Analytical Chemistry - Science method

Using water-saturated butyl chloride as a mobile phase and water-saturated chloroform as a diluent in HPLC maybe to enhance sensitivity, aid in phase separation, or reduce ionization. The specific reason for using such aqueous form of solution could differ based the type of assay and the APIs or analyte being analyzed. Alternatives can be considered, but method validation (still dependent on the analyte involved) is essential to ensure the reliability of results.

This is your research question "Will the model prediction favorize a concentration if more calibration samples at that concentration level is used in the model development?" you find the answer by doing several computations

I would say that sample preparation is a wider term.

Sometimes you do not have to perform sample cleanup because your sample is pure enough or suitable for the instrumental analysis as it is. However, you still might need some sample preparation in terms of filtering, diluting, homogenizing and so on.

Sample cleanup usually consists of some kind of extraction (either in liquid or on a sorbent), chromatographic cleanup, precipitation or similar technique. There might even be manual mechanical/macroscopic cleanup, depending on what is your sample.

Hello!

You can read the washing method and the conditions of storage for its manual, which you can download from the homepage of the manufacturer. For columns and suppressors, the conditions vary by type. The column and the suppressor (electrolytically regenerated) must be removed and stored in the specified solvent. If you follow the instructions you should have no problem.

Flame photometry is a widely used analytical technique for determining the concentration of certain metal ions in a solution based on their characteristic emission spectra when introduced into a flame. Despite its popularity, there are several scientific gaps and challenges associated with flame photometry:

Limited Element Detection: Flame photometry is primarily used for alkali and alkaline earth metal ions. There is a limitation in detecting transition metals and other elements using traditional flame photometry techniques.

Interference Issues: Flame photometry can suffer from interference due to the presence of other elements or compounds in the sample. This can lead to inaccurate results and complicates the analysis, especially when dealing with complex sample matrices.

Sensitivity and Detection Limits: The sensitivity of flame photometry is relatively lower compared to other modern spectroscopic techniques, such as inductively coupled plasma-optical emission spectroscopy (ICP-OES) or inductively coupled plasma-mass spectrometry (ICP-MS). Improving sensitivity and lower detection limits is an ongoing challenge.

Sample Preparation: Sample preparation is crucial in flame photometry, and the techniques used can affect the accuracy and precision of the results. There is a need for standardized sample preparation methods to ensure consistency and reliability across different laboratories and applications.

Quantitative Analysis: Achieving accurate quantitative analysis, especially in complex samples, is challenging. Calibration methods and techniques need continuous refinement to enhance accuracy and reliability in quantitative measurements.

Instrumentation and Miniaturization: There is a need for the development of more compact and portable flame photometers for field applications. Miniaturization of the instrumentation can open up new possibilities for on-site analysis and real-time monitoring in various fields, including environmental monitoring and clinical diagnostics.

Combination with Other Techniques: Integrating flame photometry with other analytical techniques, such as chromatography or mass spectrometry, can provide complementary information about the sample composition. Research into effective combinations and methodologies is essential for comprehensive analysis.

Data Analysis and Automation: With the advancement of technology, there is a need for improved data analysis methods, including automated data processing and interpretation algorithms. Automation can reduce human error and increase the efficiency of the analysis process.

Environmental and Safety Concerns: Research into the environmental impact of flame photometry techniques, including waste disposal and energy consumption, is important. Additionally, ensuring the safety of operators working with flame photometers and associated chemicals is a continuous concern.

Addressing these scientific gaps will contribute to the advancement of flame photometry and enhance its capabilities in various fields of research and industry.

Hi! This is how ChatGPT answered your question:

Principal Component Analysis (PCA) and Partial Least Squares (PLS) are both multivariate data analysis techniques used in chemometrics. While they share some similarities, they are used for different purposes and have different underlying principles.

Principle Component Analysis (PCA):

PCA is primarily used for dimensionality reduction and identifying patterns or relationships in high-dimensional data. It transforms the original variables into a new set of uncorrelated variables called principal components. These components are ordered in terms of the amount of variance they explain. PCA aims to maximize the explained variance with the fewest number of components.

Partial Least Squares (PLS):

PLS, on the other hand, is used for regression and predictive modeling. It finds linear combinations of the original variables (called latent variables) that are strongly related to a response variable. PLS maximizes the covariance between the predictors and the response and extracts components accordingly. It is particularly useful when the number of predictors is large, and collinearity between predictors is present.

