This study established a highly effective and reliable method for the separation and quantitative determination of five pharmacodynamic active components of I. sonchifolia using microemulsion electrokinetic chromatography (MEEKC). The MEEKC conditions were investigated. The optimal running buffer (pH 9.25) consisted of 80 mmol/L Brij-35, 0.8% (v/v) n-heptane, 8% (v/v) 1-butanol, 25% (v/v) acetonitrile, 10 mmol/L sodium dihydrogen phosphate-10 mmol/L sodium borate at 25 kV voltage. The regression equations showed good linear relationships, with 0.61-7.76 mu g/mL limit of detection and 2.04-25.85 mu g/mL limit of quantitation. The established method was also accurate, with intra-day and inter-day relative standard deviations less than 4.78% and less than 6.27%, respectively. Recovery values ranged from 98.61% to 104.76%. The proposed method was successfully applied to determine the five compounds in Kudiezi injection samples. A MEEKC method without adding neutral markers was further established for dissociation constant (pK(a)*) measurement, and reliable pK(a)* values were obtained.

A novel microemulsion electrokinetic chromatography (MEEKC) method for the simultaneous separation and quantitative determination of phenylpropanoid glycosides in Rhodiola L. was developed. The effects of many parameters influencing separation characteristics were optimized. Retention factor met rosarin<rosavin<rosin at the same 2-propanol concentration. Both selectivity and resolution of rosarin and rosavin increased with increasing 2-propanol content. The similar chemical structure led to a small difference in theoretical plates. The resolution of rosarin and rosavin showed greater improvements than rosavin and rosin with increasing buffer pH. According to the separation characteristics, the optimal running buffer was determined: 80 mmol/ L sodium dodecyl sulfate, 1.0% n-heptane, 7.5% 1-buatnol, 22.5% 2-propanol, and 10 mmol/ L sodium borate buffer at pH 9.25. Validation showed that this simple MEEKC method possesses feasible accuracy and precision. Furthermore, the developed method successfully quantified three phenylpropanoid glucosides in the Rhodiola rosea sample extracts and three oral liquids.

A sensitive micellar electrokinetic chromatographic method with laser-induced fluorescence detection was developed for the determination of alendronate sodium (ALN) and pamidronate disodium (PAM) after derivatization with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole. The developed method was first used for the determination of ALN and PAM in pharmaceutical preparations. After optimization, baseline separation of the analytes could be obtained in <10 min in a running buffer composed of 10 mM sodium borate and 30 mM sodium dodecyl sulfate (pH 9.0) at a voltage of 15 kV with 25 degrees C cartridge temperature and the samples were injected by pressure (3447.5 Pa x 3 s). The method has linearity range of 0.05-70 mu g/mL for the analytes (correlation coefficients: 0.9995 and 0.9997), the detection limits were 4 and 10 ng/mL for ALN and PAM, respectively. In intraday precision experiment, the relative standard deviation (RSD) values for migration time were 0.30% (ALN) and 0.27% (PAM), and the RSD values for peak areas were 1.19% (ALN) and 1.32% (PAM). The ranges of recovery were 95.5-101.8 and 94.6-105.3% for ALN and PAM, respectively. This method is not only rapid and accurate but also has the potential to be used for the quality control in pharmaceutical preparations of the two drugs.

The primary objective of this study is to evaluate the interactions of ellagic acid (EA) and oleuropein (OLE) with human serum albumin (HSA). Plasma protein binding model prediction and molecular modeling suggest that EA binds to HSA stronger than OLE, and that both interact with the binding pocket of HSA subdomain IIA. Furthermore, fluorescence spectroscopy confirmed that EA has a stronger HSA binding affinity than OLE. Three-dimensional fluorescence spectroscopy and CD spectroscopy, analyzed using DichroWeb, showed that the binding of EA and OLE to HSA induce conformational changes.

Objective: To control the quality of the product,quantitative fingerprint was used to evaluate the composition of the amino acids in the Xingnao Tongluo injection.Method:The method of the quantitative fingerprint to the amino acids composition was established through AccQ Tag precolumn derivatization.The quality was evaluated by the quantitative test of the amino acids and the similarity in ten batches.Result: The Xingnao Tongluo injection contained 12 amino acids and the contents of these amino acids were stable.All the ten batches of the samples had similarity of more than 0.90.Conclusion: The method was accurate,feasible and could be a simple and effective way to evaluate the quality of the traditional Chinese medicine.

