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ABSTRACT: 8 A new virus capture/release strategy for the concentration of viral particles in water is reported. The method is an improvement upon traditional approaches that rely exclusively upon electrostatic attractions between a charged substrate and charged viral particles, which can only be reversed under extremely acidic or alkaline conditions to effect surface charge reversal and subsequent release of captured viruses. This method utilizes negatively charged silica beads functionalized with amino groups using defined length spacer molecules to yield particles with a surface density optimized for efficient virus capture. Following capture, viruses can be released using soluble proteins or amino acid-based alkaline eluents. Virus recoveries are a function of the composition of elution solution used. The zeta potentials of amino-functionalized silica particles were analyzed and used to optimize the density of functionalized groups and the charge behavior of the functionalized silica surfaces. Raman spectrometry was used for the characterization of functionalized silica beads. This method is expected to apply in the analysis of viruses. 9 10 11 12 13 14 15 16 © 2006 Elsevier B.V. All rights reserved.
Analytica Chimica Acta. ;
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ABSTRACT: Catharanthus roseus is an important dicotyledonous medicinal plant that produces anticancer compounds. The active alkaloids vinblastine, vindoline, ajmalicine, catharanthine, and vinleurosine were identified by direct-injection ion trap-mass spectrometry (IT-MS) for collecting MS(1-2) spectra. The determinations of five alkaloids were accomplished by liquid chromatography (LC) with UV and MS detections. The analytes provided good signals corresponding to the protonated molecular ions [M+H](+) and product ions. The precursor ions and product ions for quantification of vinblastine, vindoline, ajmalicine, catharanthine, and vinleurosine were m/z 825→807, 457→397, 353→144, 337→144 and 809→748 by LC-IT-MS, respectively. Two methods were used to evaluate a number of validation characteristics (repeatability, LOD, calibration range, and recovery). MS provided a high selectivity and sensitivity for determination of five alkaloids in positive mode. After optimisation of the methods, separation, identification and quantification of the five components in C. roseus were comprehensively accomplished by HPLC with UV and MS detection.
Food Chemistry 08/2013; 139(1-4):845-52. · 3.65 Impact Factor
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ABSTRACT: An electrophoretically mediated microanalysis method with partial filling technique was developed for screening aromatase inhibitors in traditional Chinese medicine. The in-capillary enzymatic reaction was performed in 20 mM sodium phosphate buffer (pH 7.4) and sodium phosphate buffer (20 mM, pH 8.0) was used as a background electrolyte. A long plug of coenzyme reduced β-nicotinamide adenine dinucleotide 2'-phosphate hydrate dissolved in the reaction buffer was hydrodynamically injected into a fused silica capillary followed by the injection of reaction buffer, enzyme and substrate solution. The reaction was initiated with a voltage of 5 kV applied to the capillary for 40 s. The voltage was turned off for 20 min to increase the product amount and again turned on at a constant voltage of 20 kV to separate all the components. Direct detection was performed at 260 nm. The enzyme activity was directly assayed by measuring the peak area of the produced β-nicotinamide adenine dinucleotide phosphate and the decreased peak area indicated the aromatase inhibition. Using the Lineweaver-Burk equation, the Michaelis-Menten constant was calculated to be 50 ± 4.5 nM. The method was applied to the screening of aromatase inhibitors from fifteen natural products. Seven compounds were found to have potent aromatase inhibitory activity. This article is protected by copyright. All rights reserved.
