Recent advances in high-throughput quantitative bioanalysis by LC–MS/MS

Biological sample preparation: attempts on productivity increasing in bioanalysis

Sample preparation is an important step of any biomedical analysis. Development and validation of fast, reproducible and reliable sample preparation methods would be very helpful in increasing productivity. Except for a few direct injection methods, almost all biological samples should at least be diluted before any analysis. Sometimes dilution is not possible because of the low concentration of the target analyte in the sample, and alternative pretreatments, such as filtration, precipitation and sample clean up using different extraction methods, are needed. This review focuses on the recent achievements in the pretreatment of biological samples and investigates them in six categories (i.e., dilution, filtration/dialysis, precipitation, extraction [solid-phase extraction, liquid–liquid extraction], novel techniques [turbulent flow chromatography, immunoaffinity method, electromembrane extraction] and combined methods). Each category will be discussed according to its productivity rate and suitability for routine analysis, and the discussed methods will be compared according to the mentioned indices.

Evaluation and optimization of high-performance liquid chromatography coupled with high-resolution mass spectrometry for phospholipid quantitation

RATIONALE

High-performance liquid chromatography coupled with high-resolution mass spectrometry (HPLC/HRMS) provides an attractive alternative to the traditional triple quadrupole mass spectrometry selected reaction monitoring (SRM) methodology in the field of quantitation.

METHODS

An LTQ Orbitrap Velos mass spectrometer coupled with a Shimadzu UHPLC system was used. A mass extraction window (MEW) was defined to mathematically correlate with mass resolving power (MRP). Five MRP measurement conditions at 7500, 15,000, 30,000, 60,000, and 100,000, and five MEW widths at 10%, 20%, 50%, and 100% of ±1000000/MRP, and were utilized as the experimental conditions. Comparison of profile and centroid algorithms was evaluated as well.

RESULTS

Selection of pH 8.5 buffer, C4 column, 20% IPA, and 10 ppm H3 PO4 , minimized hydrophobic and silanol interactions to enhance separation. Narrowing the MEW minimized background noise, while over-narrowing the MEW gave signal loss due to mass accuracy deviation. The mass accuracy deviation was larger for lower MRP measurements especially with centriod data, and hence a profile algorithm was recommended. The post-ionization signal suppression was observed with low MRP and was further confirmed with the analysis of multi-level linearity.

CONCLUSIONS

It was found that the HPLC/HRMS method with conditions of 20% ±1000000/MRP as MEW, 30,000 or 60,000 MRP, and profile algorithm, provide optimum results for quantitation of seven model phospholipids.

HILIC UHPLC-MS/MS for fast and sensitive bioanalysis: accounting for matrix effects in method development

BACKGROUND

Matrix effects are considered to be a main obstacle of quantitative bioanalytical LC-MS/MS methods. Therefore it is often required to minimize them in order to increase method reliability. HILIC has been referenced as one of possible approaches. However, there is a lack of experimental evidence in scientific literature so far.

METHODOLOGY

Matrix effects were evaluated using spiked serum samples after SPE and protein precipitation prior to UHPLC-ESI-MS/MS. Chromatography was performed in both HILIC and reversed-phase mode. The influence of the matrix effects on the signal response was assessed using a set of 34 compounds of pharmaceutical interest and post-extraction addition approach.

RESULTS

The advantages and drawbacks of the HILIC and reversed-phase chromatographic modes were compared and discussed in detail.

CONCLUSION

HILIC demonstrated the potential to reduce the occurrence of matrix effects when a more thorough sample pretreatment procedure such as SPE was applied.

