Laser Diode Thermal Desorption Research Articles

Automated High-Throughput Quantification of Phenyl-γ-valerolactones and Creatinine in Urine by Laser Diode Thermal Desorption.

Quantification of nutritional biomarkers is crucial to accurately assess the dietary intake of different classes of (poly)phenols in large epidemiological studies. High-throughput analysis is mandatory to apply this methodology in large cohorts. However, the current validated methods to quantify (poly)phenols metabolites in biological fluids use ultra performance liquid chromatography (UPLC), leading to analysis time of several minutes per sample. To significantly reduce the run time, we developed and validated a method to quantify in urine the flavan-3-ols biomarkers, phenyl-γ-valerolactones (PVLs), using laser diode thermal desorption (LDTD). This mass spectrometry source allows direct introduction of sample extracts, resulting in analysis time of less than 10 s per sample. Also, to encompass the problem associated with the cost and availability of sulfated and glucuronide analytical standards, urine samples were subjected to enzymatic hydrolysis. Creatinine was also quantified to normalize the results obtained from the urinary spot. Results obtained with LDTD-MS/MS were cross-validated by UPLC-MS/MS using 155 urine samples. Coefficient of correlation was above 0.975 for PVLs and creatinine. For all analytes, the accuracy was between 90% and 113% by LDTD-MS/MS. Altogether, sample preparation was fully automated to demonstrate the application potential of this method to large cohorts.

Rapid target screening and quantitative analysis of various environmental pollutants.

The presented analytical method demonstrates a straightforward approach for environmental applications based on laser diode thermal desorption (LDTD). The study aims to examine abilities to achieve environmentally relevant outcomes for different types of pollutants with a fast method following the green chemistry principle. Treatment of environmentally relevant sample matrix (river water) was limited to filtration with a cellulose filter. Samples fortified with analytes were spotted in a LazWell plate and dried before analysis. Samples thermally desorbed using LDTD were detected with Q Exactive hybrid high-resolution mass spectrometer operation in full-scan data-dependent acquisition mode (LDTD-FullMS-dd-MS/MS). LDTD-FullMS-dd-MS/MS exhibits the lowest quantification limits for anatoxin-A, atrazine, caffeine, methamphetamine, methylbenzotriazole, paracetamol, perfluorobutanoic acid, perfluorohexanoic acid, and perfluorooctanoic acid of between 0.10 and 1.0ng mL-1 in the environmentally relevant sample matrix. The developed method was successfully evaluated for different environmental pollutants and radically reduced sample treatment and time requirements for analysis and sample preparation.

Rapid screening procedures for a variety of complex forensic samples using laser diode thermal desorption (LDTD) coupled to different mass spectrometers.

The applications shared in this paper demonstrate the wide variety of samples that can be analyzed when Laser Diode Thermal Desorption (LDTD) is interfaced with a high-resolution mass spectrometer and show the speed at which high quality data can be generated from complex matrices. Samples are solvent extracted and spotted in a 96-well plate. In the case of biological fluids, hydrolysis followed by solid-phase extraction is required. The solvent in the 96-well plate is evaporated followed by mass spectrometric (MS) analysis with atmospheric pressure chemical ionization. Where applicable, the instrument is operated in data-dependent mode, with a full-scan mass spectrum followed by MS/MS spectra of the top 10 ions with a total runtime of 0.4 min. Four applications (MAAQ and Tear Gas, twelve rodenticides, seven explosives, and 40 drugs of abuse) are reported in this paper. MAAQ, tear gas, and rodenticides were identified by full-scan, followed by MS/MS experiments at levels of 125 μg/L, 125 μg/L, and 500 μg/L, respectively. Explosives were all identified at 102 μg/L by full-scan experiments. The drugs of abuse were identified by multiple reaction monitoring (MRM) experiments at defined cutoff levels from 2 to 1000 μg/L. Interfacing LDTD with a mass spectrometer allows for rapid screening of a wide range of samples, with either minimal or complex sample preparation. Using a high-resolution mass spectrometer with the combination to perform full-scan and MS/MS experiments adds a high level of specificity.

Hand-Held Diode Laser for On-Site Analysis Using Transportable Mass Spectrometry.

