LC-MS/MS method for the determination of cynandione A in rat plasma and tissues

A rapid and sensitive method using liquid chromatography-tandem mass spectroscopy (LC-MS/MS) was developed and validated for the quantitative determination of cynandione A in rat plasma and tissues. The plasma samples were pretreated by liquid-liquid extraction with ethyl acetate after the internal standard (honokiol) had been spiked. The tissue samples were homogenized with physiological saline and treated further like the plasma samples. The separation was performed using a Zorbax SB-C(18) column (3.5 microm, 2.1 x 100 mm) and a C18 guard column (5 microm, 4.0 x 2.0 mm) with an isocratic mobile phase consisting of methanol-0.1% formic acid (78:22, v/v) at a flow rate of 0.2 mL/min. The Agilent G6410A triple quadrupole LC/MS system was operated under the multiple-reaction monitoring mode using the electrospray ionization technique in negative mode. The nominal retention times for cynandione A and honokiol were 1.41 and 2.63 min, respectively. The method was validated within the concentration range 0.2-1000 ng/mL in plasma and homogenized tissue for cynandione A, and the calibration curves were linear with correlation coefficients >0.992. The lower limit of quantification of cynandione A was 0.2 ng/mL. The intra-day and inter-day precision and accuracy of the assay in plasma were less than 14.4%, while the intra-day and inter-day precision and accuracy of the assay in tissue homogenate were less than 14.2%. This method proved to be suitable for study of pharmacokinetics and tissue distribution of cynandione A in rat.     

Simultaneous determination of tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone in rat plasma by liquid chromatography-tandem mass spectrometry: application to a pharmacokinetic study of a standardized fraction of Salvia miltiorrhiza, PF2401-SF

A rapid, sensitive and selective liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for the simultaneous determination of tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone, the active components of Salvia miltiorrhiza in rat plasma, was developed. After liquid-liquid extraction with tariquidar as an internal standard, tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone were eluted from an Atlantis dC18 column within 5 min with a mixture of methanol and ammonium formate (10 mm, pH 6.5; 85:15, v/v). The analytes were detected by an electrospray ionization tandem mass spectrometry in the selected reaction monitoring (SRM) mode. The standard curves were linear (r=0.999) over the concentration range of 0.25-80 ng/mL for tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone in rat plasma. The coefficients of variation and the relative errors of tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone for intra- and inter-assay at four quality control (QC) concentrations were 1.1-5.1% and -4.0-6.0%, respectively. The lower limit of quantification for tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone was 0.25 ng/mL from 100 microL of plasma. This method was successfully applied to the pharmacokinetic study of tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone after oral administration of PF2401-SF, the standardized fraction of Salvia miltiorrhiza enriched with tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone to male Sprague-Dawley rats.     

Simultaneous determination of tanshinone IIA and its three hydroxylated metabolites by liquid chromatography/tandem mass spectrometry

A rapid and sensitive method based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the simultaneous determination of tanshinone IIA and its three hydroxylated metabolites, tanshinone IIB, hydroxytanshinone IIA and przewaquinone A, in a rat liver microsome was developed and fully validated. A single step of liquid-liquid extraction with ethyl acetate was utilized in this method. Chromatographic separation of the sample matrix from the analytes and the internal standard diazepam was performed using a Shim-pack VP-ODS analytical column. Detection was performed on a triple quadrupole tandem mass spectrometer equipped with an electrospray ionization source and operated in selected reaction monitoring (SRM) mode. The method was linear in the concentration range of 1-500 ng/mL for all analytes. The intra- and inter-day precisions (RSD %) were within 15% and deviations of the assay accuracies were within 15.0% for all analytes. The analytes proved to be stable during sample storage, preparation and analyses. This validated method was successfully applied to the enzyme kinetic study of tanshinone IIA in liver microsome. The elimination of tanshinone IIA and formation of tanshinone IIB and hydroxytanshinone IIA in the liver microsome all exhibited a sigmoidal kinetics profile. The formation of przewaquinone A shows a typical hyperbolic profile. In addition, this method has now been applied in the analysis of other bio-samples including plasma, urine, bile and feces.     