Polyamines in biological samples: rapid and robust quantification by solid-phase extraction online-coupled to liquid chromatography-tandem mass spectrometry

Polyamines are ubiquitous active biogenic amines which contribute to basic cellular functions. Hence, their quantification in samples of diverse biological origins is essential for understanding how they function, especially in disease-relevant conditions. We present here a robust, high-throughput solid-phase extraction online coupled to a liquid chromatography-tandem mass spectrometry (SPE-LC/MS/MS) approach for the simultaneous quantification of eight polyamines in various biological samples. The polyamines include 1,3-diaminopropane, putrescine, cadaverin, N-acetyl-putrescine, spermidine, spermine, N(1)-acetyl-spermine, and l-ornithine. The novelty of the work is the use of two SPE columns online coupled to LC/MS/MS, which minimizes the sample pretreatment to a single derivatization step. The analysis is complete within 4min, making the method highly suitable for routine clinical analysis and high throughput screenings. The method was fully validated with serum samples. Dynamic ranges were 0.03 to 15μg/ml for ornithine and 1 to 500ng/ml for other polyamines, which cover physiological concentrations in serum samples. Lower limits of quantification (LLoQ) were found to be between 0.1 and 5ng/ml. As a proof of concept, we investigated gender differences in polyamine levels by analyzing the serum levels of 102 subjects.

Pharmacodynamic evaluation and physical/chemical analysis of two formulations of propofol used in target-controlled infusion

BACKGROUND AND OBJECTIVES

There are several formulations of propofol available to the anesthesiologist for clinical use. The aim of this study was to analyze the physicochemical properties, pharmacodynamic effect, and pharmaceutical and clinical equivalence of the reference drug propofol as well as a similar formulation.

METHOD

Sixteen volunteers were enrolled in this randomized, double-blind, and paired study of Diprivan® and Propovan® formulations. Formulations were given as target-controlled infusion with target concentration of 3.0 μg.mL(-1) for 15 minutes. Variables studied were the area under the curve (AUC) of the bispectral index (BIS) graph regarding time, minimum BIS reached and time to reach it, and recovery time. The two formulations were sent to analysis of particle size of lipid emulsion, surface potential, and active principle quantification.

RESULTS

There was no difference between the formulations when comparing AUC, minimum BIS reached and time to reach it. The similar formulation recovery time was lower compared to the reference formulation (eight and 10 min, respectively, p = 0.014). Mean particle size of lipid emulsion, surface potential, and active ingredient quantification were similar for both formulations.

CONCLUSION

There was no clinically significant difference between the use of propofol, reference Diprivan®, and the similar Propovan® during infusion. However, the recovery time was longer with the reference drug. Although analysis of both formulations studied show similar results regarding its physicochemical characterization, further studies should be conducted to justify this difference.

The safety and efficacy of short-term budesonide delivered via mucosal atomization device for chronic rhinosinusitis without nasal polyposis

BACKGROUND

Budesonide is a potent corticosteroid commonly prescribed for management of inflammation in chronic rhinosinusitis (CRS). The standard for prescribing budesonide is via impregnated nasal saline irrigation (INSI), although recently the mucosal atomization device (MAD) has emerged as a theoretically superior method of distributing medication into the sinuses. The MAD atomizes medication into small droplets and this is thought to enhance absorption and improve bioavailability. However, no studies have shown whether enhanced absorption and improved bioavailability of budesonide via MAD causes adrenal suppression. The objective of this study is to determine whether budesonide via MAD affects the hypothalamic-pituitary-adrenal (HPA) axis.

METHODS

Twenty CRS patients were recruited from a tertiary rhinology clinic and randomized to take budesonide (1 mg) via MAD or via INSI twice a day for 60 days. The adrenocorticotropic hormone (ACTH) stimulation test and 22-item Sinonasal Outcomes Test (SNOT-22) questionnaire were administered on days 1, 30, and 60 of the study. Plasma budesonide and cortisol levels were simultaneously quantified using a high-performance liquid chromatography-tandem mass spectrometry technique.

RESULTS

There was no indication of adrenal suppression in either group (n = 20) based on ACTH stimulation test results nor was there significant plasma budesonide levels detected in either group. Quality of life, as indicated by SNOT-22, did not differ between groups at 60 days (p = 0.404; 95% confidence interval [CI], -37.2 to 15.9), but SNOT-22 scores for patients using MAD did show statistically significant improvement at 60 days compared to baseline (p = 0.02).

CONCLUSION

The MAD is likely a safe and effective method of delivering budesonide to the sinuses in the short term.

