UPLC–MS/MS assay for simultaneous determination of four compounds in rat plasma: application to pharmacokinetic study after oral administration of Caulis Spatholobi extract

An ultra‐performance liquid chromatography tandem mass spectrometry method was developed for the simultaneous determination of protocatechuic acid, catechin, gallocatechin and formononetin in rat plasma, with genkwanin as the internal standard in this study. Plasma samples were prepared by liquid–liquid extraction with ethyl acetate. The four components were separated on an Agilent Zorbax Eclipse Plus C₁₈ column (2.1 × 50 mm, 1.8 μm) with the mobile phase consisting of water containing 0.05% formic acid and methanol (35:65, v/v), and detected by negative ion electrospray ionization in the selected reaction monitoring mode. The method was linear for all analytes over the investigated ranges, with all correlation coefficients >0.99. The validated lower limit of quantification was 0.5 ng/mL for protocatechuic acid, catechin, and gallocatechin and 0.8 ng/mL for formononetin. The intra‐ and inter‐day precisions (RSD, %) were <13.1%, and accuracy (RE, %) ranged from ?13.8 to 9.9%. The mean absolute extraction recoveries of the analytes and internal standard from rat plasma were all >80.7%. The validated method was successfully applied for the first time to investigate the pharmacokinetics of four chemical ingredients after oral administration of Caulis Spatholobi Extract in rats. Copyright © 2016 John Wiley & Sons, Ltd.     

Simultaneous determination of three active components in rat plasma by UPLC–MS/MS: Application to pharmacokinetic study after oral administration of Herba Sarcandrae extract

A rapid, specific and sensitive ultra‐performance liquid chromatography tandem mass spectrometry (UPLC‐MS/MS) method was developed and validated for determination of isofraxidin, rosmarinic acid and kaempferol‐3‐O ‐glucuronide in rat plasma using warfarin as an internal standard (IS). Separation was conducted on a Thermo Hypersil GOLD C₁₈ column with linear gradient elution using methanol and water. Mass spectrometric detection was conducted using selected reaction monitoring (SRM) via an electrospray ionization (ESI) source. All analytes exhibited good linearity within their concentration ranges (r > 0.9990). The lower limits of quantitations of isofraxidin, rosmarinic acid, and kaempferol‐3‐O‐ glucuronide were 1.31, 0.67 and 0.92 ng/mL, respectively. Intra‐ and inter‐day precisions of these investigated components exhibited an RSD within 11.7%, and the accuracy ranged from −12.5 to 15.0% at all QC levels. The developed method was successfully applied to a pharmacokinetic study of isofraxidin, rosmarinic acid, and kaempferol‐3‐O‐ glucuronide in rats after oral administration of Herba Sarcandrae Extract.     

Development and validation of a UPLC‐MS/MS method for the determination of cucurbitacin B in rat plasma and application to a pharmacokinetic study

Cucurbitacin B (CuB), one of the most abundant forms of cucurbitacins, is a promising natural anticancer drug candidate. Although the anticancer activity of CuB has been well demonstrated, information regarding the pharmacokinetics is limited. A rapid, selective and sensitive UPLC‐MS/MS for CuB was developed and validated using hemslecin A (HeA) as internal standard (IS). Plasma samples were pre‐treated by liquid–liquid extraction with dichloromethane. Separation was achieved on a reversed‐phase C₁₈ column (50 × 4.6 mm, 5 µm) at 35°C using isocratic elution with water–methanol (25:75, v/v) at a flow rate of 0.3 mL/min. The analytes were monitored by a triple quadrupole tandem mass spectrometer with positive electrospray ionization mode. The calibration curve was linear (r > 0.995) in a concentration range of 0.3–100 ng/mL with a limit of quantification of 0.3 ng/mL. Intra‐ and inter‐day accuracy and precision were validated by percentage relative error and relative standard deviation, respectively, which were both lower than the limit of 15%. This assay was successfully applied to a pharmacokinetic study of CuB in Wistar rats. Copyright © 2015 John Wiley & Sons, Ltd.     

