Automated system for on-line desorption of dried blood spots applied to LC/MS/MS pharmacokinetic study of flurbiprofen and its metabolite

This paper illustrates the development of an automated system for the on-line bioanalysis of dried blood spots (on-line DBS). In this way, a prototype was designed for integration into a conventional LC/MS/MS, allowing the successive extraction of 30 DBS toward the analytical system without any sample pretreatment.     

Characterization and quantitative determination of impurities in piperaquine phosphate by HPLC and LC/MS/MS

Four impurities in piperaquine phosphate bulk drug substance were detected by a newly developed gradient reverse phase high performance liquid chromatographic (HPLC) method. These impurities were identified by LC/MS/MS. The structures of impurities were confirmed by spectroscopic studies (NMR and IR) conducted using synthesized authentic compounds. The synthesized reference samples of the impurity compounds were used for the quantitative HPLC determination. The system suitability of HPLC analysis established the validity of the separation. The method was validated according to ICH guidelines with respect to specificity, precision, accuracy and linearity. Forced degradation studies were also performed for piperaquine phosphate bulk drug samples to demonstrate the stability indicating power of the newly developed HPLC method.     

A sensitive human bone assay for quantitation of tigecycline using LC/MS/MS

Tigecycline (Tygacil,Wyeth) is a first-in-class, broad spectrum antibiotic with activity against multiple-resistant organisms. In order to address the unexpectedly low tigecycline concentrations in human bone samples analyzed using a LC/MS/MS method developed elsewhere, we have developed and validated a new and sensitive human bone assay for the quantitation of tigecycline using LC/MS/MS. The new method utilizes the addition of a stabilizing agent to the human bone sample, homogenization of human bone in a strong acidic-methanol extraction solvent, centrifugation of the bone suspension, separation by liquid chromatography, and detection of tigecycline by mass spectrometry. Linearity was demonstrated over the concentration range from 50 to 20,000 ng/g using a 0.1g human bone sample. The intra- and inter-day accuracy of the assay was within 100+/-15%, and the corresponding precision (CV) was <15%. The stability of tigecycline was evaluated and shown to be acceptable under the assay conditions. The extraction recovery of tigecycline with the current method was 79% when using radio-labeled rat bone samples as a substitute for human bone samples. Twenty-four human bone samples collected previously from volunteers without infections who had elective orthopedic surgery after receiving a single dose of tigecycline were re-analyzed using the current validated method. Tigecycline concentrations in these samples ranged from 238 to 794 ng/g with a mean value 9 times higher than the mean concentration previously reported. The data demonstrated that the current method has significantly higher extraction efficiency than the previously reported method.     

Recent advances in use of LC/MS/MS for quantitative high-throughput bioanalytical support of drug discovery

LC/MS/MS based bioanalysis using atmospheric pressure ionization (API)-style interfaces has now been applied for over a decade. This technology, which initially found application for clinical bioanalysis, is now firmly established as the primary bioanalytical tool for ADME studies related to drug discovery and lead optimization (LO). This review focuses on recent advances in LC/MS/MS based bioanalysis in support of drug discovery and LO. The initial part of the article reviews the principal components of LC/MS/MS bioanalysis: sample preparation, chromatography, ionization and mass analysis. In each section, factors affecting high throughput bioanalysis are addressed. Because of the importance of on-line column switching methods to discovery bioanalysis, the section on sample preparation is divided into off-line and on-line approaches. In addition, the discussion of chromatography is limited to reversed phase liquid chromatography with emphasis given to the trend towards high-flow gradient elution techniques. The latter part of the review focuses on considerations for experimental design. In this section, pooling methods such as cassette dosing are discussed along with more highly integrated strategies linking bioanalysis with protocol generation and sample collection. The article concludes by briefly reviewing factors, which affect bioanalytical precision and accuracy, such as ion suppression, analyte stability and metabolite interference.     

