Simultaneous determination of unlabeled and carbon-13-labeled etoricoxib, a new cyclooxygenase-2 inhibitor, in human plasma using HPLC-MS/MS

A method for the simultaneous determination of etoricoxib and its carbon-13 analog ((13)C(6)-etoricoxib) from human plasma has been developed and used to support bioavailability studies. Plasma samples (0.5 mL) were extracted by using a 3M Empore 96-well plate (C(8)) and the resulting extracts were analyzed by using a PE-Sciex API-3000 HPLC-MS/MS with a heated nebulizer interface (500 degrees C). The method was validated with two different calibration curve ranges, one for etoricoxib (5 to 2500 ng/mL) determined in the presence of lower concentrations of (13)C(6)-etoricoxib (0.5 to 250 ng/mL), and a second curve for the quantitation of similar concentrations of both etoricoxib and (13)C(6)-etoricoxib (0.5 to 250 ng/mL). Extraction recoveries of etoricoxib, (13)C(6)-etoricoxib, and a methylated internal standard were >70% over the range of concentrations included in both calibration curves. Intraday precision and accuracy for the quantitation of etoricoxib were 7.8% relative standard deviation (RSD) or less and within 3.4% respectively over the range of 5 to 2500 ng/mL, and 10.8% RSD or less and within 4 % respectively over the range of 0.5 to 250 ng/mL. Within-batch precision and accuracy for the quantitation of (13)C(6)-etoricoxib over the range of 0.5 to 250 ng/mL were 8.3% RSD or less and within 2.3%, respectively. The validated assay was used in support of human clinical trials.     

A simple and sensitive LC/MS/MS assay for 7-ethyl-10-hydroxycamptothecin (SN-38) in mouse plasma and tissues: application to pharmacokinetic study of liposome entrapped SN-38 (LE-SN38)

An LC/MS/MS method to quantify SN-38 in mouse plasma and tissue homogenates containing liposome entrapped SN-38 (LE-SN38) was developed. Camptothecin (CPT) was used as the internal standard (IS). Sample preparation consisted of simple protein precipitation by acetonitrile containing 0.5% acetic acid. SN-38 and IS were separated by a C18 HPLC column and detected using a mass spectrometer operating in the multiple reaction monitoring (MRM) mode. The peak area of the m/z 393.3-->349.1 transition of SN-38 and that of the m/z 349.1-->305.2 transition of the IS were measured and a standard curve was generated from their ratios. The method had a LLOQ of 0.5 ng/mL in mouse plasma, which corresponds to 2.5 pg for the 5 microL injection volume. The linear range was 0.5-1000 ng/mL of SN-38 in plasma sample spiked with LE-SN38. The LLOQ in tissue homogenates (5%, w/v) quantitation was 1 ng/mL (20 ng/g tissue) of SN-38 in kidney, liver, lung, and spleen homogenates, and 2 ng/mL (40 ng/g tissue) in heart homogenate containing LE-SN38. The assay was linear up to 400 ng/mL of SN-38 in tissue homogenates, and may be extended to 120 microg/mL by proper dilution of samples over the upper limit of quantitation. Acceptable precision and accuracy were obtained for concentrations over the entire standard curve range, both between-run and within-run for plasma and tissue homogenates. The method was successfully used to quantify SN-38 in plasma and tissues samples for pharmacokinetic and tissue distribution studies of LE-SN38 in mice.     

Determination of capsaicin,nonivamide, and dihydrocapsaicin in blood and tissue by liquid chromatography-tandem mass spectrometry

A sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS-MS) method for the analysis of capsaicin, nonivamide, and dihydrocapsaicin in blood and tissue has been developed. The method utilized a one-step liquid-liquid extraction that yielded an approximate 90% recovery of capsaicinoids from blood. Chomatographic separation of the capsaicinoids was achieved using a reversed-phase high-performance liquid chromatography column and a stepwise gradient of methanol and distilled water containing 0.1% (v/v) formic acid. Identification and quantitation of the capsaicinoids was achieved using electrospray ionization-tandem mass spectrometry monitoring the precursor-to-product-ion transitions for the internal standard octanoyl vanillamide (m/z 280 --> 137), capsaicin (m/z 306 --> 137), dihydrocapsaicin (m/z 308 -->137), and nonivamide (m/z 294 --> 137). Calibration curves, 1.0 to 250 ng/mL, were constructed by plotting concentration versus peak-area ratio (analyte/internal standard) and fitting the data with a weighted quadratic equation. The accuracy of the assay ranged from 90% to 107% for all analytes. The intra-assay precision (%RSD) for capsaicin was 4% at 2.5 ng/mL, 3% at 10 ng/mL, and 7% at 100 ng/mL. The interassay precision (% RSD) for capsaicin was 6% at 2.5 ng/mL, 6% at 10 ng/mL, and 7% at 100 ng/mL. Similar values for inter- and intra-assay precision were obtained for nonivamide and dihydrocapsaicin. This method was used to assay for capsaicinoids in blood and tissue samples collected from rats exposed to capsaicinoids via nose-only inhalation. The concentration of capsaicin in these samples ranged from < 1.0 to 90.4 ng/mL in the blood, < 5.0 to 167 pg/mg in the lung, and < 2.0 to 3.4 pg/mg in the liver.     

Liquid chromatography - tandem mass spectrometry for the simultaneous quantitation of glipizide, cilostazol and its active metabolite 3, 4-dehydro-cilostazol in rat plasma: application for a pharmacokinetic study

A liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) method for the simultaneous quantitation of glipizide, cilostazol and 3, 4-dehydro-cilostazol in rat plasma was developed and validated. Glimepride was used as an internal standard (IS). The analytes were extracted by using liquid-liquid extraction procedure and separated on a reverse phase C18 column (50 mm×4.6 mm i. d., 5 μ) using acetonitrile: 2 mM ammonium acetate buffer, pH 3.2 (90:10, v/v) as mobile phase at a flow rate 0.4 mL/min in an isocratic mode. Selective reaction monitoring was performed using the transitions m/z 446.4>321.1, 370.2>288.3, 368.3>286.2, and 491.4>352.2 to quantify glipizide, cilostazol, 3, 4-dehydro-cilostazol and glimepride, respectively. Calibration curves were constructed over the range of 25-2 000 ng/mL for glipizide, cilostazol and 3, 4-dehydro-cilostazol. The lower limit of quantitation was 25 ng/mL for all the analytes. The recoveries from spiked control samples were>76% for all analytes and internal standard. Intra and inter day accuracy and precision of validated method were within the acceptable limits of at all concentration. The quantitation method was successfully applied for simultaneous estimation of glipizide, cilostazol and 3, 4-dehydro-cilostazol in a pharmacokinetic drug-drug interaction study in wistar rats.     

液相色谱-质谱-质谱联用法快速测定人血浆中法莫替丁含量

目的建立测定人血浆中法莫替丁含量的液相色谱 质谱 质谱联用法。方法取 0 2mL血浆样品经液 液萃取后 ,以乙腈 水 甲酸 (3 0∶70∶1 ,V∶V∶V)为流动相 ,采用ZorbaxSBC8柱分离 ,通过电喷雾离子化四极杆串联质谱 ,以选择反应监测 (SRM)方式进行检测。用于定量分析的离子反应分别为m/z 3 3 8→m/z1 88(法莫替丁 )和m/z2 40→m/z1 47(内标 ,沙丁胺醇 )。结果法莫替丁线性范围是 2 5～ 5 0 0 0ng/mL ,最低定量限为 2 5ng/mL。日内、日间精密度 (RSD)小于 8% ,准确度(RE)在± 2 %范围内。每个样品测试时间仅为 4min,应用此法每天可以测试 1 0 0多个样品。结论该法灵敏度高 ,样品处理简单 ,分析测试速度快 ,适用于临床药物动力学研究。     