Journal of Separation Science 06/2013; · 2.73 Impact Factor
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ABSTRACT: Jasmonic acid (JA) conjugates with amino acids (AAs) are a group of plant hormone in the family of jasmonates. The separation of stereoisomers of JA-AA conjugates is a very challenging work since these stereoisomers have similar chromatographic and electrophoretic behavior. Simultaneous separation of ten (±)-JA conjugates with five AAs including l-Tyr (tyrosine), l-leucine, l-Ile (isoleucine), l-valine, and l-phenylalanine and their stereoisomers has been achieved by MEKC with diode array detector in this work. Optimum separation of the analytes was obtained on a 61.5 cm × 75 μm id capillary using a running buffer containing 80 mM SDS and 50 mM phosphates (pH 7.0) at +18 kV applied voltage and capillary temperature of 35°C. Ten stereoisomers of JA conjugates with five AAs are completely separated in 13 min. The RSDs of the migration times and peak areas of the ten stereoisomers were in the range of 0.48-1.03% and 1.03-2.07%, respectively. In the tested concentration range, good linear relationships (correlation coefficients above 99%) between peak areas and concentrations of the analytes were observed. The proposed method has been successfully applied to the analysis of spiked rice floret sample and original reaction solution of (±)-JA-Ile conjugate and (±)-JA-Tyr conjugate. The recoveries ranged from 91.7 to 107.6% for the rice floret sample and 92.9 to 107.2% for the original reaction solution.
Journal of Separation Science 03/2013; 36(5):892-897. · 2.73 Impact Factor
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ABSTRACT: A novel berberine-imprinted polymer (MIP) monolith was prepared for extraction of berberine in aqueous medium. The MIP monolith was prepared inside a polypropylene micropipette tip by using dimethylsulfoxide as porogen, acrylamide (AA) as functional monomer and ethyleneglyol dimethacrylate (EGDMA) as cross-linker. Polymerization conditions were optimized and good permeability and selectivity was obtained when the ratio of berberine/AA/EGDMA was 1:5:30. Cross-reaction was also studied by three compounds (palmatine, coptisine, and jatrorrhizine) with similar structure. A molecularly imprinted micro solid-phase extraction (MI-μ-SPE) method was developed for selective extraction of berberine in aqueous solutions. Extraction parameters were investigated, such as sample pH value, sample flow rate, sample volume and elution solvent. By combining with HPLC/UV, MI-μ-SPE method showed a good linear range of 3-800ng/mL with a low limit of detection limit of 1.0ng/mL. The method was also applied for the pretreatment of berberbine in human plasma and urine samples. The result showed that proteins and other biological matrix were successfully eliminated and berberine was selectively enriched. Recoveries were tested in plasma and urine samples, and calculated to be 90.6-103.2% with relative standard deviations less than 4.7%.
Talanta 01/2013; 103:103-9. · 3.79 Impact Factor
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ABSTRACT: Jasmonic acid (JA), a type of plant hormone, is widely distributed in a variety of higher plants at very low concentrations, usually several nanograms per gram (ng g(-1)) fresh weight of the plant tissue. The determination of endogenous JA is challenging work. The typical electrochemical oxidation behavior of JA could only be achieved under extreme conditions such as strongly acidic medium (H(2)SO(4)) and high applied working potential (1.4-1.6 V), which cannot be used in the electrochemical detection for liquid chromatography (LC). To realize electrochemical detection for LC separation, a mild supporting electrolyte for JA oxidation is required, as the supporting electrolyte solution also serves as the mobile phase of LC. Thus, a novel electrochemical derivatization with dopamine (DA) has been developed and successfully applied to the analysis of endogenous JA in wintersweet flowers and rice florets by liquid chromatography coupled with electrochemical detection (HPLC-ECD). Under optimized experimental conditions including a detection potential of +0.90 V, and 0.04 mol L(-1) acetate buffer solution (pH 5.07) : acetonitrile (67 : 33, v/v) as the mobile phase, the contents of JA in wintersweet flowers and rice florets were respectively determined to be 7.86 μg g(-1) and 308 ng g(-1), consulting the linear relationship between the peak area of JA-DA derivatives and the standard JA concentration (1.0 × 10(-7) mol L(-1) to 2.0 × 10(-5) mol L(-1), R = 0.9986) with a detection limit of 5.0 × 10(-8) mol L(-1) (S/N = 3). The results were consistent with those by LC-UV and LC-MS methods in our group, indicating that this novel pre-column electrochemical derivatization method is feasible.