In terms of practical use in environmental chemistry or analytical chemistry:

PCA is often employed when the main objective is to reduce the dimensionality of the dataset, explore patterns and relationships between variables, or visualize high-dimensional data. It helps in identifying outliers, clustering observations, and understanding the dominant factors driving the variation in the data.

PLS is useful when there is a need for prediction or modeling, especially when dealing with complex datasets, high collinearity, or multicollinearity. It handles situations where the number of predictors is significantly larger than the number of observations.

Both methods can be combined and utilized together when necessary. For instance, PCA can be used for data preprocessing and visualization, identifying outlier samples, or selecting variables to be used in subsequent PLS modeling. By reducing the dimensionality, PCA can enhance the efficiency of PLS models by reducing noise and overfitting.

In conclusion, the choice between PCA and PLS depends on the specific goals of the analysis. PCA is suitable for dimensionality reduction and exploratory data analysis, while PLS is more appropriate for predictive modeling. Both methods can be combined to leverage the strengths of each when dealing with complex data in environmental or analytical chemistry applications.

If you need more detailed explanations, try asking ChatGPT specific questions. It is best, however, to study problems in a traditional way, i.e. from academic textbooks and specialist studies in specific fields.

ZJ

Why are so many methods and no answers the same? Other papers also mention the different results. What is actually the correct answer?

I'm ready

Back to your original question (and I am done with this thread)... You observed a small (tiny) difference in Rt from small changes you made to the mobile phase composition. No worries, this is normal because no two columns are the same and each may interact to a different degree (or none at all) when you make small changes to the mobile phase composition. Try 20 different C18 columns and you may find some show no change at all, some do. Pick and choose the one that you want for the application (this is what we do in analytical laboratories). The reason for the observed change (change, not "drift") is due to multiple interactions of the solute on the surface of the support. Hard to say if it is electronic or ionization in nature, but it is so small, practically, it does not matter. All chromatographers are familiar with this (no need to 'explain it'). Run enough samples and you will see it. In fact, the one thing that they might question is why you would use a mobile phase of just ammonium formate without an acid (e.g.formic). Why not use a buffer? For LC-MS applications, most would benefit from such a solution to promote ionization and maybe change the separation factor too (depends on samples).

Oxidative coupling reactions in analytical chemistry play a significant role in various applications, particularly in the field of spectrophotometry. These reactions involve the coupling of certain chemical species through an oxidative process, resulting in the formation of colored or fluorescent compounds. The composition of colored or fluorescent products can be measured and quantified using spectrophotometric techniques, enabling the determination of specific analytes in a sample.

1- Determination of Phenolic Compounds: Oxidative coupling reactions are commonly used to determine phenolic compounds in various samples, such as environmental samples, food, and beverages. These compounds react with specific reagents to produce colored products, and the intensity of the color formed is proportional to the concentration of the phenolic compound present in the sample. This method allows for sensitive and selective analysis of phenolic compounds.

2- Measurement of Aromatic Amines: Aromatic amines can be determined using oxidative coupling reactions with suitable reagents. The resulting colored products can be quantified using spectrophotometric techniques, providing a means for analyzing these compounds in different samples.

3- Analysis of Polyphenols: Polyphenols, which are abundant in various plant-derived products such as fruits, vegetables, and beverages, can be quantified using oxidative coupling reactions. These reactions often involve specific metal catalysts to form colored complexes with the polyphenols, allowing for their sensitive detection and measurement.

4- Detection of Nitrogen Species: Oxidative coupling reactions have been employed for the detection and measurement of nitrogen-containing species, such as nitrites and nitrates. These reactions can lead to the formation of colored products that can be easily detected and quantified.

5- Environmental Monitoring: Oxidative coupling reactions find applications in environmental monitoring to analyze pollutants and contaminants in water and soil samples. By using suitable reagents, certain pollutants can undergo oxidative coupling to produce colored products, facilitating their identification and quantification.

6- Clinical Analysis: In clinical chemistry, oxidative coupling reactions can be used for the determination of specific analytes in biological samples, such as blood and urine. These reactions can offer a sensitive and specific means of measuring certain compounds of interest in various disease diagnoses and monitoring applications.