Quantitative determination of apogossypol, a pro-apoptotic analog of gossypol, in mouse plasma using LC/MS/MS

A simple and selective liquid chromatography/tandem mass spectrometry (LC/MS/MS) method based on internal standard quantitation using apigenin as the internal standard has been developed and validated for the analysis of the gossypol analog apogossypol, a pro-apoptotic compound, in mouse plasma. The methodology involves protein precipitation of plasma samples followed by LC/MS/MS analysis. Ascorbic acid was added to the spiking solutions and plasma samples to stabilize the easily oxidized compound. Separation of apogossypol and the internal standard from the plasma matrix was achieved using a C18 column with a gradient elution profile consisting of 5 mM ammonium acetate and methanol. The validated range of the method extended from 10 to 2000 ng/mL with accuracies of 85–115% and precision of <15%. The average recovery of apogossypol at three concentrations (50, 200 and 1000 ng/mL) assayed in triplicate using this methodology was determined to be 90.8 ± 12.9%. Recovery for the internal standard (apigenin) at a concentration of 500 ng/mL was found to be 99.9 ± 6.41%. Apogossypol concentrations of 50 ng/mL and above were found to be stable in extracted plasma for 24 h when stored at 25 °C. This method has been applied to the determination of apogossypol concentrations in plasma collected from mice given an IV dose of apogossypol.     

氘代内标液质串联法测定血浆中沙丁胺醇的浓度

目的:建立液相-质谱串联法测定人血浆中的沙丁胺醇含量.方法:血浆离心后过玻璃纤维滤膜,经酶解加入氘代沙丁胺醇内标溶液,用C18小柱净化后以3%的氨水甲醇溶液对Oasis MCX小柱进行洗脱,吹干,以0.1%甲酸水溶液-甲醇溶液(95∶5)溶解残余物,用液相质谱串联法测定,以0.1%甲酸乙腈溶液和0.1%甲酸溶液为流动相梯度洗脱.结果:沙丁胺醇在0.25～10.00 μg·kg-1线性关系良好,检出限0.1μg·kg-1.结论:本法灵敏准确、重现性与特异性强、干扰少,可用于人体内沙丁胺醇药动学与生物利用度研究.     

LC/MS/MS与GC/MS法分析鉴定小鼠尿中沙美特罗的代谢产物

目的:鉴定沙美特罗在小鼠尿中的主要代谢产物.方法:ig给药后,收集小鼠尿液,经固相提取,葡萄糖醛酸酶水解,进行LC/MS/MS分析和硅烷化后进行GC/MS分析同时分离鉴定沙美特罗代谢产物.结果和结论:在给药后尿样中发现沙美特罗原型和4种代谢产物M1～M4,其结构推测为19-羟基沙美特罗(M1)、2-羰基沙美特罗(M2)、19-羰基沙美特罗(M3)和19-羟基-8-甲氧基沙美特罗(M4).     

LC/MS/MS法测定比格犬血浆中埃克替尼及其在药动学研究中的应用

目的:建立灵敏、快速的液相色谱-串联质谱(LC/MS/MS)法测定比格犬血浆中埃克替尼,并用于药动学研究。方法:健康比格犬32只,随机分成4组后,静脉(10mg/kg)或灌胃(10,20和40mg/kg)给予埃克替尼。采用LC/MS/MS法测定血药浓度,并计算出药动学参数。结果:测定埃克替尼的线性范围是0.5～10000ng/mL,日内和日间精密度(RSD)均小于10。静脉给药后AUC0-t为(27.3±15.3)μg.mL-1.h。灌胃给药后AUC0-t分别为(7.47±3.30)、(23.5±11.5)、(54.5±24.9)μg.mL-1.h,埃克替尼在犬体内的绝对生物利用度是27.4。结论:该分析方法选择性好、灵敏度高、操作简便,并成功应用于埃克替尼的比格犬药动学研究。     

Direct quantification in bioanalytical LC-MS/MS using internal calibration via analyte/stable isotope ratio

The possibility to rationalize and simplify bioanalysis, without compromising the analytical quality, by omitting the calibration curves was studied. Using mass spectrometry (MS) and a stable isotope labeled internal standard it was possible to get equally good results by calculating the results directly from the analyte/internal standard area ratio and a predetermined response factor as by the traditional way, using a calibration curve run at the same occasion. To be able to use this simplified quantification method, that we call internal calibration, in its most simple form there are some prerequisites that must be considered: (1) The relative response should not be concentration dependent. (2) The relative response should be constant between batches/days. (3) The level of analyte in the internal standard should not be detectable. (4) There should be no influence from naturally occurring isotopes of the analyte on the internal standard peak area. A bioanalytical LC-MS/MS method for a research compound was validated both with and without calibration curves and no significant differences were found regarding precision and accuracy. It was shown that all four prerequisites above were fulfilled. Validation data were very good for the whole concentration range, 0.010-30 micromol/L. Long-term data for QC samples showed excellent precision and accuracy.     