The Analyst 01/2013; · 4.23 Impact Factor
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ABSTRACT: A novel and simple poly(ether ether ketone) (PEEK) tube-based solid-phase microextraction (SPME)-HPLC method was developed in this work. A mussel inspired polydopamine method was used to functionalize the chemically resistant surface of PEEK tube and a poly(acrylamide-ethylene glycol dimethacrylate) monolith was synthesized inside the PEEK tube and chemically bonded with its surface. The stability of the polydopamine layer was investigated and found to be well enduring to most of commonly used organic solvents and strong acidic conditions. The PEEK tube-based monolith was coupled with HPLC system through a six-port valve, and the performance of the online SPME-HPLC system was demonstrated by analyzing three protoberberine alkaloids in aqueous samples, namely jatrorrhizine (Jat), palmatine (Pal) and berberine (Ber). These analytes were well extracted and separated within 10min, and enrichment factors of about 400 were obtained. The limit of detection of the proposed method was decreased to 0.01ng/mL by using UV detection. Finally, the online SPME-HPLC method was applied for determining Jat, Pal and Ber in rat plasma samples. Reproducibility was obtained by evaluating the intra- and inter-day precisions with RSDs less than 6.1% and 8.5%, respectively, and recoveries of the analytes in spiked plasma samples ranged from 89.8% to 96.7%. The proposed method was also applied to determine the concentration of Jat, Pal and Ber in rat plasma after oral administration of Cortex Phellodendri Chinensis.
Journal of chromatography. A 01/2013; · 4.19 Impact Factor
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ABSTRACT: The Amaryllidaceae are widely distributed medical plants. Lycorine, lycoramine, lycoremine, and lycobetaine are the major active alkaloids in Amaryllidaceae plants. A nonaqueous CE ESI-IT-MS method for separation, identification, and quantification of the Amaryllidaceae alkaloids has been developed. The MS(1-3) behavior has been studied and the fragmentation pathways of main fragment ions have been proposed. The effects of several factors such as composition and concentration of buffer, applied voltage, composition, and flow rate of the sheath liquid, nebulizing gas pressure, flow rate, and temperature of drying gas were investigated. Under the optimal conditions, the linear concentration range of these compounds was wide with the correlation coefficient (R(2) ) >0.99. RSDs of migration time and peak areas were <10%. The LODs were <240 ng/mL. The proposed method can be successfully applied to the determination of the related alkaloids in the Lycoris radiata roots.
Journal of Separation Science 12/2012; · 2.73 Impact Factor
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ABSTRACT: A nonaqueous CE-IT MS with a nanospray ionization interface method was developed for the identification and quantification of tetrandrine (TET), fangchinoline (FAN), and sinomenine (SIN) using berberine as internal standard. The TET, FAN, and SIN standard solutions were directly infused into IT-MS for collecting MS(1-3) spectra. The major fragment ions of analytes were confirmed and possible main cleavage pathways of fragment ions were studied. A bare fused-silica capillary was used for separation of the analytes. A sheath liquid (50% aqueous methanol containing 0.2% acetic acid) to the capillary effluent with a nanoelectrospray ionization interface was added. Separation buffer comprised 80 mM solution of ammonium acetate, in a mixture of 70% methanol, 20% ACN, and 10% water, which also contained 1% acetic acid. The CE-MS method was validated for linearity, sensitivity, accuracy, and precision, and then used to determine the content of the above components. The detection limits of TET, FAN, and SIN are 0.05, 0.08, and 0.15μg/mL, respectively. The precision was no more than 4.67% and the mean recovery of the analytes were 95.36-99.24%. This method was successfully applied to determine TET, FAN, and SIN in real samples radix Stephaniae tetrandrae and rhizomes of Menispermum dauricum.
