Total Sample Analysis Time Research Articles

Breaching the 10 Second Barrier of Total Analysis Time for Complex Matrices via Automated Coated Blade Spray.

In the development of modern analytical workflows, parameters such as sample turnaround time, cost of analysis, and ease of use must be prioritized. Automation enables reductions in total analysis time, human intervention, and cost per sample. In this report, a suitable automated coated blade spray (CBS) workflow is proposed for the screening and quantitation of multiple substances (i.e., drugs of abuse and pesticides) in complex matrices. In an attempt to reduce the total sample analysis time, several parameters were investigated, including tandem mass spectrometry (MS) dwell time, CBS spray time, and extraction time. Solid-phase microextraction (SPME) method parameters are explored, such as reduction of extraction time for increased signal-to-noise. Model compounds with a moderately wide range of molecular weights (150-500 Da), polarities, and structural diversity were selected in order to monitor analytical figures of merit during method optimization. The resultant automated CBS method proved capable of analyzing the model compounds in human urine in under 10 s total analysis time with excellent accuracy (95-120%) and precision (RSD < 12%). As an application, an automated method for the screening and quantitation of more than 150 pesticides from apple juice was demonstrated on both triple quadrupole and orbitrap instruments in under 15 s total sample analysis time.

On-line solvent exchange system: Automation from extraction to analysis

Removal of organic solvent from sample extracts is required before analysis by reversed phase HPLC to preserve chromatographic performance and allow for bigger injection volumes, boosting sensitivity. Herein, an automated on-line extraction evaporation procedure is integrated with HPLC analysis. The evaporation occurs inside a 200 μm microfluidic channel confined by a vapor permeable membrane. A feedback control algorithm regulates evaporation rate keeping the output flow rate constant. The evaporation process across this membrane was firstly characterized with water/solvent mixtures showing organic solvent removal capabilities. This system allowed continuous methanol, ethanol and acetonitrile removal from samples containing up to 80% organic solvent. An evaporative injection procedure was developed demonstrating the use of the device for fully integrated extract reconstitution coupled to HPLC analysis, applied to analysis of the antibiotic chloramphenicol in milk samples. Sample reconstitution and collection was performed in less than 10 min and can be executed simultaneously to HPLC analysis of the previous sample in a routine workflow, thus having minimal impact on the total sample analysis time when run in a sequence.

Fast quantitation of opioid isomers in human plasma by differential mobility spectrometry/mass spectrometry via SPME/open-port probe sampling interface

Mass spectrometry (MS) based quantitative approaches typically require a thorough sample clean-up and a decent chromatographic step in order to achieve needed figures of merit. However, in most cases, such processes are not optimal for urgent assessments and high-throughput determinations. The direct coupling of solid phase microextraction (SPME) to MS has shown great potential to shorten the total sample analysis time of complex matrices, as well as to diminish potential matrix effects and instrument contamination. In this study, we demonstrate the use of the open-port probe (OPP) as a direct and robust sampling interface to couple biocompatible-SPME (Bio-SPME) fibres to MS for the rapid quantitation of opioid isomers (i.e. codeine and hydrocodone) in human plasma. In place of chromatography, a differential mobility spectrometry (DMS) device was implemented to provide the essential selectivity required to quantify these constitutional isomers. Taking advantage of the simplified sample preparation process based on Bio-SPME and the fast separation with DMS-MS coupling via OPP, a high-throughput assay (10–15 s per sample) with limits of detection in the sub-ng/mL range was developed. Succinctly, we demonstrated that by tuning adequate ion mobility separation conditions, SPME-OPP-MS can be employed to quantify non-resolved compounds or those otherwise hindered by co-extracted isobaric interferences without further need of coupling to other separation platforms.

Detection of prolactin inducible protein mRNA, a biomarker for breast cancer metastasis, using a molecular beacon-based assay

Mortality due to breast cancer is increasingly linked to early, undetected metastasis, making methods for earlier detection acutely necessary. We describe the development of an assay based on molecular beacon (MB) chemistry with fluorescence detection to monitor a breast cancer biomarker for the analysis of breast cancer metastasis. The MB assay is based on the complementary base-pairing interactions of the MB nucleic acid with mRNA indicative of breast cancer metastasis. The presence of mRNA is characterized by an increase in the fluorescence intensity of the molecular beacon. The assay gives a linear, reproducible response to prolactin inducible protein mRNA, with a limit of detection in the high picomolar range. This method sensitively and specifically identifies a biomarker directly in serum samples in minimal time and with a straightforward procedure, dramatically reducing the total time for sample analysis over current methods from days to hours. The potential impact of this work in detection and understanding of breast cancer metastasis lies in improvements in simplicity, accuracy, and speed over current methods, which could allow for improved patient treatment and prognoses. Ultimately, additional sample throughput will result in better understanding of disease progression.

