Passive, continuous monitoring of carbon dioxide geostorage using muon tomography.

Carbon capture and storage is a transition technology from a past and present fuelled by coal, oil and gas and a planned future dominated by renewable energy sources. The technology involves the capture of carbon dioxide emissions from fossil fuel power stations and other point sources, compression of the CO2 into a fluid, transporting it and injecting it deep beneath the Earth's surface into depleted petroleum reservoirs and other porous formations. Once injected, the CO2 must be monitored to ensure that it is emplaced and assimilated as planned and that none leaks back to surface. A variety of methods have been deployed to monitor the CO2 storage site and many such methods have been adapted from oilfield practice. However, such methods are commonly indirect, episodic, require active signal generation and remain expensive throughout the monitoring period that may last for hundreds of years. A modelling framework was developed to concurrently simulate CO2 geostorage conditions and background cosmic-ray muon tomography, in which the potential was assessed for using variations in muon attenuation, due to changes in CO2 abundance, as a means of CO2 detection. From this, we developed a passive, continuous monitoring method for CO2 storage sites using muon tomography, the tools for which can be deployed during the active drilling phase (development) of the storage site. To do this, it was necessary to develop a muon detector that could be used in the hostile environment (saline, high temperature) of the well bore. A prototype detector has been built and tested at the 1.1 km deep Boulby potash mine on the northeast coast of England, supported by the existing STFC Boulby Underground Laboratory on the site. The detector is now ready to be commercialized.This article is part of the Theo Murphy meeting issue 'Cosmic-ray muography'.

Direct ionization of solid-phase microextraction fibers for quantitative drug bioanalysis: from peripheral circulation to mass spectrometry detection.

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 (<30%), and lack of carryover. This novel approach simplifies current bioanalytical procedures providing time and cost savings. It demonstrates considerable potential for qualitative and quantitative pharmaceutical bioanalysis as well as other areas of challenging environmental and food analysis.

Investigation of different approaches to incorporating internal standard in DBS quantitative bioanalytical workflows and their effect on nullifying hematocrit-based assay bias.

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.

Attractive design: an elution solvent optimization platform for magnetic-bead-based fractionation using digital microfluidics and design of experiments.

There is great interest in the development of integrated tools allowing for miniaturized sample processing, including solid phase extraction (SPE). We introduce a new format for microfluidic SPE relying on C18-functionalized magnetic beads that can be manipulated in droplets in a digital microfluidic platform. This format provides the opportunity to tune the amount (and potentially the type) of stationary phase on-the-fly, and allows the removal of beads after the extraction (to enable other operations in same device-space), maintaining device reconfigurability. Using the new method, we employed a design of experiments (DOE) operation to enable automated on-chip optimization of elution solvent composition for reversed phase SPE of a model system. Further, conditions were selected to enable on-chip fractionation of multiple analytes. Finally, the method was demonstrated to be useful for online cleanup of extracts from dried blood spot (DBS) samples. We anticipate this combination of features will prove useful for separating a wide range of analytes, from small molecules to peptides, from complex matrices.

Volumetric absorptive microsampling: a dried sample collection technique for quantitative bioanalysis.

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.

Dried blood spots and sparse sampling: a practical approach to estimating pharmacokinetic parameters of caffeine in preterm infants.

AIMS: Dried blood spots (DBS) alongside micro-analytical techniques are a potential solution to the challenges of performing pharmacokinetic (PK) studies in children. However, DBS methods have received little formal evaluation in clinical settings relevant to children. The aim of the present study was to determine a PK model for caffeine using a 'DBS/microvolume platform' in preterm infants. METHODS: DBS samples were collected prospectively from premature babies receiving caffeine for treatment of apnoea of prematurity. A non-linear mixed effects approach was used to develop a population PK model from measured DBS caffeine concentrations. Caffeine PK parameter estimates based on DBS data were then compared with plasma estimates for agreement. RESULTS: Three hundred and thirty-eight DBS cards for caffeine measurement were collected from 67 preterm infants (birth weight 0.6-2.11 kg). 88% of cards obtained were of acceptable quality and no child had more than 10 DBS samples or more than 0.5 ml of blood taken over the study period. There was good agreement between PK parameters estimated using caffeine concentrations from DBS samples (CL = 7.3 ml h⁻¹ kg⁻¹; V = 593 ml kg⁻¹; t(½) = 57 h) and historical caffeine PK parameter estimates based on plasma samples (CL = 4.9-7.9 ml h⁻¹ kg⁻¹; V = 640-970 ml kg⁻¹; t(½) = 101-144 h). We also found that changes in blood haematocrit may significantly confound estimates of caffeine PK parameters based on DBS data. CONCLUSIONS: This study demonstrates that DBS methods can be applied to PK studies in a vulnerable population group and are a practical alternative to wet matrix sampling techniques.