Simultaneous determination of glaucocalyxin A and glaucocalyxin B in rat plasma by LC‐MS/MS and its application to a pharmacokinetic study after oral administration of Rabdosia japonica extract

A specific and sensitive liquid chromatography tandem mass spectrometry (LC‐MS/MS) method was developed and validated for the analysis of glaucocalyxin A and glaucocalyxin B in rat plasma using praeruptorin A as an internal standard. Separation was performed on a Hypurity C₁₈ column (2.1 × 50 mm, 5 μm) with isocratic elution using 0.2% formic acid in water–acetonitrile (20:80, v/v). Mass spectrometric detection was conducted using selected reaction monitoring via an electrospray ionization source. Both analytes exhibited good linearity within their concentration ranges (r² > 0.9932). The lower limit of quantitation of glaucocalyxin A and glaucocalyxin B was 1.10 ng/mL. Intra‐ and inter‐day precision exhibited an RSD within 14.5%, and the accuracy (RE) ranged from –12.1 to 15.0% at the lower limit of quantitation and three quality control levels. The developed assay was successfully applied to a pharmacokinetic study of glaucocalyxin A and glaucocalyxin B in rats after oral administration of Rabdosia japonica extract.     

A validated LC‐MS/MS method for rapid determination of brazilin in rat plasma and its application to a pharmacokinetic study

Brazilin is a major homoisoflavonoid component isolated from the dried heartwood of traditional Chinese medicine Caesalpinia sappan L., which is a natural red pigment used for histological staining. Herein a sensitive, specific and rapid analytical LC‐MS/MS method was established and validated for brazilin in rat plasma. After a simple step of protein precipitation using acetonitrile, plasma samples were analyzed using an LC‐MS/MS system. Brazilin and the IS (protosappanin B) were separated on a Diamonsil C₁₈ analytical column (150 × 4.6 mm, 5 µm) using a mixture of water and 10 mm ammonium acetate in methanol (20:80, v/v) as mobile phase at a flow rate of 0.6 mL/min. The method was sensitive with a lower limit of quantitation of 10.0 ng/mL, with good linearity (r² ≥ 0.99) over the linear range 10.0–5000 ng/mL. All the validation data, such as accuracy and precision, matrix effect, extraction recovery and stability tests were within the required limits. The assay method was successfully applied to evaluate the pharmacokinetics parameters of brazilin after an oral dose of 100 mg/kg brazilin in rats. Copyright © 2013 John Wiley & Sons, Ltd.     

Development and validation of LC‐MS/MS method for simultaneous determination of sofosbuvir and daclatasvir in human Plasma: Application to pharmacokinetic study

A simple and highly sensitive liquid chromatography–tandem mass spectrometry (LC‐MS/MS) bioanalytical method was developed and fully validated for the first time for the simultaneous determination of newly discovered antiviral drugs, namely sofosbuvir (SOF) and daclatasvir (DAC) in human plasma. Tadalafil (TAD) was used as internal standard (IS). SOF, DAC and TAD (IS) were extracted from plasma using liquid–liquid extraction technique with methyl tert‐butyl ether. The chromatographic separation was carried out using ZorbaxSB‐C₁₈ column (4.6 × 50 mm,5 μm) and 5 mm ammonium formate buffer (pH 3.5)–acetonitrile (50:50, v/v) as mobile phase in an isocratic elution mode pumped at a flow rate 0.7 mL min⁻¹. The quantitation was performed on API4500 triple quadrupole tandem mass spectrometer with positive electrospray ionization interface in multiple reaction monitoring mode. Validation was applied according to US Food and Drug Administration guidelines for bio‐analytical methodswith respect to linearity, precision, accuracy, selectivity, carry‐over, stability and dilution integrity. Linearity was obtained over concentration ranges of 0.3–3000 and 3–3000 ng mL⁻¹ for SOF and DAC, respectively, by applying a weighted least‐squares linear regression method (1/x²). The proposed method could be applied successfully in bioequivalence and/or clinical studies for therapeutic drug monitoring of patients undergoing dual combination therapy as the latter combination proved more efficacious and powerful tool for the complete treatment of hepatitis C genotype 3 within 16 weeks. The suggested method has been applied successfully to pharmacokinetic studies with excellent assay ruggedness and reproducibility.     

