Sample preparation for LC/MS/MS: analyzing biological and environmental samples

Quantitation of thiorphan in human plasma using LC-MS/MS and its application to a bioequivalence study

Racecadotril, an anti-secretory medication, has been used as an adjuvant in an oral rehydration therapy for children experiencing severe diarrhea. Racecadotril is quickly converted to thiorphan, an active metabolite, after oral treatment, which mediates all subsequent activities. An efficient and rapid liquid chromatography-tandem mass spectrometry method was developed and fully validated to measure thiorphan in human plasma, using thiorphan-d7 as an internal standard. The extraction method used was protein precipitation while chromatographic separation was achieved using InertSil CN-3 (50 × 2.1 mm, 5 µm column). The assay was linear over the concentration range of 1-200 ng/ml with correlation coefficients of ≥0.9991. The intra- and inter-day precisions were less than 10.0 % for all concentrations investigated. 0.02 % aqueous formic acid and methanol (30:70 v: v) were used as mobile phases, with an analysis time of less than 1 min. This method proved stable under several conditions. The developed method worked well in a three-period pharmacokinetic bioequivalence study after a single oral administration of 100 mg racecadotril to 15 healthy Jordanian volunteers under fasting conditions.

A Highly Sensitive LC–MS/MS Method Development and Validation of Fedratinib in Human Plasma and Pharmacokinetic Evaluation in Healthy Rabbits

Background:

A simple and sensitive quantitation analytical technique by liquid chromatography–tandem mass spectrometry (LC-MS/MS) is essential for fedratinib in biological media with kinetic study in healthy rabbits.

Objective:

The main objectives of the present research work are to LC-MS/MS method development and validate procedure for the quantitation of fedratinib and its application to kinetic study in rabbits.

Methods:

Separation of processed samples were employed on zorbax SB C18 column (50mm×4.6 mm) 3.5µm with a movable phase of methanol, acetonitrile and 0.1% formic acid in the ratio of 30:60:10. The movable phase was monitored through column at 0.8 ml/min flow rate. The drug and ibrutinib internal standard (IS) were evaluated by monitoring the transitions of m/z -525.260/57.07 and 441.2/55.01 for fedratinib and IS respectively in multiple reaction monitoring mode.

Results:

The linear equation and coefficient of correlation (R2) results were y =0.00348x+0.00245 and 0.9984, respectively. Intra and inter-day precision RSD findings of the developed technique were found in the range of 2.4 - 5.3% for the quality control (QC)-samples (252.56, 1804.0 and 2706 ng/ml). The proposed method was subjected to pharmacokinetic study in healthy rabbits and the kinetic study, fedratinib showed mean AUClast 13190±18.1 hr*ng/ml and Cmax was found to be 3550±4.31 ng/ml in healthy rabbits.

Conclusion:

The validated method can be applicable for the pharmacokinetic and toxicokinetic studies in the clinical and forensic analysis of fedratinib in different kinds of biological matrices successfully.

Development of Fast and Simple LC-ESI-MS/MS Technique for the Quantification of Regorafenib; Application to Pharmacokinetics in Healthy Rabbits

Background:

A simple quantification technique by liquid chromatography electrospray ionization- tandem mass spectrometry (LC-ESI-MS/MS) is required for regorafenib in biological matrices with bioavailability studies in healthy rabbits, when compared with reported techniques.

Objective:

The main aim of the research work was to develop a validated LC-ESI-MS/MS technique for the quantification of regorafenib and application to bioavailability studies in healthy rabbits.

Methods:

Chromatographic separation was achieved with hypersil-C18 analytical column (50mm×4.6 mm, 4μm) and mobile phase composition of acetonitrile and 5mM ammonium acetate in the proportion of 70:30. The mobile phase was infused into the column with high pressure to get a 0.7 ml/min flow rate. The total retention time of the analyte is promising when compared with the existed methods for regorafenib. Quantitation was processed by monitoring transitions of m/z -483.0/262.0 and 450.0/260.0 for regorafenib and internal standard respectively in multiple reaction monitoring.

Results:

The linearity equation and correlation coefficient (R2) findings were y =0.9948x+2.6624 and 0.998 respectively. The intra and inter-day precision of the developed technique was found between 1.00 – 8.50% for the QC-samples (2, 4, 240 and 480ng/ml). From bioavailability study, the drug was shown Tmax of 3.688 ± 0.754; average AUC0→α and AUC0→t were 6476.81 ± 259.59 and 6213.845 ± 257.892 respectively and Cmax was found to be 676.91 ± 22.045 in healthy rabbits.