Overall, oxidative coupling reactions in analytical chemistry provide valuable tools for the selective and sensitive detection and quantification of various compounds of interest, making them essential in many research, environmental, and industrial applications.

This is feasible. You will need to define and construct your experimental design first, and the particular seed sample you are interested to work with. A mechanical oil presser machine will do to extract the fixed oil. And then, you will need to determine what kind of cell line you want to test it. Probably you would want to investigate its medicinal property thru MTT assay.

The choice of diluent for preparing standards and experimental samples in analytical methods can depend on several factors, including the solubility of the analyte, compatibility with the analysis technique, and the desired matrix for calibration.

Here are some reasons why diluting standards with plasma or other biological matrices may be preferred over diluting them with methanol/water to match the experimental samples:

It's important to note that the choice of diluent depends on the specific analytical method, the analyte being measured, and the overall objective of the analysis. Methanol/water dilution may still be appropriate for some cases where the analyte is stable and soluble in that solvent mixture and if matrix effects are not a significant concern.

Ultimately, the decision on the diluent should be made based on method requirements, validation considerations, and the desired accuracy and reliability of the results. It is recommended to consult the specific method or assay protocol, as well as relevant literature or guidelines, for guidance on appropriate dilution procedures for your specific analysis.

Here are the other points, you may lean on;

If the purpose is quantification or purity check, LC-UV would be nice to use since the octapeptide you have several aromatic rings and would be highly responsive,

secondly, 500 ppb may be a low conc. to conduct a full scan..especially when the ionization efficiency is low.

Third, I would prefer combined flow scanning in place of infusion...In this mode, you are not taking benefits of the mobile phases which present donors to improve ionization...You should combine the lc flow and infusion (acid and/or DMSO additives in phases for pos ESI in this case) and retest the response...

By solving the peptide in an alkaline condition you are directing the peptide to deprotonation and this makes the peptide more amenable to neg ESI...If it is soluble in ACN directly..prepare your stock in ACN and dilute it with the same solvent, I prefer not to use aggressive pH which is not convenient for most of the peptides to the unintended H exchanges...

Last but not least, If the peptide is hydrophobic and dissolves only in organic solvents this is susceptible to be efficiently ionized in APCI, APPI rather than ESI...You may look for these alternative ionization techniques if MS analysis is the bottleneck and the abovementioned suggestions are useless...

Good Luck...

Sir,

How can we remove blockage of Waters Spherisorb ODS2 column? Any solution you have?

Kindly find the link below for AGREE and GAPI software

https://mostwiedzy.pl/AGREE

https://mostwiedzy.pl/en/justyna-plotka-wasylka,647762-1/gapi

There are several methods for measuring the purity of neuromelanin, including:

Spectrophotometry: This technique can be used to measure the light absorption of neuromelanin at different wavelengths. The purity of neuromelanin can be determined by comparing the resulting spectra with reference spectra.

Chromatography: This technique allows the separation of different components of a brain tissue sample using appropriate solvents. The purity of neuromelanin can be determined by analyzing the chromatographic peaks corresponding to neuromelanin and comparing their intensity with other components.

Electron microscopy: With this technique it is possible to observe the structure of neuromelanin at a microscopic level. The purity of neuromelanin can be determined by analyzing the morphology and size of neuromelanin granules.

It should be noted that measuring the purity of neuromelanin can be difficult because there are other similar pigments in the brain, such as melanin and lipofuscin. Therefore, it is important to validate the obtained results using different methods and compare the results with known reference samples.

1. Easy Plus UV/VIS spectrophotometers are designed to serve your water testing for chlorine -

2. WTW 3017M DPD Chlorine Analyzer- The 3017M Chlorine Analyzer is WTW's newest online analyzer! This DPD colorimetric analyzer is used for continuous measurements of free or total chlorine in municipal drinking water and wastewater applications using an EPA approved method.

Princess Olivar Tuquero , as you noted previous researchers identified the IF band shift when affected by metals. Assuming that is correct, then the only thing necessary to correlate your FTIR results with the metal content is a graph of the amount of observed band shift to the amount of lead found.

Secondary correlations are not generally preferred analytically, but are sometimes necessary. If you are trying to identify the particular chemical/structure actually doing the adsorption of the lead I can see how combining both might seem simpler. However, as long as you have an AAS it would be better to use it for the metal analysis instead of trying to infer it from the IR. If that is just to explain why your IR peaks are shifted a bit, the metal content would explain that via reference to the paper you mentioned.