HPLC—MS／MS测定人体血浆和尿液中帕洛诺司琼的浓度

目的建立一种简便、灵敏的测定人体血浆和尿液中帕洛诺司琼浓度的高效液相色谱一串联质谱（HPLC-MS／MS）方法。方法血浆、尿液样品分别采用甲醇沉淀处理后,选样分析。采用Agilent-ZORBAX-C18色谱柱（2．1mm×50mm,5fμm）．以乙腈-0．1％甲酸溶液为流动相,采用正离子,多反应监测方式测定样品浓度。用于定量分析的检测离子质荷电（m／z）297．2→m/z110．1（帕洛诺司琼）和DI／Z285．0→M／z193．0（内标）。结果帕洛诺司琼血浆样品在0．02～10ng·mL^-1与峰面积线性关系良好（r=0．9975）;定量下限（LLOQ）为0．02ng·L^-1;日内与日间RSD均〈10％;回收率在89．6％～114．0％。尿样在2．5～100ng·mL^-1与峰面积线性关系良好,7—0．9974;定量下限（LLOQ）为2．5ng·mL^-1;日内与日间RSD均〈10％;回收率在96．4％～113．4％。结论本方法简便快速、灵敏准确,适用于帕洛诺司琼在人体体内的药物动力学研究。     

Determination of buprenorphine and norbuprenorphine in urine and hair by gas chromatography-mass spectrometry.

Buprenorphine, which is used in France as a substitution drug for opioid addiction, is widely abused, and several fatal cases have been reported. In order to confirm a recent intoxication or to establish retrospectively chronic abuse, a simple and reliable gas chromatographic-mass spectrometric method was developed and validated for quantitation of buprenorphine and its active metabolite norbuprenorphine in urine and hair. Two milliliters of urine or 50 mg of pulverized hair was submitted to a pretreatment (enzymatic hydrolysis for urine and decontamination with dichloromethane followed by incubation in 0.1 M HCI for hair). Buprenorphine-d4 was chosen as the internal standard. Selective solid-phase extraction with Bond Elut Certify columns provided recoveries higher than 85% for urine and 43% for hair. By using a mixture of MSTFA/TMSIM/TMCS (100:2:5), buprenorphine and norbuprenorphine produced stable silylated derivatives. The detection was carried out with a quadrupole mass detector working in El selected ion monitoring mode. Ions at m/z 450 and 468 were chosen for the quantitation of buprenorphine and norbuprenorphine, respectively (m/z 454 was used for the internal standard). Limits of quantitation were 0.25 and 0.20 ng/mL, respectively, for buprenorphine and norbuprenorphine in urine and 0.005 ng/mg for the two compounds in hair. Calibration curves were linear from 0 to 50 ng/mL in urine and from 0 to 0.4 ng/mg in hair. Between-day and within-day precisions were less than 8.4% in hair and 6.1% in urine for both molecules in all cases. This method was applied to urine and hair samples collected from patients in a withdrawal treatment program and demonstrated its good applicability in routine analysis and its benefit for clinicians. This technique, which requires instruments already available to many toxicology laboratories, offers an attractive alternative to more sophisticated techniques.     

LC-MS/MS法测定抑郁症患者晨尿中9种氨基酸类内源性物质的浓度

目的:建立测定人体尿液中5-羟基吲哚乙酸、谷氨酰胺、马尿酸、庚二酸、脯氨酸、酪氨酸、色氨酸、酪胺、缬氨酸浓度的方法。方法:采集抑郁症患者的晨尿,加入内标可的松,以乙腈处理后取上清液进行浓缩,采用液相色谱-质谱串联法(LC-MS/MS)进行分析。色谱柱为XTerra RP18;流动相A相为0.1%乙酸-水,流动相B相为0.1%乙酸-乙腈(梯度洗脱);柱温为40℃;流速为0.45mL/min;采用电喷雾离子源(ESI),以多反应监测方式(MRM)进行定量分析,5-羟基吲哚乙酸、谷氨酰胺、马尿酸、庚二酸、脯氨酸、酪氨酸、色氨酸、酪胺、缬氨酸和内标可的松在正离子模式下定量分析离子对分别为质荷比(m/z)192.2→146.1、147.2→130.0、180.1→105.1、161.1→125.2、116.1→70.2、205.2→188.2、138.2→121.1、182.0→123.0、118.2→72.1、361.2→163.0。结果:5-羟基吲哚乙酸、谷氨酰胺、缬氨酸、庚二酸、脯氨酸、酪胺的检测质量浓度范围为10.00~3 200 ng/mL(r=0.993 8~0.998 9,n=6),定量下限为10 ng/mL;色氨酸、酪氨酸、马尿酸的检测质量浓度范围为1 600~51 200 ng/mL(r=0.999 2~0.999 7,n=6),定量下限为1 600ng/mL,准确度试验结果为86.29%~98.65%(n=6),日内、日间精密度试验的RSD均不高于14.65%(n=6),基质效应的CV为6.18%~14.37%(n=6),提取回收率为86.21%~98.14%(n=6),稳定性试验的RE均<14.71%(n=3~6)。结论:该方法灵敏、准确,可用于测定人体内上述9种物质的浓度。     