Conclusion:

The developed technique was validated and successfully applied in the pharmacokinetic study of the drug (40 mg tablet) administered through the oral route in healthy rabbits.

A procedure for method development and protein binding ratio as the indicator of sensitivity with anticancer agents on MALDI mass spectrometry imaging

The concentration and distribution of a drug and its metabolites in tissues are key factors for elucidating both drug efficacy and toxicity in drug development. In this study we developed a pharamaco-imaging procedure for 12 agents and investigated the relationship between the properties of target compounds and the sensitivities of detection in matrix-assisted laser desorption/ionization-mass spectrometer imaging (MALDI-MSI). We prepared mock samples with mouse liver homogenates diluted with gelatin solution, limit of detection concentrations of each compound was confirmed. The correlation was evaluated between the intensities of mass signals obtained in MALDI-MSI with each test compound (the intensities of the test compounds) at a consistent concentration and the properties of each test compound. The liver homogenate diluted with gelatin solution showed easier handling and lower coefficients of variation than did liver homogenate only, and can be used as a good surrogate matrix. Based on the analysis of 12 agents, the protein binding ratios showed significant correlation to the detection sensitivities. We presented a procedure for standardization of pharmaco-imaging method development with an in-tissue method using MALDI-MS. Our results indicated the correlation between test compound's sensitivity and their protein binding ratios in plasma or serum.

Pharmacokinetic studies of a novel tubulin inhibitor SK1326 in rat plasma by UPLC-MS/MS

A sensitive method for quantitation of SK1326 in rat plasma has been established using ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI/MS/MS). SK1326 and the internal standard (tramadol) in plasma sample were extracted using acetonitrile. A centrifuged upper layer was then evaporated and reconstituted with a mobile phase of 0.5% formic acid-acetonitrile (35:65, v/v). The reconstituted samples were injected into a C₁₈ reversed-phase column. Using MS/MS in the multiple reaction monitoring mode, SK1326 and tramadol were detected without severe interference from the rat plasma matrix. SK1326 produced a protonated precursor ion ([M + H]⁺ ) at m/z 432.3 and a corresponding product ion at m/z 114.4. The internal standard produced a protonated precursor ion ([M + H]⁺ ) at m/z 264.4 and a corresponding product ion at m/z 58.1. Detection of SK1326 in rat plasma by the UPLC-ESI/MS/MS method was accurate and precise with a quantitation limit of 1.0 ng/mL. The validation, reproducibility, stability and recovery of the method were evaluated. The method has been successfully applied to pharmacokinetic studies of SK1326 in rat plasma. The pharmacokinetic parameters of SK1326 were evaluated after intravenous (at a dose of 10 mg/kg) and oral (at a dose of 20 mg/kg) administration of SK1326 in rats. After oral administration (20 mg/kg) of SK1326, the F (fraction absorbed) value was ~77.1%.

The Relevance of Mass Spectrometry Analysis for Personalized Medicine through Its Successful Application in Cancer "Omics"

Mass spectrometry (MS) is an essential analytical technology on which the emerging omics domains; such as genomics; transcriptomics; proteomics and metabolomics; are based. This quantifiable technique allows for the identification of thousands of proteins from cell culture; bodily fluids or tissue using either global or targeted strategies; or detection of biologically active metabolites in ultra amounts. The routine performance of MS technology in the oncological field provides a better understanding of human diseases in terms of pathophysiology; prevention; diagnosis and treatment; as well as development of new biomarkers; drugs targets and therapies. In this review; we argue that the recent; successful advances in MS technologies towards cancer omics studies provides a strong rationale for its implementation in biomedicine as a whole.

HRMS using a Q-Exactive series mass spectrometer for regulated quantitative bioanalysis: how, when, and why to implement

High-resolution MS (HRMS) has seen an uptake in use for discovery qual/quan workflows, however, its utilization in late discovery/development has been slow. Past reports comparing HRMS to triple quadrupole (QQQ) instrumentation to date have indicated that HRMS instruments are capable of producing data acceptable for regulated bioanalysis, however lack the sensitivity required for sub ng/ml LLOQ assays. Recent advances in HRMS instrumentation have closed the sensitivity gap with QQQ and have even provided improved selectivity and sensitivity over QQQ SRM assays. Herein, the authors will describe how, when, and why HRMS (specifically Q-Exactive series mass spectrometers) should be considered for implementation in regulated quantitative bioanalysis assays.