Comparative proteomics analysis of engineered Saccharomyces cerevisiae with enhanced biofuel precursor production

The yeast Saccharomyces cerevisiae was metabolically modified for enhanced biofuel precursor production by knocking out genes encoding mitochondrial isocitrate dehydrogenase and over-expression of a heterologous ATP-citrate lyase. A comparative iTRAQ-coupled 2D LC-MS/MS analysis was performed to obtain a global overview of ubiquitous protein expression changes in S. cerevisiae engineered strains. More than 300 proteins were identified. Among these proteins, 37 were found differentially expressed in engineered strains and they were classified into specific categories based on their enzyme functions. Most of the proteins involved in glycolytic and pyruvate branch-point pathways were found to be up-regulated and the proteins involved in respiration and glyoxylate pathway were however found to be down-regulated in engineered strains. Moreover, the metabolic modification of S. cerevisiae cells resulted in a number of up-regulated proteins involved in stress response and differentially expressed proteins involved in amino acid metabolism and protein biosynthesis pathways. These LC-MS/MS based proteomics analysis results not only offered extensive information in identifying potential protein-protein interactions, signal pathways and ubiquitous cellular changes elicited by the engineered pathways, but also provided a meaningful biological information platform serving further modification of yeast cells for enhanced biofuel production.

Simultaneous determination of imperatorin and its metabolite xanthotoxol in rat plasma by using HPLC-ESI-MS coupled with hollow fiber liquid phase microextraction

The objective of the present study was to develop a new method for the simultaneous quantitation of imperatorin and its metabolite xanthotoxol in rat plasma. The samples were prepared with hollow fiber liquid phase microextraction (HF-LPME). The optimized extraction procedure was acquired by assessing extraction solvent, length of the fiber, agitation rate, extraction temperature and time. A comparison of sample pretreatment ways between HF-LPME and deproteinization with methanol was performed, which demonstrated less ion suppression and better sensitivity of HF-LPME. Analytes were separated on a C18 column with a gradient elution consisted of methanol and water containing 1mmol/L ammonium acetate. The detection was accomplished by electrospray ionization (ESI) source operating in the positive ionization mode. Selected-multiple-reaction monitoring (SMRM) scanning was employed, which guaranteed a higher sensitivity compared with MRM mode. Calibration curves were linear over investigated ranges with correlation coefficients greater than 0.9979. Precision varied from 0.26% to 14%, and the accuracy varied within ±5.5%. The developed method was successfully applied to the pharmacokinetic research of imperatorin and its metabolite xanthotoxol after oral administration of imperatorin to rats.

Mass spectrometry and NMR spectroscopy: modern high-end detectors for high resolution separation techniques--state of the art in natural product HPLC-MS, HPLC-NMR, and CE-MS hyphenations

Current natural product research is unthinkable without the use of high resolution separation techniques as high performance liquid chromatography or capillary electrophoresis (HPLC or CE respectively) combined with mass spectrometers (MS) or nuclear magnetic resonance (NMR) spectrometers. These hyphenated instrumental analysis platforms (CE-MS, HPLC-MS or HPLC-NMR) are valuable tools for natural product de novo identification, as well as the authentication, distribution, and quantification of constituents in biogenic raw materials, natural medicines and biological materials obtained from model organisms, animals and humans. Moreover, metabolic profiling and metabolic fingerprinting applications can be addressed as well as pharmacodynamic and pharmacokinetic issues. This review provides an overview of latest technological developments, discusses the assets and drawbacks of the available hyphenation techniques, and describes typical analytical workflows.

Determination of rosiglitazone and 5-hydroxy rosiglitazone in rat plasma using LC–HRMS by direct and indirect quantitative analysis: a new approach for metabolite quantification

Background: With recent advances in mass spectrometry instrumentation, HRMS is of increasing interest for quantitative bioanalysis due to its high sensitivity, rapid acquisition of full scan data, and advanced software for metabolite identification. In particular, there is strong interest in use of HRMS for simultaneous quantification of parent drug and metabolites without authentic metabolite standard materials. Materials & methods: Rosiglitazone and 5-hydroxy rosiglitazone in rat plasma were analyzed using LC–Q-TOF by both direct and indirect quantitative analysis. Direct quantitative analysis used an authentic metabolite standard (5-hydroxy rosiglitazone). Indirect quantitative analysis firstly used the parent drug (rosiglitazone) calibration curve to provide a semiquantitative measure of metabolite concentration. A correction factor was then applied to the original data to re-calculate the 5-hydroxy rosiglitazone metabolite concentration. Results: The ratio of the calibration curve slope of rosiglitazone to that of 5-hydroxy rosiglitazone was determined to be 2.09 ± 0.28 using different batches of mobile phases and columns. The correction factor 2.09 was then used to correct for the 5-hydroxy rosiglitazone concentrations found from the semiquantitative results using the rosiglitazone calibration standard curve. The concentrations of 5-hydroxy rosiglitazone found by direct and indirect quantitative analysis were highly comparable (within ±8%). Conclusion: Indirect quantitative analysis provides an alternative approach for metabolite quantification for discovery PK studies.

