Direct Analysis In Real Time Mass Spectrometry Research Articles

Suitable in-situ derivatization of alcohols by reaction with basic amines in Direct Analysis in Real Time mass spectrometry

This work highlights the discovered in-situ analytical reaction between primary/secondary alcohols and nitrogenous bases (pyridine, quinoline) that involves the substitution of hydroxyl groups for nitrogen-containing charged species and proceeds in an ionization region of Direct Analysis in Real Time mass spectrometry (DART-MS) instrument at gas stream temperature of 150–450 °C. Resulted cations provide strong signals in mass spectra and this ensures high sensitivity of the analysis. Collision induced dissociation of such precursor ions gives rise to characteristic and simple fragmentation mass spectra revealing mainly protonated nitrogenous bases and carbonium cations resulting from the elimination of neutral nitrogen-containing bases. The dependence of signal response on gas stream temperature was elucidated. It was also found that, independently of gas stream temperature, high volatility low-molecular weight alcohols did not demonstrate characteristic DART spectra owing to a high rate of desorption/evaporation which does not provide sufficient probability of the reaction. To the best of our knowledge, this type of specific reactions in a plasma-based source of DART mass spectrometer is reported for the first time. It represents a new and interesting derivatization approach providing a rapid and sensitive complement method for the detection and identification of individual monools of various origin, profiling plant sterols and other steroid alcohols in different matrices.

Nighttime secondary organic aerosol formation from unburned fuel vapors

Nighttime secondary organic aerosol (SOA) formation was investigated for unburned vapors of three different fuels (Fuel #1, Fuel #2, and Fuel #3) in the presence of NO and ozone. Fuel #1 and Fuel #2 contained gasoline-range components with Fuel #1 being rich in aromatics and Fuel #2 being rich in olefins. Fuel #3 contained diesel-range components. The SOA formation from Fuel #1 and Fuel #3 showed a continuous increase in the aerosol mass loading as a function of initial NO concentration. However, for Fuel #2, while the aerosol mass loading increased at higher NO concentrations, the results from this study indicated they were initially suppressed by the presence of olefins that can rapidly react with nitrate radicals. The evolution of the mass spectra of the formed aerosols indicated that their chemical composition continued to change even after termination of aerosol formation due to additional oxidation reactions during the aging process. Off-line Direct Analysis in Real Time Mass Spectrometry (DART-MS) was conducted on the formed SOA collected on filters and the analysis indicated that the SOA was mainly composed of highly oxidized compounds. It is hypothesized that olefins could interact with NO3∙ leading to the formation of heavier organic nitrates through addition or oligomerization reactions. Insights from the current study may help to improve regional air quality control policies and methodologies for future multi-day modeling studies.

Detection and Classification of Ignitable Liquid Residues in the Presence of Matrix Interferences by Using Direct Analysis in Real Time Mass Spectrometry.

Conventional Gas Chromatography-Mass Spectrometry (GC-MS) methods for the analysis of ignitable liquids (ILs) are usually time-consuming, and the data produced are difficult to interpret. A fast IL screening method using direct analysis in real time mass spectrometry (DART-MS) is proposed in this study. GC-MS, QuickStrip DART-MS, and thermal desorption DART-MS methods were used to analyze neat ILs and thermal desorption DART-MS without extraction was used to analyze ILs on five substrates (e.g., carpet, wood, cloth, sand, and paper). Compared to GC-MS, DART-MS methods generated different spectral profiles for neat ILs with more peaks in the higher mass range and also provided better detection of less volatile compounds. ILs on substrates were successfully classified (98±1%) using partial least squares discriminant analysis (PLS-DA) models based on thermal desorption DART-MS data. This study shows that DART-MS has great potential for the high-throughput screening of ILs on substrates.

