Comprehensive Two-dimensional Gas Chromatography-quadrupole Mass Research Articles

Non-target screening and prioritization of organic contaminants in seawater desalination and their ecological risk assessment

The impact of desalination brine on the marine environment is a global concern. Regarding this, salinity is generally accepted as the major environmental factor in desalination concentrate. However, recent studies have shown that the influence of organic contaminants in brine cannot be ignored. Therefore, a non-targeted screening method based on comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC × GC-qMS) was developed for identifying organic contaminants in the desalination brine. A total of 404 compounds were tentatively identified from four seawater desalination plants (three reverse osmosis plants and one multiple effect distillation plant) in China. The identified compounds were prioritized based on their persistence, bioaccumulation, ecotoxicity, usage, and detection frequency. Twenty-one (21) compounds (seven phthalates, ten pesticides, four trihalomethanes) were then selected for further quantitative analysis and ecological risk assessment, including compounds from the priority list along with substances from the same chemical classes. Ecologically risky substances in brine include diisobutylphthalate and bis(2-Ethylhexyl) phthalate, atrazine and acetochlor, and bromoform. Most of the contaminants come from raw seawater, and no high risk contaminants introduced by the desalination process have been found except for disinfection by-products. In brine discharge management, people believed that all pollution in raw seawater was concentrated by desalination process. This study shows that not all pollutants are concentrated during the desalination process. In this study, the total concentration of pesticide in the brine increased by 58.42%. The concentration of ∑PAEs decreased by 13.65% in reverse osmosis desalination plants and increased by 10.96% in the multi-effect distillation plant. The concentration of trihalomethane increased significantly in the desalination concentrate. The change in the concentration of pollutants in the desalination concentrate was related to the pretreatment method and the chemical characteristics of the contaminants. The method and results given in this study hinted a new idea to identify and control the environmental impact factors of brine.

A GC×GC-MS method based on solid-state modulator for non-targeted metabolomics: Comparison with traditional GC-MS method

The formidable challenge posed by the presence of extremely high amounts of compounds and large differences in concentrations in plasma significantly complicates non-targeted metabolomics analyses. In this study, a comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC×GC-qMS) method with a solid-state modulator (SSM) for non-targeted metabolomics in beagle plasma was first established based on a GC-MS method, and the qualitative and quantitative performance of the two platforms were compared. Identification of detected compounds was accomplished utilizing NIST database match scores, retention indices (RIs) and standards. Semi-quantification involved the calculation of peak area ratios to internal standards. Metabolite identification sheets were generated for plasma samples on both analytical platforms, featuring 22 representative metabolites chosen for validating qualitative accuracy, and for conducting comparisons of linearity, accuracy, precision, and sensitivity. The outcomes revealed a threefold increase in the number of identifiable metabolites on the GC×GC-MS platform, with lower limits of quantitation (LLOQs) reduced to 0.5–0.05 times those achieved on the GC-MS platform. Accuracy in quantification for both GC×GC-MS and GC-MS fell within the range of 85–115%, and the vast majority of intra- and inter-day precisions were within the range of 20%. These findings underscore that relative to the conventional GC-MS method, the GC×GC-MS method developed in this study, combined with SSM, exhibits enhanced qualitative capabilities, heightened sensitivity, and comparable accuracy and precision, rendering it more suitable for non-targeted metabolomics analyses.

Addressing new chemicals of emerging concern (CECs) in an indoor office

Indoor pollutants change over time and place. Exposure to hazardous organics is associated with adverse health effects. This work sampled gaseous organics by Tenax TA tubes in two indoor rooms, i.e., an office set as samples, and the room of chassis dynamometer (RCD) set as backgrounds. Compounds are analyzed by a thermal desorption comprehensive two-dimensional gas chromatography-quadrupole mass spectrometer (TD-GC × GC-qMS). Four new chemicals of emerging concern (CECs) are screened in 469 organics quantified. We proposed a three-step pipeline for CECs screening utilizing GC × GC including 1) non-target scanning of organics with convincing molecular structures and quantification results, 2) statistical analysis between samples and backgrounds to extract useful information, and 3) pixel-based property estimation to evaluate the contamination potential of addressed chemicals. New CECs spotted in this work are all intermediate volatility organic compounds (IVOCs), containing mintketone, isolongifolene, β-funebrene, and (5α)-androstane. Mintketone and sesquiterpenes may be derived from the use of volatile chemical products (VCPs), while (5α)-androstane is probably human-emitted. The occurrence and contamination potential of the addressed new CECs are reported for the first time. Non-target scanning and the measurement of IVOCs are of vital importance to get a full glimpse of indoor organics.