Simultaneous determination and pharmacokinetic study of gambogic acid and gambogenic acid in rat plasma after oral administration of Garcinia hanburyi extracts by LC‐MS/MS

Gambogic acid and gambogenic acid are two major bioactive components of Garcinia hanburyi, and play a pivotal role in biologic activity. In this study, a specific and sensitive liquid chromatography–tandem mass spectrometry was developed and validated for simultaneous determination of gambogic acid and gambogenic acid in rat plasma. Chromatographic separation was achieved on a C₁₈ column using an isocratic elution with methanol–10 m m ammonium acetate buffer–acetic acid (90:10:0.1, v/v/v) as the mobile phase. The detection was performed on a triple–quadrupole tandem mass spectrometer equipped with electrospray positive ionization using multiple reaction monitoring modes. The transitions monitored were m/z 629.3 [M + H]⁺ → 573.2 for gambogic acid, m/z 631.2 [M + H]⁺ → 507.2 for gambogenic acid and m/z 444.2 [M + NH₄]⁺ → 83.1 for IS. Linear calibration curves were obtained in the concentration range of 2.00–1000 ng/mL for gambogic acid and 0.500–250 ng/mL for gambogenic acid. The lower limits of quantification of gambogic acid and gambogenic acid in rat plasma were 2.00 and 0.500 ng/mL, respectively. The intra‐ and inter‐day precision (RSD) values were <11.7% and accuracy (RE) was ?10.6–12.4% at three QC levels for both analytes. The assay was successfully applied to evaluate pharmacokinetics behavior in rats after oral administration of Garcinia hanburyi extracts. Copyright © 2014 John Wiley & Sons, Ltd.     

A validated HPLC‐MS/MS method for determination of genipin‐1‐o‐glucuronic acid in rat plasma after administration of genipin and its application to a pharmacokinetic study

A sensitive and specific method was developed and validated for the quantitation of one major metabolite of genipin in rats plasma. The major metabolite was isolated from rat bile via semi‐preparative HPLC technology and its chemical structure was identified as genipin‐1‐o‐glucuronic acid (GNP‐GLU), which was for the first time used as a standard compound for quantitative analysis in rat plasma after administration of genipin. The application of high‐performance liquid chromatography–tandem mass spectrometry in negative mode in multiple reaction monitoring mode was investigated. Chromatographic separation was achieved on an Eclipse XDB‐C₁₈ column using a mobile phase consisting of water with 0.1% formic acid (A)–acetonitrile (B). The limit of detecation was 0.214 ng/mL and the lower limit of quantification was 0.706 ng/mL. The calibration curve was linear from 1.27 to 3810 ng/mL for plasma samples, with a correlation coefficient of 0.9924. The intra‐ and inter‐day precisions and accuracy were all within 15%. The recoveries of GNP‐GLU and puerarin were above 90.0 and 76.2%, respectively. The highly sensitive method was successfully applied to estimate pharmacokinetic parameters of GNP‐GLU following oral and intravenous administration of genipin to rats. Copyright © 2013 John Wiley & Sons, Ltd.     