Simultaneous determination of multiple components in cigarettes by mechanochemical extraction and direct analysis in real time mass spectrometry in minutes

A simple, rapid and high throughput analytical approach with combination of mechanochemical extraction (MCE) and direct analysis in real time mass spectrometry (DART-MS) analysis was developed for the simultaneous determination of multiple chemical components in cigarette fillers. Different kinds of substances including nicotine, cigarette alkaloids, carbohydrates, organic acids, humectants and other additives were successfully extracted using MCE and detected by high resolution DART-MS. Six solvents of various polarities were compared during MCE process and significant differences were observed. Different brands of cigarettes as well as standard research cigarette exhibited distinctive chemical features and DART-MS fingerprints. Principle component analysis showed clear differentiation among different cigarettes extracted with the same solvent and different solvent extracts of the same type of cigarette. The putative chemical formulas were proposed based on accurate m/z values with <10 ppm mass errors. The relative contents of nicotine and other identified substances were compared and significant differences were observed among cigarettes of different locations. The whole procedure of MCE combined with DART-MS only takes minutes from raw cigarette fillers to obtaining the semi-quantitative results. The operation is simple and high throughput, providing an efficient method to analyze cigarette composition, and to establish a methodology to acquire the rapid cigarette fingerprints for quality control.

Forensic Analysis and Differentiation of Black Powder and Black Powder Substitute Chemical Signatures by Infrared Thermal Desorption-DART-MS.

The trace detection and forensic analysis of black powders and black powder substitutes, directly from wipe-based sample collections, was demonstrated using infrared thermal desorption (IRTD) coupled with direct analysis in real time mass spectrometry (DART-MS). Discrete 15 s heating ramps were generated, creating a thermal desorption profile that desorbed more volatile species (e.g., organic and semivolatile inorganic compounds) at lower temperatures (250-400 °C) and nonvolatile inorganic oxidizers at high temperatures (450-550 °C). Common inorganic components of black powders (e.g., sulfur and potassium nitrate) as well as the alternative and additional organic and inorganic components of common black powder substitutes (e.g., dicyandiamide, ascorbic acid, sodium benzoate, guanidine nitrate, and potassium perchlorate) were detected from polytetrafluoroethylene-coated fiberglass collection wipes with no additional sample preparation. IRTD-DART-MS enabled the direct detection of intact inorganic salt species as nitrate adducts (e.g., [KClO4+NO3]-) and larger clusters. The larger ion distributions generated by these complex mixtures were differentiated using principal component analysis (PCA) of the mass spectra generated at two points during the thermal desorption profile (low and high temperatures), as well as at high in-source collision-induced dissociation. The PCA framework generated by the analysis of the two black powders and five black powder substitutes was used to classify samples collected from a commercial firecracker containing both flash powder and black powder. The coupling of IRTD-DART-MS and multivariate statistics demonstrated the powerful utility for detection and discrimination of trace fuel-oxidizer mixtures.

Combined direct analysis in real-time mass spectrometry (DART-MS) with analytical pyrolysis for characterization of Chinese crude propolis

A combination of direct analysis in real-time mass spectrometry (DART-MS) with analytical pyrolysis comprising evolved gas analysis-mass spectrometry (EGA-MS) and heart-cut EGA-gas chromatography (GC)/MS was used for characterization of Chinese crude propolis samples. DART-MS allowed us to profile general whole chemical components in propolis including terpenoids, phenolic acids and esters, flavonoid aglycones, flavonoid glycosides, phenolic glycerides and hydrocarbons with their molecular weights in the range of 100 – 800. EGA-MS was used to investigate the thermal behaviors of main components observed by DART-MS. The results revealed three temperature zones for the releasing behaviors of main constituents: (1) vaporization of terpenoids within 120–160 °C, (2) vaporization of phenolic acids and flavonoid aglycones, and pyrolysis of some flavonoid glycosides and beeswax within 160–300 °C, (3) pyrolysis of some flavonoid glycosides, phenolic glycerides and beeswax within 300–550 °C. Based on extracted ion thermograms of flavonoids, it is clear that chrysin and tectochrysin existed only as aglycones, while pinocembrin, galangin, 2′, 6′-dihydroxy-4′-methoxychalcone and naringenin existed as both aglycones and glycosides. According to temperature zones, heart-cut EGA GC/MS data clearly indicated that 43 components were identified for 3 crude propolis samples collected from different origins, and grouped into 7 classes: alcohols/phenols, aldehydes/ketones, terpenoids, phenolic acids and esters, flavonoids, hydrocarbons and others. Among them, terpenoids, phenolic acids and esters, and flavonoids were main bioactive classes. Terpenoids accounted for 43.5–82.1 % in zone A, and flavonoids accounted for 3.7–23.9 % in zone B and 5.2–46.5 % in zone C, showing their different origins. In addition, flavonoid aglycones and their glycosides also could be semiquantitatively analyzed separately by analytical pyrolysis techniques used. Flavonoid aglycones accounted for a majority of total flavonoids with its proportions more than 52.6–66.7 % in propolis samples. All the obtained results demonstrate that the combination of these methods is effective for profiling all main components in Chinese crude propolis.

