AIM: To study the HPLC fingerprints and establish a sensitive and specific method for the quality control of Andrographis paniculata(Burm.f.) Nees. METHODS: All 23 samples of Andrographis paniculata(Burm.f.) Nees collected from 10 different places were determined by RP-HPLC.Shimadzu-ODS column was used with maxtures of 0.1% formic acid-acetonitrile and 0.2% formic acid-water as mobile phase in gradient mode.The flow rate was set at 1.0 mL/min.The column temperature was set at 25℃ and detecting wavelength at 254 nm.Hierarchical clustering,nonlinear mapping and similarity criteria were applied to evaluate the fingerprints. RESULTS: The simple and specific method with good repeatability was established.There were different contents of each component contained in habitat samples produced in individual area. CONCLUSION: The proceeding is suitable to differentiate Andrographis paniculata(Burm.f.) Nees from different places conveniently and can be used for the quality control of this herb.

Electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) techniques for liquid chromatography–tandem mass spectrometry (LC–MS/MS) determination of levonorgestrel were evaluated. In consideration of difference in ionization mechanism, the two ionization sources were compared in terms of LC conditions, MS parameters and performance of method. The sensitivity for detection of levonorgestrel with ESI was 0.25 ng/mL which was lower than 1 ng/mL with APCI. Matrix effects were evaluated for levonorgestrel and canrenone (internal standard, IS) in human plasma, and the results showed that APCI source appeared to be slightly less liable to matrix effect than ESI source. With an overall consideration, ESI was chosen as a better ionization technique for rapid and sensitive quantification of levonorgestrel. The optimized LC–ESI–MS/MS method was validated for a linear range of 0.25–50 ng/mL with a correlation coefficient≥0.99. The intra-and inter-batch precision and accuracy were within 11.72%and 6.58%, respectively. The application of this method was demonstrated by a bioequivalence study following a single oral administration of 1.5 mg levonorgestrel tablets in 21 Chinese healthy female volunteers.

A sensitive and selective method using high-performance liquid chromatography coupled with elec-trospray ionization tandem mass spectrometry (HPLC–ESI–MS) to determine the concentration of tor-asemide in human plasma samples was developed and validated. Tolbutamide was chosen as the internal standard (IS). The chromatography was performed on a Gl Sciences Inertsil ODS-3 column (100 mm ? 2.1 mm i.d., 5.0 mm) within 5 min, using methanol with 10 mM ammonium formate (60:40, v/v) as mobile phase at a flow rate of 0.2 mL/min. The targeted compound was detected in negative io-nization at m/z 347.00 for torasemide and 269.00 for IS. The linearity range of this method was found to be within the concentration range of 1–2500 ng/mL (r?0.9984) for torasemide in human plasma. The accuracy of this measurement was between 94.05%and 103.86%. The extracted recovery efficiency was from 84.20% to 86.47% at three concentration levels. This method was also successfully applied in pharmacokinetics and bioequivalence studies in Chinese volunteers.

Objective To establish a rapid, sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of acyclovir (the metabolite of valacyclovir hydrochloride) in human plasma. Methods After addition of ganciclovir as internal standard (IS), plasma samples were prepared by one-step protein precipitation using acetonitrile as precipitant, followed by an isocratic elution with 0.1% formic acid 3.5μm) column. Detection was performed on a triple-quadrupole mass spectrometer utilizing electrospray ionization (ESI) interface operating in positive ion and selected reaction monitoring (SRM) mode with the precursor to product ion transitions m/z 226.2→152.1 for acyclovir and m/z 256.2→152.1 for the IS. Results The analytical results demonstrated a good linearity over the ranges from 0.005 to 4μg/mL (r=0.9999) for valacyclovir hydrochloride. The relative standard deviations (RSD) of intra-batch and inter-batch were less than 4.06% and 9.23%, respectively. The limit of detection and lower limit of quantification in human plasma were 2ng/mL and 5ng/mL, respectively. Conclusion The method was simple, sensitive, accurate and reproducible and has been successfully applied to a bioequivalence study of valacyclovir hydrochloride capsules in Chinese healthy male volunteers.