Development and validation of HPLC‐MS/MS method for the determination of lixivaptan in mouse plasma and its application in a pharmacokinetic study

The aim of the present study was to develop a simple, sensitive and accurate liquid chromatography–electrospray ionization tandem mass spectrometry (ESI‐MS/MS) method for the determination of lixivaptan (LIX) in mouse plasma using vildagliptin as the internal standard (IS). A precipitation procedure was used for the extraction of LIX and vildagliptin from mouse plasma. Chromatographic separation of LIX was achieved using a C₁₈ analytical column (50 × 2.1 mm, 1.8 μm) at 25°C. The mobile phase comprised acetonitrile and ammonium formate (10 mm , pH 3.1; 40:60, v /v) pumped at a flow rate of 0.3 mL min⁻¹. A tandem mass spectrometer with an electrospray ionization source was used to perform the assay. Quantification of LIX at m/z 290 → 137 and IS at 154 → 97 was attained through multiple reaction monitoring. The investigated method was authenticated following the bio‐analytical method of validation guidelines of the US Food and Drug Administration. The developed method showed a good linearity over the concentration range from 5 to 500 ng mL⁻¹, and the calibration curve was linear (r = 0.9998). The mean recovery of LIX from mouse plasma was 99.2 ± 0.68%. All validation parameters for LIX were within the levels required for acceptance. The proposed method was effectively used for a pharmacokinetic study of LIX in mouse plasma.     

Development and validation of liquid chromatography-mass spectrometric method for simultaneous determination of moxifloxacin and ketorolac in rat plasma: application to pharmacokinetic study

A highly sensitive, selective and rapid liquid chromatography–electrospray ionization mass spectrometry (LC‐MS) method has been developed and validated for simultaneous determination of moxifloxacin (MFX) and ketorolac (KTC) in rat plasma. Gemifloxacin (GFX) was used as an internal standard (IS). A simple protein precipitation method was used for the extraction of analytes from rat plasma. Effective chromatographic separation of MFX, KTC and GFX was achieved on a Kromasil C₁₈ column (100 × 4.6 mm, 5 µm) using a mobile phase consisting of acetonitrile–10 mm ammonium acetate (pH 2.5)–0.1% formic acid (50:25:25) in an isocratic elution, followed by detection with positive ion electrospray ionization mass spectrometry using target ions of [M + H]⁺ at m/z 402 for MFX, m/z 256 for KTC and m/z 390 for GFX in selective ion recording mode. The method was validated over the calibration range of 5–100 ng/mL for MFX and 10–6000 ng/mL for KTC. The method demonstrated good performances in terms of intra‐ and inter‐day precision (0.97–5.33%) and accuracy (93.91–101.58%) for both MFX and KTC, including lower and upper limits of quantification. The recoveries from spiked control samples were >75% for MFX and >79% for KTC. The matrix effect was found to be negligible and the stability data were within acceptable limits. Further, the method was also successfully applied to a single‐dose pharmacokinetic study in rats. This method can be extended to measure plasma concentrations of both drugs in human to understand drug interaction and adverse effects. Copyright © 2012 John Wiley & Sons, Ltd.     

Determination of bergenin in human plasma after oral administration by HPLC-MS/MS method and its pharmacokinetic study

A highly sensitive, simple and selective high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed and applied to the determination of bergenin concentration in human plasma. Bergenin and the internal standard (IS) thiamphenicol in plasma were extracted with ethyl acetate, separated on a C(18 )reversed-phase column, eluted with mobile phase of acetonitrile-water, ionized by negative ion pneumatically assisted electrospray and detected in the multi-reaction monitoring mode using precursor --> product ions of m/z 327.1 --> 192 for bergenin and 354 --> 185.1 for the IS, respectively. The linear range of the calibration curve for bergenin was 0.25-60 ng mL(-1), with the lowest limit of quantification of 0.25 ng mL(-1), and the intra/inter-day relative standard deviation (RSD) was less than 10%. The method is suitable for the determination of low bergenin concentration in human plasma after therapeutic oral doses, and has been first and successfully used for its pharmacokinetic studies in healthy Chinese volunteers.     