Unraveling the difference in flavor characteristics of Huangjiu fermented with different rice varieties using dynamic sensory evaluation and comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry.

To investigate the specific differences in flavor characteristics of Huangjiu fermented with different rice varieties, dynamic sensory evaluation, comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC × GC-qMS) and multivariate statistical analysis were employed. Dynamic sensory evaluation methods including temporal dominance of sensations (TDS) and temporal check all that apply (TCATA) were applied to explore the differences and variations in sensory attributes. The sensory results showed that the intensity of astringency and post-bitterness in the Huangjiu fermented with glutinous rice was weaker while ester and alcoholic aroma were more prominent than the one fermented with japonica rice. The results of free amino acids and aroma compounds analysis indicated that the amino acids were mainly sweet and bitter amino acids, and some key aroma compounds were predominant in the Huangjiu fermented with glutinous rice, such as ethyl butyrate (OAV: 38-59), 3-methylthiopropionaldehyde (OAV: 47-96), ethyl caprylate (OAV: 30-38), while nonanal, phenyl acetaldehyde and vanillin contributed significantly to the Huangjiu fermented with japonica rice. The multivariate statistical analysis further confirmed that 17 compounds (VIP > 1 and p < 0.05) could be supposed to be the key compouns that cause significant flavor differences in Huangjiu samples fermented with different brewing rice. Moreover, partial least-squares analysis revealed that most compounds (ethyl butyrate, 3-penten-2-one, isoamyl acetate, and so on) correlated with ester and alcoholic aroma. The results could provide basic data and theoretical basis for the selection of raw materials in Huangjiu.

Non-target scanning of organics from cooking emissions using comprehensive two-dimensional gas chromatography-mass spectrometer (GC×GC-MS)

Cooking emission is a major source influencing human health and air quality. To elucidate the emission pattern of cooking fumes, gaseous and particulate organics were sampled by Tenax TA desorption tubes and quartz filters, respectively. Organics were analyzed by a comprehensive two-dimensional gas chromatography-quadrupole mass spectrometer (GC × GC-qMS) coupled with a thermal desorption system (TDS). A non-target analysis was conducted identifying 166 (gas-phase) and 349 (particle-phase) compounds emitted from cooking fumes. We propose a four-step identification procedure, containing comparison with standards, homologs identification by selected ion chromatograms (SICs), searching spectrums in the National Institute of Standard Technology (NIST) library, and recognitions of unresolved complex mixtures (UCMs). The identified organics are then quantified or semi-quantified by surrogates in the same chemical class with an uncertainty of 27%. Intermediate volatility organic compounds (IVOCs) are extensively detected accounting for 20.5% and 81.4% of the total mass concentration and emission rates (ERs) in gas- and particle-phase samples. Aldehydes (30.6%) and acids (82.7%) dominate the mass concentration of organics in the gas- and particle-phase, respectively. Our work provides a detailed identification procedure in the non-target analysis and emphasizes the importance of IVOC measurement in cooking emissions.

Unraveling the difference in aroma characteristics of Huangjiu from Shaoxing region fermented with different brewing water, using descriptive sensory analysis, comprehensive two-dimensional gas chromatography–quadrupole mass spectrometry and multivariate data analysis

To investigate the specific difference in aroma characteristics of Huangjiu (Chinese rice wine) in Shaoxing region fermented with different brewing water, descriptive sensory analysis, comprehensive two-dimensional gas chromatography–quadrupole mass spectrometry (GC × GC–qMS) and multivariate statistical analysis were employed. The descriptive sensory analysis proved that Huangjiu fermented with Jianhu water had higher overall aroma intensity, and was more prominent in ester, sweet and alcoholic aroma than those fermented with deionized water and Nenjiang water. The results of aroma components analysis by GC × GC–qMS showed that the Huangjiu fermented with Jianhu water had higher concentration of some key aroma compounds, such as ethyl butyrate (OAV: 29–196), isoamyl acetate (OAV: 11–18) and ethyl hexanoate (OAV: 38–47). The multivariate statistical analysis further confirmed that 14 compounds could be used as key markers to distinguish the Huangjiu samples fermented with different brewing water. The correlation network between the volatile compounds in Huangjiu and the inorganic components in water indicated that the ions played an important role in the formation of the difference in aroma characteristics among the samples.