Pharmacokinetics and brain uptake of HIV-1 replication inhibitor DB213 in Sprague-Dawley rats

The current study aims to investigate the pharmacokinetics and brain uptake of HIV-1 replication inhibitor DB213 via a developed LC/MS/MS analytical method. A sensitive, selective, accurate and reliable LC/MS/MS method for determination and quantification of DB213 in rat plasma and brain was developed and validated. A triple quadrupole mass spectrometer equipped with electrospray ionization (ESI) source was applied for the detection of DB213 and benzamidine (Internal Standard). The analytes were quantified by using multiple reaction monitoring (MRM) mode with m/z 333.4→86.1 and m/z 121.2→104 for DB213 and benzamidine respectively. Chromatographic separation of DB213 and benzamidine was achieved on a SunFire C8 (4.6×250mm, i.d. 5μm) analytical column with gradient elution of a mobile phase consisted of acetonitrile and 20mM ammonium formate buffer (containing 0.5% formic acid). The method achieved good linearity from 1.95∼1000ng/ml (r(2)=0.999) in plasma and 0.98∼125ng/ml (r(2)=0.999) in brain. The validated method was successfully applied to plasma pharmacokinetics (PK) and brain uptake of intravenous administration of DB213 water solution (1mg/kg) to Sprague-Dawley rats. It was found that the area under the plasma concentration-time curve from 0 to 360min (AUC0→360min) was 184422.1±42450.8ngmin/ml and the elimination half-life of DB213 after intravenous administration was 70.9±16.1min. In addition, DB213 has demonstrated a potential to cross the blood-brain barrier via intravenous administration with a brain tissue concentration of 11.3±3.6ng/g peaked at 30min post-dosing.

Collagenase as an effective tool for drug quantitation in tissues

BACKGROUND

In early drug-discovery research, traditional techniques to analyze drug concentrations in tissues for bioanalytical needs include bead beaters and probe homogenization devices, but are not as effective for tough fibrous tissues. To prepare these tissues, the enzyme collagenase was used to digest the collagen fibers present in epithelial and connective tissue.

RESULTS

The benefits of tissue homogenization using a bead beater following collagenase treatment of samples, as opposed to using bead beating alone, was investigated. Matrix effect, recovery factor and stability with and without collagenase were assessed.

CONCLUSION

Little to no effects on the quality and reliability of collagenase treated samples were observed. This enzymatic approach is a feasible and effective tool for tissue homogenization and subsequent analysis by LC-MS/MS.

Fourier Transform Mass Spectrometry: The Transformation of Modern Environmental Analyses

Unknown compounds in environmental samples are difficult to identify using standard mass spectrometric methods. Fourier transform mass spectrometry (FTMS) has revolutionized how environmental analyses are performed. With its unsurpassed mass accuracy, high resolution and sensitivity, researchers now have a tool for difficult and complex environmental analyses. Two features of FTMS are responsible for changing the face of how complex analyses are accomplished. First is the ability to quickly and with high mass accuracy determine the presence of unknown chemical residues in samples. For years, the field has been limited by mass spectrometric methods that were based on knowing what compounds of interest were. Secondly, by utilizing the high resolution capabilities coupled with the low detection limits of FTMS, analysts also could dilute the sample sufficiently to minimize the ionization changes from varied matrices.

Methods for urine drug testing using one-step dilution and direct injection in combination with LC–MS/MS and LC–HRMS

The advent of LC combined with MS made it possible to design analytical methods for urine drug testing based on the very simple concept of diluting urine with an internal standard as the sole preparation procedure prior to instrumental analysis. The number of publications using this method design increased after the development of high-efficiency LC based on sub-2 μm particles. The success of this method design for drug testing, doping control and toxicological investigations of urine is now well documented and comprise both screening and confirmation methods. The nondiscriminating nature of this method design makes it even more attractive in combination with high-resolution MS for multicomponent target and general unknown analysis applications.