Journal of Separation Science 12/2012; · 2.73 Impact Factor
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ABSTRACT: A simple and sensitive method for the detection of jasmonic acid (JA) by liquid chromatography-ion trap mass spectrometry (LC-IT-MS/MS) after derivatization is described. The highlight of this method was that it involved a rearrangement reaction which was often considered as a side reaction in the formation of amides and esters using N,N'-dicyclohexylcarbodiimide (DCC) as a condensation reagent. While in this study, DCC was used as a derivatization reagent directly. Internal standard dehydrojasmonic acid (DHJA) was used to ensure the accuracy. Derivatives provided good signals corresponding to the protonated molecular ions [M + H](+) and product ions. Sensitivity had been improved 100-fold with the LOD being 0.1 ng mL(-1) in comparison with the LC-IT-MS analysis without derivatization. This proposed method was reliable with good recoveries found in rice floret and wintersweet, allowing quantification in real samples to be more accurate and efficient, thus offering a good way to further study the physiological and biological activities of jasmonic acid in plants.
The Analyst 10/2012; 137(22):5436-40. · 4.23 Impact Factor
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ABSTRACT: A poly(4-vinylpridine-co-ethylene glycol dimethacrylate) monolith was synthesized in a capillary and constructed as a concentrator for the in-line polymeric monolith microextraction coupling with capillary electrophoresis. The integrated system was then used for the simultaneous determination of five trace phenols (2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2-chlorophenol, and 2,4-dichlorophenol) in water samples. The experimental parameters for in-line solid-phase extraction, such as composition and volume of the elution plug, pH of sample solution, and the time for sample loading were optimized. The sensitivity for the mixture of phenols (2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2-chlorophenol, and 2,4-dichlorophenol) enhanced to 615-2222 folds at the optimum condition was compared to the sensitivity for a normal hydrodynamic injection in capillary electrophoresis. Linearity ranged from concentration of 10-500 ng mL(-1) (R(2) > 0.999) for all five phenols with the detection limits of 1.3-3.3 ng mL(-1) . In tap, snow and Yangtze River water spiked with 20 ng mL(-1) and 200 ng mL(-1) , respectively, the recoveries of 84-105% were obtained. It has been demonstrated that this work has great potential for the analysis of phenols in genuine water samples.
Electrophoresis 09/2012; 33(18):2911-9. · 3.30 Impact Factor
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ABSTRACT: A sensitive and precise high performance liquid chromatography (HPLC)-electrochemical detection (ECD) method has been developed for the simultaneous determination of four isoquinoline alkaloids including berberine, jatrorrhizine, coptisine and palmatine in Chinese medicine Coptis chinensis. The typical HPLC analysis was performed on WondaSil(®) C18-WR column (250×4.6 mm, 5 μm) with the mobile phase comprising 40 mM phosphate buffer (pH 7.0)-acetonitrile (40:60, v/v) at the flow rate of 0.8 mL min(-1). The electrochemical detection employed a three electrode system with a bare glassy carbon electrode at +1.3 V versus the Ag/AgCl reference electrode. The limits of detection (LODs) of four alkaloids ranged from 0.01 to 0.03 μmol L(-1) and the LOD of berberine was 80 times lower than LOD obtained by UV detection. The rat plasma samples were assayed after oral administration of the traditional Chinese medicine Coptis chinensis by the proposed HPLC-ECD method. The recoveries of this method were ranging from 88.0 to 116%, with the relative standard deviation lower than 3.1% for intra-day precision and 5.7% for inter-day precision. These results show that HPLC-ECD is a useful tool for the quality control of herbal medicine Coptis chinensis and also for pharmacokinetic studies.
Analytica chimica acta 08/2012; 737:99-104. · 4.31 Impact Factor
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ABSTRACT: Bavachin and isobavachalcone are the isomeric compounds in the fructus Psoraleae. The ion trap mass spectrometric fragmentation pathways of the bavachin and isobavachalcone in negative ion mode were elucidated for the identification. A novel method for determination of isomeric bavachin and isobavachalcone has been developed by capillary electrophoresis coupled with mass spectrometric detection. The effects of several factors such as concentration, pH of ammonium acetate buffer, separation voltage, composition and flow rate of the sheath liquid were investigated. Under optimal conditions, the linear concentration range for bavachin and isobavachalcone were 0.8-100 μg/mL with the correlation coefficient of 0.996 and 0.995, respectively. Relative standard deviations of migration time and peak areas were lower than 5%. The limits of detection (signal/noise = 3) were 60 ng/mL. The proposed method can be successfully applied to the determination of bavachin and isobavachalcone in the fructus Psoraleae and six fructus Psoraleae-containing preparations.