As normal growth in plants transports nutrients from the roots ultimately to the leaves it is not surprising to find the highest concentrations of any other compound taken up there as well. I would not expect to find them in the same concentrations evenly throughout the plant structure.

Olá, ensaios com culturas celulares.

Antes de testar em células, sugiro fazer uma ampla caracterização de sua amostra (planta), tanto com HPLC, como testes básicos de atividade antioxidante (colorimétrico) entre outros. De acordo com a caracterização você consegue direcionar para algumas linhagens celulares.

Dependendo da estrutura da sua Universidade e verba você consegue fazer muitos testes.

To my understanding, acetonitrile, methanol, isopropoanol etc. act as electron donors in ESI conditions, enhancing ionization in ESI+. This is one of the reason why ionization in ESI+ is enhanced by solvents (the other is their faster vaporization than water in ESI conditions).

some solvents are better electron donors than others, and you may notice signal enhancement switching from one to another...

hope this helps...

Noor Ul Ain , Generally atomic adsorption spectroscopy will be better. You have better selectivity and lower quantification limit.

The ferrous chloride salt (possibly hydrated) can be generally expected to be partially oxidized, at least to trace level. When (freshly) dissolved in aq. dil. HCl, you may consider to reduce contaminant ferric ions to the ferrous state by adding electrolytic iron powder (a few wt% of the weighted salt). Then the sol. should be heated (not boiled) to facilitate ferric to ferrous reduction and the dissolution of any possibly excess of ferrous chloride; cooled to room temperature; being then either vacuum filtered while using nitrogen as blanketing gas, or pressure filtered by using nitrogen as pressurizing gas. Hydrogen can possibly be released during the purification process, owing to the concomitant reaction of metallic iron with HCl: Fe + 2HCl → FeCl₂ + H₂. Water should be either distilled or both deionized and N₂-purged or boiled. The purified ferrous chloride / HCl aq. solution may then be redox-titrated, if required.

Dear Sir you may try the protein separation with foam fractionation coloumn. it would suppose to help you

Greetings Ali Safaa

To solve for molarity (M) in the equation:

ppm = M x m.wt x 1000

We can rearrange the equation as follows:

M = ppm / (m.wt x 1000)

So if you have a solution with a concentration of 50 ug/ml and you want to know the molarity, you would first need to know the molecular weight of the solute. Let's say the molecular weight is 100 g/mol.

50 ug/ml x 1000 = 50,000 ppm

M = 50,000 ppm / (100 g/mol x 1000)

M = 0.5 M

Therefore, the molarity of the solution is 0.5 M.

It is important to note that ug/ml and ppm are not equivalent units of measurement. Ug/ml is a unit of concentration based on mass per volume, while ppm is a unit of concentration based on the number of parts per million. To convert from ug/ml to ppm, you would need to know the density of the solution and the molecular weight of the solute.

Treating bark with acid (HCl) first and then with base (NaOH) second is a common method for isolating plant compounds for analysis or extraction, such as tannins, lignin, and cellulose. This method is known as acid-base treatment or A/B extraction.

The reason for this order of treatment is that acid treatment hydrolyzes and breaks down the plant cell walls, making the cell contents more accessible for extraction. Acid treatment can also help to remove impurities, such as pigments and waxes, from the sample.

After acid treatment, the sample is then neutralized with a base, typically sodium hydroxide (NaOH), to restore the pH to a neutral or slightly alkaline state. The neutralization step is important to prevent the acid from interfering with subsequent analytical techniques or reactions.

The use of acid and base treatments in this order allows for selective extraction of different plant compounds based on their solubility and chemical properties. For example, tannins are more soluble in acidic solutions, while lignin and cellulose are more soluble in basic solutions.

Treating the bark with base first would result in a saponification reaction, where the ester linkages in the plant compounds would be hydrolyzed by the base, resulting in a loss of their original structure and properties. Therefore, treating the bark with acid first and then with base is the preferred order for A/B extraction of plant compounds from bark.

Mohammed Almajidi

I appreciate your response,

you wrote " Prepare a series of quality control samples by spiking known amounts of the target analytes and RS into a matrix. Extract the QC samples to prepare them for analysis"

I have some questions:

1) It seems the QC sample preparation is the same with the sample preparation, what is the difference exactly?