Strategies for ascertaining the interference of phase II metabolites co-eluting with parent compounds using LC-MS/MS

LC-MS/MS is currently the most selective and efficient tool for the quantitative analysis of drugs and metabolites in the pharmaceutical industry and in clinical assays. However, phase II metabolites sometimes negatively affect the selectivity and efficiency of the LC-MS/MS method, especially for the metabolites that possess similar physicochemical characteristics and generate the same precursor ions as their parent compounds due to the in-source collision-induced dissociation during the ionization process. This paper proposes some strategies for examining co-eluting metabolites existing in real samples, and further assuring whether these metabolites could affect the selectivity and accuracy of the analytical methods. Strategies using precursor-ion scans and product-ion scans were applied in this study. An example drug, namely, caffeic acid phenethyl ester, which can generate many endogenous phase II metabolites, was selected to conduct this work. These metabolites, generated during the in vivo metabolic processes, can be in-source-dissociated to the precursor ions of their parent compounds. If these metabolites are not separated from their parent compounds, the quantification of the target analytes (parent compounds) would be influenced. Some metabolites were eluted closely to caffeic acid phenethyl ester on LC columns, although long columns and relatively long elution programs were used. The strategies can be utilized in quantitative methodologies that apply LC-MS/MS to assure the performance of selectivity, thus enhancing the reliability of the experimental data.

Bioanalytical method validation: An updated review

The development of sound bioanalytical method(s) is of paramount importance during the process of drug discovery and development, culminating in a marketing approval. The objective of this paper is to review the sample preparation of drug in biological matrix and to provide practical approaches for determining selectivity, specificity, limit of detection, lower limit of quantitation, linearity, range, accuracy, precision, recovery, stability, ruggedness, and robustness of liquid chromatographic methods to support pharmacokinetic (PK), toxicokinetic, bioavailability, and bioequivalence studies. Bioanalysis, employed for the quantitative determination of drugs and their metabolites in biological fluids, plays a significant role in the evaluation and interpretation of bioequivalence, PK, and toxicokinetic studies. Selective and sensitive analytical methods for quantitative evaluation of drugs and their metabolites are critical for the successful conduct of pre-clinical and/or biopharmaceutics and clinical pharmacology studies.

Surface-activated chemical ionization-electrospray ionization mass spectrometry combined with two-dimensional serial chromatography is a powerful tool for drug stability studies

RATIONALE

Drug stability is an important quality-control issue for pharmaceutical and clinical practices. Among the analytical techniques that address this issue, liquid chromatography/mass spectrometry (LC/MS) can be very useful, especially when assessing the quality of liquid formulations, because it is intrinsically sensitive, selective, and a rapid analytical technique. However, LC/MS suffers from technical drawbacks, e.g., matrix effects, and the production of in-source degradation products, which can limit its usefulness.

METHODS

To overcome the aforementioned drawbacks associated with LC/MS, we introduce an innovative approach (2D-LC/SACI-ESI-MS/MS) that incorporates two-dimensional liquid chromatography (2D-LC) in conjunction with an MS system consisting of a surface-activated chemical ionization-electrospray ionization chamber (SACI-ESI), an ion trap MS analyzer, and tandem mass spectrometry.

RESULTS

To validate our 2D-LC/SACI-ESI-MS/MS system stability studies were performed on the computerized tomography contrast agents, iohexol, iodixanol, iopamidol, iomeprol, iopromide, and iobitridol, either alone or in binary combination. The matrix effects, in-source analyte degradation, and analytical performance were compared with those obtained using a one-dimensional LC/MS configuration. The accuracy coefficient of variance (CV) = 1-4%, and degradation (loss of water and other chemical moieties) was greatly reduced, attesting to the usefulness of this system for drug stability measurements.

