Moving from fast to ballistic gradient in liquid chromatography/tandem mass spectrometry pharmaceutical bioanalysis: Matrix effect and chromatographic evaluations

Measuring the Residual Levels of Fenpyroximate and Its Z-Isomer in Citrus Using Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry and Assessing the Related Dietary Intake Risks

Fenpyroximate is an efficient, broad-spectrum phenoxypyrazole acaricide which is used for controlling various mites. In this study, we measured the levels of terminal fenpyroximate residues in citrus fruits, and estimated the dietary intake risks posed by fenpyroximate. To this end, a QuEChERS analytical method was used in combination with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) to determine the residual levels of fenpyroximate and its Z-isomer (Z-fenpyroximate) in citrus fruits collected from 12 fields under good agricultural practices (GAPs). The average recoveries of fenpyroximate in whole fruits and citrus flesh were 104-110% and 92-109%, respectively, with corresponding RSDs of 1-4% and 1-3%. The average recoveries of Z-fenpyroximate were 104-113% and 90-91%, respectively, with RSDs of 1-2% in both cases. Each limit of quantification (LOQ) was 0.01 mg kg-1. Fifteen days after application with 56 mg kg-1, the terminal residues of fenpyroximate in whole fruits and citrus flesh were <0.010-0.18 mg kg-1 and <0.010-0.063 mg kg-1, respectively; the corresponding values for total fenpyroximate (the sum of fenpyroximate and Z-fenpyroximate) were <0.020-0.19 and <0.020-0.053 mg kg-1. The levels of terminal fenpyroximate residues in citrus fruit were less than the maximum residue limits (MRLs) specified in all the existing international standards. In addition, the risk quotients RQc and RQa were both less than 100%, indicating that the long-term and short-term dietary intake risks posed to Chinese consumers by fenpyroximate in citrus fruit are both acceptable after a 15-day harvest interval.

Implementation of a novel ultra fast metabolic stability analysis method using exact mass TOF-MS

AIM

Increasing numbers of compounds requiring stability data means highly optimized methods capable of rapid turnaround are desirable during early discovery. Materials and methods/results: An advanced, generic analytical workflow for metabolic stability has been developed that utilizing ballistic gradient LC (sub 1 min run times), exact mass TOF-MS (Waters Xevo-G2-XS Q-TOF) and automated data processing (Waters UNIFI software) allowed for rapid integration and interpretation of all data produced, eliminating the need for method development and manual processing. We can analyze and process 96 compounds across two species in quadruplicate in a 24-h period with no method development.

CONCLUSION

An advanced bioanalytical workflow has increased our capacity threefold and reduced our instrument/processing needs threefold.

Development and validation of sensitive and rapid UPLC-MS/MS method for quantitative determination of daclatasvir in human plasma: Application to a bioequivalence study

A rapid and sensitive UPLC-MS/MS method was developed and validated for determination of daclatasvir (DAC) in human plasma using sofosbuvir (SOF) as an internal standard (IS). The Xevo TQD LC-MS/MS was operated under the multiple-reaction monitoring mode using electrospray ionization. Precipitation with acetonitrile was used in sample preparation. The prepared samples were chromatographed on Acquity UPLC HSS C18 (50×2.1mm, 1.8μm) column by pumping 10mM ammonium formate (pH 3.5) and acetonitrile in an isocratic mode at a flow rate of 0.30ml/min. Method validation was performed as per the FDA guidelines and the standard curves were found to be linear in the range of 5-4000ng/ml for DAC. The intra-day and inter-day precision and accuracy results were within the acceptable limits. A very short run time of 1.2min made it possible to analyze more than 500 human plasma samples per day. The wider range of quantification of DAC allowed the applicability of the developed method for its determination in a bioequivalence study in human volunteers.

