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Background: The hemaPEN is a liquid microsampling device for the reproducible collection and storage of blood samples as dried blood spots, for subsequent quantitative analysis. Materials & methods: We examined the device’s ability to collect accurate and precise blood volumes, at different hematocrit levels, via in vitro studies using acetaminophen in human blood. We also investigated the impact of different user training approaches on device performance. Results: The hemaPEN demonstrated acceptable volumetric accuracy and precision, regardless of the training medium used. Issues with apparent hematocrit-dependent bias were found to be associated with the extraction process, rather than the volumetric performance of the device. Conclusion: The hemaPEN is capable of readily producing high quality blood microsamples for reproducible and accurate quantitative bioanalysis.

There is growing interest in the implementation of microsampling approaches for the quantitation of circulating concentrations of analytes in biological samples derived from nonclinical and clinical studies involved in drug development. This interest is partly due to the ethical advantages of taking smaller blood volumes, particularly for studies in rodents, children and the critically ill. In addition, these technologies facilitate sampling to be performed in previously intractable locations and occasions. Further, they enable the collection of samples for additional purposes (extra time points, biomarkers, sampling during a clinical event, etc). This article gives a comprehensive insight to the utilization of these approaches in drug discovery and development, and provides recommendations for best practice for nonclinical, clinical and bioanalytical aspects.

A previous Senior Editor, and the present Senior Editor of Bioanalysis reflect on their journeys in the field of bioanalysis, and with the journal. They discuss the evolution and progress of journal since its launch 10 years ago, and where they would like to see it heading in the future.

There is continuing interest in the development and application of various microsampling technologies for drug development. The AAPS bioanalytical community microsampling subgroup and the European Bioanalysis Forum conducted a survey of their members (39 individual organizations). This gives a snapshot of current practices and demonstrates that implementation of microsampling approaches is becoming increasingly commonplace, but not universal. Greater adoption was observed for nonclinical studies, particularly nonregulatory. A number of respondents reported that they have included microsampling data in regulatory submissions. Another important observation was that where microsampling is employed for clinical studies, dried blood approaches predominate, reflecting the interest in their use where they enable sample collection which is not feasible with standard approaches or to derive richer data sets.

Background: Control blood plasma is regularly used in bioanalysis, biomarkers and proteomics, and is often obtained from commercial sources. It has always been assumed that this plasma will be comparable to plasma drawn during a drug development study. Results: When compared using total protein concentrations, plasma from only one species (dog) demonstrated statistical comparability, plasma from all other species tested (human, rabbit, mouse and rat) shows a statistically significant difference. Conclusion: If endogenous components of blood plasma are being measured, or if an assay technique does not significantly limit matrix effects, any assay controls should be prepared using control plasma from the drug development site, or using commercial plasma that has been screened against drug development site plasma.

Background: Automated DBS direct elution systems are available that incorporate IS spray modules which, unlike conventional IS addition via the extraction solvent, apply IS prior to DBS samples prior to extraction, allowing analyte and IS to be coextracted. Results: IS spray system parameters were optimized to identify the conditions that produced the best analytical performance in quantitative bioanalytical assays, without interfering with the integrity of the DBS sample prior to extraction. Conclusion: LC–MS/MS method validations across four representative small molecule assays using the optimized IS spray conditions were demonstrated to produce analytical performance comparable to conventional methods of IS addition, demonstrating that the spray technique is a viable alternative.

Background: Automated DBS direct elution techniques eliminate the manual extraction burden of DBS bioanalysis, offer good quantitative performance, the ability to eliminate hematocrit-based assay bias, and, previous reports have demonstrated that significant increases in assay sensitivity compared with manual DBS extraction are possible. Results: An investigation into elucidating parameters for optimized generic DBS direct elution for high sample throughput quantitative bioanalytical applications is presented for the first time. Generic direct elution conditions were identified that enabled LC–MS/MS assay sensitivity to be maximized while retaining acceptable chromatographic performance. Conclusion: Compared with generic conventional DBS manual extraction, assay sensitivity was demonstrated to be increased up to 33-fold across four representative small molecule compounds, using the recommended direct elution conditions.