Quantitative determination of paclitaxel in human plasma using semi-automated liquid-liquid extraction in conjunction with liquid chromatography/tandem mass spectrometry

This paper describes a high-throughput sample preparation procedure combined with LC-MS/MS analysis to measure paclitaxel in human plasma. Paclitaxel and an internal standard were extracted from plasma by a semi-automated robotic method using liquid-liquid extraction. Thereafter compounds were separated on a RP C18 column. Detection was by a PE Sciex API 3000 mass spectrometer equipped with a TurboIonSpray interface. The compounds were detected in positive ion mode using the mass transition m/z 854.6-->286.2 and m/z 831.6-->263.2 for paclitaxel and the internal standard, respectively. The limit of quantitation for paclitaxel was 1 ng/ml with an imprecision of 5.2% following extraction of 0.1 ml of plasma. Linearity was confirmed over the whole calibration range (1-1000 ng/ml) with correlation coefficients higher than 0.99 indicating good fits of the regression models. The inter and intra-day precision was better than 9.5% and the accuracy ranged from 90.3 to 104.4%. The assay was simple, fast, specific and exhibited excellent ruggedness.     

Rapid and sensitive LC/MS/MS analysis of the novel tyrosine kinase inhibitor ZD6474 in mouse plasma and tissues

ZD6474 (N-(4-Bromo-2-fluorophenyl)-6-methoxy-7-[(1-methylpiperidin-4-yl)methoxy] quinazolin-4-amine) is a tyrosine kinase inhibitor with anti-angiogenic and anti-tumor activity that is currently undergoing human trials for cancer treatment. Pharmacokinetic studies in animal models are an important component in clinical development of this agent to relate pre-clinical models to patient treatment. A liquid chromatography tandem mass spectrometry method was developed for the determination of ZD6474 levels in mouse plasma and tissues. Plasma (0.05 mL) and tissue homogenates (0.1 mL of 10 mg/mL) were extracted under alkaline conditions with ethyl acetate:pentane (1:1, v/v) after addition of the internal standard (trazodone, 2-[3-[4-(3-chlorophenyl)-1-piperazinyl]propyl]-1,2,4-triazolo[4,3-a]pyridine-3(2H)-one). Separation was achieved on a C18, 50 mm x 2 mm column with quantitation by internal standard reference and multiple reaction monitoring of the ion transitions m/z 475-->112 (ZD6474) and m/z 372-->176 (trazodone). The calibration curve was linear from a range spanning 20-20,000 ng/mL in plasma and 10-320 ng/mg in tissue homogenates. Mean recoveries from plasma and tissue homogenates were 88 and 90%, respectively. The accuracy in plasma was 88% at the lower limit of quantitation (20 ng/mL with a 50 microL plasma sample) with high precision (R.S.D.%<10%). Assay performance in liver and other tissue homogenates is also reported. The assay was applied to a pharmacokinetic study in mice to determine dosing schedules that would approximate therapeutic ZD6474 levels determined in humans.     

高效液相色谱-质谱/质谱联用法测定人血浆中莫沙必利

建立测定人血浆中莫沙必利的高效液相色谱-质谱/质谱联用法。取血浆样品经液-液萃取后，以乙腈为有机相，0.3%甲酸水溶液为水相，采用梯度洗脱的方式，用C₁₈柱分离，通过电喷雾离子化，以多反应监测(MRM)方式进行正离子检测。莫沙必利线性范围为0.17~68.00 ng·mL^-1，定量下限为0.17 ng·mL^-1，每个样品测试时间仅2.8 min，日内、日间精密度(RSD)均小于13%，准确度(RE)在±6.3%范围内。应用此法研究了20名志愿者单剂量口服枸橼酸莫沙必利片后的药代动力学特点。该方法、灵敏、准确、快速，适用于莫沙必利的药代动力学及生物等效性研究。     