Heterogeneous Chlorination of Squalene and Oleic Acid.

Washing with chlorine bleach leads to high mixing ratios of gas-phase HOCl. Using two methods that are sensitive to surface film composition-attenuated total reflection fourier transform infrared (ATR-FTIR) spectroscopy and direct analysis in real time mass spectrometry (DART-MS)-we present the first study of the chlorination chemistry that occurs when gaseous HOCl reacts with thin films of squalene and oleic acid. At mixing ratios of 600 ppbv, HOCl forms chlorohydrins by adding across carbon-carbon double bonds without breaking the carbon backbone. The initial uptake of one HOCl molecule occurs on the time scale of a few minutes at these mixing ratios. For oleic acid, ester formation proceeds immediately thereafter, leading to dimeric and trimeric chlorinated products. For squalene, subsequent HOCl uptake occurs until all six of its carbon-carbon double bonds become chlorinated within 1-2 h. These results indicate that chlorination of skin oil, which contains substantial carbon unsaturation, is likely to occur rapidly under common cleaning conditions, potentially leading to the irritation associated with chlorinated bleach. This chemistry will likely also proceed with cooking oils, in the human respiratory system which has unsaturated surfactants as important components of lung fluid, and with organic components of the sea surface microlayer.

The unexpected identification of the cannabimimetic, 5F-ADB, and dextromethorphan in commercially available cannabidiol e-liquids

Electronic cigarettes (e-cigarettes) were developed as an alternative method for nicotine delivery and had a significant surge in popularity. E-liquids are formulations used in e-cigarettes, and consist of a ratio of propylene glycol (PG) and vegetable glycerin (VG), a pharmaceutical and/or herbal remedy and, usually, a flavoring agent. Presented is the evaluation of nine cannabidiol (CBD) e-liquids from a single manufacturer for cannabinoids and other psychoactive compounds by Direct Analysis in Real Time Mass Spectrometry (DART-MS) and Gas Chromatography Mass Spectrometry (GC/MS). The analysis of these products resulted in the detection of CBD in all nine produces and the unexpected detections of 5-fluoro MDMB-PINACA (5F-ADB) in four of the products and dextromethorphan (DXM) in one of the products. The analysis of these products illustrates the potential quality control issues that can occur in an unregulated industry. CBD products are believed by many users to offer heath benefits, but the detection of a dangerous cannabimimetic, 5F-ADB, and DXM in these products illustrates the need for oversight.

Rapid mapping of various chemicals in personal care and healthcare products by direct analysis in real time mass spectrometry

Residual chemicals on personal care and healthcare products, such as sanitary articles, sterile gauze bandages, nappies, plasters, were studied by direct analysis in real time mass spectrometry (DART-MS). We have identified around 40 compounds in seventeen different commercially available items. The tentative identification was further supported for about half of the chemicals by tandem mass spectrometric experiments (DART MS/MS). The most notable hazardous substances were tributyl phosphate, tris(2,4-di-tert-butylphenyl) phosphite, phthalic acid esters, erucamide, and nonylphenol ethoxylates (NPEs). In addition, we developed an efficient DART-MS analysis to determine the concentration of NPE in a swab sample. The quantitative result obtained by DART-MS was confirmed by liquid chromatography with mass spectrometric detection (LC-MS).

Ajothiolanes: 3,4-Dimethylthiolane Natural Products from Garlic ( Allium sativum).