Characterization of metabolites of tanshinone IIA in rats by liquid chromatography/tandem mass spectrometry

The metabolism of tanshinone IIA was studied in rats after a single-dose intravenous administration. In the present study, 12 metabolites of tanshinone IIA were identified in rat bile, urine and feces with two LC gradients using LC-MS/MS. Seven phase I metabolites and five phase II metabolites of tanshinone IIA were characterized and their molecular structures proposed on the basis of the characteristics of their precursor ions, product ions and chromatographic retention time. The seven phase I metabolites were formed, through two main metabolic routes, which were hydroxylation and dehydrogenation metabolism. M1, M4, M5 and M6 were supposedly tanshinone IIB, hydroxytanshinone IIA, przewaquinone A and dehydrotanshinone IIA, respectively, by comparing their HPLC retention times and mass spectral patterns with those of the standard compounds. The five phase II metabolites identified in this research were all glucuronide conjugates, all of which showed a neutral loss of 176 Da. M9 and M12 were more abundant than other identified metabolites in the bile, which was the main excretion path of tanshinone IIA and the metabolites. M12 was the main metabolite of tanshinone IIA. M9 and M12 were proposed to be the glucuronide conjugates of two different semiquinones and these semiquinones were the hydrogenation products of dehydrotanshinone IIA and tanshinone IIA, respectively. This hydrogenized reaction may be catalyzed by the NAD(P)H: quinone acceptor oxidoreductase (NQO). The biotransformation pathways of tanshinone IIA were proposed on the basis of this research.     

Pharmacokinetic comparison of five tanshinones in normal and arthritic rats after oral administration of Huo Luo Xiao Ling Dan or its single herb extract by UPLC‐MS/MS

A fast, sensitive and reliable ultra performance liquid chromatography–tandem mass spectrometry (UPLC‐MS/MS) method has been developed and validated for simultaneous quantitation and pharmacokinetic study of five tanshinones (tanshinone I, tanshinone IIA, tanshinone IIB, dihydrotanshinone I, cryptotanshinone), the bio‐active ingredients of Huo Luo Xiao Ling Dan (HLXLD) in rat plasma. After liquid–liquid extraction, chromatographic separation was accomplished on a Shim‐pack XR‐ODS column (75 × 3.0 mm, 2.2 µm particles) and eluted with a mobile phase consisting of acetonitrile–0.05% formic acid aqueous solution (80:20, v/v) at a flow rate of 0.4 mL/min, and the total run time was 7.0 min. The detection was performed on a triple quadrupole tandem mass spectrometry equipped with an electrospray ionization source in positive ionization and multiple reaction monitoring mode. The lower limits of quantification were 0.050–0.400 ng/mL for all the analytes. Linearity, precision and accuracy, the mean extraction recoveries and matrix effects all satisfied criteria for acceptance. This validated method was successfully applied to a comparative pharmacokinetic study of five bio‐active components in rat plasma after oral administration of HLXLD or Salvia miltiorrhiza extract in normal and arthritic rats. The results showed that there were different pharmacokinetic characteristics among different groups. Copyright © 2016 John Wiley & Sons, Ltd.     

Determination of plasma topiramate concentration using LC-MS/MS for pharmacokinetic and bioequivalence studies in healthy Korean volunteers

A rapid, simple and validated liquid chromatography coupled to tandem mass spectrometric method (LC-MS/MS) for topiramate analysis in human plasma has been applied to pharmacokinetic and bioequivalence studies in 24 healthy male Korean volunteers. The procedure involves a simple liquid extraction of topiramate and prednisone (internal standard) with acetonitrile and separation by HPLC equipped with a Capcell Pak C18 column using acetonitrile-0.1% triethylamine (80:20, v/v) as a mobile phase. Detection was carried out on an API 2000 MS system by multiple reactions monitoring mode. The ionization was optimized using ESI(-) and selectivity was achieved by MS/MS analysis, m/z 338.0 --> 77.5 and m/z 357.1 --> 327.2 for topiramate and prednisone, respectively. The method had a total run time of 2.5 min and showed good linearity over a working range of 20-5000 ng/mL in human plasma with a lower limit of quantification of 20 ng/mL. No metabolic compounds were found to interfere with the analysis. The inter-day and intra-day accuracy were in the ranges of 99.24-116.63 and 93.45-108.68%, respectively, and inter-day and intra-day precisions were below 6.24 and 5.25%, respectively. This method was successfully applied for pharmacokinetic and bioequivalence studies by analysis of blood samples taken up to 96 h after an oral administration of 100 mg of topiramate in 24 healthy Korean volunteers.     