2) what do you mean by "series of QC samples" ?

my advisor told me the feature of QC samples is the fact that we can consider their recovery as 100%,, I thought it means we have to do the same process like the sample preparation BUT add the RS after the extraction process (because in this way we know that the QC recovery is 100%)

I dont know, maybe I am wrong. I am working with HPLC-ESI-mass

another question, you wrote I need to spike the RS into the calibration serial dilution too, is there any extraction process for calibration serial dilution?

waiting for your response, Zeinab.

It is likely the presence of water will help to stabilise the metal ions. In the presence of pure acetone the inorganic metal may be insoluble and unavailable to react?

As per above, taking the 0,5 gram and dissolving in pure acetone, then making this up to 100ml, maybe using 50mL acetone, and then using distilled water to complete the volume requirement?

The reaction time and the temprature depends on the level of deacetylation that you would like to achieve. If you let your mixture react longer then the level of deacetylation will be higher.

You might need to experiment a bit till you get a product that has the desired characteristics. Or if you have a procedure for a product with the desired characteristics in the literature then you can simply follow that and get some good results.

May explode on heating

There are some good recommendations here. However, my caveat is that it exemplifies the danger of trusting (or using) statistics as a substitute for valid science. If you can't OBSERVE it in some way (<LOD) you really cannot make valid assumptions or conclusions about it. Wether you need more accurate assay methods or more experiments for more data, you really cannot legitimately just ignore that weakness and obscure it with mathematical manipulations of other data.

When calculating ratios with a Limit of Detection (LOD) in the denominator, there are a few different approaches that can be used, depending on the specific context and the desired level of accuracy. Here are a few examples:

It is important to note that the best approach will depend on the specific context of the measurement, the desired level of accuracy, and the intended use of the ratio. It's always advisable to consult with an expert or statistician to determine the most appropriate approach.

Noor Ul Ain

That is depends upon the which based polyurethan water based or solvent based , chromatography technique also useful

Of course you will have to perform a QA audit of the new manufacturer's facility, but you could have a limited method validation (which should include specificity, linearity (which you could derive the LOD and LOQ), repeatability... Don't be surprised if the impurity profile is different since it is dependent on the manufacturing process. You should also put the finished drug product that is using the new manufacturer's API, on stability.

Dear Genesis Marrero ,

please forget about those ugly very low numbers of % and even the variation of these numbers in your maps.

To my opinion you only 'see' the noise in the background of your EDS spectra around the energy position the Mg K-alphas ( ~1,25keV) and the Sr L-alphas (~1,8keV).

You may share some typical measured spectra; so we will have an impression on the quality of the statistical noise or even of peak overlapings in these regions.

Many thanks in advance

and best regards

G.M.

SD estimates the variability of the measurement (mean) for a single sample/population.

SE estimates the variability of the measurement (mean) when repeating different samples within the same total population.

As such, and I'm using the exact same LOD/LOQ methodology as you are, my philosophy so far is to use :

Thus, SD provides a very conservative estimation for LOD/LOQ at the start of the project and SE will provide a better estimation when the method has become routiine.

EPDM can be found in parts such as water system O-rings, hoses, and gaskets, as well as in electrical insulators and connectors for wires and cables. It is also used in accumulator bladders, diaphragms, grommets, and belts.

I completely agree with Mr. Drazen C. Nicely explained.

Typically, tailing is an indication that the API is not 'happy' with the mobile phase system and the retention (separation) it provides. It can be resolved by using a stronger solvent (IPA instead of Methanol) or a higher percentage of organic (60% instead of 50% Methanol) in order to 'boot' the molecule off the column. This will lower you retention time and sharpen the peak.

Please find the attached article - Determination of Chloride Content in Cementitious Materials. (It may be helpful)

Hope u have this at back of ur mind: "Chromophore"

Dear Harsh,

Maybe i will not properly answer your question, but in my understanding tannic acid has a lot phenolic groups which are already very reactive to hydroxyl radical.

Have you ever tried to performe irradiation of tannic acid aqueous solution with ionizing radiations (i.e. electorn beam or gamma-rays ?). You will produced a lot of hydroxyl radical throught water radiolysis which should react with tannic acid.