A rapid and effective method of micellar electrokinetic chromatography with laser-induced fluorescence detection was developed for the simultaneous determination of amino acids in tea leaves. Pre-column derivatization of the analytes used 4-chloro-7-nitrobenzofurazan (NDB-CI). Optimal separation was achieved at +20 kV using an uncoated fused silica capillary (40.0 cm effective length, 50.2 cm total length, 75 mu m internal diameter), as well as 20 mM sodium borate (pH 8.5), 20 mM Brij 35, and acetonitrile 10% (v/v) as running buffers. Within 11 min, 15 amino acids were separated completely. The optimized method demonstrated good linearity (r(2) >= 0.9990), precision (<= 0.65%), accuracy (85.50-112.74%), and sensitivity (0.1 ng/mL-100 mu g/mL). The method successfully determined the quantity of amino acids in five different tea leaves; furthermore, theanine was identified as the most abundant amino acid in teas. The proposed method showed great potential in further investigations on the biofunctions of different tea samples. (C) 2013 Elsevier Ltd. All rights reserved.

A simple and reliable method based on capillary electrophoresis with laser-induced fluorescence detection was developed for the analysis of the antiepileptic drug Gabapentin in human plasma and urine. 4-Chloro-7-nitrobenzofurazan was used for precolumn derivatization of the drug. With an uncoated fused silica capillary (40.0 cm effective length, 50.2 cm total length and 75 μm internal diameter), optimal separation was achieved with 30 mM sodium dodecyl sulfate, 40 mM sodium borate (pH 10.25) and acetonitrile 10% (v/v) as running buffer. The applied voltage was 20 kV and the samples were injected by pressure (3.45 kPa × 3 s). The method was fully validated with regard to linear range, sensitivity, precision, limit of detection and limit of quantification in human plasma and urine samples. Linear ranges were 0.1-15 μg mL(-1) for plasma and urine. The intra- and interday precisions were ≤9.02 and 13.90%, respectively. The recoveries were 96.0-109.3% for plasma and 94.3-98.0% for urine. The method was successfully applied for the determination of Gabapentin in human plasma and urine.

Near infrared spectroscopy (NIRs) in combination with chemometrical techniques partial least squares is an effective, expeditious and nondestructive technique to analyse various parameters of interest to the pharmaceutical industry. In this work, we explored the use of NIR spectroscopy for the determination of physical (compression force, tablet hardness, mean particle size and particle size distribution) and chemical parameters (content uniformity). To measure tablet content uniformity, naproxen tablets with drug content ranging from 80% to 120% were made and analyzed using high performance liquid chromatography (HPLC) and NIR spectroscopy. For models of the compression force and hardness, the tablets were made by Rotary tablet press and the compression force was varied from 5.7 to 46.0 kN. The samples of mean particle size and particle size distribution were passed through sieves of different sieve opening to obtain six size fractions. The correlation coefficient (R), root mean square error of calibration (RMSEC), root mean square error of prediction (RMSEP) and root mean square error of cross-validation (RMSECV) have been used to assess the predictive ability and robustness of the different partial least squares (PLS) models.

A capillary electrophoresis method with laser-induced fluorescence detection(LIFD)was developed for the determination of oxidation and reduced glutathione,glutamic acid,cysteine and glycine after derivatization with 4-chloro-7-nitrobenzofurazan(NBD-Cl).The five chemicals could be well separated with in 11 min at a voltage of 20 kV with 25 °C cartridge temperature in a running buffer consisting of 25 mmol/L borate sodium,20 mmol/L Brij-35 and 5%acetonitrile(pH9.5),and the samples were injected by pressure 3447.5 Pa(0.5 psi)× 3 s.Under the optimum condition,the method has good linearity relationships(square of correlation coefficients:0.9994-0.9999)with ranges of 1-50 μg/mL for GSH,GSSG,Cys;0.5～25 μg/mL for Glu and 0.1～20 μg/mL for Gly,respectively.The limit of detection(LOD)for analytes were in the range of 0.001-0.1 μg/mL.This method was applied to the quantitation of GSH powder injection with the recoveries in the range of 99.5%～110.7%and the relative standard deviation(RSD)were 0.26%～3.272%(n=3).This method is accurate,fast,sensitive and has a low detection limit.It can be used for the content of oxidation and reduced glutathione and amino acids that form the glutathione in samples.This method has a good prospect in the analysis of real samples.