Untargeted volatile metabolomics using comprehensive two-dimensional gas chromatography-mass spectrometry – A solution for orange juice authentication

Orange juice is one of the most consumed fruit juices worldwide and its adulteration has been a long-lasting concern. In this study, an untargeted volatile metabolomics using a comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC × GC-qMS) was developed to systematically authenticate orange juice. At least 405 citrus whole fruits were collected, belongs to 58 types of orange samples and 23 types of non-orange citrus. The fruit juices were prepared in the laboratory and analyzed using the comprehensive GC × GC-qMS instrument. After optimizing the instrumental settings, this novel method was able to identified ~250 volatiles in each juice sample, covering a variety types of hydrocarbons, esters, alcohols, aldehydes, ketones and others. Combining with unsupervised principal component analysis and supervised partial least squares-discriminant analysis , this novel analytical tool was able to authenticate orange juice from a broad perspectives with a high accuracy in the cross-validation model: 1) differentiating orange juice from non-orange citrus juice (99% accuracy), 2) recognizing orange harvesting years (100% accuracy) and geographical origins (96% accuracy), and 3) distinguishing original pure orange juice from the reconstituted juice (94% accuracy). Key volatile metabolites associated with different categories of samples were also identified after thorough investigation of the loading values of the classification models. These metabolites have high potential to be used as food-markers to design targeted analytical methods for orange juice authentication. This novel comprehensive GC × GC-qMS-based method is ideal for governmental laboratories and the food industry to routinely authenticate orange juice.

In-Depth Qualitative Analysis of Lime Essential Oils Using the Off-Line Combination of Normal Phase High Performance Liquid Chromatography and Comprehensive Two-Dimensional Gas Chromatography-Quadrupole Mass Spectrometry.

The present research is focused on the in-depth qualitative analysis of three types of lime essential oil (EO), viz., Key (A and B) and Persian, using the off-line combination of normal phase high performance liquid chromatography (NP-HPLC) and comprehensive two-dimensional gas chromatography–quadrupole mass spectrometry (GC × GC-QMS). The first analytical dimension (NP-HPLC) was exploited for the isolation of the hydrocarbon constituents from the oxygenated ones. Each fraction was then reduced in volume and analyzed using (cryogenic modulation) GC × GC-QMS. Peak assignment was carried out through the combined use of mass spectral database and linear retention index matching processes. The powerful four-dimensional technology enabled the separation and identification of a very high number (153) of lime essential oil volatile compounds.

Comprehensive two-dimensional gas chromatography-mass spectrometry using milder electron ionization conditions: A preliminary evaluation

The present research is based on the use of comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC × GC-QMS), using “milder” electron ionization (EI) conditions. The term milder refers to the use of lower energy EI conditions (e.g., 20 eV), instead of the most common electron energy of 70 eV. The effects of using lower source temperatures were also evaluated. Within such an analytical context, GC × GC-QMS was applied to the analysis of a variety of different molecular-mass compounds with various polarities (sterols, linear alkanes, fatty acid methyl esters, vitamin E, squalene, a linear alcohol, and a group of fifteen pesticides).In general, the results attained indicate that milder EI conditions, and lower source temperatures, generate mass spectra with a higher relative abundance of ions at higher mass-over-charge (m/z) values, comprising the molecular ion, and reduced fragmentation at lower m/z values. The extent to which such a phenomenon occurred was obviously related to the chemical structure of each analyte. Spectral repeatability was also assessed, and was found to be satisfactory. Finally, with regard to analyte signal-to-noise ratios these were generally comparable in applications involving different electron ionization energies.

Analysis of volatile organic compounds using cryogen-free thermal modulation based comprehensive two-dimensional gas chromatography coupled with quadrupole mass spectrometry

A single-channel comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GCxGC-qMS) system was developed using a recently introduced solid-state thermal modulator. By modulation on a special column, extremely light hydrocarbons down to C2 can be successfully modulated without use of any cryogens. Paired with a polar secondary dimension column, a hybrid primary dimension column was developed to provide complete two-dimensional separation of all target volatile organic compounds (VOCs) from C2 to C12. This single-channel GCxGC-qMS system is used to analyze VOC standards containing 57 PAMS and 64 TO-15 gas mixtures, as well as real-world samples. This study demonstrates that a low resource GCxGC-qMS system may serve as a feasible tool for routine VOCs monitoring.