Overcoming selectivity and sensitivity issues of direct inject electrospray mass spectrometry via DAPNe-NSI-MS

Direct inject electrospray mass spectrometry offers minimal sample preparation and a "shotgun" approach to analyzing samples. However, complex matrix effects often make direct inject an undesirable sample introduction technique, particularly for trace level analytes. Highlighted here is our solution to the pitfalls of direct inject mass spectrometry and other ambient ionization methods with a focus on trace explosives. Direct analyte-probed nanoextraction coupled to nanospray ionization mass spectrometry solves selectivity issues and reduces matrix effects while maintaining minimal sample preparation requirements. With appropriate solvent conditions, most explosive residues can be analyzed with this technique regardless of the nature of the substance (i.e., nitroaromatic, oxidizing salt, or peroxide).

Applications of high-resolution MS in bioanalysis

High-resolution MS (HRMS) in conjunction with LC (LC–HRMS) has become available to many laboratories in the pharmaceutical industry. Due to its enhanced, though sometime perceived, specificity using the high-resolution power and its capability of simultaneous quantitation and structural elucidation using the post-acquisition data mining feature, utilization of LC–HRMS for bioanalysis could lead to potential rapid and reliable method development as well as sample analysis, thus generating both cost and resource savings. Here, we would like to share our perspectives about several current and future applications of LC–HRMS in bioanalysis. We will also discuss the factors influencing the quality of method establishment and potential pitfalls that need to be considered for the utilization of LC–HRMS in the field of regulated bioanalysis. We believe when utilized appropriately, LC–HRMS will play a significant role in the future landscape of quantitative bioanalysis.

Development and application of salting-out assisted liquid/liquid extraction for multi-mycotoxin biomarkers analysis in pig urine with high performance liquid chromatography/tandem mass spectrometry

Direct determination of urinary mycotoxins is a better approach to assess individual's exposure than the indirect estimation from average dietary intakes. In this study, a new analytical method was developed and validated for simultaneous analysis of aflatoxin B1, deoxynivalenol, fumonisin B1, ochratoxin A, zearalenone and T2 toxin and their metabolites in pig urine. In total 12 analytes were selected. A salting-out assisted liquid-liquid extraction procedure was used for sample preparation. High performance liquid chromatography/tandem mass spectrometry was used for the separation and detection of all the analytes. The extraction recoveries were in a range of 70-108%, with the intra-day relative standard deviation and inter-day relative standard deviation lower than 25% for most of the compounds at 3 different concentration levels. Meanwhile the method bias for all the analytes did not exceed 20%. The limits of quantification ranged from 0.07ngmL(-1) for ochratoxin A to 3.3ngmL(-1) for deoxynivalenol. Matrix effect was evaluated in this study and matrix-matched calibration was used for quantification. The developed method was also validated for human urine as an extension of its application. Finally, the developed method was applied in a pilot study to analyze 28 pig urine samples. Deoxynivalenol, aflatoxin B1, fumonisin B1 and ochratoxin A were detected in these samples.

Evaluation of an accurate mass approach for the simultaneous detection of drug and metabolite distributions via whole-body mass spectrometric imaging

In drug discovery and development, in vitro absorption and metabolism assays along with in vivo pharmacokinetic (PK), pharmacodynamic (PD), and toxicokinetic (TK) studies are used to evaluate a potential drug candidate. More recently, imaging mass spectrometry approaches have been successfully reported to aid in the preclinical assessment of drug candidates, resulting in the rapid and noteworthy acceptance of the technique in pharmaceutical research. Traditionally, drug distribution studies via mass spectrometric imaging (MSI) are performed as targeted MS/MS analyses, where the analytes of interest, drug and/or metabolite, are known before the imaging experiment is performed. The study presented here describes a whole-body mass spectrometric imaging (WB-MSI) approach using a hybrid MALDI-LTQ-Orbitrap-MS to detect the distribution of reserpine at 2 h post a 20 mg/kg oral dose. This study effectively demonstrates the utility of obtaining accurate mass measurements across a wide mass range combined with postprocessing tools to efficiently identify drug and metabolite distributions without the need for any a priori knowledge.

SPE–MS analysis of absorption, distribution, metabolism and excretion assays: a tool to increase throughput and steamline workflow

In an effort to create faster and more efficient bioanalytical methods for drug development, many investigators have evaluated a variety of SPE–MS systems. Over the past 15 years online systems have evolved from run times of >1.5 min/sample to <10 s/sample. High-throughput SPE–MS methods for in vitro absorption, distribution, metabolism and excretion screening assays have been described by several laboratories and shown to produce results comparable to conventional LC–MS/MS systems. While quantitative analysis of small molecules in biological matrixes holds many challenges, for several applications SPE–MS methods have achieved comparable results to LC–MS/MS with the benefit of 10–30-times the throughput. Based on its distinct advantages of throughput and streamlined workflow efficiencies, SPE–MS is a useful tool for the analysis of many in vitro absorption, distribution, metabolism and excretion assays and in vivo bioanalytical studies. Further development of SPE–MS methods and analysis workflows has the potential to expand the capabilities of this technology for other challenging bioanalytical applications.

