Thanks very much
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The aquaculture industry's endeavour to avoid diseases casing microbes/carrier/macro predator to keep the farm-reared animals healthy to achieve good profit in the aquaculture business. Has the subsurface intake system has the ability to solve this problem?
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I need to prepare or dilute TGF-B3 in the mentioned solutions: sterile-filtered 10mM acetic acid with 20% ethanol, or 4mM HCl.
I have just searched through videos from YouTube, sterile filtration is to simply filter any solutions through a 0.2um pore size filter unit using a sterile syringe, to remove microorganisms. I am wondering if this so-called "sterile-filtered" solution safe for use to dilute or reconstitute the growth factors and used for cell culture? Are they considered aseptically clean for cell culture work? I hope I will not introduce any contaminants to my neuron differentiation work which is very tedious. Thank you.
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There is no need at all. I use sterile-filtered solution immediately without any problem. I never get contaminations in my cultures. It seems you are still not confident using sterile filtered solutions directly. But for your satisfaction you can keep sterile-filtered 10mM acetic acid with 20% ethanol, or 4mM HCl under UV in the biosafety cabinet for sometime. There should be no problem.
All the Best.
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How do you achieve mass purification of Coxsackie virus B3? Is it through an ultrafiltration concentrator?
Due to limited laboratory conditions, membrane encapsulation, tangential flow filtration and ion-exchange chromatography cannot be deployed. Density gradient centrifugation cannot achieve a large number of purification.
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Thank you dear colleaque,Coxsackievirus B3 purified by ion exchange Chromatography ,elicit strong immune response in mice.Thanks
Ref: Antiviral research,volume,104,2o14
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After soaking costus powder in hexane for 72 hour .
The filtrate was concentrated using vacuum rotary evaporator.
I got oily extract and some crystals .
I want to convert this oily extract to powder extract .
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I think it depends on the quality of the Rotary, if the pump is very strong ( high quality) the extract becomes powder.
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I bought a dialysis tube of 10kD of molecular weight. But I need the actual pore size of this dialysis tube as I am going to use it for filtration purpose. It will be very helpful if anybody can help in this regards.
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For 10,000 MWCO dialysis tubing, the average pore size is roughly 20-25 Angstroms, although there will be a distribution of pore sizes.
You can also buy ultrafiltration membrane with defined pore sizes.
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Hello,
I am working on developing a thin film for solar steam evaporation.
In these papers, the common technique used to deposit the nanoparticles onto the substrate, to form the film, is vacuum filtration.
In my current lab I do not have a standard vacuum filtration set up available and I was planning on purchasing a pump to use for this purpose.
Given the high cost