An LC‐MS/MS method for determination of curculigoside with anti‐osteoporotic activity in rat plasma and application to a pharmacokinetic study

A rapid, simple, selective and sensitive LC‐MS/MS method was developed for the determination of curculigoside in rat plasma. The analytical procedure involves extraction of curculigoside and syringin (internal standard, IS) from rat plasma with a one‐step extraction method by protein precipitation. The chromatographic resolution was performed on an Agilent XDB‐C₁₈ column (4.6 × 50 mm, 5 µm) using an isocratic mobile phase of methanol with 0.1% formic acid and H₂O with 0.1% formic acid (45:55, v/v) at a flow rate of 0.35 mL/min with a total run time of 2.0 min. The assay was achieved under the multiple‐reaction monitoring mode using positive electrospray ionization. Method validation was performed according to US Food and Drug Administration guidelines and the results met the acceptance criteria. The calibration curve was linear over 4.00–4000 ng/mL (R = 0.9984) for curculigoside with a lower limit of quantification of 4.00 ng/mL in rat plasma. The intra‐ and inter‐day precisions and accuracies were 3.5–4.6 and 0.7–9.1%, in rat plasma, respectively. The validated LC‐MS/MS method was successfully applied to a pharmacokinetic study of curculigoside in rats after a single intravenous and oral administration of 3.2 and 32 mg/kg. The absolute bioavailability of curculigoside after oral administration was 1.27%. Copyright © 2013 John Wiley & Sons, Ltd.     

LC–MS/MS method for simultaneous determination of flavonoids and physalins in rat plasma: Application to pharmacokinetic study after oral administration of Physalis alkekengi var. franchetii (Chinese lantern) extract

A rapid and sensitive liquid chromatography with tandem mass spectrometry (LC‐MS/MS) method was developed and validated for the simultaneous determination of luteolin, luteolin‐7‐O ‐β ‐D‐glucopyranoside, physalin A, physalin D and physalin L in rat plasma. Scutellarein and dexamethasone were used as the internal standards (IS). Plasma samples were prepared by liquid‐liquid extraction with ethyl acetate. The five constituents were separated on an Acquity UPLC BEH C₁₈ column (100 mm × 2.1 mm, 1.7 μm). A gradient elution procedure was used with acetonitrile (A)‐0.1% aqueous formic acid (B). Mass spectrometric detection was performed in negative ion multiple reaction monitoring mode with an electrospray ionization (ESI) source. This method showed good linearity (r ² > 0.997) over a concentration range of 2.0–500 ng/mL with a lower limit of quantification of 2.0 ng/mL for all five compounds. The inter‐ and intra‐day accuracy ranged from 91.7 to 104%, and precisions (RSD) were <6.46% for all analytes. The extraction recoveries of all analytes were >85%. This validated method was successfully applied for the first time to the pharmacokinetic study of five ingredients after oral administration of 70% ethanol extract of Chinese lantern in rats.     

Simultaneous determination of gelsemine and koumine in rat plasma by UPLC‐MS/MS and application to pharmacokinetic study after oral administration of Gelsemium elegans Benth extract

A simple, rapid and sensitive method using UPLC‐MS/MS was established and validated for simultaneous determination of gelsemine and koumine in rat plasma after oral administration of Gelsemium elegans Benth extract. Plasma was performed with methanol precipitation and berberine was chosen as the internal standard. Plasma samples were separated on an Acquity UPLC® BEH C₁₈ column (3.0 × 50 mm, 1.7 μm) with gradient elution using acetonitrile and 0.1% formic acid aqueous solution as the mobile phase at a flow rate of 0.4 mL/min. Multiple reaction monitoring mode in positive ion mode was utilized for detection. The calibration curves were linear over the range of 0.2–100 ng/mL for gelsemine and 0.1–50 ng/mL for koumine, with the lower limits of quantification 0.2 and 0.1 ng/mL, respectively. The intra‐ and inter‐precision and accuracy were well within the acceptable ranges. The developed method was successfully applied to an in vivo pharmacokinetic study in rat after oral administration of 10 mg/kg Gelsemium elegans Benth extract.     