Evaluation of homogenization techniques for the preparation of mouse tissue samples to support drug discovery

BACKGROUND

In early drug-discovery research, understanding the tissue distribution of drug at the site of action can help to predict the toxicity, efficacy and exposure level of the drug. The bottleneck of tissue analysis by LC-MS/MS is the time-consuming homogenization step.

RESULTS

Both mechanical and enzymatic techniques for mouse tissue homogenization were evaluated, which included bead beater, polytron and enzymatic digestion. Brain, bone marrow, kidney, spleen and liver tissues can be homogenized effectively using the bead beater alone. Lung and heart tissues were best treated with collagenase first and then homogenized by the bead beater.

CONCLUSION

Homogenization conditions for seven mouse tissues have been evaluated and optimized. These findings will expedite the preparation of tissue samples for analysis.

Sample treatment based on extraction techniques in biological matrices

The importance of sample preparation methods as the first stage in bioanalysis is described. In this article, the sample preparation concept and strategies will be discussed, along with the requirements for good sample preparation. The most widely used sample preparation methods in the pharmaceutical industry are presented; for example, the need for same-day rotation of results from large numbers of biological samples in pharmaceutical industry makes high throughput bioanalysis more essential. In this article, high-throughput sample preparation techniques are presented; examples are given of the extraction and concentration of analytes from biological matrices, including protein precipitation, solid-phase extraction, liquid–liquid extraction and microextraction-related techniques. Finally, the potential role of selective extraction methods, including molecular imprinted phases, is considered.

Quantitative analysis of PD 0332991 in mouse plasma using automated micro-sample processing and microbore liquid chromatography coupled with tandem mass spectrometry

In the oncology therapeutic area, the mouse is the primary animal model used for efficacy studies. Often with mouse pharmacokinetic (PK) and pharmacokinetic/pharmacodynamic (PK/PD) studies, less than 20 μL of total plasma sample volume is available for bioanalysis due to the small size of the animal and the need to split samples for other measurements such as biomarker analyses. The need to conduct automated "small volume" sample processing for quantitative bioanalysis has therefore increased. An automated fit for purpose protein precipitation (PPT) method using a Hamilton MicroLab Star (Reno, NV, USA) to support mouse PK and PK/PD studies for an oncology drug candidate PD 0332991, (a specific inhibitor of cyclin-dependent kinase 4 (CDK-4) currently in development) for processing "small volumes" was developed. The automated PPT method was achieved by extracting and processing 10 μL out of a minimum sample volume of 15 μL plasma utilizing the Hamilton MicroLab Star. A 96-conical shallow well plate by Agilent Technologies, Inc (Wilmington, DE, USA) was the labware of choice used in the automated Hamilton "small volume" method platform. Analyses of a 10 μL plasma aliquot from 15 μL of plasma study samples were conducted by both automated and manual PPT method. All plasma samples were quantitated using a Sciex API 4000 triple quadrupole mass spectrometer coupled with an Eksigent Express HT Ultra HPLC system. The chromatography was achieved using an Agilent microbore C(18) Extend, 1.0 × 50 mm, 3.5 μm column at a flow rate of 0.150 mL/min with a total run time of 1.8 min. Accuracy and precision of standard and QC concentration levels were within 90-107% and <14%, respectively. Calibration curves were linear over the dynamic range of 1.0-1000 ng/mL. PK studies for PD 0332991 were conducted in female C3H mice following intravenous administration at 1mg/kg and oral administration at 2mg/kg. PK values such as area under curve (AUC), volume of distribution (Vd), clearance (Cl), half life (T(1/2)) and bioavailability (F%) demonstrated less than 11% difference between the automated Hamilton and manual PPT methods. The results demonstrate that the automated Hamilton PPT method can accurately and precisely aliquot 10 μL of plasma from 15 μL or larger volume plasma samples. The fit for purpose Hamilton PPT method is suitable for routine analyses of plasma samples from micro-sampling PK and PK/PD samples to support discovery studies.