Regulated LC-MS/MS bioanalysis technology for therapeutic antibodies and Fc-fusion proteins using structure-indicated approach

In recent studies, the development of bioanalysis technologies using liquid chromatography-tandem mass spectrometry (LC-MS/MS) has attracted attention. Our developed nano-surface and molecular-orientation limited (nSMOL) proteolysis enables Fab-specific proteolysis and is optimal for LC-MS/MS analysis of antibody drugs and Fc-fusion proteins in biological samples. In this nSMOL method, antibodies and Fc-fusion proteins are held in pores of the particle and the subsequent proteolysis is carried out with protease-immobilized nanoparticles. The Fab of antibodies or fused region of Fc-fusion protein can be held to orient toward the reaction solution. The access of the immobilized protease is limited to a part in the structure of protein substrate on the particle surface. Thus, nSMOL proteolysis reacts selectively at the Fab complementarity-determining region of antibodies or N-terminal specific domain of Fc-fusion proteins and can be applied to both types of drugs. We have already evaluated drug concentrations in biological samples pretreated with nSMOL proteolysis using LC-MS/MS for more than twenty drugs, of which ten drugs have been fully validated and published. In this review, we discuss the development and application of LC-MS/MS bioanalysis, which enables the bioanalysis of therapeutic antibodies and Fc-fusion proteins by focusing on a structure-based approach.     

高效液相色谱-质谱联用测定人血浆中辛伐他汀浓度

目的建立测定人血浆中辛伐他汀浓度的方法。方法血浆样品中加入内标,用乙醚提取,浓缩后采用高效液相色谱-质谱联用进行测定。结果血浆样品中辛伐他汀线性范围为0.1～20ng·mL-1(r=0.9999);萃取回收率为94.3%。结论本方法灵敏度高、专属性强、重现性好、准确,可用于辛伐他汀片人体药动学及生物等效性研究。     

Development and validation for high selective quantitative determination of metformin in human plasma by cation exchanging with normal-phase LC/MS/MS

An assay based on cation exchange solid-phase extraction and liquid chromatography-tandem mass spectrometry (LC/MS/MS) has been developed for the quantitative determination of metformin in human plasma. The analytical method consists of cation exchange solid-phase extraction (VersaPlate CBA) without any further evaporation/dissolution steps and cation exchange-based HPLC separation (Capcell Pak SCX column) with a normal-phase gradient system followed by semi-micro LC/MS/MS in positive ion selected reaction monitoring mode using electrospray ionization. The method exhibited excellent performance in terms of selectivity, robustness, short run time (7 min/sample) and simplicity of sample preparation.

The calibration range was 10–1000 ng/ml with 0.2 ml of plasma. Intra- and inter-day mean accuracies were within the ranges of 100.3–105.0% and 101.2–105.3%, respectively. Intra- and inter-day precisions were within the ranges of 0.8–1.9% and 1.5–8.6%, respectively. Mean absolute recovery was 67.0% for metformin. No apparent loss of metformin after extraction was observed in an autosampler at 10 °C for 24 h. Dilution of metformin by blank human plasma up to 20-fold was tested and revealed no impact on the results of determination. Furthermore, the method exhibited high selectivity, since no effect on metformin analysis was observed on comparison of samples with or without nateglinide and other agents in plasma. Results obtained with the method were also comparable to a published LC–UV method on cross-validation.

This method can be applied to various clinical pharmacokinetic studies of metformin.     

Advanced glycation end-products/peptides: a preliminary investigation by LC and LC/MS

An investigation on AGE-peptides, originating by proteolysis of in vitro glycated proteins, was carried out by LC methods with different detection applied to the mixture produced by proteinase K digestion of in vitro glycated human serum albumin (HSA). Classical approaches, like spectroscopic (UV, fluorescence) and mass spectrometric methods (MALDI, LC/ESI/MS), show that the digestion mixture is highly complex. However, there are clearcut differences between the digestion mixtures of glycated and unglycated HSA, in the former case allowing identification of possible glycated peptides belonging to the AGE-peptide class. MS/ MS experiments on selected species seem to be promising as regards structural information.     