Novel and sensitive UPLC-MS/MS method for quantification of sofosbuvir in human plasma: application to a bioequivalence study

A novel and sensitive LC-MS/MS method was developed and validated for determination of sofosbuvir (SF) using eplerenone as an internal standard. The Xevo TQD LC-MS/MS was operated under the multiple-reaction monitoring mode using electrospray ionization. Extraction with tert-butyl methyl ether was used in sample preparation. The prepared samples were chromatographed on Acquity UPLC BEH C18 (50 × 2.1 mm, 1.7 μm) column by pumping 0.1% formic acid and acetonitrile in an isocratic mode at a flow rate of 0.35 mL/min. Method validation was performed as per the US Food and Drug Administration guidelines and the standard curves were found to be linear in the range of 0.25-3500 ng/mL for SF. The intra- and inter-day precision and accuracy results were within the acceptable limits. A very short run time of 1 min made it possible to analyze more than 500 human plasma samples per day. A very low quantification limit of SF allowed the applicability of the developed method for determination of SF in a bioequivalence study in human volunteers. Copyright © 2016 John Wiley & Sons, Ltd.

Development of a sensitive UPLC-ESI-MS/MS method for quantification of sofosbuvir and its metabolite, GS-331007, in human plasma: Application to a bioequivalence study

A rapid and simple LC-MS/MS method was developed and validated for the simultaneous estimation of sofosbuvir (SF) and its metabolite GS-331007 (GS) using famotidine as an internal standard (IS). The Xevo TQD LC-MS/MS was operated under the multiple-reaction monitoring mode using electrospray ionization. Extraction with ethyl acetate was used in sample preparation. The prepared samples were chromatographed on Acquity UPLC HSS C₁₈ (50 mm × 2.1 mm, 1.8 μm) column by pumping 0.1% formic acid and acetonitrile (50:50, v/v) in an isocratic mode at a flow rate of 0.3 ml/min. Method validation was performed as per the FDA guidelines and the standard curves were found to be linear in the range of 10-2500 ng/ml for both SF and its metabolite. The intra-day and inter-day precision and accuracy results were within the acceptable limits. A very short run time of 1.2 min made it possible to analyze more than 300 human plasma samples per day. The developed assay method was successfully applied to a bioequivalence study in human volunteers.

Profiling cholinesterase adduction: a high-throughput prioritization method for organophosphate exposure samples

A high-throughput prioritization method was developed for use with a validated confirmatory method detecting organophosphorus nerve agent exposure by immunomagnetic separation high-performance liquid chromatography tandem mass spectrometry. A ballistic gradient was incorporated into this analytical method to profile unadducted butyrylcholinesterase (BChE) in clinical samples. With Zhang et al.'s Z' factor of 0.88 ± 0.01 (SD) of control analytes and Z factor of 0.25 ± 0.06 (SD) of serum samples, the assay is rated an "excellent assay" for the synthetic peptide controls used and a "double assay" when used to prioritize clinical samples. Hits, defined as samples containing BChE Ser-198 adducts or no BChE present, were analyzed in a confirmatory method for identification and quantitation of the BChE adduct, if present. The ability to prioritize samples by highest exposure for confirmatory analysis is of particular importance in an exposure to cholinesterase inhibitors such as organophosphorus nerve agents, in which a large number of clinical samples may be collected. In an initial blind screen, 67 of 70 samples were accurately identified, giving an assay accuracy of 96%, and it yielded no false-negatives. The method is the first to provide a high-throughput prioritization assay for profiling adduction of Ser-198 BChE in clinical samples.

Perspectives on recent advances in the speed of high-performance liquid chromatography

Perhaps the most consistent trend in the development of high-performance liquid chromatography (HPLC) since its inception in the 1960s has been the continuing reach for ever faster analyses. The pioneering work of Knox, Horvath, Halasz, and Guiochon set forth a theoretical framework that was used early on to improve the speed of HPLC, primarily through the commercialization of smaller and smaller particles. Over the past decade, approaches to improving the speed of HPLC have become more diverse, and now practitioners of HPLC are faced with the difficult task of deciding which of these approaches will lead them to the fastest analysis for their application. Digesting the rich literature on the optimization of HPLC is a difficult task in itself, which is further complicated by contradictory marketing messages from competing commercial outlets for HPLC technology. In this perspectives article we provide an overview of the theoretical and practical aspects of the principal modern approaches to improving the speed of HPLC. We present a straightforward theoretical basis, informed by decades of literature on the problem of optimization, that is useful for comparing different technologies for improving the speed of HPLC. Through mindful optimization of conditions, high-performance separations on the subminute timescale are now possible and becoming increasingly common under both isocratic and gradient elution conditions. Certainly the continued development of ultrafast separations will play an important role in the development of two-dimensional HPLC separations. Despite the relatively long history of HPLC as an analytical technique, there is no sign of a slow-down in the development of novel HPLC technologies.