A rapid ultra-performance liquid chromatography-electrospray Ionisation mass spectrometric method for the analysis of saponins in the adventitious roots of Panax notoginseng

INTRODUCTION

Saponins are bioactive compounds employed in the prevention and treatment of cardiovascular and cerebrovascular diseases. The adventitious roots of Panax notoginseng may offer an alternative source of saponins. Identification and determination of saponins in the crude extract is challenging owing to their similar structures and the lack of standards.

OBJECTIVE

To develop a rapid, sensitive and accurate method based on solid-phase extraction followed by ultra-performance liquid chromatography-electrospray ionisation mass spectrometry (UPLC-ESI-MS) for the identification and quantification of saponins in P. notoginseng.

METHODOLOGY

Following extraction using Waters Oasis(TM) HLB cartridges, the analytes were subjected to a UPLC system with a Waters Acquity BEH C(18) chromatographic column and a binary mobile phase system consisting of 0.05% formic acid in water and acetonitrile under gradient elution conditions, with final detection by ESI-MS in the positive ion mode.

RESULTS

The UPLC-ESI-MS method gave limits of detection and quantification within the range 0.015-0.382 and 0.052-1.124 microg/mL, respectively, for 15 studied saponins. The instrumentation/injection precision (RSD) was 4.5% for a low concentration and 3.2% for an intermediate concentration sample. The intra- and inter-day repeatability was less than 2.65% (RSD). The method described was validated using spiked samples with different amounts of saponin standards.

CONCLUSION

This UPLC-ESI-MS assay provides a suitable quality control method for the tentative identification and determination of major biological active constituents in adventitious and native roots of P. notoginseng.

Direct injection LC/ESI-MS horse urine analysis for the quantification and identification of threshold substances for doping control. I. Determination of hydrocortisone

Two simple and rapid LC/MS methods with direct injection analysis were developed and validated for the quantification and identification of hydrocortisone in equine urine using the same sample preparation but different mass spectrometric systems: ion trap mass spectrometry (IT-MS) and time-of-flight mass spectrometry (TOF-MS). The main advantage of the proposed methodology is the minimal sample preparation procedure, as particle-free diluted urine samples were directly injected into both LC/MS systems. Desonide was used as internal standard (IS). The linear range was 0.25-2.5 microg ml(-1) for both methods. Matrix effects were evaluated by preparing and analyzing calibration curves in water solutions and different horse urine samples. A great variation of the signal both for hydrocortisone and the internal standard was observed in different matrices. To overcome matrix effects, the unavailability of blank matrix and the excessive cost of the isotopically labeled internal standard, standard additions calibration method was applied. This work is an exploration of the performance of the standard additions approach in a method where neither nonisotopic internal standards nor extensive sample preparation is utilized and no blank matrix is available. The relative standard deviations of intra and interday analysis of hydrocortisone in horse urine were lower than 10.2 and 5.4%, respectively, for the LC/IT-MS method and lower than 8.4 and 4.4%, respectively, for the LC/TOF-MS method. Accuracy (bias percentage) was less than 9.7% for both methods.

Flexible Automated Approach for Quantitative Liquid Handling of Complex Biological Samples

A fully automated protein precipitation technique for biological sample preparation has been developed for the quantitation of drugs in various biological matrixes. All liquid handling during sample preparation was automated using a Hamilton MicroLab Star Robotic workstation, which included the preparation of standards and controls from a Watson laboratory information management system generated work list, shaking of 96-well plates, and vacuum application. Processing time is less than 30 s per sample or approximately 45 min per 96-well plate, which is then immediately ready for injection onto an LC-MS/MS system. An overview of the process workflow is discussed, including the software development. Validation data are also provided, including specific liquid class data as well as comparative data of automated vs manual preparation using both quality controls and actual sample data. The efficiencies gained from this automated approach are described.