Aims: A cross-laboratory experiment has been performed on a novel dried blood sampler in order to investigate whether it overcomes issues associated with blood volume and hematocrit (HCT) that are observed when taking a subpunch from dried blood spot samples. Materials & methods: An average blood volume of 10.6 μl was absorbed by the samplers across the different HCTs investigated (20–65%). Results: No notable change of volume absorbed was noted across the HCT range. Furthermore, the variation in blood sample volumes across six different laboratories was within acceptable limits. Conclusion: The novel volumetric absorptive microsampling device has the potential to deliver the advantages of dried blood spot sampling while overcoming some of the issues associated with the technology.

A novel approach is described for the quantitative bioanalysis of drugs in blood samples by ionization of the analytes collected on solid-phase microextraction (SPME) fibers by mass spectrometry (MS). The technique combines the attractive features of SPME microsampling using minimal sample volumes with the speed, selectivity, and sensitivity capabilities of MS detection. The method reported in this study involved generating gas-phase ions directly from SPME fibers without the need for any additional sample preparation or chromatographic separation; the entire process was completed within 5 min. Traditionally, analytes extracted by SPME fibers are desorbed by washing with suitable solvents followed by a transfer into a sample vial and subsequent liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis to quantify the amount of analyte extracted and thereby determining the analyte concentration in the matrix. These sample preparation steps are completely eliminated by inserting the SPME fiber directly into the MS. Physiologically relevant concentrations of metoprolol and propranolol in blood samples were measured over several orders of magnitude down to concentration levels of 10 ng/mL. This preliminary assessment of direct SPME-MS showed high sensitivity (ng/mL), acceptable reproducibility (

The 2014 8th Workshop on Recent Issues in Bioanalysis (8th WRIB), a 5-day full immersion in the evolving field of bioanalysis, took place in Universal City, California, USA. Close to 500 professionals from pharmaceutical and biopharmaceutical companies, contract research organizations and regulatory agencies worldwide convened to share, review, discuss and agree on approaches to address current issues of interest in bioanalysis. The topics covered included both small and large molecules, and involved LCMS, hybrid LBA/LCMS, LBA approaches and immunogenicity. From the prolific discussions held during the workshop, specific recommendations are presented in this 2014 White Paper. As with the previous years’ editions, this paper acts as a practical tool to help the bioanalytical community continue advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2014 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 1) covers the recommendations for small molecule bioanalysis using LCMS. Part 2 (Hybrid LBA/LCMS, Electronic Laboratory Notebook and Regulatory Agencies’ input) and Part 3 (Large molecules bioanalysis using LBA and Immunogenicity) will be published in the upcoming issues of Bioanalysis.

This article discusses the benefits of dried blood spot sampling and the recent issues that have emerged when this technique is used in the regulated quantitative bioanalytical environment. The author explores what the way forward might be for this important technique and what some of the unexpected benefits of this change in sampling methodologies have been.

Circulating drug concentrations (clinical or preclinical) underly many interactions between industry and regulators; expressing safety coverage, pharmacokinetic-pharmacodynamic relationships or defining bioequivalence and dosing regimens. Accurate and precise measurement of these circulating concentrations is pivotal to the evolution and validation of any bioanalytical method that supports regulatory interactions. Since the bioanalyst is presented with a sub-aliquot of sampled biological matrix, how do they ensure this aliquot reflects the concentration in the subject at the time of collection? Here we share experiences from project support (internal and at CROs) that suggests we need to be ever vigilant translating the needs of bioanalysis with those of project teams. The simple mantra is for bioanalytical measurements to be physiologically relevant to the patient.