All the best,

Nicolas

Dear Joseph Dubrovkin ,

Though it may be a bit outdated it is one of the rare publications that studied exactly what you are looking for: Hubbard, D.E. (2011), "Chemistry book reviews: their value, sources, and number", Collection Building, Vol. 30 No. 4, pp. 172-178. https://doi.org/10.1108/01604951111181146 In Table II (see enclosed file) you see excellent titles like Journal of the American Chemical Society and Angewandte Chemie International Edition. Obviously not sure how, more than 10 years later, the ‘landscape’ of journals is, but I found a nice example in Frontiers of Chemistry (https://www.frontiersin.org/articles/10.3389/fchem.2017.00065/full ). See for more info regarding book reviews (and especially the reply by Wolfgang R. Dick ) the following question here on RG https://www.researchgate.net/post/Is_a_book_review_considered_a_publication

Best regards.

PS. Be careful with the suggestions like JETIR and IOSR. There are predatory journals out there nowadays. See for example:

Dear Dol Lamsal,

The best and simplest choice for the phase-equilibrium calculations and studying such systems (Including Water+Alcohols+Hydrocarbons) is the CPA (Cubic Plus Association) equation of state. I suggest you verify the following references:

Yes but also FTIR (point 2.4), elemental analysis via chemical or spectroscopic techniques is another way. If you are close to a biology institute, you may find Kjeldahl analyzer. My Regards

For Developing the good Electrochemical sensor choosing the suitable nanomaterials related to the your project like Carbon nanotubes (CNTs) and gold nanoparticles (AuNPs) is the first condition.

Dear, Amani Albalawi

I suggest that the easiest and the cheapest way is using web-version of MetaboAnalyst (https://www.metaboanalyst.ca/MetaboAnalyst/ModuleView.xhtml).

Best regards,

Ivan

Dear Franklin Uriel Parás Hernández, both degradation and crystallization are behind the change in color aspect. My Regards

Hii Dr. Harsh

You may visit NIPER ,MOHALI, PUNJAB for the same.

Thank you sir

The simplest and most accurate, also working with a very high speed (many thousand measurements in one second) method of the measurement of solution in which the concentration of one substance is changing (unknown) is the measurement of sound speed in this solution.

This can be made with extrem accuracy. Requires only calibration if the dependance of sound speed on the concentration is not known. We have many such systems for chemicists, that are controlling the concentration of dirrerent substances or their processes.

A potentiostat is the electronic hardware required to control a three electrode cell and run most electroanalytical experiments. A Bipotentiostat and polypotentiostat are potentiostats capable of controlling two working electrodes and more than two working electrodes, respectively. In order to measure the I-V of the electrode one drives a constant current in it till the required potential between the electrode and the reference electrode is reached this is accomplished by the potentiostat. Since the reference electrode does no conduct any current and its function is to sense the potential of the electrolyte only, the current in the working electrode must continue flowing in the counter electrode.

Photoelectrocatalysis takes advantage of the heterogeneous photocatalytic process by applying a biased potential on a photoelectrode in which the catalyst is supported. This configuration allows more effectiveness of the separation of photogenerated charges due to light irradiation with energy being higher compared to that of the band gap energy of the semiconductor, which thereby leads to an increase in the lifetime of the electron-hole pairs. Due to their unique properties, TiO2NTs have been used in many applications such as in photo(electro)catalysis , sensors , biosensors, dye-sensitized solar cells , hydrogen generation by water photoelectrolysis , photocatalytic reduction of CO2 , and biomedical-related applications .

You are right, but slightly difference, In voltammetric sensors, the current response is measured as a function of applied potential. The potential is varied either step by step or continuously in order to determine the current as a function of the cells potential. A voltammetric sensor is usually composed of three electrodes, that is, working, auxiliary, and reference.

This is a typical calibration procedure. You will need multiple concentrations to develop a quantitative response relation that you will use to estimate concentrations in your samples

The study of the interaction of nanoparticles (NPs) with proteins is of great importance due to its relevance in several fields including nano-biosafety, nano-bioscience, nano-biomedicine, and nano-biotechnology. an introduction and a discussion of merits of fluorescent NPs compared to molecular fluorophores, labels and probes, the article assesses the kinds and specific features of nanomaterials often used in bioimaging. These include fluorescently doped silicas and sol–gels, hydrophilic polymers (hydrogels), hydrophobic organic polymers, semiconducting polymer dots, quantum dots, carbon dots, other carbonaceous nanomaterials, upconversion NPs, noble metal NPs (mainly gold and silver), various other nanomaterials, and dendrimers. Another section covers coatings and methods for surface modification of NPs..