Stereoisomers of 5-(2-allylsulfinyl)-3,4-dimethylthiolane-2-ol, a family of 3,4-dimethylthiolanes of formula C9H16O2S2 we name ajothiolanes, were isolated from garlic ( Allium sativum) macerates and characterized by a variety of analytical and spectroscopic techniques, including ultraperformance liquid chromatography (UPLC), direct analysis in real time-mass spectrometry (DART-MS), and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Ajothiolanes were found to be spectroscopically identical to a family of previously described compounds named garlicnins B1-4 (C9H16O2S2), whose structures we demonstrate have been misassigned. 2D 13C-13C NMR incredible natural abundance double quantum transfer experiments (INADEQUATE) were used to disprove the claim of nine contiguous carbons in these compounds, while X-ray absorption spectroscopy (XAS) along with computational modeling was used to disprove the claim that these compounds were thiolanesulfenic acids. On the basis of the similarity of their NMR spectra to those of the ajothiolanes, we propose that the structures of previously described, biologically active onionins A1-3 (C9H16O2S2), from extracts of onion ( Allium cepa) and Allium fistulosum, and garlicnin A (C12H20O2S4), from garlic extracts, should also be reassigned, in each case as isomeric mixtures of 5-substituted-3,4-dimethylthiolane-2-ols. We conclude that 3,4-dimethylthiolanes may be a common motif in Allium chemistry. Finally, we show that another garlic extract component, garlicnin D (C7H12O2S3), claimed to have an unprecedented structure, is in fact a known compound from garlic with a structure different from that proposed, namely, 2( E)-3-(methylsulfinyl)-2-propenyl 2-propenyl disulfide.

Discrimination of brands of gasoline by using DART-MS and chemometrics

In this study, Direct Analysis in Real Time Mass Spectrometry (DART-MS) was used to analyze four different brands of gasoline collected from five local fuel service stations. Chemometric methods including analysis of variance-principal component analysis (ANOVA-PCA) and partial least squares discriminant analysis (PLS-DA) were applied to classify the gasoline samples based on brand and identify characteristic features for gasoline discrimination. To test the robustness of this method, the gasoline samples were collected once per week for eight weeks and they were analyzed by DART-MS within 24 h of collection and again two weeks after the last sample collection. Both full DART-MS spectra data and selected ion spectra data were used to construct PLS-DA models and the average classification rates of both models were 99.9 ± 0.1% for 100 independent evaluations with bootstrapped Latin partitions and were 100% for a new validation set collected two weeks later with no parametric changes. The major characteristic features corresponded to polymeric compounds in fuel additives which supported our hypothesis that proprietary additives blended in gasoline should be the marker components to distinguish gasoline with different brands. The weathered gasoline samples at different extents, i.e. 30%, 50%, 70%, and 90%, were studied and compared with un-weathered samples. The polymeric compound patterns in gasoline were found to be brand dependent and weathering extent dependent and the patterns for the weathered gasoline with different brands were still significantly different. DART-MS is demonstrated as a promising tool for the discrimination of brands of gasoline.

Microwave assisted extraction for the determination of chlorogenic acid in Flos Lonicerae by direct analysis in real time mass spectrometry (DART-MS)

Flos Lonicerae was an important Chinese medicine. In this research, a microwave assisted extraction method was applied for the extraction of chlorogenic acid from Flos Lonicerae. The operating conditions were optimized using a Box–Behnken design test. Under the optimal conditions, the extraction yield of chlorogenic acid reached 32.52 ± 1.31 mg/g. Next, a direct analysis in real time mass spectrometry (DART-MS) method was utilized to quantify of chlorogenic acid in Flos Lonicerae extracts. The primary parameters were optimized to obtain maximum signal intensity. In the detection process of the actual samples, the results obtained by DART–MS are consistent with those obtained by HPLC method with short detection time and acceptable repeatability and precision (<15%). In addition, the DART–MS/MS method has several advantages, such as speed, low cost and simplicity. Therefore, the DART-MS method is an efficient method that can be applied in the quantification of chlorogenic acid in Flos Lonicerae.

Detection of Nonvolatile Inorganic Oxidizer-Based Explosives from Wipe Collections by Infrared Thermal Desorption-Direct Analysis in Real Time Mass Spectrometry.

Infrared thermal desorption (IRTD) was coupled with direct analysis in real time mass spectrometry (DART-MS) for the detection of both inorganic and organic explosives from wipe collected samples. This platform generated discrete and rapid heating rates that allowed volatile and semivolatile organic explosives to thermally desorb at relatively lower temperatures, while still achieving elevated temperatures required to desorb nonvolatile inorganic oxidizer-based explosives. IRTD-DART-MS demonstrated the thermal desorption and detection of refractory potassium chlorate and potassium perchlorate oxidizers, compounds difficult to desorb with traditional moderate-temperature resistance-based thermal desorbers. Nanogram to sub-nanogram sensitivities were established for analysis of a range of organic and inorganic oxidizer-based explosive compounds, with further enhancement limited by the thermal properties of the most common commercial wipe materials. Detailed investigations and high-speed visualization revealed conduction from the heated glass-mica base plate as the dominant process for heating of the wipe and analyte materials, resulting in thermal desorption through boiling, aerosolization, and vaporization of samples. The thermal desorption and ionization characteristics of the IRTD-DART technique resulted in optimal sensitivity for the formation of nitrate adducts with both organic and inorganic species. The IRTD-DART-MS coupling and IRTD in general offer promising explosive detection capabilities to the defense, security, and law enforcement arenas.