A direct LC/MS/MS method for the determination of ciclopirox penetration across human nail plate in in vitro penetration studies

Due to severe chelating effect caused by N-hydroxylpyridone group of ciclopirox, there is no published direct HPLC or LC/MS/MS method for the determination of ciclopirox in any in vitro or in vivo matrix. Instead, the time-consuming pre-column derivatization methods have been adapted for indirect analysis of ciclopirox. After overcoming the chelating problem by using K₂EDTA coated tubes, a direct, sensitive and high-throughput LC/MS/MS method was successfully developed and validated to determine the amount of ciclopirox that penetrated across the nail plate during in vitro nail penetration studies. The method involved adding a chemical analog, chloridazon as internal standard (IS) in K₂EDTA coated tubes, mixing IS with ciclopirox in a 96-well plate and then proceeding to LC/MS/MS analysis. The MS/MS was selected to monitor m/z 208.0 → 135.8 and 221.8 → 77.0 for ciclopirox and IS, respectively, using positive electrospray ionization. The method was validated over a concentration range of 8–256 ng/mL, yielding calibration curves with correlation coefficients greater than 0.9991 with a lower limit of quantitation (LLOQ) of 8 ng/mL. The assay precision and accuracy were evaluated using quality control (QC) samples at three concentration levels. Analyzed concentrations ranged from 101% to 113% of their respective nominal concentration levels with coefficients of variation (CV) below 10.6%. The average recovery of ciclopirox from nail matrix was 101%.     

Determination of a selection of synthetic cannabinoids and metabolites in urine by UHPSFC‐MS/MS and by UHPLC‐MS/MS

Two different analytical techniques, ultra‐high performance supercritical fluid chromatography‐tandem mass spectrometry (UHPSFC‐MS/MS) and reversed phase ultra‐high performance liquid chromatography‐tandem mass spectrometry (UHPLC‐MS/MS), were used for the determination of two synthetic cannabinoids and eleven metabolites in urine; AM‐2201 N‐4‐OH‐pentyl, AM‐2233, JWH‐018 N‐5‐OH‐pentyl, JWH‐018 N‐pentanoic acid, JWH‐073 N‐4‐OH‐butyl, JWH‐073 N‐butanoic acid, JWH‐122 N‐5‐OH‐pentyl, MAM‐2201, MAM‐2201 N‐4‐OH‐pentyl, RCS‐4 N‐5‐OH‐pentyl, UR‐144 degradant N‐pentanoic acid, UR‐144 N‐4‐OH‐pentyl, and UR‐144 N‐pentanoic acid. Sample preparation included a liquid‐liquid extraction after deconjugation with ß‐glucuronidase. The UHPSFC‐MS/MS method used an Acquity UPC^{2 TM} BEH column with a mobile phase consisting of CO₂ and 0.3% ammonia in methanol, while the UHPLC‐MS/MS method used an Acquity UPLC® BEH C₁₈ column with a mobile phase consisting of 5 mM ammonium formate (pH 10.2) and methanol. MS/MS detection was performed with positive electrospray ionization and two multiple reaction monitoring transitions. Deuterated internal standards were used for six of the compounds. Limits of quantification (LOQs) were between 0.04 and 0.4 µg/L. Between‐day relative standard deviations at concentrations ≥ LOQ were ≤20%, with biases within ±19%. Recoveries ranged from 40 to 90%. Corrected matrix effects were within 100 ± 10%, except for MAM‐2201 with UHPSFC‐MS/MS, and for UR‐144 N‐pentanoic acid and MAM‐2201 N‐4‐OH‐pentyl with UHPLC‐MS/MS. Elution order obtained by UHPSFC‐MS/MS was almost opposite to that obtained by UHPLC‐MS/MS, making this instrument setup an interesting combination for screening and confirmation analyses in forensic cases. The UHPLC‐MS/MS method has, since August 2014, been successfully used for confirmation of synthetic cannabinoids in urine samples revealing a positive immunoassay screening result. Copyright © 2015 John Wiley & Sons, Ltd.     