Multistep derivatization method for the determination of multifunctional oxidation products from the reaction of α-pinene with ozone

A novel three-step analytical method was developed which enables the simultaneous detection and identification of multifunctional oxygenated products resulting from the reaction of α-pinene with ozone. The method consists of the following steps: conversion of carbonyl groups to methyloximes using methyloxyamine, conversion of carboxylic acids to methyl esters using trimethylsilyldiazomethane (TMSD), and conversion of alcohols to trimethylsilyl ethers using N,O-bis(trimethylsilyl)-trifluoroacetamide (BSTFA). The derivatization procedure at each stage was optimized yielding the appropriate amount of derivatization reagent, reaction temperature and time. The newly developed analytical procedure manages without processes of extraction and evaporation to dryness at any stage. Total time for sample analysis is short ca. 3 h. The characteristic ions of derivatives and common pattern for ion fragmentation in capillary gas chromatography electron impact mass spectrometry (GC–EI–MS) analysis were elucidated and discussed.

Automated in-tube solid-phase microextraction coupled with HPLC for the determination of N-nitrosamines in cell cultures.

An automated in-tube solid-phase microextraction (SPME) HPLC analysis method for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and several metabolites has been developed. NNK is one of the tobacco-specific N-nitrosamines (TSNA), which has been linked to cancers associated with the use of or exposure to tobacco products. In-tube SPME is an on-line extraction technique in which analytes are extracted and concentrated from the sample directly into a coated capillary by repeated draw/eject steps. In this study, a tailor-made polypyrrole (PPY)-coated capillary and several commercially available capillaries (capillary GC columns) were used to evaluate their extraction efficiencies for NNK and several metabolites in cell cultures. Compared with commercial capillaries that were currently used for in-tube SPME, the PPY-coated capillary showed better extraction efficiency for all of the compounds studied. After optimization of the extraction conditions, NNK and five metabolite compounds were analyzed in spiked cell cultures, confirming the applicability of the developed method. Excellent linearity was observed for all compounds (av R2 = 0.9942) and detection limits that ranged from 20 to 250 ng/mL. The average within-day and between day variations (% RSD) were 2.9 and 3.6%, respectively. This automated extraction and analysis method simplified the determination of the TSNA, requiring a total sample analysis time of only approximately 30 min.

A rapid screening procedure for cholesterol and dehydrocholesterol by electrospray ionization tandem mass spectrometry

The mono-(dimethylaminoethyl) succinyl (MDMAES) ester is a new derivative for rapid, mild, and sensitive electrospray ionization tandem mass spectrometry (ESI-MS/MS) analysis of cholesterol and dehydrocholesterol. It is an order of magnitude more sensitive than the previous most practical alternative, the N-methylpyridyl ether derivative. The MDMAES derivative was used to develop a rapid screening procedure for the biochemical diagnosis of Smith-Lemli-Opitz syndrome (SLOS) by measuring the dehydrocholesterol/cholesterol ratio in plasma (5 μl) and plasma spotted onto filter paper. Details of the synthesis of [25,26,26,26,27,27,27-2H7]-7-dehydrocholesterol, used as a standard for quantitation, are included. The measurement of total sterols as MDMAES esters, after base hydrolysis of plasma, afforded a dehydrocholesterol/cholesterol ratio of 0.05–2.95 for SLOS patient samples (n = 5) compared with 0.001–0.003 for normal adult controls (n = 20).Direct hexane extraction of plasma without base hydrolysis enabled the measurement of free sterols with a total sample analysis time of <1 h. The free dehydrocholesterol/cholesterol ratio was 0.10–4.47 for SLOS patient samples (n = 5) and 0.003–0.011 for normal adult controls (n = 20).

The use of turbulent flow chromatography/mass spectrometry for the rapid, direct analysis of a novel pharmaceutical compound in plasma.