液相色谱-电喷雾串联质谱法检测鸡组织中5种聚醚类药物残留

建立了鸡组织中聚醚类药物多残留检测的高效液相色谱-电喷雾串联质谱方法。采用甲醇提取鸡组织中的拉沙洛菌素、盐霉素、莫能菌素、甲基盐霉素和马杜霉素,经硅胶柱净化,以乙腈(含0.1%甲酸)-0.1%甲酸水溶液(体积比为97:3)为流动相,Symmetry Shield RP18作为色谱分析柱,多反应监测(MRM)正离子扫描方式进行质谱检测。当5种聚醚类药物的添加水平为鸡肉0.1～1500 μg/kg、鸡肝0.2～4500 μg/kg时,平均回收率为71.6%～99.1%,日内测定的相对标准偏差(RSD)(n=5)为3.2%～10.7%,日间RSD(n=3)为4.6%～14.7%。2种鸡组织中5种聚醚类药物的定量限为0.1～1.0 μg/kg。该方法的灵敏度、准确度和精密度均符合兽药残留分析技术的要求,适用于鸡肉和鸡肝中5种聚醚类药物的多残留检测。     

The high throughput analysis of N-methyl carbamate pesticides in fruits and vegetables by liquid chromatography electrospray ionization tandem mass spectrometry using a short column

We developed a new analysis method for the nine N-methyl carbamate pesticides in fruits and vegetables using ESI LC/MS/MS with direct sample injection into a short column. After extraction of the pesticides with ethyl acetate from sample, the extract is evaporated to dryness and redissolved in ultra pure water before injection into LC/MS/MS. The method needs no cleanup steps. The average recoveries from fruits and vegetables fortified at the level of 0.01 μg/g ranged from 56.0 to 119.1% with the coefficients of variation ranging from 0.2 to 7.6% for intra-day (n = 5 × 3 days) and from 0.8 to 18.4% for inter-day (n = 15). At the fortified level of 0.5 μg/g, the recoveries ranged from 67.7 to 119.3% with the coefficients of variation ranging from 0.5 to 7.8% for intra-day (n = 5 × 3 days) and from 0.9 to 14.8% for inter-day (n = 15). The method is considered to be satisfactory for the monitoring of the carbamate pesticide residues in fruits and vegetables, suggesting that the present method is applicable to other pesticide residues in foods.     

Development of a rapid and sensitive liquid chromatography/tandem mass spectrometry method for the determination of 1,2-[bis(1,2-benzisoselenazolone-3(2H)-ketone)]-ethane (BBSKE), a novel anti-cancer agent in rat plasma

A rapid and sensitive liquid chromatography/electrospray ionization tandem mass spectrometric (LC/ESI-MS/MS) method has been developed to determine 1, 2-[bis(1,2-benzisoselenazolone-3(2H)-ketone)]-ethane (BBSKE), a novel antineoplastic agent, in rat plasma. The analytes were separated on a C18 column with a mobile phase of methanol-water (75:25, v/v) and detected using a triple-quadrupole mass spectrometer in positive mode with the selective reaction monitoring. The characteristic ion dissociation transitions were m/z 603.0 --> 448.9 for derivatized BBSKE and m/z 631.0 --> 476.8 for derivatized internal standard. The assay was linear over a range of 1-1000 ng/mL with a lower limit of quantification of 1 ng/mL. Intra- and inter-day precisions were less than 9.6 and 5.0%, respectively, and the accuracy ranged from -5.2 to 4.0%. The validated method was successfully applied to the characterization of pharmacokinetic profile of BBSKE after oral administration in rats. Cop     

A rapid and specific approach for direct measurement of donepezil concentration in human plasma by LC-MS/MS employing solid-phase extraction

A selective, rapid and simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) method is described for assay of donepezil in human plasma using escitalopram as an internal standard. Chromatographic separation was achieved on a Betabasic-C(8), 5 microm, 100 x 4.6 mm column using methanol:water:formic acid (90:9.97:0.03, v/v/v) as mobile phase. Detection of donepezil and internal standard was achieved by ESI MS/MS in positive ion mode using 380.20/91.10 and 325.13/262.00 transitions, respectively. The linearity over the concentration range of 0.15-50 ng/mL for donepezil was obtained and the lower limit of quantification was 0.15 ng/mL. For each level of quality control samples, inter-day and intra-day precisions (RSD) were < or =8.92 and 10.35% and accuracy (%RE) were < or =7.33% and 9.33%, respectively. The recovery was more than 88.50% for both donepezil and internal standard by solid-phase extraction, eliminating evaporation and reconstitution steps.     