CONCLUSIONS

Our new approach improves the performance (sensitivity, accuracy, and signal stability) of LC/MS instrumentation for drug stability measurements by reducing signal suppression effects and in-source chemical reactions.

Enabling quantitative analysis in ambient ionization mass spectrometry: internal standard coated capillary samplers

We describe a sampling method using glass capillaries for quantitative analysis of trace analytes in small volumes of complex mixtures (~1 μL) using ambient ionization mass spectrometry. The internal surface of a sampling glass capillary was coated with internal standard then used to draw liquid sample and so transfer both the analyte and internal standard in a single fixed volume onto a substrate for analysis. The internal standard was automatically mixed into the sample during this process and the volumes of the internal standard solution and sample are both fixed by the capillary volume. Precision in quantitation is insensitive to variations in length of the capillary, making the preparation of the sampling capillary simple and providing a robust sampling protocol. Significant improvements in quantitation accuracy were obtained for analysis of 1 μL samples using various ambient ionization methods.

A critical review of microextraction by packed sorbent as a sample preparation approach in drug bioanalysis

Sample preparation is widely accepted as the most labor-intensive and error-prone part of the bioanalytical process. The recent advances in this field have been focused on the miniaturization and integration of sample preparation online with analytical instrumentation, in order to reduce laboratory workload and increase analytical performance. From this perspective, microextraction by packed sorbent (MEPS) has emerged in the last few years as a powerful sample preparation approach suitable to be easily automated with liquid and gas chromatographic systems applied in a variety of bioanalytical areas (pharmaceutical, clinical, toxicological, environmental and food research). This paper aims to provide an overview and a critical discussion of recent bioanalytical methods reported in literature based on MEPS, with special emphasis on those developed for the quantification of therapeutic drugs and/or metabolites in biological samples. The advantages and some limitations of MEPS, as well as its comparison with other extraction techniques, are also addressed herein.

Salting-out assisted liquid–liquid extraction for bioanalysis

Salting-out assisted liquid–liquid extraction (SALLE) applies the salting-out effect to separate water-miscible organic solvent such as acetonitrile from plasma or other aqueous biofluids, and can extract a wide range of drug and metabolites, including many hydrophilic compounds. In most cases, the separated organic phase can be directly injected for bioanalysis, or with a simple dilution. SALLE provides similar simplicity to protein precipitation, but cleaner extracts due to a true phase separation. SALLE is also faster, more environmentally friendly and more cost-efficient than conventional liquid–liquid extraction and SPE. Through 96-well automation, SALLE can be easily integrated into the overall high-throughput LC–MS/MS bioanalysis strategy to increase productivity. This article provides a critical overview of the literatures on SALLE and perspectives of the future bioanalytical application of this often overlooked extraction technique. Important parameters impacting SALLE-LC–MS/MS assays are also discussed.

Simultaneous determination of asenapine and valproic acid in human plasma using LC-MS/MS: Application of the method to support pharmacokinetic study

Combination of asenapine with valproic acid received regulatory approval for acute treatment of schizophrenia and maniac episodes of bipolar disorders. A simple LC–MS/MS method was developed and validated for simultaneous quantification of asenapine and valproic acid in human plasma. Internal standards were added to 300 μL of plasma sample prior to liquid–liquid extraction using methyl tertiary butyl ether (MTBE). Chromatographic separation was achieved on Phenomenex C18 column (50 mm×4.6 mm, 5 μm) in isocratic mode at 40 °C. The mobile phase used was 10 mM ammonium formate–acetonitrile (5:95, v/v) at a constant flow rate of 0.8 mL/min monitored on triple quadrupole mass spectrometer, operating in the multiple reaction monitoring (MRM) mode. The injection volume used for LC–MS/MS analysis was 15 μL and the run time was 2.5 min. These low run time and small injection volume suggest the high efficiency of the proposed method. The method was validated over the concentration range of 0.1–10.02 ng/mL and 10–20,000 ng/mL for asenapine and valproic acid respectively. The method recoveries of asenapine (81.33%), valproic acid (81.70%), gliclazide (78.45%) and benzoic acid (79.73) from spiked plasma samples were consistent and reproducible. The application of this method was demonstrated by a pharmacokinetic study in 8 healthy male volunteers with 5 mg asenapine and 250 mg valproic acid administration.