Spatial variations in the occurrence of potentially genotoxic disinfection by-products in drinking water distribution systems in China

We investigated the occurrence of disinfection by-products (DBPs) with genotoxic potential in plant effluent and distribution water samples from four drinking water treatment plants in two Chinese cities using comprehensive two-dimensional gas chromatography–quadrupole mass spectrometry. We tested the samples for 37 DBPs with genotoxic potential, which we had previously identified and prioritized in water under controlled laboratory conditions. Thirty of these DBPs were found in the water samples at detection frequencies of between 10% and 100%, and at concentrations between 3.90 and 1.77 × 103 ng/L. Of the DBPs detected, the concentrations of 1,1,1-trichloropropan-2-one were highest, and ranged from 299 to 1.77 × 103 ng/L with an average of 796 ng/L. The concentrations of 6-chloro-2-N-propan-2-yl-1,3,5-triazine-2,4-diamine and 2,6-ditert-butylcyclohexa-2,5-diene-1,4-dione were also much higher, and ranged from 107 to 721 ng/L, and from 152 to 504 ng/L, respectively. Concentrations of 1,1,1-trichloropropan-2-one, 2-chloro-1-phenylethanone, 2,2-dichloro-1-phenylethanone and 6-chloro-2-N-propan-2-yl-1,3,5-triazine-2,4-diamine were highest at or near the treatment plants and decreased with increasing distance from the plants. Patterns in the concentrations of benzaldehyde, 2-phenylpropan-2-ol, and 1-methylnaphthalene differed between plants. The levels of DBPs such as 4-ethylbenzaldehyde, (E)-non-2-enal, and 1-phenylethanone were relatively constant within the distribution systems, even at the furthest sampling points (20 km < d < 30 km). A risk assessment showed that there was no risk to human health. It is, however, important to note that, because of limited availability of toxicity data, only five DBPs were evaluated in this study. The risks to health associated with exposure to the target potentially genotoxic DBPs should not be ignored because of their prolonged existence in drinking water.

Tracking changes in composition and amount of dissolved organic matter throughout drinking water treatment plants by comprehensive two-dimensional gas chromatography–quadrupole mass spectrometry

Dissolved organic matter (DOM) can affect the performance of water treatment processes and produce undesirable disinfection by-products during disinfection. Several studies have been undertaken on the structural characterization of DOM, but its fate during drinking water treatment processes is still not fully understood. In this work, the nontargeted screening method of comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC×GC-qMS) was used to reveal the detailed changes of different chemical classes of compounds in DOM during conventional and advanced drinking water treatment processes at three drinking water treatment plants in China. The results showed that when the dissolved organic carbon removal was low, shifts in the DOM composition could not be detected with the specific ultraviolet absorbance at 254nm, but the changes were clear in the three-dimensional fluorescence excitation-emission matrix or GC×GC-qMS analyses. Coagulation-sedimentation processes selectively removed 37–59% of the nitrogenous compounds, alcohols and aromatic hydrocarbons but increased the concentrations of halogen-containing compounds by 17–26% because of the contact time with chlorine in this step. Filtration was less efficient at removing DOM but preferentially removed 21–60% of the acids. However, other organic matter would be released from the filter (e.g., nitrogenous compounds, acids, and aromatic hydrocarbons). Biological activated carbon (BAC) treatment removed most of the compounds produced from ozonation, particularly ketones, alcohols, halogen-containing compounds and acids. However, it should be noted that certain highly polar or high molecular weight compounds not identified in this study might be released from the BAC bed. After the whole treatment processes, the concentrations of nitrogenous compounds, alcohols, alkenes, aromatic hydrocarbons and ketones were decreased more by the advanced treatment processes than by the conventional treatment processes. Alcohol and ketone removals were probably related to the reduction in protein-like materials. Alkane removal was probably related to the reduction in fulvic acid-like and humic acid-like materials.