Journal of Separation Science 07/2012; 35(13):1644-50. · 2.73 Impact Factor
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ABSTRACT: A nitric oxide (NO) electrochemical sensor was developed via one-step construction of gold nanoparticles (GNPs)–chitosan (CS)
nanocomposite sensing film on a glassy carbon electrode (GCE) surface. This method is very simple and convenient. The GNPs–CS
film which is controllable and stable exhibits catalytic activity to NO oxidation. The anodic peak potential significantly
shifted negatively compared with that at bare GCE. The high sensitivity and good stability of developed method have been coupled
to a wide linear range from 3.60 × 10−8 to 4.32 × 10−5M for the quantitative analysis of NO. The detection limit of 7.20nM is much lower than the vast majority of reported methods.
This NO sensor has been successfully applied to NO measurement in biological and pharmaceutical samples. Real-time amperometric
data show that the addition of L-arginine (L-Arg) can cause a slow release of NO from a whole rat kidney with a maximum concentration
of ca. 150nM. The concentration of NO monitoring from the drug sample was calculated to be ca. 1.60μM.
KeywordsElectrochemical sensor–Gold nanoparticles–Nitric oxide detection–Pharmaceutical analysis
Journal of Solid State Electrochemistry 04/2012; 15(4):829-836. · 2.13 Impact Factor
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ABSTRACT: A new liquid chromatography-mass spectrometry method for the determination of carbamazepine, clonazepam, alprazolam, estazolam
and phenytoin in human plasma has been developed by using diazepam as an internal standard. Chromatographic separation was
performed on a Zorbax SB-C18 column (30 mm × 2.1 mm, 3.5 μm) with a mobile phase consisting of methanol and aqueous 25 mM
ammonium acetate using gradient elution. A diethyl ether extraction method was used for the extraction of five anti-epilepsy
drugs. The final extract was injected for analysis by LC-MS/MS. The method was validated within the concentration range of
50–5000 ng mL−1 for five anti-epilepsy drugs. The precision of the assay (RSD%) was less than 10% at all concentration levels within the
tested range. The method recoveries for all samples were more than 90%. The results indicate that the method is specific,
sensitive and accurate, and suitable to study the pharmacokinetics, to adjust the dosage for individual administration, and
to monitor the drug-concentration and drug abuse of the five anti-epilepsy drugs.
Keywordsliquid chromatography-mass spectrometry-anti-epilepsy drugs-plasma concentration
Science China-Chemistry 04/2012; 53(11):2373-2378. · 1.02 Impact Factor
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ABSTRACT: Peptidomics has emerged as a new discipline in recent years. Mass spectrometry (MS) is the most universal and efficient tool
for structure identification of proteins and peptides. However, there is a limitation for the identification of peptides with
the same amino acid composition but different sequences because these peptides have identical mass spectra of molecular ions.
This paper presents a high performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) method
for the separation of small molecular peptides with the same amino acid composition but different sequences. Two tripeptides
of Gly-Ser-Phe and Gly-Phe-Ser were used as a model sample. The separation behavior has been investigated and the separation
conditions have been optimized. Under the optimum conditions, good repeatability was achieved. The developed method could
provide a helpful reference for the separation of other peptides with the same amino acid composition but different sequences
in the study of proteomics and peptidomics.