Understanding the Improved High-Temperature Cycling Stability of a LiNi0.5Mn0.3Co0.2O2/Graphite Cell with Vinylene Carbonate: A Comprehensive Analysis Approach Utilizing LC-MS and DART-MS

An analysis approach utilizing liquid chromatography mass spectrometry (LC-MS) and direct analysis in real time mass spectrometry (DART-MS) is applied to discern the influence of vinylene carbonate (VC) on the cycling performance of a LiNi0.5Mn0.3Co0.2O2 (NMC)/graphite cell at elevated temperature. The VC-containing cell exhibits much improved cycling performance against the elevated temperature rather than the VC-free one. On the basis of the LC-MS results, more decomposition compounds including carbonate oligomers and organophosphates are present in the electrolyte without VC after the initial cycling, while they are less identifiable in the VC-containing electrolyte. On the other hand, the DART-MS results show that a thermally resistant film, which is primarily composed of the cyclic organophosphates, favors forming on the graphite anode surface of the VC-containing cell rather than the VC-free one, preventing further electrolyte decomposition. Moreover, a reaction scheme is proposed to reasonably expl...

Direct Analysis in Real Time Mass Spectrometry for Characterization of Large Saccharides.

Polysaccharide characterization posts the most difficult challenge to available analytical technologies compared to other types of biomolecules. Plant polysaccharides are reported to have numerous medicinal values, but their effect can be different based on the types of plants, and even regions of productions and conditions of cultivation. However, the molecular basis of the differences of these polysaccharides is largely unknown. In this study, direct analysis in real time mass spectrometry (DART-MS) was used to generate polysaccharide fingerprints. Large saccharides can break down into characteristic small fragments in the DART source via pyrolysis, and the products are then detected by high resolution MS. Temperature was shown to be a crucial parameter for the decomposition of large polysaccharide. The general behavior of carbohydrates in DART-MS was also studied through the investigation of a number of mono- and oligosaccharide standards. The chemical formula and putative ionic forms of the fragments were proposed based on accurate mass with less than 10 ppm mass errors. Multivariate data analysis shows the clear differentiation of different plant species. Intensities of marker ions compared among samples also showed obvious differences. The combination of DART-MS analysis and mechanochemical extraction method used in this work demonstrates a simple, fast, and high throughput analytical protocol for the efficient evaluation of molecular features in plant polysaccharides.

The coupling of capillary microextraction of volatiles (CMV) dynamic air sampling device with DART-MS analysis for the detection of gunshot residues

A novel apparatus interfacing capillary microextraction of volatiles (CMV) and direct analysis in real time mass spectrometry (DART-MS) was evaluated for the trace detection and characterization of organic compounds found in smokeless powders and consequently in gunshot residues (GSR). Target analytes included nitroglycerin (NG), diphenylamine (DPA), ethyl centralite (EC), 2,4-dinitrotoluenes (2,4-DNT), methyl centralite (MC), 2,4,6-trinitrotoluene (2,4,6-TNT) and derivatives of DPA generated from the degradation of the energetic material such as 4-nitrosodiphenylamine (4-NODPA), 2-nitrodiphenylamine (2-NDPA) and 4-nitrodiphenylamine (4-NDPA). The results from CMV-DART-MS were compared to the previously reported CMV-GC–MS method through the application of an efficient and calibrated vapor source based on an inert pre-heated GC split/splitless injector port, to simulate field sampling of GSR in the air surrounding a person’s hands. It was found that both DART-MS and GC–MS could be used in succession to detect a suite of compounds at 15 ng sampled vapor within 2.5 L of air to provide more comprehensive characterization of a sample. Overall, a method was developed for the analysis of compounds associated with GSR applying fast, dynamic air sampling (2–5 min) using the CMV device coupled for the first time to DART-MS for fast analysis (∼1 min), compared to GC–MS results under the same sampling conditions of ng quantities of the target analytes of interest.