Background: The surge in interest in switching from traditionally used wet plasma to dried matrix spot (DMS) sampling and analysis to support pharmaceutical drug development is due to the significant ethical, financial and data quality advantages on offer. Unfortunately these advantages do not extend to sample bioanalysis, as DMS extraction is more complex than the protein precipitation method typically used for wet plasma analysis. Direct elution techniques coupled to HPLC–MS/MS have been identified as a potential means to counter this additional complexity. Results: The robustness and reproducibility of DMS HPLC–MS/MS data generated using a CAMAG DBS–MS 16 prototype automated direct elution instrument has been demonstrated to meet or exceed results obtained using a conventional manual extraction methodology. Conclusion: The data generated suggest that a simple and fast direct elution method of DMS samples that does not require additional sample or extract clean-up, offers sufficiently robust performance to be compatible with high-sample-throughput quantitative analysis. Further evaluation of the technique and the development of more advanced fully automated direct elution instrumentation is fully warranted.

Background: Dried blood spot (DBS) sampling, the collection of whole blood samples on paper, is being evaluated for its use in quantitative analysis. The aim of this investigation was to evaluate the impact of sample hematocrit (HCT) and punch location on assay bias in the measurement of compounds with varying physicochemical properties, when a portion of a DBS sample is analyzed. In addition, the statistical significance of factors such as compound, card type, HCT level, spot position on a card and the location of the punch on the spot were evaluated. Results: The results of this work indicate that for quantitative analysis using a portion of the DBS, notable bias (>15%) exists due to the effect of HCT and nonhomogeneous distribution of compound across the spot. The statistical analysis of results from a split-split-plot designed study showed that the factors of compound, card type and HCT were statistically significant (p < 0.05) both individually and in complex interactions, which affect the accuracy of quantitative concentrations obtained from DBS samples for each compound on each card type. Conclusion: To achieve the acceptance criteria (±15%) for accuracy when removing a portion of the DBS spot for quantitative analysis, HCT and punch location for each selected card type will need to be assessed during validation and sample analysis.

Background: A study was performed to evaluate the suitability of stored EDTA-treated control whole blood for use in the preparation of calibration standards and quality control samples for quantitative bioanalytical methods employing dried blood spot (DBS) samples to support pharmaceutical exposure studies. Results: It has been demonstrated that a storage time of 14 days for control human and animal blood is suitable for producing quantitative analytical results within internationally recognised acceptance criteria for two analytes. Furthermore, blood hemolysis and chill–thaw cycles have been evaluated and shown not to affect bioanalytical results notably. Aggressive mixing techniques can result in rat blood coagulation; however, this does not occur with other species tested and can be affected by the method of blood collection. Conclusion: Control whole blood handled and stored using the recommendations generated from this study will not notably affect quantitative bioanalytical results when used for the preparation of calibration standards and quality control samples for DBS assays. It was demonstrated that control human and animal blood can be stored for periods long enough to effectively eliminate wastage.

The CAMAG thin-layer chromatography mass spectrometer (TLC-MS) interface has been assessed as a tool for the direct quantitative bioanalysis of drugs from dried blood spot (DBS) samples, using an MS detector, with or without high-performance liquid chromatography (HPLC) separation. The approach gave acceptable sensitivity, linearity, accuracy, and precision data for bioanalytical validations with and without the inclusion of HPLC separation. In addition, the direct elution technique was shown to increase assay sensitivity for a range of analytes representing a wide "chemical space" for pharmaceutical-type molecules over that obtained by conventional manual extraction of samples (punching of DBS and elution with solvent prior to HPLC-MS analysis). Investigations were performed to optimize extraction time, minimize sample-to-sample carry-over, and compare chromatographic performance. On the basis of this preliminary assessment, it has been demonstrated that the TLC-MS interface has the potential to be an effective tool for the direct analysis of drugs in DBS samples at physiologically relevant concentrations, an approach that could provide significant time and cost savings and greatly simplify bioanalytical procedures compared to current manual practices. Further, the increased sensitivity compared to that of manual extraction may enable the analysis of analytes not currently amenable to DBS sampling due to limitations in assay sensitivity.