The primary objective of this study is to evaluate the interactions of human serum albumin (HSA) with peimine (PE) and peiminine (PEN) in physiological conditions by fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD) spectroscopy, Raman spectroscopy, and molecular modeling. PE and PEN were isolated from Bulbus Fritillariae thunbergii miq. The binding constants Ka and the number of binding sites n were calculated at different temperatures. Enthalpy change (ΔH), entropy change (ΔS), and Gibbs free energy change (ΔG) were also determined. The results suggested that quenching of HSA fluorescence by PE and PEN is a static process. Three-dimensional fluorescence, FT-IR, CD, and Raman spectra showed that the binding of PE and PEN to HSA can induce conformational changes in the latter. Moreover, important differences in binding ability were observed between PE and PEN, and PE showed stronger binding affinity to HSA than PEN.

An optimized and validated spectrofluorimetric method has been developed for the rapid determination of aluminum in absolute ethanol. The method is based on the chelation of aluminum and luteolin which results in a complex exhibiting an intense emission signal. The characterization of Al-luteolin complex was studied using ultraviolet-visible spectrometry, infrared spectrometry, fluorescence and mass spectrometry. The complex stoichiometry ratio of aluminum:luteolin was 1:2. The fluorescence of the complex was monitored at an emission wavelength of 545 nm with excitation at 518 nm. The linear concentration range was 6.5 × 10(-7) to 4.0 × 10(-5)  M with a correlation coefficient of r = 0.998. The detection limit was 5.0 × 10(-7)  M. The method was appropriately validated and yielded relative standard deviations of < 2.3% (n = 5), which was considered acceptable. The method was successfully applied in the determination of aluminum in river water, skin care products and pharmaceutical samples.

A novel nonionic microemulsion electrokinetic chromatography (MEEKC) method has been developed and validated for the determination of uric acid. The optimum microemulsion consisted of 80 mmol L-1 Brij-35, 2% (v/v) n-heptane, 14% (v/v) 1-butanol, 2.5% (v/v) acetonitrile and 10 mmol L-1 sodium borate buffer (pH 9.25). Under the optimum conditions, the method had a good linear relationship (correlation coefficient: 0.9996) with a range of 5-200 mu g mL(-1) for uric acid. The limit of detection for uric acid was 0.50 mg mL(-1). The intra-day RSD values for migration time and peak area ratio were less than 0.71% and 0.78% (n = 5), and inter-day values were less than 1.64% and 1.82% (n = 5), separately. The method was applied for the quantitation of uric acid in gout patients' plasma and urine with recoveries in the range of 99.84-119.36% and 97.15-108.48%, respectively.

A novel micellar electrokinetic chromatographic method with laser induced fluorescence detection after derivatization with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) was developed for the determination of muscle relaxant drug baclofen (BAL). After optimization, baseline separation of the derivatives of BAL and gabapentin (internal standard) was obtained within 7 min in a running buffer (pH 9.75) composed of 15 mmol/L sodium borate, 20 mmol/L sodium dodecyl sulfate and 10% (v/v) acetonitrile. The separation voltage was 17.5 kV. The column temperature was 25 degrees C. The samples were injected by a pressure of 3.45 kPa (0.5 psi) for 3 s. The method has a linear range of 0.025 - 25 mg/L for BAL with the correlation coefficient of 0.999 9. The limit of detection (LOD, S/N = 3) and the limit of quantification (LOQ, S/N = 10) were 0.90 microg/L and 6.25 microg/L, respectively. The developed method was used for the analysis of BAL pharmaceutical preparation and urine samples spiked with BAL standard. The ranges of recovery were 101.6% - 107.9% for BAL preparation and 107.0% - 109.6% for urine samples. This method can be applied to the quality assessment of baclofen drug products, and provide supplementary means for the drug metabolism research of baclofen.