Inflammation and cardiovascular status impact midazolam pharmacokinetics in critically ill children: An observational, prospective, controlled study.

Altered physiology caused by critical illness may change midazolam pharmacokinetics and thereby result in adverse reactions and outcomes in this vulnerable patient population. This study set out to determine which critical illness-related factors impact midazolam pharmacokinetics in children using population modeling. This was an observational, prospective, controlled study of children receiving IV midazolam as part of routine care. Children recruited into the study were either critically-ill receiving continuous infusions of midazolam or otherwise well, admitted for elective day-case surgery (control) who received a single IV bolus dose of midazolam. The primary outcome was to determine the population pharmacokinetics and identify covariates that influence midazolam disposition during critical illness. Thirty-five patients were recruited into the critically ill arm of the study, and 54 children into the control arm. Blood samples for assessing midazolam and 1-OH-midazolam concentrations were collected opportunistically (critically ill arm) and in pre-set time windows (control arm). Pharmacokinetic modeling demonstrated a significant change in midazolam clearance with acute inflammation (measured using C-Reactive Protein), cardio-vascular status, and weight. Simulations predict that elevated C-Reactive Protein and compromised cardiovascular function in critically ill children result in midazolam concentrations up to 10-fold higher than in healthy children. The extremely high concentrations of midazolam observed in some critically-ill children indicate that the current therapeutic dosing regimen for midazolam can lead to over-dosing. Clinicians should be aware of this risk and intensify monitoring for oversedation in such patients.

Method of applying internal standard to dried matrix spot samples for use in quantitative bioanalysis.

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.

Solid-phase microextraction for assessment of plasma protein binding, a complement to rapid equilibrium dialysis.

Aim: Determination of plasma protein binding (PPB) is considered vital for better understanding of pharmacokinetic and pharmacodynamic activities of drugs due to the role of free concentration in pharmacological response. Methodology & results: Solid-phase microextraction (SPME) was investigated for measurement of PPB from biological matrices and compared with a gold standard approach (rapid equilibrium dialysis [RED]). Discussion & conclusion: SPME-derived values of PPB correlated well with literature values, and those determined by RED. Respectively, average protein binding across three concentrations by RED and SPME was 33.1 and 31.7% for metoprolol, 89.0 and 86.6% for propranolol and 99.2 and 99.0% for diclofenac. This study generates some evidence for SPME as an alternative platform for the determination of PPB.

Strong constraints from COSINE-100 on the DAMA dark matter results using the same sodium iodide target.

We present new constraints on dark matter interactions using 1.7 years of COSINE-100 data. The COSINE-100 experiment, consisting of 106 kg of tallium-doped sodium iodide [NaI(Tl)] target material, is aimed to test DAMA's claim of dark matter observation using the same NaI(Tl) detectors. Improved event selection requirements, a more precise understanding of the detector background, and the use of a larger dataset considerably enhance the COSINE-100 sensitivity for dark matter detection. No signal consistent with the dark matter interaction is identified and rules out model-dependent dark matter interpretations of the DAMA signals in the specific context of standard halo model with the same NaI(Tl) target for various interaction hypotheses.

In vitro testing of the hemaPEN microsampling device for the quantification of acetaminophen in human blood.

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.

Direct quantitative bioanalysis of drugs in dried blood spot samples using a thin-layer chromatography mass spectrometer interface.

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.

Dried blood spots as a sample collection technique for the determination of pharmacokinetics in clinical studies: considerations for the validation of a quantitative bioanalytical method.

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).

Reflecting on Bioanalysis with the Senior Editors.

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.

Microsampling for quantitative bioanalysis, an industry update: output from an AAPS/EBF survey.

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.

Microsampling: considerations for its use in pharmaceutical drug discovery and development.

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.

Validation of methods for determining pediatric midazolam using wet whole blood and volumetric absorptive microsampling.

Aim: Collection and quantitative analysis in dry blood using volumetric absorptive microsampling (VAMS™) potentially offers significant advantages over conventional wet whole blood analysis. This manuscript explores their use for pediatric sampling and explores additional considerations for the validation of the bioanalytical method. Results: HPLC-MS/MS methods for the determination of midazolam and its major metabolite 1-OH midazolam in both whole wet blood, and dry blood collected on VAMS were developed, validated, and used to support an observational clinical study to compare pharmacokinetic parameters in pediatric patients. Conclusion: Validation data met internationally accepted guideline criteria. A strong correlation was observed in calculated concentrations between wet and dry test samples, indicating that VAMS is a suitable technique for use in pediatric clinical studies.

Application of dried blood spots combined with HPLC-MS/MS for the quantification of acetaminophen in toxicokinetic studies.

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 microL) 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 microg/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.

Evaluation of ultra-performance liquid chromatography in the bioanalysis of small molecule drug candidates in plasma.

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 (