A hand-held laser diode thermal desorption electrospray ionization (LDTD-ESI) mass spectrometry (MS) method was developed for rapid screening of illegal substances in solid samples. To achieve that, a simple, inexpensive, battery-powered surgical laser diode at 940 nm was employed to ablate the solid samples. The potential of using a black polytetrafluoroethylene substrate to enhance the analytes’ desorption to the gas phase was investigated and demonstrated. Among the optimized ESI parameters, the solvent (methanol/water, 50:50, v/v) and the flow rate (50 μL h–1) were critical to obtain the best sensitivity. The applicability was demonstrated for the rapid identification of selective androgen receptor modulators (SARMs) in pills and powders based on accurate mass measurements by time-of-flight MS. Also, the hand-held LDTD-ESI was combined with a transportable single quadrupole MS. The same SARMs samples were analyzed, and identifications were based on in-source cone voltage fragmentation patterns observed. These initial results demonstrate the applicability of the developed simplified LDTD-ESI MS method for future on-site testing of organic compounds in solid samples.

Development of a High-Throughput Affinity Mass Spectrometry (AMS) Platform Using Laser Diode Thermal Desorption Ionization Coupled to Mass Spectrometry (LDTD-MS).

Affinity selection mass spectrometry (MS) or, simply, affinity mass spectrometry (AMS) is a label-free technology that has been used to identify high-affinity ligands of target proteins of interest by screening against small-molecule compound libraries and identifying molecules that are enriched in the presence of the target protein. We have previously applied Agilent Technology's (Santa Clara, CA) RapidFire solid-phase extraction (SPE)-based high-throughput MS technology to screen small-molecule libraries using AMS. However, SPE-based technologies rely on fluidics for desalting and separation prior to mass analysis with attendant high solvent consumption, relatively high sample volume requirements, risk of sample carryover, and frequent maintenance. To address these challenges, we have established an AMS platform using a laser diode thermal desorption-atmospheric pressure chemical ionization (LDTD-APCI) ionization source (Phytronix, Quebec, Canada) coupled with a SCIEX 5600+ TripleTOF MS (Framingham, MA). We also validated a data-independent acquisition (DIA) Sequential Window Acquisition of All Theoretical Mass Spectra (SWATH-MS) method for the robust detection and analysis of small-molecule affinity hits. An informatics platform developed in-house has resulted in a streamlined data analysis workflow for high-throughput AMS screening campaigns and reduced data processing time without compromising data quality. Finally, 68,000 compounds were screened in a single plate and affinity selected hits were confirmed in an orthogonal enzyme activity assay.

Feasibility of on/at Line Methods to Determine Boar Taint and Boar Taint Compounds: An Overview.

Simple SummaryDue to welfare issues, the physical castration of male pigs is decreasing, and the entire male pig production is increasing. Fattening entire male pigs requires control due to the possibility of accumulating off odour/flavour called boar taint, which is mainly due to two compounds - skatole and androstenone. If carcasses with boar taint reach the market, it can cause a negative consumer reaction which may have economic consequences for the whole meat chain. Thus, it is necessary to sort out carcasses at the slaughter line. Today, a sensory quality control (human nose method) is used in some slaughter plants for this purpose. Detection by physical or chemical methods is also envisaged. A colorimetric method to determine skatole has been used in Danish abattoirs for decades, but it is foreseen that it will soon be replaced by the laser diode thermal desorption ion source coupled with a mass spectrometry equipment that allows a fully automated classification based on skatole and androstenone levels at speed line, with a delay of less than 40 min. Other potential methods such as the electrochemical biosensors, rapid evaporative ionization mass spectroscopy and Raman spectroscopy, still need further development and validation for an application at abattoir level.Classification of carcasses at the slaughter line allows an optimisation of its processing and differentiated payment to producers. Boar taint is a quality characteristic that is evaluated in some slaughter plants. This odour and flavour is mostly present in entire males and perceived generally by sensitive consumers as unpleasant. In the present work, the methodologies currently used in slaughter plants for boar taint classification (colorimetric method and sensory quality control-human nose) and the methodologies that have the potential to be implemented on/at the slaughter line (mass spectrometry, Raman and biosensors) have been summarized. Their main characteristics are presented and an analysis of strengths, weaknesses, opportunities and threats (SWOT) has been carried out. From this, we can conclude that, apart from human nose, the technology that arises as very promising and available on the market, and that will probably become a substitute for the colorimetric method, is the tandem between the laser diode thermal desorption ion source and the mass spectrometry (LDTD-MS/MS) with automation of the sampling and sample pre-treatment, because it is able to work at the slaughter line, is fast and robust, and measures both androstenone and skatole.