Hi Zhepeng Tang , Did you compare the molecular diffusivity values obtained from the Fuller-Giddings and Chapman-Enskog methods? What I meant that is the Fueller-Giddings correlation is accurate too, as most of the literature suggests Chapman-Enskog method?

@Shaina Mercy Fernandes

I think there must be some problem with your solvent (water/aqueous buffer in this case). Check the fluorescence of blank solvent. To avoid such interference, always use triple distilled water.

In the good(?) old days the answer would have been obvious: carbon tetrachloride. Since this solvent has been practically eliminated from modern labs for health reasons, your most straightforward options are:

1. cyclohexane

2. glacial acetic acid (Thermo Fisher sells a 1M solution of bromine in acetic acid).

Store such solutions in glass containers in a cool dark place, like under a well-ventilated hood.

Dear Anna Turbanova ,

Interesting question. I agree with Andrei Blasko and Saeed Ayaz Khan . However, you did not mean a regular analytical method validation. You are dealing with dissolution kinetics. The dissolution itself will depend on the physicochemical parameters you used, so the kinetics.

You find in the literature different behavior of the same AFI, for instance losartan, in several mediums, pH, ionic strength, and solvation conditions. Therefore several other surface and chemical interactions may influence the kinetics, not the determination method itself.

For your safety, check the validation with the already used media. The kinetics of significant different media will change. Therefore, the dissolution kinetics may have different parameters that may affect or not the determination method.

Best regards,

WNM

Hello Viraj,

thank you for posting this very interesting technical question on RG. We work in the field of synthetic inorganic chemistry, so that I would not call myself a proven expert in the field of heterogeneous catalysis and transesterification. However, I can suggest to you two very instructive review articles which will certainly help you in your analysis. Thus please have a look at the following references:

Fortunately this paper has been posted by the authors as public full text on RG, so that you can freely download it as pdf file.

The other paper can also be accessed as public full text as it has been published Open Access:

(Please see the attached pdf file)

I hope this helps. Good luck with your work!

Dear Noor Ul Ain, please have a look at the following recent review document and the references therein. My Regards

Actually, reading the question with very strict meanings, he might be looking for a conversion to grams. If the density is known, multiply the volume by the density to get the weight. The concentration of a pure liquid compound is 100%.

The following useful RG link is also very useful:

How the calculate optamic products as per ICH guideline because of optamic products dose is very low and impurity calculate as per ICH is very high

Good luck.

Tamjid Us Sakib depends on the type of technology selection and project

microlage is preferred in case of biological and if you have space and time with low cost investment however if you go via chemical route there are many like activated carbon, haaluminum sulphate or few other sales can also be used

Nalidixic acid - A NSAID grs of drugs or pain killer .REF : en.wikipedia.org ( Image Source ) .

The subject of specialisations does not depend on the feature income rather your subject if interest . Organic chemistry has too much scopes as a synthetic( R&D) chemist in multinational pharmaceutical houses like Chem biotech , Pfizer , DRL labs etc etc. Even in post doc level abroad from India very high scope in organic nano synthesis like CNT . So scope of income is naturally very high in organic chemistry indeed . But in analytical chemistry the scope is narrow compared to organic chemistry . Since analytical and quality control laboratories are also guided by organic chemists / phyto chemists / petrochemicals for mainly UV-Visible spectrophotometric analysis / Chromatography like GC , HPLC , HPTLC , GC-Mass spectrophotometer and fluroscence spectroscopy .Yes analyical chemists are useful in effluent treatment / waste water analysis as well as drinking water analysis of trace heavy metals like Cu , Cd, As , Pb , Hg ( II , I ) by AAS ( Atomic abs Spectrophotometry ) AES ( Atomic emission spectrophotometry. In drinking / waste water lab there are so many important analytical parameters like B.O.D , C.O.D , D.O , pH , TDS , TSS and limit tests for heavy metals in trace metals .

Dear Franklin,

I have attached one file which I have made an example for transforming %w to phr. I hope it would be useful.