High-Throughput Analysis for Artemisinins with Deep Eutectic Solvents Mechanochemical Extraction and Direct Analysis in Real Time Mass Spectrometry.

A fast, simple, efficient, and high-throughput analytical protocol using deep eutectic solvents (DES) for mechanochemical extraction (MCE) combined with direct analysis in real time mass spectrometry (DART-MS) was developed to quantify heat-labile bioactive compounds artemisinin (AN), arteannuin B, and artemisinic acid from Aretemisia annua. MCE is performed at room temperature, and target analytes are released into DESs within seconds; this method demonstrated multiple advantages over traditional extraction methods and organic solvents. DART-MS was then used for the structure confirmation and quantification for the three artemisinin major components extracted from plants of five locations. Liquid chromatography (LC) measurements were performed as well for results verification and comparison, and the amounts obtained were consistent between the two techniques. DART-MS showed advantages in simplicity, low limit of detection (5-15 ng mL-1), and superior speed (10-20 s), but with slightly higher relative standard deviation (0.7-10.8%). The entire protocol can be accomplished in a few minutes from raw materials to quantitative results. This study aims to establish a methodology combining high-efficiency sample pretreatment and rapid chemical analysis from complex matrixes, where the time-consuming separation procedure can be eliminated. Additionally, the use of toxic organic solvents needed in the process of chemical extraction and analysis is largely avoided. In general, this investigation provides a robust analytical procedure that can be widely used in many areas of research and industrial activities.

Rapid qualitative analysis of 2 flavonoids, rutin and silybin, in medical pills by direct analysis in real-time mass spectrometry (DART-MS) combined with in situ derivatization.

Direct analysis in real-time mass spectrometry (DART-MS) with in situ silylation was used for the rapid analysis of the flavonoids silybin ((2R,3R)-3,5,7-trihydroxy-2-[3-(4-hydroxy-3-methoxyphenyl)-2-hydroxymethyl-2,3-dihydrobenzo[1,4]dioxin-6-yl]chroman-4-one) and rutin (quercetin-3-O-rutinoside). Three different derivatization reagents, hexamethyldisilazane/trimethylchlorosilane/pyridine (HMDS/TMCS/pyridine), N,O-bis(trimethylsilyl)acetamide/trimethylchlorosilane/N-trimethylsilyimidazole (BSA/TMCS/TMSI), and N,O-bis(trimethylsilyl)trifluoroacetamide/trimethylchlorosilane (BSTFA/TMCS), were applied. Silybin and rutin were detected with various degrees of silylation, and the formation of dimers with pyridine and imidazole was also observed. HMDS/TMCS/pyridine was the best choice for the DART-MS analysis of silybin, and BSA/TMCS/TMSI was the most effective for the detection of rutin. The effects of the DART source temperature on desorption, ionization, in-source fragmentation, dimer formation, and hydrolysis of the trimethylsilyl groups were also studied. In addition, the collision-induced dissociation properties of the derivatized silybin and rutin were explored. With our in situ silylation method, the derivatized bioactive compounds in intact medical pills could also be detected by DART-MS.

Direct analysis in real time mass spectrometry (DART-MS) of discrete sample areas without heat damage

Direct analysis in real time mass spectrometry (DART-MS) analyzes intact object surfaces by exposing them to a stream of heated gas.

High-Throughput Extraction and Detection of Drugs in Urine: Parallel Sampling with Solid-Phase Microextraction (SPME) Fibers Coupled with Direct Analysis in Real Time-Mass Spectrometry (DART-MS) Detection.

Determination of drugs of abuse in urine is routinely accomplished by utilizing solid-phase extraction to isolate the drugs and gas chromatography/mass spectrometry (GC/MS) for their detection. Although robotic systems are employed, throughput is limited by the extraction process and GC chromatographic separation.A method that utilizes an array of 12 solid-phase microextraction (SPME) fibers for simultaneous isolation of drugs of abuse from urine is provided as a means to increase productivity. A SPME probe holder that permits movement of up to 12 fibers through the various steps of the extraction process in parallel is utilized. Use of an automated stage for fiber presentation into the ionization region of a Direct Analysis in Real Time equipped LC/MS facilitates rapid interrogation of each SPME.