Determination of citalopram in fish brain tissue: benefits of coupling laser diode thermal desorption with low- and high-resolution mass spectrometry.

Recent state-of-the-art methods developed for the analysis of polar xenobiotics from different types of biological matrices usually employ liquid chromatography with mass spectrometry. However, there are limitations when a small amount of sample mass is available. For example, individual benthic invertebrates or fish tissue samples often weigh less than 100mg (e.g., brain, liver) but are necessary to understand environmental fate and bioaccumulation dynamics. We developed ultra-fast methods based on a direct sample introduction technique. This included coupling laser diode thermal desorption with atmospheric pressure chemical ionization mass spectrometry (LDTD-APCI-MS). We then quantitated a common selective serotonin reuptake inhibitor (citalopram) in brain tissues of individual juvenile fish after in vivo exposure to environmentally relevant concentration. Two mass spectrometric methods based on low (LDTD-APCI-triple quadrupole (QqQ)-MS/MS) and high (LDTD-APCI-high-resolution product scan (HRPS)) resolutions were developed and evaluated. Individual instrument conditions were optimized to achieve an accurate and robust analytical method with minimum sample preparation requirements. We achieved very good recovery (97-108%) across the range of 1-100ngg-1 for LDTD-APCI-HRPS. LDTD-APCI-QqQ-MS/MS showed poorer performance due to interferences from the matrix at the lowest concentration level. LDTD-APCI ionization was successfully validated for analysis of non-filtered sample extracts. Evaluation of final methods was performed for a set of real fish brain samples, including comparison of LDTD-APCI-HRPS with a previously validated LC-heated electrospray ionization-HRPS method. This new LDTD-APCI-HRPS method avoids the chromatographic step and provides important benefits such as analysis of limited sample masses, lower total sample volume (typically μL), and reduction in analysis time per sample run to a few seconds. Graphical abstract.

Further studies on the signal enhancement effect in laser diode thermal desorption-triple quadrupole mass spectrometry using microwell surface coatings.

The laser diode thermal desorption (LDTD) ionization source allows ultrafast and sensitive analysis of small molecules by mass spectrometry. Signal enhancement in LDTD has been observed when coating the surface of sample microwells with a solution of ethylenediaminetetraacetic acid (EDTA) or nitrilotriacetic acid. Here we present a quantitative analysis of signal enhancement using solutions of diverse commercial proteins (lysozyme, immunoglobulin G, albumin, and fibrinogen) as coatings. Results showed that compounds with polar chemical functions such as carboxylic acid, sulfonyl, and nitro had signal enhancement factors, in most cases higher than 10, when using any of the tested proteins as coating agent. Analysis of variance revealed that immunoglobulin G and fibrinogen gave the best results. However, the signal enhancement factors obtained with these proteins were not superior to those observed with EDTA. To explain the signal enhancement effect of proteins, analysis by scanning electron microscopy of dried samples on the microwell sample plates was carried out. Images showed that salicylic acid, one of the compounds with the highest observed signal enhancement, formed a thick layer when applied directly on the uncoated surface, but it formed small crystals (<1μm) in the presence of protein or EDTA coatings. Further crystallographic studies using powder X-ray diffraction showed that the crystalline form of salicylic acid is modified in the presence of EDTA. Salicylic acid when mixed with EDTA had a higher percentage of amorphous phase (38.1%) than without EDTA (23.1%). These results appear to confirm that the diminution of crystal size of analytes and the increase of amorphous phase are implicated in signal enhancement effect observed in LDTD using microwell surface coatings. To design better coatings and completely elucidate the signal enhancement effect in LDTD, more studies are necessary to understand the effects of coatings on the ionization of analytes.