A high-performance liquid chromatography coupled with mass spectrometry (HPLC–MS) method was established for the separation and determination of acetyl-glutamine enantiomers (acetyl-L-glutamine and acetyl-D-glutamine) simultaneously. Baseline separation was achieved on Chiralpak AD-H column (250 mm × 4.6 mm, 5 μm). n-Hexane (containing 0.1% acetic acid) and ethanol (75:25, v/v) were used as mobile phase at a flow rate of 0.6 mL/min. The detection was operated in the negative ion mode with an ESI source. [M-H]? m/z 187.0540 for enantiomers and [M-H]? m/z 179.0240 for aspirin (IS) were selected as detecting ions. The linear range of the calibration curve for each enantiomer was 0.05–40 μg/mL. The precision of this method at concentrations of 0.5–20 μg/mL was within 7.23%, and the accuracy was 99.81%–107.81%. The precision at LOQ (0.05 μg/mL) was between 16.28% and 17.56%, which was poor than that at QC levels. The average extraction recovery was higher than 85% for both enantiomers at QC levels. The pharmacokinetics of enantiomers was found to be stereoselective. There was not chiral inversion in vivo or in vitro between enantiomers.

A high-performance liquid chromatography coupled with mass spectrometry (HPLC–MS) method was established for the separation and determination of acetyl-glutamine enantiomers (acetyl-L-glutamine and acetyl-D-glutamine) simultaneously. Baseline separation was achieved on Chiralpak AD-H column (250 mm × 4.6 mm, 5 μm). n-Hexane (containing 0.1% acetic acid) and ethanol (75:25, v/v) were used as mobile phase at a flow rate of 0.6 mL/min. The detection was operated in the negative ion mode with an ESI source. [M-H]? m/z 187.0540 for enantiomers and [M-H]? m/z 179.0240 for aspirin (IS) were selected as detecting ions. The linear range of the calibration curve for each enantiomer was 0.05–40 μg/mL. The precision of this method at concentrations of 0.5–20 μg/mL was within 7.23%, and the accuracy was 99.81%–107.81%. The precision at LOQ (0.05 μg/mL) was between 16.28% and 17.56%, which was poor than that at QC levels. The average extraction recovery was higher than 85% for both enantiomers at QC levels. The pharmacokinetics of enantiomers was found to be stereoselective. There was not chiral inversion in vivo or in vitro between enantiomers.

Aim To investigate the effects of CYP2C19 polymorphism on the pharmacokinetics and comparative bioavailability of omeprazole in Chinese population.Methods Eighteen healthy male volunteers were selected,of whom 6 were CYP2C19 wild type(w/w),6 were CYP2C19 heterozygous variant(w/m) and the rest were CYP2C19 homozygous variant(m/m).A randomized two-period crossover study was performed.Subjects were assigned to receive test or reference omeprazole as a single oral dose of 40 mg randomly.After a washout period of one week,subjects received the alternative omeprazole formulation.Multiple blood samples of 3 ml were obtained over 12 h after dosing and plasma concentrations of omeprazole were measured by LC/MS method.The modeling of individual pharmacokinetics and the pharmacokinetic parameters of omeprazole were estimated by 3P97.Results The AUC and Cmax of reference omeprazole formulation in w/w,w/m,m/m groups were 1178.44±340.24,2328.10±1011.83,5062.02±1097.29 μg·h·L~(-1) and 602.87±118.25,926.43±134.48,1406.29±233.58 μg·L~(-1),respectively,with significant differences among the three groups(P<0.05).Significant differences were also observed in other pharmacokinetic parameters such as k_e、CL/F、t_(1/2) and Vd/F among the three groups(P<0.05).With regard to test omeprazole formulation,the AUC and C_(max) in w/w,w/m,m/m groups were 1224.82±531.67,2723.34±519.29,5692.49±1575.35 μg·h·L~(-1) and 618.74±231.43,910.67±125.99,1303.31±152.01 μg·L~(-1),respectively,which,as well as k_e,CL/F,t_(1/2) and Vd/F were significant different among the three groups(P<0.05).No significant differences were observed in comparative bioavailability among groups with the values of 94.29%±14.06%,93.08%±11.22%,91.84%±13.03% in w/w,w/m,m/m groups respectively(P>0.05).Conclusions Different CYP2C19 genotypes,leading to functional heterogeneity of CYP2C19,may affect pharmacokinetic profile of omeprazole.Therefore,genotyping CYP2C19 gene before omeprazole therapy will be of great benefit for optimizing individual therapy regimen.There is no significant difference of omeprazole comparative bioavailability with regard to CYP2C19 genetic polymorphism.