Postmortem identification and quantitation of 2,5-dimethoxy-4-n-propylthiophenethylamine using GC-MSD and GC-NPD

2,5-Dimethoxy-4-n-propylthiophenethylamine (2C-T-7) has structural and pharmacodynamic similarities to methylenedioxymethamphetamine (MDMA). This compound was initially identified from a routine screening procedure in postmortem urine from a 20-year-old male that died in a local emergency room after reportedly insufflating 35 mg. This report describes the development of a quantitative method for 2C-T-7. A number of method parameters were studied including internal standard selection, liquid-liquid extraction scheme, and drug stability in preserved refrigerated blood. The adopted method for blood and urine involves the addition of trimethoxyamphetamine (TMA) as internal standard, alkalinization with ammonium hydroxide, and liquid-liquid extraction with n-chlorobutane. To facilitate recovery from liver, a 1:4 aqueous homogenate was pretreated with dilute perchloric acid, centrifuged, and the supernatant was extracted as previously described. In each case, 0.1% hydrochloric acid in methanol was added during the final concentration step to prevent loss of drug caused by evaporation. Samples were analyzed by gas chromatography with nitrogen-phosphorus detection (GC-NPD) and electron ionization GC-mass spectrometry (MS) utilizing selected ion monitoring. For the GC-MS analysis, the characteristic ions monitored for 2C-T-7 were m/z 226, 255, and 183 and for TMA, m/z 182. The limits of detection and quantitation in blood were 6.0 and 15.6 ng/mL, respectively, by both GC-NPD and GC-MS. The results from the postmortem case were as follows: heart blood, 57 ng/mL; femoral blood, 100 ng/mL; urine, 1120 ng/mL; and liver, 854 ng/g.     

A high-performance liquid chromatographic-atmospheric pressure chemical ionization-tandem mass spectrometric method for determination of risperidone and 9-hydroxyrisperidone in human plasma

Risperidone, a benzisoxazole derivative, is an antipsychotic agent used for the treatment of schizophrenia. We developed a liquid chromatographic-atmospheric pressure chemical ionization-tandem mass spectrometric (LC-APCI-MS-MS) method with improved sensitivity, selectivity, and dynamic range for determination of risperidone and 9-hydroxyrisperidone in human plasma. A structural analogue of risperidone, RO68808 (5 ng/mL), is added as the internal standard to 1 mL of human plasma. Plasma is made basic, extracted with pentane/methylene chloride (3:1), the organic phase evaporated to dryness, and the residue is reconstituted in water with 0.1% formic acid/acetonitrile (20:1). For LC-MS-MS analysis, a Metachem Inertsel HPLC column (2.1 x 150 mm, 5-microm particle size) is connected to a Finnigan TSQ7000 tandem MS via the Finnigan API interface. Both electrospray (ESI) and APCI produced predominantly MH(+) ions for the two analytes and the internal standard. Ions detected by selected reaction monitoring correspond to the following transitions: m/z 411 to 191 for risperidone, m/z 427 to 207 for 9-hydroxyrisperidone, and m/z 421 to 201 for the internal standard. APCI provided a larger dynamic range (0.1 to 25 ng/mL) and better precision and accuracy than ESI. Intrarun accuracy and precision determined at 0.1, 0.25, 2.5, and 15 ng/mL were within 12% of target with %CVs not exceeding 10.9%. Interrun accuracy and precision determined at the same concentrations were within 9.6% of target with %CVs not exceeding 6.7%. Analytes were stable in plasma after 24 h at room temperature, 2 freeze-thaw cycles, and 490 days at -20 degrees C.     