Ultrafast laser diode thermal desorption method for analysis of representative pharmaceuticals in soil leachate samples

We developed and evaluated a novel analytical method combining ambient ionization technique - laser diode thermal desorption with chemical ionization (LDTD-APCI) and tandem mass spectrometry detection. The LDTD/APCI-MS/MS method was developed for determination of representative pharmaceuticals from different classes (carbamazepine, sulfamethoxazole, irbesartan, fexofenadine) in leachate samples from soil sorption experimentation. We then optimized laser pattern, laser energy and spiked sample volume, which are crucial parameters for this LDTD/APCI-MS/MS method. We further identified utility of a chelating agent (Na2-EDTA) to obtain the highest achievable and reproducible signal of target analytes. Achieved method performance parameters (LODs, LOQs, trueness and precision) were comparable with those obtained from LC-MS/MS. However, application of this novel LDTD/APCI-MS/MS method reduced analysis time by two orders of magnitude (to 12 s), compared to more conventional LC-MS/MS approaches, without use of organic solvents. We expect this novel method will reduce costs and increase throughput for future analyses of pharmaceuticals in the environment while advancing a timely principle of green chemistry.

Fast analysis of caffeinated beverages using laser diode thermal desorption mass spectrometry (LDTD-MS/MS)

ABSTRACTA rapid method for quantitative caffeine analysis in carbonated and non-carbonated beverages and liquid dietary supplement products was developed based on the direct sample introduction technique of laser diode thermal desorption atmospheric pressure chemical ionisation with tandem mass spectrometry (LDTD-MS/MS). Product samples were diluted with a mixture of methanol, water, and d3-caffeine internal standard. Sample aliquots were filtered, spotted on a metal-lined LDTD microtitre plate, dried, and thermally desorbed for subsequent ionisation and analysis by MS/MS analysis. Each sample required a 6 s desorption, and sample-to-sample analysis time of less than 30 s per sample. Caffeine yielded a linear calibration curve over the range 0.5–100 μg mL−1 (R2 > 0.995). Caffeine recoveries from fortified samples ranged from 97% to 107% with <5% RSD. The caffeine determination was not affected by matrix interferences despite the large range of ingredients, vitamins, sweeteners, extracts, and additives present in the products tested, even though LDTD-MS/MS is a whole-sample desorption technique with no separation of matrix background. The method detection limit was below 0.12 μg mL−1. The method was applied to 33 caffeinated products and LDTD-MS/MS quantitative results closely correlated (R2 > 0.998) with the regulatory standard HPLC-UV method (AOAC Official Method 979.08).

Mass spectra alignment using virtual lock-masses

Mass spectrometry is a valued method to evaluate the metabolomics content of a biological sample. The recent advent of rapid ionization technologies such as Laser Diode Thermal Desorption (LDTD) and Direct Analysis in Real Time (DART) has rendered high-throughput mass spectrometry possible. It is used for large-scale comparative analysis of populations of samples. In practice, many factors resulting from the environment, the protocol, and even the instrument itself, can lead to minor discrepancies between spectra, rendering automated comparative analysis difficult. In this work, a sequence/pipeline of algorithms to correct variations between spectra is proposed. The algorithms correct multiple spectra by identifying peaks that are common to all and, from those, computes a spectrum-specific correction. We show that these algorithms increase comparability within large datasets of spectra, facilitating comparative analysis, such as machine learning.

A 6 Second Analytical Method for Quantitation of Tacrolimus in Whole Blood by Use of Laser Diode Thermal Desorption Tandem Mass Spectrometry.