Formation of known and unknown disinfection by-products from natural organic matter fractions during chlorination, chloramination, and ozonation

Natural organic matter (NOM) is the main precursor of disinfection by-products (DBPs) formed during drinking water treatment processes. Previous studies of the relationships between DBP formation and NOM fractionation have mainly been focused on currently regulated DBPs and a few certain emerging DBPs. In this work, the Suwannee River NOM solution was fractionated into groups with different hydrophobicities using DAX-8 resins, and volatile and semi-volatile DBPs formed during the chlorination, chloramination and ozonation of the NOM fractions were examined by a nontargeted screening of comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry procedure. The results showed that a total of 302 DBPs representing nine chemical classes were detected, of which 266 were possibly newly detected, based on library searching with NIST 08 library (using similarity and reverse values of at least 600 and 700, respectively) and linear retention indices. The characterization of DBP precursors suggests that hydrophobic (HPO) NOM contains the major fraction of precursor for the formation of nitrogenous DBPs (contributing about 60% of the total nitrogenous DBPs) during all three disinfection processes. Much larger amounts of heterocyclic DBPs were formed from the HPO fraction than from the hydrophilic fraction during chlorination. During chloramination and ozonation, 5–15 times more ketones were formed from the hydrophilic fraction than from the HPO fraction. During ozonation, more than twice the amounts of esters and alcohols were formed from the hydrophilic fraction than from the HPO fraction. Three-dimensional excitation-emission matrix spectra suggest that similar to the formation of regulated DBPs, humic acid-like substances are probably the precursors of halogen-containing DBPs. Relatively higher nitrogenous DBPs formation from the HPO fraction might be because of the existence of protein-like materials.

Discriminating Lacustrine and Marine Organic Matter Depositional Paleoenvironments of Brazilian Crude Oils Using Comprehensive Two-Dimensional Gas Chromatography–Quadrupole Mass Spectrometry and Supervised Classification Chemometric Approaches

The knowledge about the organic matter predominant depositional paleoenvironment in which crude oils gave rise is essential for the extensive understanding of their corresponding geochemical features. This task is laborious and conventionally performed through the extensive search for classical biomarkers contained in specific saturate, aromatic, resin, and asphaltene (SARA) fractions of the crude oils. In this work, the well-established analytical technique comprehensive two-dimensional gas chromatography–quadrupole mass spectrometry (GC × GC–QMS) was used to analyze the first two fractions (maltenes) of crude oils, performing the chromatographic data treatment with chemometrics to evaluate the lacustrine or marine predominant origin of the organic matter depositional paleoenvironment of the crude oils. In this approach, the extraction of the target information contained in the GC × GC–QMS data for discriminating between crude oils derived from lacustrine or marine organic matter environments was evaluat...

Detailed Profiling of the Volatile Oxygenated Fraction of Mandarin Essential Oils by Using the Off-Line Combination of High-Performance Liquid Chromatography and Comprehensive Two-Dimensional Gas Chromatography-Mass Spectrometry

The aim of the herein described research was the detailed qualitative analysis of the volatile oxygenated fractions of four genuine mandarin (Citrus deliciosa Ten.) essential oils (green, yellow, red, and Mexican), by using the off-line combination of high-performance liquid chromatography (HPLC) and comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC×GC-qMS). Detailed qualitative profiling was performed through a pre-separation (normal phase) HPLC process aimed at the isolation of the oxygenated compounds; the target fraction was then concentrated and subjected to cryogenically modulated GC×GC-qMS analysis. The oxygenated constituents contribute most to the essential oil aroma and are also used for the evaluation of quality and genuineness. In such a respect, a deeper analytical view on the qualitative composition of such constituents is certainly useful. In fact, many compounds are herein related to mandarin essential oils for the first time.

Identifying unknown by-products in drinking water using comprehensive two-dimensional gas chromatography–quadrupole mass spectrometry and in silico toxicity assessment

Improvements in extraction and detection technologies have increased our abilities to identify new disinfection by-products (DBPs) over the last 40 years. However, most previous studies combined DBP identification and measurement efforts with toxicology to address concerns on a few expected DBPs, making it difficult to better define the health risk from the individual DBPs. In this study, a nontargeted screening method involving comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC × GC-qMS) combined with OECD QSAR Toolbox Ver. 3.2 was developed for identifying and prioritizing of volatile and semi-volatile DBPs in drinking water. The method was successfully applied to analyze DBPs formed during chlorination, chloramination or ozonation of the raw water. Over 500 compounds were tentatively identified in each sample, showing the superior performance of this analytical technique. A total of 170 volatile and semi-volatile DBPs representing fourteen chemical classes were then identified, according to the criteria that the DBP was presented in the duplicate treated samples. The genotoxicity and carcinogenicity of the DBPs were evaluated using Toolbox, and 58 DBPs were found to be actual or potential genotoxicants. The accuracy of the compound identification was determined by comparing 47 identified compounds with commercially available standards. About 90% (41 of the 47) of the compounds that were automatically identified using the library were correct. The results show that GC×GC-qMS coupled with a quantitative structure–activity relationship model is a powerful and fast nontargeted screening technique for compounds. The method and results provide us a new idea for identification and prioritization of DBPs.