Hematocrit (HCT)-based assay bias (composed of area and recovery bias) is an important contributing factor to the barriers that currently hinder the development and acceptance of dried blood spots (DBS) as a widely used quantitative bioanalytical sampling technique for regulatory studies. This article describes the evaluation of a practical internal standard spray addition technique, used prior to LC-MS/MS analysis, which is demonstrated to nullify the effect of recovery bias. To our knowledge, this is the first time a potential solution to HCT-based recovery bias has been investigated in detail and reported in the literature. This new technique is coupled with accurate volume DBS sampling, whole-spot extraction, and automated direct elution techniques to demonstrate a workflow that both nullifies HCT-based assay bias and the additional manual extraction burden associated with DBS analysis.

Volumetric absorptive microsampling (VAMS) is a simple intuitive technique for collecting and quantitative analysis of dried blood samples. It enables the collection of an accurate blood volume (approximately 10μL) regardless of blood hematocrit. A bioanalytical method for the determination of paracetamol in dried blood supported on VAMS samplers has been validated and used to support a toxicokinetic (TK) study in rat. The calculated TK parameters were comparable to those obtained from blood-water (1:1, v/v) samples. VAMS is demonstrated to be a robust method that simplifies both the blood sample collection and bioanalytical laboratory procedures and generates high quality quantitative data. However, problems were encountered with controlling the bleed rate during sample collection, resulting in the VAMS tips being flooded and highlighting the need for bleeding methods to be compatible with microsampling techniques to avoid wasting blood. Alternative sample collection procedures are discussed that minimize these issues.

Further to the discussions on the bioanalysis of samples generated using microsampling techniques [1–6] and more specifically the ongoing work of the European Bioanalysis Forum (EBF) Liquid Microsampling Consortium [7], this article seeks to highlight some of the ‘philosophical’ aspects around liquid microsampling and to introduce some of the experimental elements that will form part of future efforts by the Consortium. Discussion will be focused on three major areas: sample manipulation, homogeneity of samples and validation of assays. The scope of this manuscript will be liquid microsampling and will not focus on adsorption techniques such as dried blood spots (DBS) and solid phase microextraction. Different microsampling techniques have created great interest from toxicokinetic (TK) and pharmacokinetic (PK) scientists, since they offer the potential to reduce sample volumes for exposure assessment in biofluids. For preclinical studies microsampling can facilitate the generation of serial profiles in rodent exposure evaluation studies, rather than working with composite designs. Microsampling has facilitated the removal of satellite animal groups leading to substantial reductions in the number of animals required and the reduction or elimination of rodent warming. Benefits in the clinical environment include the ability to take reduced sample volumes from pediatric, elderly and critically ill patient populations. In a recent publication the NC3R group proposes the following definition of a blood microsample: the sample should ideally not contain more than 50 μl whole blood [8]. As a consequence the subsequent plasma volumes are 20 μl or lower. Another, more philosophical consideration would be the impact of sampling volume on the animal or subject; for example, 50 μl of blood may not be considered as a ‘microsample’ in the context of juvenile animals or newborn babies. Two major liquid microsampling approaches can be envisaged

Volumetric absorptive microsampling (VAMS) is a novel approach to obtaining a dried blood sample for quantitative bioanalysis that overcomes the area bias and homogeneity issues associated with conventional dried blood spot (DBS) sample when a subpunch is taken. The VAMS sampler absorbs a fixed volume of blood (∼10 μL) in 2–4 s with less than 5% volume variation across the hematocrit range of 20–70% with low tip-to-tip variability. There is no evidence of selective absorption by the tip of the plasma component over whole blood. Recommendations for best practice when collecting samples were developed based upon the results of tests examining a number of potential abuse scenarios.

Background: To ensure that PK data generated from DBS samples are of the highest quality, it is important that the paper substrate is uniform and does not unduly contribute to variability. This study investigated any within and between lot variations for four cellulose paper types: Whatman™ FTA®DMPK-A, -B and -C, and 903®(GE Healthcare, Buckinghamshire, UK). The substrates were tested to demonstrate manufacturing reproducibility (thickness, weight, chemical coating concentration) and its effect on the size of the DBS produced, and the quantitative data derived from the bioanalysis of human DBS samples containing six compounds of varying physicochemical properties. Results & discussion: Within and between lot variations in paper thickness, mass and chemical coating concentration were within acceptable manufacturing limits. No variation in the spot size or bioanalytical data was observed. Conclusion: Bioanalytical results obtained for DBS samples containing a number of analytes spanning a range of chemical space are not affected by the lot used or by the location within a lot.