Toxicokinetic and bioavailability studies on retrorsine in mice,and ketoconazole-induced alteration in toxicokinetic properties

Retrorsine (RTS) is a toxic retronecine-type pyrrolizidine alkaloid, which is widely distributed. The purpose of this study was to develop a high-performance liquid chromatography–tandem mass spectrometric (LC–MS/MS) method for serum RTS determination in mice. Serum samples were deproteinated by acetonitrile, separated on a C₁₈-PFP column and delivered at 0.8 ml/min with an eluting system composed of water containing 0.1% (v/v) formic acid and acetonitrile containing 0.1% (v/v) formic acid as mobile phases. RTS and the internal standard S-hexylglutathione (H-GSH) were quantitatively monitored with precursor-to-product transitions of m/z 352.1 → 120.1 and m/z 392.2 → 246.3, respectively. The method showed excellent linearity over the concentration range 0.05–50 μg/ml, with correlation coefficient r² = 0.9992. The extraction recovery was >86.34%, and the matrix effect was not significant. Inter- and intra-day precisions (RSD) were <4.99%. The validated LC–MS/MS method was successfully applied to study the toxicokinetic profiles of serum RTS in mice after intravenous, oral administration and co-treated with ketoconazole, which showed that RTS displayed a long half-life (~11.05 h) and good bioavailability (81.80%). Co-administration of ketoconazole (KTZ) increased the peak serum concentration and area under the concentration–time curve and decreased the clearance and mean residence time. Summing up, a new standardized method was established for quantitative determination of RTS in sera.     

Identification of tanshinone IIA metabolites in rat liver microsomes by liquid chromatography-tandem mass spectrometry

Tanshinone IIA, the major component extracted from Radix salvia miltiorrhiza, has been observed to possess various kinds of pharmacological activities including antioxidant, prevention of angina pectoris and myocardial infarction and anticancer. Tanshinone IIA was incubated with rat liver microsomes and the resulting metabolites were identified by liquid chromatography/tandem mass spectrometry. The results showed the formation of three main hydroxyl metabolites. The three hydroxyl metabolites of tanshinone IIA were proved to be tanshinone IIB, hydroxytanshinone IIA and przewaquinone A by comparing the tandem mass spectra and the chromatographic retention time with that of the respective authentic compounds. Tanshinone IIB, hydroxytanshinone IIA and przewaquinone A are all the chemical components of total tanshinones. It was reasonable to presume that the three hydroxy metabolites of tanshinone IIA were pharmacologically active the same as tanshinone IIA and the total tanshinones.     

Quantitative determination of periplocymarin in rat plasma and tissue by LC‐MS/MS: application to pharmacokinetic and tissue distribution study

A simple, rapid and sensitive liquid chromatography with tandem mass spectrometry (LC‐MS/MS) method for the determination of periplocymarin in biological samples was developed and successfully applied to the pharmacokinetic and tissue distribution study of periplocymarin after oral administration of periplocin. Biological samples were processed with ethyl acetate by liquid–liquid extraction, and diazepam was used as the internal standard. Periplocymarin was analyzed on a C₁₈ column with isocratic eluted mobile phase composed of methanol and water (containing 0.1% formic acid) at a flow rate of 0.2 mL/min (73:27, v/v). Detection was performed on a triple‐quadrupole tandem mass spectrometer using positive‐ion mode electrospray ionization in the selected reaction monitoring mode. The MS/MS ion transitions monitored were m/z 535.3→355.1 and 285.1→193.0 for periplocymarin and diazepam, respectively. Good linearity was observed over the concentration ranges. The lower limit of quantification was 0.5 ng/mL in plasma and tested tissues. The intra‐and inter‐day precisions (relative standard deviation) were <10.2 and 10.5%, respectively, and accuracies (relative error) were between ?6.8 and 8.9%. Recoveries in plasma and tissue were >90%. The validated method was successfully applied to the pharmacokinetic and tissue distribution studies of periplocymarin in rats. Copyright © 2016 John Wiley & Sons, Ltd.     