Quantitative determination of BMS-378806 in human plasma and urine by high-performance liquid chromatography/tandem mass spectrometry

BMS-378806 is a human immunodeficiency virus (HIV) entry inhibitor that is being developed for the oral treatment of HIV infection. Human plasma and urine LC/MS/ MS methods have been developed and validated for the quantitation of BMS-378806. For human plasma method, methyl t-butyl ether was used to extract BMS-378806 from plasma in a 96-well format, and the organic layers were dried down and then reconstituted for the injection, while a dilute-and-shoot approach was used for human urine method in a 96-well format. Chromatographic separation was achieved isocratically on a Phenomenex C18 (2) Luna column (2 x 50 mm2, 5 microm). The mobile phase contained 60:40 v/v of 0.1% formic acid in water and ACN. Detection was by positive ion electrospray MS/MS. The standard curves ranged from 1.25 to 1000 ng/mL for the plasma assay and from 10 to 5000 ng/mL for the urine assay. The curves were fitted to a 1/x2 weighted quadratic regression model for both methods. The validation results demonstrated that both methods had satisfactory precision and accuracy across the calibration ranges. The methods were applied to the analysis of human plasma and urine samples from a single ascending dose clinical study to assess the pharmacokinetics of the drug. The pharmacokinetic analysis results indicated the absorption and disposition of the drug was rapid. The systemic exposure of BMS-378806 was generally dose proportional among the doses from 100 to 1200 mg, but not dose proportional to 1600 mg. There were modest increases in the systemic exposure when the drug was given with food or given as a solution formulation. Renal excretion was not a substantial elimination pathway of the drug. BMS378806 was safe and well tolerated over a dose range of 100-1600 mg administered as a single oral dose.

Liquid–liquid extraction of strongly protein bound BMS-299897 from human plasma and cerebrospinal fluid, followed by high-performance liquid chromatography/tandem mass spectrometry

BMS-299897 is a gamma-secretase inhibitor that is being developed for the treatment of Alzheimer's disease. Liquid-liquid extraction (LLE), chromatographic/tandem mass spectrometry (LC/MS/MS) methods have been developed and validated for the quantitation of BMS-299897 in human plasma and cerebrospinal fluid (CSF). Both methods utilized (13)C6-BMS-299897, the stable label isotope analog, as the internal standard. For the human plasma extraction method, two incubation steps were required after the addition of 5 mM ammonium acetate and the internal standard in acetonitrile to release the analyte bound to proteins prior to LLE with toluene. For the human CSF extraction method, after the addition of 0.5 N HCl and the internal standard, CSF samples were extracted with toluene and no incubation was required. The organic layers obtained from both extraction methods were removed and evaporated to dryness. The residues were reconstituted and injected into the LC/MS/MS system. Chromatographic separation was achieved isocratically on a MetaChem C18 Hypersil BDS column (2.0 mm x 50 mm, 3 microm). The mobile phase contained 10 mM ammonium acetate pH 5 and acetonitrile. Detection was by negative ion electrospray tandem mass spectrometry. The standard curves ranged from 1 to 1000 ng/ml for human plasma and 0.25-100 ng/ml for human CSF. Both standard curves were fitted to a 1/x weighted quadratic regression model. For both methods, the intra-assay precision was within 8.2% CV, the inter-assay precision was within 5.4% CV, and assay accuracy was within +/-7.4% of the nominal values. The validation and sample analysis results demonstrated that both methods had acceptable precision and accuracy across the calibration ranges.

Combined approach for high-throughput preparation and analysis of plasma samples from exposure studies

In drug discovery today, drug exposure is determined in preclinical efficacy and safety studies and drug effects are related to measured concentrations rather than to the administered dose. This leads to a strong increase in the number of bioanalytical samples, demanding the development of higher throughput methods to cope with the increased workload. Here, a combined approach is described for the high-throughput preparation and liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis of drug levels in plasma samples from the preclinical efficacy and safety studies, i.e. exposure studies. Appropriate pharmacokinetic (PK) compartmental models were fitted to data from PK screening studies in the rat, which were subsequently used to simulate the expected plasma concentrations of the respective exposure studies. Information on the estimated drug concentrations was used to dilute the samples to appropriate concentration levels. A Tecan Genesis RSP liquid handling system was utilized to perform automated plasma sample preparation including serial dilution of standard solutions, dilution of plasma samples, addition of internal standard solution and precipitation with acetonitrile. This robotic sample preparation process permitted two studies of 1-96 samples each to be run simultaneously. To ensure the performance of this method the accuracy and precision for diazepam were examined. Two novel drugs were used to illustrate the suggested approach. In conclusion, our method for sample preparation of exposure samples, based on the combined use of PK simulations, a liquid handling system and a fast LC/MS/MS method, increased the throughput more than three times and minimized the errors, while maintaining the required accuracy and precision.