Background: A novel device and procedure for the collection and isolation of microvolumes of plasma have been developed and two pilot rodent PK studies have been completed. Results: This method involves collection of blood into a plastic-wrapped, EDTA-coated capillary tube, containing a small amount of a thixotropic gel and a porous plug. Following blood collection, the capillary is placed into a secondary labeled container suitable for centrifugation and plasma is generated. During centrifugation, the thixotropic gel isolates the plasma from the red blood cells and creates a physical barrier between the two matrices. The plasma is then dispensed from the capillary tube into a separate container for storage or processing. Conclusion: A simple and robust novel approach for the collection of small plasma volumes from rodent TK studies has been demonstrated.

Background: At the start of their work, the European Bioanalysis Forum dried blood spots microsampling consortium did not form a dedicated team to investigate the spot homogeneity. However, two teams performed experiments that produced results relating to sample homogeneity. Results: The data, which were produced via two different approaches (a radiolabeled and a nonradiolabeled approach), are highly complementary and demonstrate clear effects on sample inhomogeneity due to the substrate type, compound and hematocrit levels. Conclusion: The results demonstrate that sample inhomogeneity is a significant hurdle to the use of dried blood spots for regulated bioanalysis that should be investigated further in the method establishment phase if the whole spot is not sampled. © 2013 Future Science Ltd.

A novel technique is presented that addresses the issue of how to apply internal standard (IS) to dried matrix spot (DMS) samples that allows the IS to integrate with the sample prior to extraction. The TouchSpray, a piezo electric spray system, from The Technology Partnership (TTP), was used to apply methanol containing IS to dried blood spot (DBS) samples. It is demonstrated that this method of IS application has the potential to work in practice, for use in quantitative determination of circulating exposures of pharmaceuticals in toxicokinetic and pharmacokinetic studies. Three different methods of IS application were compared: addition of IS to control blood prior to DBS sample preparation (control 1), incorporation into extraction solvent (control 2), and the novel use of TouchSpray technology (test). It is demonstrated that there was no significant difference in accuracy and precision data using these three techniques obtained using both manual extraction and direct elution.

Dried bloodspot (DBS) technology has been available for many decades but only in the last five years has it been considered for routine bioanalysis of blood samples collected on preclinical and clinical studies as part of a drug development programme. Advantages of using DBS versus typical plasma samples include smaller blood volumes, less processing of the samples (e.g. no centrifugation) and no requirement for storing or shipping of the samples at frozen temperatures. The current study compared blood concentrations (AUC0− t and Cmax) from rats given an oral dose of acetaminophen (APAP) using two different sampling sites (caudal venepuncture versus tail snip), two different collection methods (3 separate 15 μL ethylenediaminetetraacetic acid [EDTA]-coated capillary tubes versus an EDTA integrated capillary blood collection system) and variability between blood spots on one card. There were no noteworthy differences (i.e. two-fold or greater) in blood concentrations of APAP using the different sites or methods. Furthermore, comparisons of the APAP blood concentrations in the original spot to a duplicate bloodspot from the same bloodspot card were within 12% of the original concentration.

The use of dried blood and dried plasma spots for storage and transportation of samples derived from clinical trials holds the promise to reduce cost, simplify storage and shipping as well as reducing animal usage. From the bioanalysts’ point of view, these dried-paper samples add an extra layer of complexity to the analysis introducing extra matrix effects from the paper itself and sometimes from antiviral treatments applied to the card. In this article we demonstrate the use of the sub-2-µm particle LC–MS/MS for the bioanalysis of samples derived from a dried blood spot. The higher resolution provided by these small-particle separations allowed for greater resolution of the analyte from the endogenous components in blood samples and from the card-treatment chemicals. The method -development process was enhanced by the use of MS, which could simultaneously acquire full scan and multiple reaction monitoring data, allowing resolution from metabolites and endogenous matrix components. The use of this approach produced sensitivity levels in the 50–100 pg/ml range and analysis times in the 1–2 min range, which was five-times more sensitive and three-times faster than HPLC. This throughput and sensitivity makes this approach ideal for the analysis of preclinical and clinical studies derived from dried blood spots.