液相色谱-串联质谱法同时测定人血浆中二甲双胍和格列吡嗪

建立了快速、灵敏的液相色谱-串联质谱法测定人血浆中的二甲双胍和格列吡嗪。血浆样品经0.3%甲酸-乙腈(v/v)沉淀蛋白后，以乙腈-水-甲酸(70∶30∶0.3，v/v/v)为流动相，流速为0.50 mL·min^-1。Zorbax Extend C₁₈柱分离，采用大气压化学电离源；以选择反应监测(SRM)方式进行正离子检测。用于定量分析的离子反应分别为m/z 130→m/z 60(二甲双胍)，m/z 446→m/z 321(格列吡嗪)和m/z 256→m/z 167(内标，苯海拉明)。测定血浆中二甲双胍的线性范围为2.00～2 000 ng·mL^-1， 定量下限为2.00 ng·mL^-1； 格列吡嗪的线性范围为1.00～1 000 ng·mL^-1， 定量下限为1.00 ng·mL^-1。该方法专属性好，灵敏度高，准确快捷，适用于二甲双胍和格列吡嗪的临床药代动力学研究。     

Analyzing normetabolites of the fentanyls by gas chromatography/electron capture detection

A selective and sensitive gas-liquid chromatographic (GC) method has been developed for analyzing the normetabolites of fentanyl and 3-methylfentanyl in urine. The method employs differential pH extraction of 1 mL samples, extractive acylation with pentafluoropropionic anhydride (PFPA), GC separation on a fused-silica capillary column (DB-1701), and detection by electron capture detector (ECD) or mass spectroscopy (MS). Limit of sensitivity for this method is 2 ng/mL for norfentanyl (NF) and nor-3-methylfentanyl (N-3-MF) using a 1-mL urine sample and a 2-microL injection from a final volume of 20 microL. Within-run precision, expressed as the coefficient of variation (CV), was 14% and 5% for 4 ng/mL and 16 ng/mL of NF and 9% and 4% for the same concentrations of N-3-MF. Between-run precision was 30% and 12% for NF and 11% and 10% for N-3-MF, at 4 ng/mL and 16 ng/mL, respectively. Metabolites are stable in urine for at least one month at room temperature (25 degrees C) or -20 degrees C. PFP-derivatives of the metabolites were confirmed by high-resolution MS in the electron-impact mode. Three characteristic ions for each metabolite were identified-m/z 392 (molecular ion), m/z 336 (loss of propionyl), and m/z 244 (loss of propionanilide) for N-3-MF-PFP and m/z 378 (molecular ion), m/z 322 (loss of propionyl), and m/z 230 (loss of propionanilide) for NF-PFP, suitable for use in GC/MS with selected ion monitoring as a complimentary confirming technique. This method was validated by analyzing urine samples from individuals suspected of using fentanyl or 3-methylfentanyl.(ABSTRACT TRUNCATED AT 250 WORDS)     

Quantification of aflatoxin-B1-N7-Guanine in human urine by high-performance liquid chromatography and isotope dilution tandem mass spectrometry

We report validation of the first isotope dilution mass spectrometry method for determination of aflatoxin B(1)-N(7)-guanine (AFB(1)-N(7)-Gua), a major human aflatoxin-DNA adduct that is excreted in the urine. Measurement of urinary AFB(1)-N(7)-Gua, a biomarker of the biologically effective dose following dietary aflatoxin B(1) (AFB(1)) exposure, has helped identify AFB(1) as a risk factor in the development of hepatocellular carcinoma, a common cancer worldwide. Triple-quadrupole mass spectrometry, coupled with the use of a stable isotope-labeled internal standard (AFB(1)-N(7)-(15)N(5)-Gua) and better solid phase extraction and immunoaffinity column chromatography, have enabled us to greatly improve accuracy, precision, specificity, and sensitivity over previously published determinations. The limit of quantitation for AFB(1)-N(7)-Gua was 0.8 pg/20 mL urine (0.07 pg/mg creatinine). The method was validated for accuracy and precision over the range of 0.8-25 pg/20 mL urine, with between-day and within-day reproducibility for analysis of six aliquots of a human urine sample containing 6.0 pg/20 mL measured at <6% coefficient of variation. AFB(1)-N(7)-Gua concentrations were measured in 20 human urine samples collected in a region with known aflatoxin exposure. The mean concentration of AFB(1)-N(7)-Gua, measured in 16/20 urine samples with levels above the method's limit of quantitation, was 2.9 pg/20 mL urine (0.28 pg/mg creatinine) with a range of <0.8-7.2 pg/20 mL urine (0.04-65 pg/mg creatinine). With improved accuracy and precision, this sensitive biomarker for recent human exposure to AFB(1) will be especially useful for measuring the efficacy of planned interventions to reduce aflatoxin-related liver cancer in AFB(1)-exposed populations.     

