Simultaneous Determination of Glutamate, Glycine, and Alanine in Human Plasma Using Precolumn Derivatization with 6-Aminoquinolyl-N-hydroxysuccinimidyl Carbamate and High-Performance Liquid Chromatography

A simple, sensitive and reproducible high-performance liquid chromatography (HPLC) method has been validated for determining concentrations of glutamate, glycine, and alanine in human plasma. Proteins in plasma were precipitated with perchloric acid, followed by derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC). Simultaneous analysis of glutamate, glycine, and alanine is achieved using reversed-phase HPLC conditions and ultraviolet detection. Excellent linearity was observed for these three amino acids over their concentration ranges with correlation coefficients (r)>0.999. The intra- and inter-day precision were below 10%. This method utilizes quality control samples and demonstrates excellent plasma recovery and accuracy. The developed method has been successfully applied to measure plasma glutamate, glycine, and alanine in twenty volunteers.

Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Drop with High Performance Liquid Chromatography for Determination of Decabrominated Diphenyl Ether in Surficial Sediments / 分析化学

A method for the determination of decabrominated diphenyl ether(decaBDE) in sediment samples at trace level using dispersive liquid-liquid microextraction based on the solidification of floating organic drop (DLLME-SFO) and high performance liquid chromatography-ultraviolet detector (HPLC-UV) has developed.Based on the data of interactive orthogonal array design, the optimization experimental conditions were obtained with BP artificial neural network model: 1.00 mL methanol as dispersive solvent, 35.0 μL dodecanol as extractive solvent, 10.00% NaCl, pH 5, and extraction in 10 min.The extraction recovery (ER) was 62.22% at the extraction conditions.The proposed method exhibited a wide linear range(3.5-1400 ng/g) with R~2 =0.9921.The limit of detection (LOD) and the limit of quantification (LOQ) of this method were 2.3 pg/g(S/N =2) and 5.6 pg/g(S/N = 5), respectively.The recoveries of real samples at different spiking levels of decaBDE were 104.2%, 98.4% and 97.7%, respectively.Extraction, concentration and separation procedures for decaBDE from the sediment sample were carried out by one step, and hence, the process of DLLME-SFO for decaBDE was shortened.

Pharmacokinetic Study of Midazolam-A Cytochrome P450 3A Activity Probe / 中药新药与临床药理

Objective To develop a high performance liquid chromatography-ultraviolet detection(HPLC-UV) method for the determination of midazolam in rat plasma,and to study the pharmacokinetics of midazolam in single dose intravascular administration in rats.These results can provide a methodological reference for evaluating cytochrome P450 3A(CYP3A) activity.Methods Firstly,common carotid artery(CCA) intubate was set in rats,Midazolam was injected into rat vena caudalis and plasma samples were collected in different time.Then,the sample was extracted using dichlormethane and evaporated to dry thoroughly with N2 soft stream at 37 ℃.Finally,the residues were reconstituted with 150 ?L 30 %methanol and further analyzed by HPLC.A Phenomenex C18 column(4.6?150 mm i.d,5 ?m)was employed at 20 ℃.The mobile phase consisted of(A) methanol-acetonitrile-0.03 %phosphate solution(pH 2.85) in the proportion of 5:10:85(V/V/V) and(B) methanol-acetonitrile-0.03 %phosphate solution(pH 2.85) in the proportion of 5:10:85(V/V/V),using a linear gradient elution of 0 %B～100 %B at 0～18 minutes,then retaining for 5 minutes and returning to A.The flow rate was set at 0.5 mL/min and the ultraviolet detector was operated at 240 nm.Results Midazolam and internal standard were isolated on baseline in plasma apart from all other material.The the linear range was from 0.025～2.0 ?g/mL,and the detection limit was 2.5 ng/mL.The standard addition recoveries were from 99.98 %to 105.71 %and the extraction rates were from 91.29 %to 92.58 %.All of the intraday and interday variations were less then 14 %.The primary pharmacokinetics parameters of rat single dose intravascular administration were as follows:t1/2?was 0.582 h,Vd was 0.214 L,Cl was 0.584 L/h and AUC0→t was 0.419 ?g?h-1?mL-1.Conclusion Midazolam single dose intravascular administration has the characteristics of rapid distribution and elimination in blood and quick transport from blood to tissue.The method is sensitive,simple and suitable for the research of pharmacokinetie parameters of midazolam and description of possible pharmacological interactions of rat CYP3A1/2 or human CYP3A4/5 enzymes.

Determination of the Concentration of Midazolam in Plasma by RP-HPLC-UV Detection / 中国药房

OBJECTIVE:To build up a method of determining the concentration of midazolam in plasma by RPHPLC-UV detection.METHODS:The separation was carried out by a reversed-phase Hypersil ODS column(250mm?4.0mm,5?m) with a mobile phase consisting of methanol-acetonitrile-0.02mol/L potassium phosphate buffer(pH 7.4) (65∶25∶10,V/V).Mida_zolam was extracted from alkalinizing plasma and soluted in the mobile phase then detected at 221nm.RESULTS:The calibration curve had the fine linearity in the concentration range 50～1 600ng/ml(r=0.9 999).The detection limit was 2ng/ml.The absolute recovery was 90.8%～95.4%,the relative recovery was 99.3%～101.3%.The within-day and between-day precision(CV%) was 1.94%～5.16%,3.00%～6.39% respectively.CONCLUSION:The method is simple,stable and highly sensitive and could meet with the research of clinical pharmacokinetics.