Optimization of CZE for analysis of phytochemical bioactive compounds

Advantages of CZE such as high efficiency, low cost, short analysis time, and easy implementation result in its wide applications for analysis of phytochemical bioactive compounds (e.g. flavonoids, alkaloids, terpenoids, phenolic acid, saponins, anthraquinones and coumarins). However, several aspects, including sample preparation, separation, and detection have significant effects on CZE analysis. Therefore, optimization of these procedures is necessary for development of the method. In this review, sample preparation such as extraction method and preconcentration, separation factors including buffer type, concentration and pH, additives, voltage and temperature, as well as detection, e.g. direct and indirect UV detection, LIF and MS were discussed for optimization of CZE analysis on phytochemical bioactive compounds. The optimized strategies were also reviewed.

Capillary scale monolithic trap column for desalting and preconcentration of peptides and proteins in one- and two-dimensional separations

Monolithic columns based on poly-(styrene-divinylbenzene) (PS-DVB) were utilized both for preconcentration (in 10 mm x 0.20 mm I.D. format) and analytical separation (in 60 mm x 0.20 and 0.10 mm I.D. format) of peptides and proteins in column switching micro-scale high-performance liquid chromatography. A special holder for short monolithic preconcentration columns was designed and pressure durability tests approved long-term stability up to 400 bar. An 11-20% decrease in the average peak widths of nine peptides was obtained upon combining a preconcentration column with an analytical column as compared with a setup using an analytical column only. Trapping efficiency, especially for small and hydrophilic peptides, was optimized by using 0.10% heptafluorobutyric acid instead of 0.050% trifluoroacetic acid as solvent additive during sample loading. Using a 10 mm x 0.20 mm I.D. preconcentration column, loadabilities between 0.5 and 1.6 microg were determined by frontal analysis of proteins and bioactive peptides, respectively. A 100-fold concentration followed by direct on-line intact mass determination is demonstrated for diluted (3 micromolL(-1)) protein solutions. The applicability of the monolithic preconcentration column for multidimensional chromatography was tested by off-line two-dimensional separation, combining strong cation-exchange chromatography and ion-pair reversed-phase chromatography. Peptide identification data from digested protein mixtures demonstrated reproducibilities of 46-75% in triplicate analyses, and confident peptide identifications of low abundant peptides even in the presence of a 650-fold molar excess of high abundant peptides.

Horizontal distribution of steroid estrogens in surface sediments in Tokyo Bay

A monitoring survey was conducted to investigate the distribution of steroid estrogens and their conjugates in surface sediments of Tokyo Bay for the first time, which is known as one of the most heavily polluted marine embayments in the world. The surface sediment samples were collected at 20 locations covering the whole area of Tokyo Bay and analyzed for steroid estrogens and their conjugates using liquid chromatography-tandem mass spectrometry. The concentrations of 17beta-estradiol (beta-E2) and estrone (E1) ranged from ND (below the detection limit; <0.07) to 0.59 and from 0.05 to 3.60 ng g-1 dry, respectively. Those concentrations were higher in the northern part of the bay, which is directly receiving huge quantities of pollutants from adjacent rivers containing a large amount of municipal and industrial wastewater. 17alpha-Estradiol (alpha-E2) and estrone-3-sulfate (E1-3S) were detected in some of the samples, whereas neither of the other conjugates, estriol (E3) or 17alpha-ethynylestradiol (EE2), was found.

Compliance analysis of phenylurea and related compounds in drinking water by liquid chromatography/electrospray ionization/mass spectrometry coupled with solid-phase extraction

A liquid chromatography/electrospray ionization/mass spectrometry method was reported for the compliance analysis of seven phenylurea compounds and two related herbicides (tebuthiuron and propanil) in drinking water. The volumes of the sample and final extract used in the method were 500 mL and 10 mL, respectively. The obtained method detection limits were less than 0.03 microg/L, and the mean recoveries were 74-128% with a relative standard deviation of 2.6-8.3% for all the studied compounds. The peak-to-peak signal-to-noise ratios ranged from 3.3 for cis-siduron to 34.2 for fluometuron. The accuracy and precision resulting from reagent and drinking water samples fortified at higher concentration levels were similar to these results. Several analytes were detected in the drinking water samples, including tebuthiuron at 0.5 microg/L, propanil at 0.7 microg/L, diuron at 0.1-2.1 microg/L, and linuron at 0.1-0.8 microg/L.