An LC-MS/MS method was developed to investigate the pharmacokinetic parameters in healthy Chi-nese volunteers following single and multiple oral administration of dimemorfan phosphate. In the Single-dose study,two-period and crossover study was conducted in 12 healthy volunteers,which were administered with single-dose of 10 mg or 40 mg of dimemorfan phosphate. And another 12 volunteers were administered with 20 mg. The values of AUC0-48 h,t1/2,and cmax were (11. 81 ±14. 46),(52. 60 ±96. 01 )and (34. 70 ±29. 59)ng. h/mL,(12. 11 ±2. 54),(12. 16 ±2. 01)and (12. 77 ±1. 27)h,and (0. 9653 ±0. 8178),(3. 150 ±3. 451)and (2. 167 ±1. 650)ng/mL for 10 mg,40 mg and 20 mg oral administration. The same 12 healthy volunteers as the group of single-dose of 20mg were participated in multiple-dose study,which were administered dimemorfan phos-phate 20 mg,three-time a day until the day-8,showed AUC0-48 h,t1/2,and cmax were (115. 9 ±135. 2)ng.h/mL, (11. 22 ±1. 61)h,and (7. 418 ±7. 010)ng/mL. The accumulation parameter Rcmax and RAUC was (3. 14 ±1. 34) and (3. 38 ±1. 22),respectively. Dose proportional of cmax and AUC was not concluded ranging from 10 mg to 40 mg after confidence interval criteria method. An accumulation was occurred after multiple -dose administra-tion with the consequence. And the results demonstrated significant individual difference.

Aim: To establish an analytical method for the simultaneous determination of norfloxacin,ofloxacin,pefloxacin,ciprofloxacin,lomefloxacin,danofloxacin,enrofloxacin,sarafloxacin and difloxacin in eggs using solid-phase extraction-LC-MS/MS.Methods: Egg samples were deproteinized with acetonitrile,followed by defatting with hexane.Then the samples were processed by solid-phase extraction and analyzed by LC-MS/MS using an electrospray source.The separation was carried out on a Shimadzu Shim-pack VP-ODS C_(18) column,with a mobile phase consisting of acetonitrile-0.1% formic acid(13: 87).Results: The validated method was proved to be of high specificity,accuracy and sensitivity.Conclusion: The established method is suitable for the routine residual monitoring of fluoroquinolones.

Object To investigate the chromatographic fingerprints of Radix Salviae Miltiorrhizae (RSM), its intermediate and INJECTION by HPLC-UV-MS. Methods Separation was performed on an Alltima C 18 analytical column with the mobile phase consisting of methanol-water-acetic acid as gradient eluent at the flow rate of 1 mL/min. The UV detection was set at 281 nm and TIC was recorded by an electrospray ionization mass spectrometer in negative ion mode. Results The HPLC-UV and HPLC-MS fingerprints of RSM, its intermediate and INJECTION were obtained with perfect isolation. Conclusion The fingerprints could be used for the control of RSM, its intermediate and INJECTION.