Development of a high sensitivity bioanalytical method for alprazolam using ultra-performance liquid chromatography/tandem mass spectrometry

A rapid, specific, assay was developed for the benzodiapine alprazolam in rat plasma using sub-2 µm particle liquid chromatography (LC) and tandem quadrupole mass spectrometry (MS/MS). The limit of quantification using protein precipitation was determined to 10 pg/mL, whereas the limit of quantification using solid-phase extraction (SPE) was determined to be 1.0 pg/mL. The assay was optimized for throughput and resolution of the analyte of interest from the hydroxy metabolite. During the method development process the plasma matrix signal was monitored, for lipids and other endogenous metabolites, to maximize signal response and minimize ion suppression. This was achieved by using a tandem quadrupole mass spectrometer equipped with a novel collision cell design which allowed for the simultaneous collection of full scan MS and multiple reaction monitoring (MRM) data. The lipid profile from the SPE process was significantly less than obtained with the protein precipitation approach.

Compensation of matrix effects by postcolumn infusion of a monitor substance in multiresidue analysis with LC-MS/MS

This study systematically compares matrix effects in liquid chromatography (LC) coupled by electrospray ionization (ESI) in the positive mode with tandem mass spectrometry (MS/MS) for 129 pesticides in 20 plant matrixes. In total, 2388 analyte/matrix combinations were evaluated. Permanent postcolumn infusion (PCI) of analyte standards was used to quantify matrix effects over the whole chromatographic run time. This allowed the analyte signal suppression or enhancement, by different coeluting matrix components, to be assessed throughout the duration of an entire chromatographic run, i.e., independent of a specific retention time. Matrix effects occurring at a certain retention time in one matrix were surprisingly similar for different analytes with diverse physicochemical properties. On the basis of this finding, a new approach for matrix effect compensation in multiresidue analysis was developed in which one single monitor substance is permanently added postcolumn. Signal intensities of all analytes obtained by LC-MS/MS analysis of sample extracts are then corrected for the matrix effect recorded by the monitor substance. With the use of this approach, strong matrix effects could be reduced and apparent recoveries increased from 45% to 85% on average. With dependence on the particular sample matrix, between 69% and 100% of the analytes showed recoveries between 60% and 140% after correction. Thus this approach may significantly reduce the number of cases in which standard addition is required to confirm violations of maximum residue levels.

Increasing high-throughput discovery bioanalysis using automated selected reaction monitoring compound optimization, ultra-high-pressure liquid chromatography, and single-step sample preparation workflows

QuickQuan is an integrated software package for Thermo Scientific triple quadrupole mass spectrometers that allows users to automate routine operations ranging from method development to data processing. QuickQuan automated optimization of compound-selected reaction monitoring (SRM) transitions by evaluating both positive and negative polarities during an infusion. Whichever mode produces the most intense Q1 scan is then carried to product ion spectra. QuickQuan then writes these SRM methods to a shared network database. The total volume of compound needed is 100 microL infused over approximately 1.6 min. The auto-optimization is carried out in 96-well plates and does not require an operator present. The SRM database was shared between two identical TSQ Quantum mass spectrometers. For data acquisition, QuickQuan automatically created a sequence file complete with a data processing method pre-populated with compound IDs and corresponding SRM transitions. To increase throughput we coupled each Finnigan Quantum with ultra-high-pressure liquid chromatography (uHPLC) accomplished using 4x Ultra Flux quaternary pumps that were designed to handle pressures up to 15 000 psi. The total run time for all analyses was 1.2 min using BEH 1.7 microm particle C18 columns. Further time reductions were realized with sample preparation accomplished using Strata Impact protein precipitation plates which provided an in-well protein crash and 0.20 micron filtering in a one-step process. Pharmacokinetic data turnaround time was significantly improved by combining these three techniques of automated method development with the speed efficiency of uHPLC and a single step in well sample preparation.