Therapeutic drug monitoring of immunosuppressive drugs is imperative for organ transplant recipients. High-performance LC-MS/MS is considered gold standard; however, immunoassays provide rapid turnaround time. New technology was developed to reduce mass spectrometry analytical run-time. The laser diode thermal desorption source coupled with tandem mass spectrometry (LDTD-MS/MS) eliminates chromatographic separation to increase analytical throughput. A rapid, 6 second, LDTD-MS/MS analytical method was developed for the quantification tacrolimus in whole blood. Whole blood samples were lysed, followed by protein precipitation and solid-phase extraction. Extracted samples with desorption solution were spotted onto a LazWell plate then dried and loaded into the LDTD source for analysis with an AB SCIEX 5500 mass spectrometer in positive multiple reaction monitoring mode. The LDTD laser profile ramps from 0% to 65% of full power over 3 s and is held at 65% for 1 s before returning to initial conditions for 2 s. Data presented include tacrolimus by LDTD-MS/MS comparison to LC-MS/MS, sensitivity, imprecision, interference, linearity, and stability. Method comparison between LDTD-MS/MS and a validated in-house LC-MS/MS assay yielded the following: (LDTD-MS/MS) = 1.119 (LC-MS/MS) + 0.23 ng/mL, Sy/x = 1.26, r = 0.9871 (n = 122). The limit of quantification by LDTD-MS/MS for tacrolimus was <0.3 ng/mL and total imprecision was <10%. Laser diode thermal desorption tandem mass spectrometry technology can provide rapid turnaround time to result for tacrolimus. The analytical time for LDTD-MS/MS was 6 s compared to 135 s by LC-MS/MS, a >95% decrease in analytical time.

Signal enhancement in laser diode thermal desorption-triple quadrupole mass spectrometry analysis using microwell surface coatings.

Laser-diode thermal desorption (LDTD) is an ionization source usually coupled to triple quadrupole mass spectrometry (QqQMS) and specifically designed for laboratories requiring high-throughput analysis. It has been observed that surface coatings on LDTD microwell plates can improve the sensitivity of the analysis of small polar molecules. The objective of the present study is to understand and quantify the effect of microwell surface coatings on signal intensity of small organic molecules of clinical, environmental, and forensic interest. Experiments showed that the peak areas of diclofenac, chloramphenicol, salicylic acid, and 11-nor-9-carboxy-Δ9 -tetrahydrocannabinol obtained by LDTD-QqQMS increased by up to 3 orders of magnitude when using microwells coated with ethylenediaminetetraacetic acid (EDTA). Tests with different chelating agents and polytetrafluoroethylene as microwell surface coatings showed that nitrilotriacetic acid gave significantly higher peak areas for five out of the nine compounds that showed signal enhancement using chelating agents as coatings. Scanning electron microscopy studies of EDTA-coated and uncoated microwells showed that analytes deposited in the former formed more uniform and thinner films than in the latter. The enhancement effect of surface coatings in LDTD-QqQMS was explained mainly by the formation of homogenous and thinner layers of nanocrystals of analytes that are easier to desorb thermally than the layers formed when the analytes dry in direct contact with the bare stainless-steel surface. Chemisorption of some analytes to the stainless-steel surface of the microwell plate appeared to be a minor factor. Surface coatings widen the number of compounds analyzable by LDTD-QqQMS and can also improve sensitivity and limits of detection.

Solid Sampling with a Diode Laser for Portable Ambient Mass Spectrometry.

A hand-held diode laser is implemented for solid sampling in portable ambient mass spectrometry (MS). Specifically, a pseudocontinuous wave battery-powered surgical laser diode is employed for portable laser diode thermal desorption (LDTD) at 940 nm and compared with nanosecond pulsed laser ablation at 2940 nm. Postionization is achieved in both cases using atmospheric pressure photoionization (APPI). The laser ablation atmospheric pressure photoionization (LAAPPI) and LDTD-APPI mass spectra of sage leaves (Salvia officinalis) using a field-deployable quadrupole ion trap MS display many similar ion peaks, as do the mass spectra of membrane grown biofilms of Pseudomonas aeruginosa. These results indicate that LDTD-APPI method should be useful for in-field sampling of plant and microbial communities, for example, by portable ambient MS. The feasibility of many portable MS applications is facilitated by the availability of relatively low cost, portable, battery-powered diode lasers. LDTD could also be coupled with plasma- or electrospray-based ionization for the analysis of a variety of solid samples.

Rapid analysis of forensic-related samples using two ambient ionization techniques coupled to high-resolution mass spectrometers.