Rapid determination and pharmacokinetics study of lignans in rat plasma after oral administration of Schisandra chinensis extract and pure deoxyschisandrin

A simple, sensitive and rapid method for analysis of six lignans in rat plasma after oral administration of Schisandra chinensis extracts, utilizing liquid chromatography tandem mass spectrometry (LC‐MS), was established and validated. Plasma samples were prepared by one‐step protein precipitation using acetonitrile and the analytes were separated on an SB‐C₁₈ column (100 mm × 3.0 mm, 3.5 µm) with the mobile phase of acetonitrile–water at a flow‐rate of 0.8 mL/min. Analytes were determined in a single‐quadrupole mass spectrometer in the selected ion monitoring (SIM) mode using electrospray source with positive mode. The method was proved to be rapid, sensitive and reproducible, and it was successfully applied to the pharmacokinetic studies of six lignans in rat plasma after oral administration of Schisandra chinensis extracts. In this research, the pharmacokinetics of deoxyschisandrin was also studied following oral administration of the pure deoxyschisandrin. It was found that most of the pharmacokinetic parameters of deoxyschisandrin in the extract were changed significantly compared with those in monomer. The content assay also revealed that the concentrations of the lignan in the extract increased in vivo compared with the pure monomer. Some ingredients in the extract may increase the dissolution of deoxyschisandrin, delay its elimination and enhance its bioavailability in rat. Copyright © 2010 John Wiley & Sons, Ltd.     

Development and validation of an LC-ESI-MS/MS method for simultaneous quantitation of olmesartan and pioglitazone in rat plasma and its pharmacokinetic application

A simple, high‐throughput and specific high‐performance liquid chromatography tandem mass spectrometry method has been developed and validated according to the FDA guidelines for simultaneous quantification of olmesartan and pioglitazone in rat plasma. The bioanalytical method consists of liquid–liquid extraction and quantitation by triple quadrupole mass spectrometry using electrospray ionization technique, operating in multiple reaction monitoring and positive ion modes. The compounds were eluted isocratically on a C₁₈ column with a mobile phase consisting of a mixture of methanol and water (containing 0.5% formic acid) in a ratio of 9:1. The response to olmesartan and pioglitazone was linear over the range 0.01–10 µg/mL. The validation results demonstrated that the method had satisfactory precision and accuracy across the calibration range. Intra‐ and inter‐day precisions ranged from 0.66 to 3.32 and from 0.94 to 2.93% (%CV), respectively. The accuracy determined at three quality control levels was within 91.27–107.28%. There was no evidence of instability of the analytes in rat plasma following the stability studies. The method proved highly reproducible and sensitive and was successfully applied in a pharmacokinetic study after single dose oral administration of olmesartan and pioglitazone to the rat. Copyright © 2010 John Wiley & Sons, Ltd.     

Development and validation of GC/MS method for determination of pramipexole in rat plasma

A simple, rapid and sensitive method has been developed and validated for the determination of pramipexole in rat plasma by using gas chromatography mass spectrometry. The lower limit of quantification (LLOQ) is superior to the other reported LC‐MS/MS methods. After being made alkaline with NaOH, plasma samples (0.1 mL) were subjected to liquid–liquid exteraction using methyl‐t‐butyl ether. Analytes were determined using electron impact ionization in a single quadrupole mass spectrometer. GC/MS was performed in the selected ion monitoring mode using target ions at m/z 211, 212 and 152 for pramipexole and m/z 194 and 165 for caffeine as internal standard. A linear calibration curve was plotted over the range of 20–1000 pg/mL for pramipexole (r² > 0.996). The LLOQ was 20.0 pg/mL, respectively, which offered high sensitivity and selectivity enough for bioanalytical investigation. Inter‐ and intraday precisions ranged from 0.3 to 8.8% and from 0.9 to 11.33%, respectively. The recovery of pramipexole from plasma ranged from 82.4 ± 7.1 to 87.8 ± 5.7%. The method fulfills all standards required for bioanalytical methods and can be successfully applied to a pharmacokinetic study of pramipexole in rats. Copyright © 2010 John Wiley & Sons, Ltd.     