Clinical applications of fast liquid chromatography: a review on the analysis of cardiovascular drugs and their metabolites

One of the major challenges facing the medicine today is developing new therapies that enhance human health. To help address these challenges the utilization of analytical technologies and high-throughput automated platforms has been employed; in order to perform more experiments in a shorter time frame with increased data quality. In the last decade various analytical strategies have been established to enhance separation speed and efficiency in liquid chromatography applications. Liquid chromatography is an increasingly important tool for monitoring drugs and their metabolites. Furthermore, liquid chromatography has played an important role in pharmacokinetics and metabolism studies at these drug development stages since its introduction. This paper provides an overview of current trends in fast chromatography for the analysis of cardiovascular drugs and their metabolites in clinical applications. Current trends in fast liquid chromatographic separations involve monolith technologies, fused-core columns, high-temperature liquid chromatography (HTLC) and ultra-high performance liquid chromatography (UHPLC). The high specificity in combination with high sensitivity makes it an attractive complementary method to traditional methodology used for routine applications. The practical aspects of, recent developments in and the present status of fast chromatography for the analysis of biological fluids for therapeutic drug and metabolite monitoring, pharmacokinetic studies and bioequivalence studies are presented.

Tandem mass spectrometry in hormone measurement

Mass spectrometry methods have the potential to measure different hormones during the same analysis and have improved specificity and a wide analytical range compared with many immunoassay methods. Increasingly in clinical laboratories liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays are replacing immunoassays for the routine measurement of testosterone, 17-hydroxyprogesterone, and other steroid hormones. Reference LC-MS/MS methods for steroid, thyroid, and peptide hormones are being used for assessment of the performance and calibration of commercial immunoassays. In this chapter, the general principles of tandem mass spectrometry and examples of hormone assays are described.

HybridSPE: A novel technique to reduce phospholipid-based matrix effect in LC-ESI-MS Bioanalysis

When complex biological materials are analyzed without an adequate sample preparation technique, MS signal and response undergo significant alteration and result in poor quantification and assay. This problem generally takes place due to the presence of several endogenous materials component in samples. One of the major causes of ion suppression in bioanalysis is the presence of phospholipids during LC-MS analysis. The phospholipid-based matrix effect was investigated with a commercially available electro spray ionization (ESI) source coupled with a triple quadrupole mass spectrometer. HybridSPE dramatically reduced the levels of residual phospholipids in biological samples, leading to significant reduction in matrix effects. This new procedure that combines the simplicity of precipitation with the selectivity of SPE allows obtaining much cleaner extracts than with conventional procedures. HybridSPE-precipitation procedure provides significant improvement in bioanalysis and a practical and fast way to ensure the avoidance of phospholipids-based matrix effects. The present review outlines the HybridSPE technique to minimize phospholipids-based matrix effects on LC–ESI-MS bioanalysis.

Analysis of chloroquine and metabolites directly from whole-body animal tissue sections by liquid extraction surface analysis (LESA) and tandem mass spectrometry

The rapid and direct analysis of the amount and spatial distribution of exogenous chloroquine (CHQ) and CHQ metabolites from tissue sections by liquid extraction surface sampling analysis coupled with tandem mass spectrometry (LESA-MS/MS) was demonstrated. LESA-MS/MS results compared well with previously published CHQ quantification data collected by organ excision, extraction and fluorescent detection. The ability to directly sample and analyze spatially resolved exogenous molecules from tissue sections with minimal sample preparation and analytical method development has the potential to facilitate the assessment of target tissue penetration of pharmaceutical compounds, to establish pharmacokinetic/pharmacodynamic relationships, and to complement established pharmacokinetic methods used in the drug discovery process during tissue distribution assessment.