This paper highlights the versatility of interfacing two ambient ionization techniques, Laser Diode Thermal Desorption (LDTD) and Atmospheric Solids Analysis Probe (ASAP), to high-resolution mass spectrometers and demonstrate the method's capability to rapidly generate high-quality data from multiple sample types with minimal, if any, sample preparation. For ASAP-MS analysis of solid and liquid samples, the material was transferred to a capillary surface before being introduced into the mass spectrometer. For LDTD-MS analysis, samples were solvent extracted, spotted in a 96-well plate, and the solvent was evaporated before being introduced into the mass spectrometer. All analyses were performed using Atmospheric Pressure Chemical Ionization in positive mode. Seven consumer "Spice" packets were combined and analyzed by both ASAP and LDTD, which identified 11 synthetic cannabinoids/cathinones by full MS and MS/MS experiments. To further show the usefulness of these techniques, black tar heroin was analyzed, which resulted in the identification of heroin and its impurities (monoacetylmorphine, papaverine, and noscapine). These experiments were performed on the LTQ-Orbitrap to demonstrate the ability to perform both parallel and serial MS and MSn experiments. Interfacing LDTD and ASAP to high-resolution mass spectrometers allows for expeditious analysis of a wide range of samples, with minimal or no sample preparation. Both allow for rapid full scan, MS/MS, and/or MSn experiments from a single sample introduction. Published in 2017. This article is a U.S. Government work and is in the public domain in the USA.

Detection of Cyanotoxins in Algae Dietary Supplements.

Algae dietary supplements are marketed worldwide as natural health products. Although their proprieties have been claimed as beneficial to improve overall health, there have been several previous reports of contamination by cyanotoxins. These products generally contain non-toxic cyanobacteria, but the methods of cultivation in natural waters without appropriate quality controls allow contamination by toxin producer species present in the natural environment. In this study, we investigated the presence of total microcystins, seven individual microcystins (RR, YR, LR, LA, LY, LW, LF), anatoxin-a, dihydroanatoxin-a, epoxyanatoxin-a, cylindrospermopsin, saxitoxin, and β-methylamino-l-alanine in 18 different commercially available products containing Spirulina or Aphanizomenon flos-aquae. Total microcystins analysis was accomplished using a Lemieux oxidation and a chemical derivatization using dansyl chloride was needed for the simultaneous analysis of cylindrospermopsin, saxitoxin, and β-methylamino-l-alanine. Moreover, the use of laser diode thermal desorption (LDTD) and ultra-high performance liquid chromatography (UHPLC) both coupled to high resolution mass spectrometry (HRMS) enabled high performance detection and quantitation. Out of the 18 products analyzed, 8 contained some cyanotoxins at levels exceeding the tolerable daily intake values. The presence of cyanotoxins in these algal dietary supplements reinforces the need for a better quality control as well as consumer’s awareness on the potential risks associated with the consumption of these supplements.

Effect of temperature Ramp on hydrocarbon desorption profiles from zeolite ZSM‐12

AbstractZeolite ZSM‐12 with different Si:Al molar ratios and one‐dimensional channels with 12 oxygen ring apertures (12R) was synthesized and characterized by different techniques such as: X‐ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer‐Emmett‐Teller surface area (BET), elemental analysis by atomic absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR) of adsorbed pyridine, and NH3 temperature‐programmed desorption (TPD). The synthesized samples were tested as hydrocarbon (HC) trap adsorbents using toluene and ethylene as heavy and light probe molecules for HCs in the exhaust stream at engine cold‐start. High heating rate desorption experiments were performed using the Phytronix Laser Diode Thermal Desorption system (S‐960 LDTD) coupled with an Atmospheric Pressure Chemical Ionization (APCI) chamber (Phytronix Technologies, Canada) after adsorption of toluene‐ethylene mixtures. Three heating rates, which reflect the actual heating rates of the catalytic muffler, were used for the desorption process: 3 °C/s, 5 °C/s, and 9 °C/s. For all solids considered in this study, the two HCs desorbed above 240 °C, which is the light‐off temperature of the three‐way catalyst. Ag‐ZSM‐12 with different Si:Al ratios was found the most appropriate HC trapping adsorbent in spite of its slightly lower adsorption capacity. A high desorption temperature for ethylene and toluene was associated with the large density of strong Lewis acid sites in this solid.