Rapid LC‐MS/MS determination and pharmacokinetic application of linarin in rat plasma

A sensitive, selective and robust liquid chromatography tandem mass spectrometry (LC‐MS/MS) method was developed for the rapid determination of linarin in rat plasma. Separation of the analyte and warfarin as internal standard (IS) from 100 μL rat plasma was carried out by simple protein precipitation treatment. Chromatographic separation of the analyte was performed on a Diamonsil® C₁₈ column (150 × 4.6 mm, 5 µm) using isocratic mobile phase consisting of methanol–0.5% formic acid (80:20, v/v). The flow rate was 0.6 mL/min and the total run time was not more than 4.0 min. The method was validated over a wide dynamic concentration range of 1.00–1000 ng/mL for linarin. The precision and accuracy values for linarin met the acceptance criteria according to US Food and Drug Administration guidelines. Linarin was stable in the stability studies including a long‐term test (?80°C for 43 days), a short‐term test (ambient for 2 h and autosampler for 8 h) and three freeze–thaw cycles (?80–25°C). The developed assay method was applied to the pharmacokinetic study in rats after a single intramuscular administration of 713 µg/kg linarin. Copyright © 2012 John Wiley & Sons, Ltd.     

A LC‐MS/MS method for simultaneous determination of seven alkaloids in rat plasma after oral administration of Phellodendri chinensis cortex extract and its application to a pharmacokinetic study

A sensitive and rapid liquid chromatography with tandem mass spectrometry method has been developed for simultaneous determination of berberine (I), jateorhizine (II), palmatine (III), tetrahydropalmatine (IV), phellodendrine (V), protopine (VI) and columbamine (VII) in rat plasma after oral administration of Phellodendri chinensis cortex extraction. The plasmas were extracted by liquid‐liquid extraction. The tandem mass spectrometric detection was performed in the multiple reaction monitoring mode in the positive ionization. The intra‐ and interday precisions and accuracies were in range from ?12.18 to 13.21%. Mean absolute recoveries of all analytes and internal standard were between 78.6 and 98.9%. The seven alkaloids were proven to be stable during sample storage and analysis procedures. The established method was validated and successfully applied to pharmacokinetics study in rat plasma after oral administration of Phellodendri chinensis cortex extract. The t_1/2 of palmatine, columbamine, pellodendrine, berberine, tetrahydropalmaine, jatrorrhizine, and protopine were 5.16, 5.96, 7.18, 19.84, 6.28, 7.08, 6.90 h, respectively. The seven compounds could be rapidly absorbed into blood (time for maximal concentration, 1.80–1.93 h). This study could establish a foundation for further research of Phellodendri chinensis cortex and might provide more useful information to guide the clinical usage.     

An LC‐MS/MS method for the simultaneous determination and pharmacokinetic studies of bergenin,chlorogenic acid and four flavonoids in rat plasma after oral administration of a QingGanSanJie decotion extract

A rapid, simple and sensitive, liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method was developed and validated for simultaneous determination of bergenin, chlorogenic acid and four flavonoids in a QingGanSanJie preparation in rat plasma. Puerarin was selected as the internal standard (IS). Plasma samples were precipitated with methanol and separated with a reverse phase Agilent Poroshell 120 EC‐C₁₈ column using a gradient mobile phase of methanol–water containing 0.1% formic acid (v/v). A triple quadruple mass spectrometer was used for quantification (limit of detection 0.36–5.55 ng/mL). Intra‐day and inter‐day precisions were within 15% and the average extraction recoveries ranged from 85 to 115% for each analyte. The method allowed simultaneous quantification for the first time of the pharmacokinetics of bergenin, chlorogenic acid and four flavonoids after intragastric administration of a QingGanSanJie extract in Sprague–Dawley rats. It was found that bergenin and chlorogenic acid had typical extravascular administration concentration–time curves; flavonoids had a bimodal distribution improving bioavailability and extending the pharmacodynamics period. Copyright © 2014 John Wiley & Sons, Ltd.