Matrix effect elimination during LC–MS/MS bioanalytical method development

Due to the presence of endogenous components in biofluids, ionization suppression or enhancement may occur for bioanalytical assays using LC–MS or LC–MS/MS technologies. The matrix effect may affect the precision and accuracy of a bioanalytical method and, therefore, compromise the quality of the results. Protein precipitation sample preparation along with LC–MS/MS is a high-throughput method most commonly used in bioanalysis and is largely affected by the matrix effect. In order to eliminate the matrix effect during the method development, some considerations may be used: cleaner sample preparations, more sensitive instruments, which allow less material to be injected, different chromatographic separations and much more must be investigated. More than giving tools to adequately assess the matrix effect during the method development, this review gives scientists numerous ways to eliminate or reduce the matrix effect based on novel sample-preparation techniques, new chromatographic optimization methods and new technologies.

Isobaric metabolite interferences and the requirement for close examination of raw data in addition to stringent chromatographic separations in liquid chromatography/tandem mass spectrometric analysis of drugs in biological matrix

In addition to matrix effects, common interferences observed in liquid chromatography/tandem mass spectrometry (LC/MS/MS) analyses can be caused by the response of drug-related metabolites to the multiple reaction monitoring (MRM) channel of a given drug, as a result of in-source reactions or decomposition of either phase I or II metabolites. However, it has been largely ignored that, for some drugs, metabolism can lead to the formation of isobaric or isomeric metabolites that exhibit the same MRM transitions as parent drugs. The present study describes two examples demonstrating that interference caused by isobaric or isomeric metabolites is a practical issue in analyzing biological samples by LC/MS/MS. In the first case, two sequential metabolic reactions, demethylation followed by oxidation of a primary alcohol moiety to a carboxylic acid, produced an isobaric metabolite that exhibits a MRM transition identical to the parent drug. Because the drug compound was rapidly metabolized in rats and completely disappeared in plasma samples, the isobaric metabolite appeared as a single peak in the total ion current (TIC) trace and could easily be quantified as the drug since it was eluted at a retention time very close to that of the drug in a 12-min LC run. In the second example, metabolism via the ring-opening of a substituted isoxazole moiety led to the formation of an isomeric product that showed an almost identical collision-induced dissociation (CID) MS spectrum as the original drug. Because two components were co-eluted, the isomeric product could be mistakenly quantified and reported by data processing software as the parent drug if the TIC trace was not carefully inspected. Nowadays, all LC/MS data are processed by computer software in a highly automated fashion, and some analysts may spend much less time to visually examine raw TIC traces than they used to do. Two examples described in this article remind us that quality data require both adequate chromatographic separations and close examination of raw data in LC/MS/MS analyses of drugs in biological matrix.

A rapid and sensitive method for the quantitation of montelukast in sheep plasma using liquid chromatography/tandem mass spectrometry

A rapid LC-MS/MS method was developed and partially validated for the quantitation of montelukast in spiked sheep plasma. A total run time of 1.5 min was achieved using a short monolithic column and employing a rapid gradient. Sample preparation involved protein precipitation with twofold acetonitrile by volume during which a deuterated internal standard (montelukast D-6) was incorporated. The MRM transitions for montelukast and the deuterated internal standard were 586/422 and 592/427, respectively. A linear dynamic range of 0.25-500 ng/mL with a correlation coefficient of 0.9999 was achieved. Precision was below 5% at all levels except at the LOQ (0.36 ng/mL) which demonstrated an overall of R.S.D. of 8%. Post-column infusion experiments were performed with precipitated plasma matrix and showed minimal interference with the peaks of interest.

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.