Determination of sodium tanshinone IIA sulfonate in plasma by liquid chromatography-electrospray ionisation-tandem mass spectrometry

Sodium tanshinone IIA sulfonate (STS) is a water-soluble derivative of tanshinone IIa, an important lipophilic component contained in Salvia miltiorrhizae. A simple, sensitive and robust quantification method for STS based on LC-ESI-MS/MS was developed and validated, and has been successfully applied to the pharmacokinetic study. Liquid-liquid extraction was used for extracting STS from biological samples, with a satisfactory recovery exceeding 75% at all test concentrations. Isocratic mobile phase consisted of 75% acetonitrile and 25% water containing 0.005% ammonia acetate (pH 3). Good retention and baseline separation for STS and the selected internal standard, diclofenac sodium, were obtained on a Shim-pack VP-ODS analytical column under this condition. The method was linear in the concentration range of 1-500 ng/mL. The intra- and inter-day precisions (RSD%) were within 9.0%. The deviation of the assay accuracies was within +/-10.0%. STS was proved to be stable during all sample storing, preparation and analytic procedures. With a lower limit of quantitation at 1 ng/mL, this method has been proved to be sensitive enough for the pharmacokinetic study of STS. The plasma profile of STS followed a single intravenous dosing was well fitted to a three compartmental model.     

Simultaneous determination and pharmacokinetic study of water-soluble and lipid-soluble components of danshen in rat plasma using HPLC-UV method

A sensitive and specific HPLC-UV method was developed for the simultaneous determination of major active components of danshen in rat plasma. Both water-soluble and lipid-soluble compounds were included, i.e. danshensu, salvianolic acid B and tanshinone IIA. Protocatechuic aldehyde and diazepam were used as internal standards. The chromatographic separation was achieved on a reversed-phase C(18) column by gradient elution using acetonitrile and 0.025% (v/v) phosphoric acid solution as mobile phase, at a flow rate of 1.0 mL/min. Salvianolic acid B, danshensu and internal standards were detected at 281 nm, while the detection of tanshinone IIA was carried out at 272 nm. All calibration curves showed good linearity (r(2) > 0.999) within test ranges. The limit of detection and the limit of quantification for danshensu, salvianolic acid B and tanshinone IIA in plasma were 0.065, 0.043, 0.022, 0.131, 0.085 and 0.044 microg/mL, respectively. This is the first report on the determination and pharmacokinetic study of danshensu, salvianolic acid B and tanshinone IIA in rat plasma and the results indicated that this method was reliable for the determination of the major active components of danshen in rat plasma.     

Determination of fifteen bioactive components in Radix et Rhizoma Salviae Miltiorrhizae by high-performance liquid chromatography with ultraviolet and mass spectrometric detection

A high-performance liquid chromatographic (HPLC) method coupled with ultraviolet (UV) and electrospray ionization time-of-flight mass spectrometry (ESI-TOF/MS) was established for simultaneous qualitative and quantitative determination of nine phenolic acids and six diterpenoids in Radix et Rhizoma Salviae Miltiorrhizae (RRSM). The optimal chromatographic conditions were achieved on a Zorbax C(18) column by gradient elution with 0.1% (v/v) aqueous formic acid and acetonitrile as mobile phase at the flow rate of 1.0 mL/min. The detection wavelength at 281 nm was chosen to determine the 15 bioactive components, namely danshensu (1), protocatechuic acid (2), protocatechuic aldehyde (3), caffeic acid (4), rosmarinic acid (5), lithospermic acid (6), salvianolic acid B (7), salvianolic acid A (8), salvianolic acid C (9); dihydrotanshinone I (10), cryptotanshinone (11), tanshinone I (12), methylene tanshiqunone (13), tanshinone IIA (14) and miltirone (15). Additionally, LC-ESI-TOF/MS was used to make definite identification of the constituents in samples in comparison with those reference compounds. The validation of the method included tests of linearity, sensitivity, repeatability, stability and recovery. The proposed method was successfully applied to quantify the 15 components in 21 samples; significant variations were demonstrated in the contents of the samples from diverse species and origins. The developed method could be used to effectively and comprehensively evaluate the quality of RRSM for its clinical safety and efficacy.     

Pharmacokinetics and tissue distribution study of bisabolangelone from Angelicae Pubescentis Radix in rat using LC–MS/MS