Coupling Laser Diode Thermal Desorption with Acoustic Sample Deposition to Improve Throughput of Mass Spectrometry–Based Screening

The move toward label-free screening in drug discovery has increased the demand for mass spectrometry (MS)–based analysis. Here we investigated the approach of coupling acoustic sample deposition (ASD) with laser diode thermal desorption (LDTD)–tandem mass spectrometry (MS/MS). We assessed its use in a cytochrome P450 (CYP) inhibition assay, where a decrease in metabolite formation signifies CYP inhibition. Metabolite levels for 3 CYP isoforms were measured as CYP3A4-1′-OH-midazolam, CYP2D6-dextrorphan, and CYP2C9-4′-OH-diclofenac. After incubation, samples (100 nL) were acoustically deposited onto a stainless steel 384-LazWell plate, then desorbed by an infrared laser directly from the plate surface into the gas phase, ionized by atmospheric pressure chemical ionization (APCI), and analyzed by MS/MS. Using this method, we achieved a sample analysis speed of 2.14 s/well, with bioanalytical performance comparable to the current online solid-phase extraction (SPE)–based MS method. An even faster readout speed was achieved when postreaction sample multiplexing was applied, where three reaction samples, one for each CYP, were transferred into the same well of the LazWell plate. In summary, LDTD coupled with acoustic sample deposition and multiplexing significantly decreased analysis time to 0.7 s/sample, making this MS-based approach feasible to support high-throughput screening (HTS) assays.

Diclofenac in municipal wastewater treatment plant: quantification using laser diode thermal desorption—atmospheric pressure chemical ionization—tandem mass spectrometry approach in comparison with an established liquid chromatography-electrospray ionization–tandem mass spectrometry method

Diclofenac (DCF), a prevalent non-steroidal anti-inflammatory drug (NSAID) is often detected in wastewater and surface water. Analysis of the pharmaceuticals in complex matrices is often laden with challenges. In this study a reliable, rapid and sensitive method based on laser diode thermal desorption/atmospheric pressure chemical ionization (LDTD/APCI) coupled with tandem mass spectrometry (MS/MS) has been developed for the quantification of DCF in wastewater and wastewater sludge. An established conventional LC-ESI–MS/MS (liquid chromatography-electrospray ionization–tandem mass spectrometry) method was compared with LDTD-APCI-MS/MS approach. The newly developed LDTD-APCI-MS/MS method reduced the analysis time to 12s in lieu of 12min for LC-ESI–MS/MS method. The method detection limits for LDTD-APCI-MS/MS method were found to be 270ngL−1 (LOD) and 1000ngL−1 (LOQ). Furthermore, two extraction procedures, ultrasonic assisted extraction (USE) and accelerated solvent extraction (ASE) for the extraction of DCF from wastewater sludge were compared and ASE with 95.6±7% recovery was effective over USE with 86±4% recovery. The fate and partitioning of DCF in wastewater (WW) and wastewater sludge (WWS) in wastewater treatment plant was also monitored at various stages of treatment in Quebec Urban community wastewater treatment plant. DCF exhibited affinity towards WW than WWS with a presence about 60% of DCF in WW in contrary with theoretical prediction (LogKow=4.51).

Quantitative analysis of poly- and perfluoroalkyl compounds in water matrices using high resolution mass spectrometry: Optimization for a laser diode thermal desorption method

An alternative analysis technique for the quantitation of 15 poly- and perfluoroalkyl substances (PFASs) in water matrices is reported. Analysis time between each sample was reduced to less than 20s, all target molecules being analyzed in a single run with the use of laser diode thermal desorption atmospheric pressure chemical ionization (LDTD/APCI) coupled with high resolution accurate mass (HRMS) orbitrap mass spectrometry. LDTD optimal settings were investigated using either one-factor-at-a-time or experimental design methodologies, while orbitrap parameters were optimized simultaneously by means of a Box–Behnken design. Following selection of an adequate sample concentration and purification procedure based on solid-phase extraction and graphite clean-up, the method was validated in an influent wastewater matrix. Environmentally significant limits of detection were reported (0.3–4ngL−1 in wastewater and 0.03–0.2ngL−1 in surface water) and out of the 15 target analytes, 11 showed excellent accuracies (±20% of the target values) and recovery rates (75–125%). The method was successfully applied to a selection of environmental samples, including wastewater samples in 7 locations across Canada, as well as surface and tap water samples from the Montreal region, providing insights into the degree of PFAS contamination in this area.