Simultaneous determination of GFA and its active metabolites in human plasma by liquid chromatography electrospray ionization mass spectrometry and its application to pharmacokinetic studies

A sensitive and rapid liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) method has been developed and validated for simultaneous quantification of guanfu base A (GFA) and its metabolites guanfu base I (GFI) and guanfu alcohol-amine (AA) in human plasma with phenoprolamine hydrochloride (DDPH) as the internal standard. The analytes were extracted from human plasma by using liquid-liquid extraction with ethyl acetate and the LC separation was performed on a Diamonsil C(18) analytical column (150 mm x 2.1 mm i.d., 5 microm). The MS acquisition was performed in selected ion monitoring (SIM) mode of positive ions. Analysis was carried out in SIM mode at m/z 430.25 for GFA [M+H](+), m/z 388.25 for GFI [M+H](+), m/z 346.25 for AA [M+H](+) and m/z 344.20 for the IS DDPH [M+H](+). The calibration curves were linear over the range of 50-5000 ng/mL for GFA and 5-1000 ng/mL for GFI and AA, with coefficients of correlation above 0.999. The lower limit of quantification for GFA was 1 ng/mL, while for GFI and AA were both 5 ng/mL. The intra- and inter-day precisions (CV) of analysis were within 9%, and the accuracy ranged from 91% to 108%. The overall recoveries for GFA, GFI and AA were about 94.2%, 87.8% and 80.6%, respectively. The total LC-MS run-time was only 5.5 min. This quantitation method was successfully applied to the simultaneous determination of GFA and its metabolites in human plasma for the metabolic study and pharmacokinetic evaluation.     

A GC-MS method for the determination of isoxsuprine in biological fluids of the horse utilizing electron impact ionization

Isoxsuprine is used to treat navicular disease and other lower-limb problems in the horse. Isoxsuprine is regulated as a class 4 compound by the Association of Racing Commissioners, International (ARCI) and, thus, requires regulatory monitoring. A gas chromatography-mass spectrometry method utilizing electron impact ionization was developed and validated for the quantitation of isoxsuprine in equine plasma or equine urine. The method utilized robotic solid-phase extraction and tri-methyl silyl ether products of derivatization. Products were bis-trimethylsilyl (TMS) isoxsuprine and tris-TMS ritodrine, which released intense quantifier ions m/z 178 for isoxsuprine and m/z 236 for ritodrine that were products of C-C cleavage. To our knowledge, this procedure is faster and more sensitive than other methods in the literature. Concentrations in urine and plasma of isoxsuprine were determined from a calibrator curve that was generated along with unknowns. Ritodrine was used as an internal standard and was, therefore, present in all samples, standards, and blanks. Validation data was also collected. The limit of detection of isoxsuprine in plasma was determined to be 2 ng/mL, the limit of quantitation of isoxsuprine in plasma was determined to be < 5 ng/mL. The mean coefficient of determination for the calibrator curves for plasma was 0.9925 +/- 0.0052 and for calibrator curves for urine 0.9904 +/- 0.0075. The recovery efficiencies at concentrations of 50, 200, and 300 ng/mL were 76%, 73%, and 76%, respectively, in plasma and 92%, 89%, and 91% in urine.     

液相色谱-串联质谱法测定大鼠血浆中的汉黄芩素

目的建立测定大鼠血浆中汉黄芩素浓度的液相色谱-串联质谱法。方法血浆样品经液-液萃取后,进行色谱分离,采用三重四极杆串联质谱检测,使用大气压化学电离源(APCI),在正离子条件下选择反应监测(SRM)方式进行扫描,用于定量分析的离子分别为m/z 284.8→m/z 269.5(汉黄芩素)和m/z 254.7→m/z 198.5(葛根黄豆苷元,内标)。结果线性范围为0.25～20 ng·mL^-1,最低定量浓度为0.25 ng·mL^-1。以质控样品(QC)计算,在各浓度水平下,此法的批内精密度(RSD)为2.2%～13.1%,批间精密度为5.9%～7.3%;准确度(RE)为-0.3%～1.3%。结论 此法灵敏、快速、准确,可用于大鼠血浆中汉黄芩素浓度测定及临床前药动学研究。