A sensitive and accurate LC–MS/MS method was established for quantifying bisabolangelone in rat plasma and tissues. Bisabolangelone was isolated and purified from Angelicae Pubescentis Radix. The pharmacokinetic and tissue distribution of bisabolangelone after administration to rat was performed by LC–MS/MS. Separation was carried out on a C₈ (4.6 × 100 mm, 1.8 μm) column. The MS/MS transitions of bisabolangelone and tussilagone (internal standard) were set at m/z 249.1 → 109.1 and m/z 391.4 → 217.4, respectively. The lower limit of quantification in plasma and other tissues ranged from 1 to 4 ng/mL. The biosamples were prepared using protein precipitation method with acetonitrile. The recovery was >92%. The results showed that values of maximum concentrations and area under the curve depended linearly on the studied doses (2.5, 5 and 7.5 mg/kg body weight). The other ingredients in Angelicae Pubescentis Radix extract possibly reduce the absorption of bisabolangelone in rat. Tissue distribution revealed that bisabolangelone was widely distributed in vivo. The highest and lowest concentrations of bisabolangelone were found in the stomach and in the brain, respectively. It was concluded that the newly established HPLC–MS/MS method was suitable to describe the pharmacokinetic characteristics of bisabolangelone in rat after administration.     

Quantification of rosiglitazone in rat plasma and tissues via LC–MS/MS: Method development,validation, and application in pharmacokinetic and tissue distribution studies

A bioanalytical method for the quantification of rosiglitazone in rat plasma and tissues (adipose tissue, heart, brain, bone, and kidney) using LC–MS/MS was developed and validated. Chromatographic separation was achieved on a Gemini C₁₈ column (50 × 4.6 mm, 3 μm) using a mobile phase consisting of 10 mM ammonium formate (pH 4.0) and acetonitrile (10:90, v/v) at a flow rate of 0.8 mL/min and injection volume of 10 μL (internal standard: pioglitazone). LC–MS detection was performed with multiple reaction monitoring mode using target ions at m/z → 358.0 and m/z → 357.67 for rosiglitazone and pioglitazone (internal standard), respectively. The calibration curve showed a good correlation coefficient (r²) over the concentration range of 1–10,000 ng/mL. The mean percentage recoveries of rosiglitazone were found to be over the range of 92.54–96.64%, with detection and lower quantification limit of 0.6 and 1.0 ng/mL, respectively. The developed method was validated per U.S. Food and Drug Administration guidelines and successfully utilized to measure rosiglitazone in plasma and tissue samples. Further, the developed method can be utilized for validating specific organ-targeting delivery systems of rosiglitazone in addition to conventional dosage forms.     

Determination of tanshinone I in rat plasma by high-performance liquid chromatography and its application to pharmacokinetic studies

This paper describes a rapid and sensitive high-performance liquid chromatographic (HPLC) method for the determination of the concentration of tanshinone I in rat plasma, and applies the method to pharmacokinetic study. The plasma is deproteinized with acetonitrile containing an internal standard (estradiolbenzoate). The HPLC assay is carried out using a Cosmosil C18 column. The mobile phase is acetonitrile, 0.05 mol/L(-1) ammonium acetate buffer with 1% acetic acid (66:34, v/v). The flow rate is 1.0 mL/min. The detection wavelength is set at 263 nm. The assay accuracy is better than 92%, and the precision of tanshinone I at low to high concentrations is better than 9% and 11% for intra-day and inter-day assays, respectively. The recovery of the method exceeds 88.3% for tanshinone I. The assay shows good linearity (r = 0.9998) over a relatively wide concentration range from 0.05 to 10.0 microg/mL. The method is used to determine the concentration-time profiles of tanshinone I in plasma following an intravenous injection of tanshinone I solution, and the pharmacokinetic parameters of tanshinone I are calculated for the first time by the Drug and Statistics 1.0 program. This assay is successfully applied to the determination of tanshinone I in rat plasma, and the developed method is applied to pharmacokinetic studies for the first time.     

Rapid and sensitive liquid chromatography tandem mass spectrometry method for the quantification of ambroxol in human plasma

A sensitive, specific and rapid high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was described and validated for the quantification of ambroxol in human plasma using enalaprilat as the internal standard (IS). Chromatographic separation was performed on a Lichrospher CN column with a mobile phase of methanol and water (containing 0.1% formic acid) (70:30, v/v). The total run time was 5.0 min for each sample. The analytes was detected by mass spectrometry with electrospray ionization source in positive selected reaction monitoring mode. The precursor-fragment ion reaction for ambroxol was m/z 378.9 --> 263.8, and for IS was m/z 349.0 --> 205.9. The linearity was established over the concentration range of 1.56-400.00 ng/mL. The inter-day and the intra-day precisions were all within 10%. A simple protein precipitation with methanol was adopted for sample preparation. The extraction recoveries of ambroxol and IS were higher than 90.80%. The validated method was successfully applied in pharmacokinetic study after oral administration of 90 mg ambroxol to 24 healthy volunteers.