液相色谱-串联质谱法测定秋水仙碱片在人尿中的含量

目的建立LC/MS/MS法测定人尿中的秋水仙碱浓度,初步研究人体口服秋水仙碱片剂后的排泄规律。方法色谱柱:Agilent Eclipse XDB C18柱,流动相:甲醇-10 mmol.L-1乙酸铵(60∶40),以ESI源正离子MRM模式测定。结果线性范围为3～3000 ng.mL-1(γ=0.9978),相对回收率为91.6%～93.7%,日内、日间变异(RSD)均<15%,基质效应为80.9%～90.9%。服药24,96 h后的原药平均累积尿排率分别为15.2%和20.9%。结论本方法适于秋水仙碱的尿药浓度测定,其在人体内仅经尿液排泄少部分原药。     

LC/MS/MS analysis of vesnarinone and its principal metabolites in plasma and urine

An LC/MS/MS assay was developed and successfully used to quantitate vesnarinone and its principal metabolites (OPC-8230, OPC-18136, and OPC-18137) in human plasma and urine. Samples were pre-treated with liquid–solid extraction followed by simultaneous monitoring of primary and daughter ions which were used for the identification and quantitation of the analytes on LC/MS/MS. This assay offers advantages of specificity, speed and greater sensitivity over the previously developed HPLC-UV assay. The lower limit of quantitation is 500 ng ml⁻¹ for vesnarinone and 20 ng ml⁻¹ for OPC-8230, OPC-18137, and OPC-18136 in plasma. Methodology is similar for the estimation of these analytes in urine with the lower limit of quantitation being 500 ng ml⁻¹ for vesnarinone and 100 ng ml⁻¹ for each metabolite. Ascorbic acid was added to stabilize the analytes from degradation. This LC/MS/MS method was developed to overcome many practical problems associated with the HPLC method. The LC/MS/MS method offers the flexibility of analyzing additional metabolites and changing the linearity range to accommodate the differences in linear range (200–10 000 ng ml⁻¹ for vesnarinone and 20–1000 for metabolites) for the analytes.     

LC／MS／MS法测定人血中硫普罗宁的浓度及药物动力学研究

目的建立LC／MS／MS法测定人血中硫普罗宁浓度的方法,并研究其在健康男性受试者体内的药物动力学。方法采用LC／MS／MS（ESI源）测定硫普罗宁的血浆浓度,计算药物动力学参数。结果硫普罗宁线性范围为25．0-5000ng·mL^-1,定量下限为25．0ng·mL^-1日内、日间精密度（RSD）均〈15％,准确度（RE）在15％以内。应用本法测得20名健康男性受试者口服200mg硫普罗宁胶囊后主要药代动力学参数为：tmax,为（4．20±1．01）h,t1／2为（5．61±4．42）h,Cmax为（4456±2447）ng·mL^-1,AU C0-24h为（20566±9902）ng·mL^-1,Ke为（0．173±0．094）h^-1。结论该法操作简便、快速、灵敏,可用于测定血浆中硫普罗宁浓度。     

Quantitative determination of opioids in whole blood using fully automated dried blood spot desorption coupled to on‐line SPE‐LC‐MS/MS

Opioids are well known, widely used painkillers. Increased stability of opioids in the dried blood spot (DBS) matrix compared to blood/plasma has been described. Other benefits provided by DBS techniques include point‐of‐care collection, less invasive micro sampling, more economical shipment, and convenient storage. Current methodology for analysis of micro whole blood samples for opioids is limited to the classical DBS workflow, including tedious manual punching of the DBS cards followed by extraction and liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) bioanalysis. The goal of this study was to develop and validate a fully automated on‐line sample preparation procedure for the analysis of DBS micro samples relevant to the detection of opioids in finger prick blood. To this end, automated flow‐through elution of DBS cards was followed by on‐line solid‐phase extraction (SPE) and analysis by LC‐MS/MS. Selective, sensitive, accurate, and reproducible quantitation of five representative opioids in human blood at sub‐therapeutic, therapeutic, and toxic levels was achieved. The range of reliable response (R² ≥0.997) was 1 to 500 ng/mL whole blood for morphine, codeine, oxycodone, hydrocodone; and 0.1 to 50 ng/mL for fentanyl. Inter‐day, intra‐day, and matrix inter‐lot accuracy and precision was less than 15% (even at lower limits of quantitation (LLOQ) level). The method was successfully used to measure hydrocodone and its major metabolite norhydrocodone in incurred human samples. Our data support the enormous potential of DBS sampling and automated analysis for monitoring opioids as well as other pharmaceuticals in both anti‐doping and pain management regimens. Copyright © 2015 John Wiley & Sons, Ltd.