Science in China Series B Chemistry 04/2012; 52(12):2264-2268. · 1.20 Impact Factor
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ABSTRACT: Nickel oxide nanoparticles (NiO-NPs) were electrodeposited on a film of multi-walled carbon nanotubes to improve the electro-oxidation
of nitric oxide (NO). The resulting sensor film exhibits excellent electrocatalytic activity towards NO and was used for the
construction of an amperometric sensor for NO that was applied to monitoring the release of NO from sodium nitroprusside in
rat kidney. Key operational parameters such as the conditions for deposition, kind of electrolyte and pH value were optimized.
The nano-structured sensor possesses numerous active sites for oxidation of NO and thus exhibits good performance including
wide linearity, simple operation, and good stability. The response to NO is linear in the concentration range from 80.0nmol·L−1 to 0.117mmol·L−1, the limit of detection is 20.0 n mol·L−1. The sensor was developed for real-time monitoring of NO.
FigureAmperometric response of the sensor to NO released from rat kidney.
KeywordsNickel oxide–Carbon nanotubes–Nanoparticles–Sensors–Nitric oxide release–Biology and medicine
Microchimica Acta 04/2012; 173(1):65-72. · 3.03 Impact Factor
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ABSTRACT: Copper nanoparticles (Cu-NPs) were incorporated into chitosan hydrogel to form a film on the surface of a glassy carbon electrode
(GCE) leading to a sensing element for D-arabinitol with excellent oxidative catalytic activity. The electrochemical response
to D-arabinitol was studied by cyclic voltammetry and differential pulse voltammetry. Operational parameters affecting the
response were examined and optimized, and a simple and sensitive method was established for the determination of D-arabinitol.
Response is linear in the concentration range from 10μmol·L−1 to 10mmol·L−1, and the limit of detection is 1.0μmol·L−1. The method may be combined with separation techniques in order to analyze for the ratio of D- and L-arabinitol which is
a diagnostic marker for candidiasis.
KeywordsCopper nanoparticles-D-arabinitol-Electrodeposition-Chemically modified electrode-Invasive candida infection
Microchimica Acta 04/2012; 170(1):9-15. · 3.03 Impact Factor
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ABSTRACT: In this work, the electrochemical behavior of methyl jasmonate (MeJA) on a glassy carbon electrode was investigated in 0.1
mol/L H2SO4 by voltammetry. MeJA exhibited enhanced oxidation behavior in the presence of sodium dodecyl sulfate (SDS). The electrochemical
reaction of MeJA on the electrode was carried out with SDS micelles to improve the solubility of MeJA by hydrophobic interaction.
Consequently, the oxidation peak current was sensitively enhanced. The effect of experimental parameters on the oxidative
peak current was investigated including the surfactant concentration, supporting electrolyte, accumulation potential and time,
and scan rate.
Keywordelectrochemical behaviors-glassy carbon electrode (GCE)-methyl jasmonate (MeJA)-sodium dodecyl sulfate (SDS)-voltammetry
Chinese Science Bulletin 04/2012; 55(21):2225-2230. · 1.32 Impact Factor
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ABSTRACT: A simple and selective method was developed for the simultaneous determination of tetrandrine and fangchinoline in herbal medicine by HPLC with electrochemical detection (ECD) on a bare glassy carbon electrode. The HPLC separation and ECD conditions have been optimized. The separation was carried out on a WondaSil C18-WR column (4.6 mm × 250 mm, 5 μm), with the mobile phase of acetonitrile-ammonium acetate buffer (pH 6.5; 40 mM) (32:68, v/v) using an isocratic elution at the flow rate of 0.5 mL/min. The electrochemical detection potential was set at +0.9 V. The obtained LODs for tetrandrine and fangchinoline were 0.26 and 0.27 μmol/L, respectively. The method was successfully applied to the analysis of tetrandrine and fangchinoline contents in Stephania tetrandra S. Moore. It has been demonstrated that the LC-ECD method is an excellent technique for analysis of the herbal medicine. The mean recoveries were in the range of 95-105%, while the precision expressed as repetition of peak area was lower than 2.7%.
Journal of pharmaceutical and biomedical analysis 12/2011; 61:252-5. · 2.45 Impact Factor