Background: As hematocrit levels are known to vary between individuals and with disease state, its effect on the physical characteristics of dried blood spot (DBS) samples and on the accurate quantification of analytes within these samples is examined. Results: The area of DBS samples decreases with increasing hematocrit levels in a linear manner on the three cellulose paper substrates tested. Furthermore, a bias was observed in the concentrations of two analytes determined in DBS samples at different hematocrits, which in some cases exceeded acceptable values, particularly for hematocrits outside normal values. Conclusion: If it is expected that the hematocrit of study samples will vary from values considered normal, then its effect on the quantitative determination of an analyte in DBS samples should be investigated as part of the method development and validation. If an unacceptable effect is observed, then this will need to be addressed, by modification of the analytical method, or the inclusion of quality control samples at different hematocrit levels to show control of the assay.

A novel approach has been developed for the quantitative determination of circulating drug concentrations in clinical studies using dried blood spots (DBS) on paper, rather than conventional plasma samples. A quantitative bioanalytical HPLC-MS/MS assay requiring small blood volumes (15 microL) has been validated using acetaminophen as a tool compound (range 25 to 5000 ng/mL human blood). The assay employed simple solvent extraction of a punch taken from the DBS sample, followed by reversed phase HPLC separation, combined with selected reaction monitoring mass spectrometric detection. In addition to performing routine experiments to establish the validity of the assay to internationally accepted criteria (precision, accuracy, linearity, sensitivity, selectivity), a number of experiments were performed to specifically demonstrate the quality of the quantitative data generated using this novel sample format, namely, stability of the analyte and metabolites in whole human blood and in DBS samples; effect of the volume of blood spotted, the device used to spot the blood, or the temperature of blood spotted. The validated DBS approach was successfully applied to a clinical study (single oral dose of 500 mg or 1 g acetaminophen).

A reversed phase HPLC-MS/MS method has been developed and validated for the quantitative bioanalysis of acetaminophen in dried blood spots (DBS) prepared from small volumes (15 μL) of dog blood. Samples were extracted for analysis with methanol. Detection was by positive ion TurboIonSpray™ ionisation combined with selected reaction monitoring MS. The analytical concentration range was 0.1–50 μg/mL. The intra-day precision and bias values were both less than 15%. Acetaminophen was stable in DBS stored at room temperature for at least 10 days. The methodology was applied in a toxicokinetic (TK) study where the data obtained from DBS samples was physiologically comparable with results from duplicate blood samples (diluted 1:1 (v/v) with water) analysed using identical HPLC-MS/MS conditions. This work demonstrates that quantitative analysis of a drug extracted from DBS can provide high quality TK data while minimising the volume of blood withdrawn from experimental animals, to an order of magnitude lower than is current practice in the pharmaceutical industry. This is the first reported application of DBS analysis to a TK study in support of a safety assessment study. The success of this and similar, related studies has led to the intent to apply DBS technology as the recommended analytical approach for the assessment of pharmacokinetics (PK)/TK for all new oral small molecule drug candidates, which have previously demonstrated a successful bioanalytical validation.

Ultra-performance liquid chromatography (UPLC) combined with mass spectrometric detection (MS) is used successfully in the bioanalysis of small molecule drug candidates in plasma. UPLC-MS is shown to increase sample throughput by reducing run times over 3-fold, without compromising analytical sensitivity or analyte resolution. The technique is demonstrated to be practical and robust on a commercially available ultra-high pressure system when injecting extracts of plasma and has also shown to be a technique that can be used effectively on a conventional high-performance liquid chromatography system fitted with short columns (