The use of turbulent flow chromatography coupled to mass spectrometry (turbulent flow LC/MS) shows great potential for the rapid, direct analysis of pharmaceutical compounds in plasma and serum. The use of turbulent flow LC/MS has removed the need for any time-consuming sample preparation such as solid phase extraction, and allowed a total sample analysis time of approximately 2.5 min to be achieved. The coupling of a mass spectrometer with HPLC often not only results in greater sensitivity, but also the added specificity of the mass spectrometer reduces the need for complete resolution of the analyte from endogenous material in the matrix. This allows an on-line analysis approach to be used for the analysis of pharmaceuticals in biological matrices. Turbulent flow chromatography is achieved by the use of high flow rates and large particle size stationary phases. When coupled with mass spectrometric detection, the technique allows the direct analysis of plasma or serum samples with very rapid chromatography and, therefore, extremely high throughout. This work demonstrates the suitability of this technique for the validated analysis of biological samples for a novel isoquinoline pharmaceutical and offers some ideas on the future continued development, optimization and application of turbulent flow liquid chromatography.

Determination of Methyl 2-Benzimidazolecarbamate in Bulk Fruit Juice Concentrates by Competitive-Inhibition Enzyme Immunoassay

A polyclonal enzyme immunoassay (EIA) was used to quantitate methyl 2-benzimidazolecarbamate (MBC or carbendazim), a degradation product of benomyl, in bulk fruit juice concentrates. These concentrates are used by industrial producers to prepare juice or juice concentrates sold in supermarkets. Total sample analysis time was less than 18 min without cleanup or 35 min with cleanup. As many as 8 samples can be analyzed simultaneously, with a limit of quantitation of 10 ppb. The assay's dynamic range ran from 0.5 to 20 ppb MBC but was best from 0.5 to 10 ppb. Intra-assay coefficients of variation (CVs) varied from 4.0 to 13% for standards and from 4.1 to 26% for samples. Interassay CVs varied from 4.5 to 47% for standards and 5.6 to 22% for samples. Average recovery of several juice concentrates spiked at 10 to 290 ppb was 97%. A total of 140 juice concentrates comprising 20 different kinds of juice were analyzed by 2 EIA methods and one liquid chromatographic (LC) procedure. MBC-positive samples gave the following correlation coefficients: 0.954 for EIA without cleanup vs LC, 0.956 for EIA with cleanup vs LC, and 0.978 for EIA with cleanup vs EIA without cleanup. MBC concentrations in MBC-positive juice samples ranged from 5 to 2960 ppb.

Measurement of the 6Li/ 7Li isotope ratio for lithium salts by FT NMR spectroscopy

We require a relatively fast and simple analytical method for direct determination of the ‘LQ7Li isotopic ratio in solution samples taken from chemical-exchange processes being studied for lithium isotope separation. In general, mass spectrometry is used for the measurement of isotopic ratios. This technique can provide very precise results under optimum conditions, but there are several drawbacks, including inevitable sample destruction, memory effects, and, occasionally, rather complicated sample prep aration procedures. In the case of lithium, a precision of f l-2% (1 a) is typical for 6Li/7Li analysis by thermionic source mass spectrometry (I). Various factors affecting the accuracy and precision of isotopic analysis of lithium samples by mass spectrometry have been reviewed recently (2). If an electron-impact ionization source instrument is used, lithium samples must first be converted to a “semivolatile” salt, such as LiI, before introduction by means of a heated direct insertion probe. Thermal ionization spectrometers are equally restrictive on the form of the sample since most compounds must first be converted to a suitable inorganic salt such as LiN03 (I). In addition, the occurrence of isotopic fractionation when the sample leaves the filament is a serious problem (I). As an alternative to mass spectrometry, we are investigating the application of 6Li and 7Li FT NMR spectroscopy to the measurement of lithium isotopic ratios. Since the 1960s there have been several successful applications of NMR spectroscopy to isotopic analysis. For the earliest cases, satellite peaks in the ‘H spectrum were used to determine concentrations of 13C (3, 4) “B and “B (4, 5), 199Hg (4) 29Si (4) and 207Pb (6). With the recent development of higher power multinuclear IT spectrometers direct measurement of the nucleus of interest is now possible. For example, the deuterium content at the natural abundance level in water has been measured by ‘H NMR with a reproducibility of + 1% (1 a?) (7). The accuracy of data obtained for boron both by ‘H satellite (5) and by “B spectra (8) compares very favorably with that obtained by mass spectrometry (8) and with a significant reduction in total sample analysis time. A cw NMR spectrometer was used about fifteen years ago to measure lithium isotope ratios; those tests involved sample tube substitution and conversion