New Spectral Deconvolution Algorithms for the Analysis of Polycyclic Aromatic Hydrocarbons and Sulfur Heterocycles by Comprehensive Two-Dimensional Gas Chromatography-Quadrupole Mass Spectrometery

New mass spectral deconvolution algorithms have been developed for comprehensive two-dimensional gas chromatography/quadrupole mass spectrometry (GC × GC/qMS). This paper reports the first use of spectral deconvolution of full scan quadrupole GC × GC/MS data for the quantitative analysis of polycyclic aromatic hydrocarbons (PAH) and polycyclic aromatic sulfur heterocycles (PASH) in coal tar-contaminated soil. A method employing four ions per isomer and multiple fragmentation patterns per alkylated homologue (MFPPH) is used to quantify target compounds. These results are in good agreement with GC/MS concentrations, and an examination of method precision, accuracy, selectivity, and sensitivity is discussed. MFPPH and SIM/1-ion concentration differences are also examined.

The off-line combination of high performance liquid chromatography and comprehensive two-dimensional gas chromatography–mass spectrometry: A powerful approach for highly detailed essential oil analysis

The present contribution is focused on the off-line combination of high performance liquid chromatography (HPLC) and comprehensive two-dimensional gas chromatography–quadrupole mass spectrometry (GC×GC–quadMS), and its application to the detailed qualitative analysis of essential oils. Specifically, a silica column was exploited for the separation of the essential oil constituents in two groups, namely hydrocarbon and oxygenated compounds. After, each HPLC-fraction was reduced in volume, and then subjected to cryogenically modulated GC×GC–quadMS analysis. The volatiles were separated on a normal-phase GC×GC column set, and identified through database matching and linear retention index information. The concentrated HPLC fractions gave origin to unexpectably crowded chromatograms, due to two fundamental GC×GC characteristics, namely the enhanced separation power and sensitivity. The results attained were particularly stimulating with regards to the oxygenated compounds, namely those constituents which contribute most to the essential oil aroma, and are of more use for the evaluation of quality and genuineness. Two genuine Citrus essential oils, bergamot and sweet orange, were subjected to analysis, and compared to applications carried out with a GC–quadMS instrument.

Determination of Polycyclic Aromatic Hydrocarbons in Seafood

The aim of this project is to determine polycyclic aromatic hydrocarbons (PAHs) in several seafood matrices, i.e., fish, and mussel, by the use of comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GCXGC-MS). The procedure involves a simple extraction of PAHs, a filtration and concentration step followed by GCXGC-MS analysis. PAHs were determined in fish tissue samples by GCXGC-MS and by a standard high-pressure liquid chromatography fluorescence detector method. A Bland–Altman analysis of the two methods was performed. It indicated equivalence between the two methods. Analysis of mussel tissue (National Institute of Standards and Technology (NIST)-SRM 2974a) was performed. The results were in line with the official results of NIST.

An Arson Investigation by using Comprehensive Two-dimensional Gas Chromatography-Quadrupole Mass Spectrometry

The aim of this investigation is to develop a new tool for the investigation of hydrocarbon accelerants. The chemical analysis of fire debris in an arson investigation has gone through several developmental stages. The nature of the analysis has been divided into three essential components due to the complexity of the samples. The first has been the extraction of the accelerants from the debris. The second has been the development of instrumental techniques for the analysis of extracted samples. The interpretation of the results is the final stage. In our investigation, we have used comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GCXGC-qMS). GCXGC-qMS is well suited for the analysis of complex hydrocarbon accelerants. We applied the resolution and separation powers of the GCXGC with the high precision mass scanning capabilities of a quadrupole mass spectrometer to investigate these complex samples. Total and selective ion scans were performed on samples obtained from an arson investigation. By using this process, we were able to conclusively determine the presence of hydrocarbon accelerants in fire debris.