Direct bioanalytical sample injection with 2D LC–MS

New analytical platforms have been developed in response to the need for attaining increased peak capacity for multicomponent complex analysis with higher sensitivity and characterization of the analytes, and high-throughput capabilities. This review outlines the fundamental principles of target and comprehensive 2D LC method development and encompasses applications of LC–LC and LC × LC coupled to MS in bioanalysis using a variety of online analytical procedures. It also provides a rationale for the usage of the most employed mass analyzers and ionization sources on these platforms.

Investigation of microbore UPLC and nontraditional mobile phase compositions for bioanalytical LC-MS/MS

BACKGROUND

The movement towards environmentally friendly or green chemistry solutions has gained more prominence recently in the scientific community. One way in which scientists can address this issue is to limit the use of hazardous chemicals in their everyday processes. Therefore, the focus of this study was on the utilization of microbore-scale chromatography and nontraditional alcoholic mobile phases as an alternative approach to traditional bioanalytical LC-MS/MS assay parameters.

RESULTS

Replacement of the traditional narrowbore LC column with a microbore format reduced solvent consumption and produced a greater than threefold increase in S/N. The nontraditional alcoholic mobile phases, ethanol or isopropanol, produced either greater peak area counts, or S/N, for over half of the compounds evaluated, compared with the traditional organic mobile phases of acetonitrile and methanol. These nontraditional alcoholic mobile phases also showed improved capability in the removal of plasma phospholipid components from the chromatographic column. The ionizable background detected in each of the organic mobile phases utilized in this study produced a unique background that may or may not interfere with compounds undergoing analysis.

CONCLUSION

The combination of microbore columns and nontraditional alcoholic mobile phases has been shown to produce effective, alternative method conditions to traditional bioanalytical LC-MS/MS method parameters.

LC–MS systems for quantitative bioanalysis

LC–MS has become the method-of-choice in small-molecule drug bioanalysis (molecular mass <800 Da) and is also increasingly being applied as an alternative to ligand-binding assays for the bioanalytical determination of biopharmaceuticals. Triple quadrupole MS is the established bioanalytical technique due to its unpreceded selectivity and sensitivity, but high-resolution accurate-mass MS is recently gaining ground due to its ability to provide simultaneous quantitative and qualitative analysis of drugs and their metabolites. This article discusses current trends in the field of bioanalytical LC–MS (until September 2012), and provides an overview of currently available commercial triple quadrupole MS and high-resolution LC–MS instruments as applied for the bioanalysis of small-molecule and biopharmaceutical drugs.

The current status of clinical proteomics and the use of MRM and MRM(3) for biomarker validation

The transfer of biomarkers from the discovery field to clinical use is still, despite progress, on a road filled with pitfalls. Since the emergence of proteomics, thousands of putative biomarkers have been published, often with overlapping diagnostic capacities. The strengthening of the robustness of discovery technologies, particularly in mass spectrometry, has been followed by intense discussions on establishing well-defined evaluation procedures for the identified targets to ultimately allow the clinical validation and then the clinical use of some of these biomarkers. Some of the obstacles to the evaluation process have been the lack of the availability of quick and easy-to-develop, easy-to-use, robust, specific and sensitive alternative quantitative methods when immunoaffinity-based tests are unavailable. Multiple reaction monitoring (MRM; also called selected reaction monitoring) is currently proving its capabilities as a complementary or alternative technique to ELISA for large biomarker panel evaluation. Here, we present how MRM(3) can overcome the lack of specificity and sensitivity often encountered by MRM when tracking minor proteins diluted by complex biological matrices.

Challenges in the development of bioanalytical liquid chromatography-mass spectrometry method with emphasis on fast analysis

The development of bioanalytical methods has become more and more challenging over the past years due to very demanding requirements in terms of method reliability, sensitivity, speed of analysis and sample throughput. LC-MS/MS has established itself as a method of choice for routine analysis of biological materials. A development of such method consists of several steps including sample preparation and clean-up step, efficient chromatographic separation, sensitive and selective detection of analytes in complex matrices, a choice of convenient data processing and calibration approach and finally method validation. Each of these steps has its own constraints and challenges, which are discussed in detail in this review. Novel and modern approaches in sample preparation, chromatography and detection are especially emphasized. Attention is paid to proper calibration approach and matrix effects that can seriously affect method accuracy and precision.