Detection of the Synthetic Coolant Menthone 1,2-Glycerol Ketal in an e-Liquid and in Electronic Waterpipe Aerosols Therefrom.

The presence and toxicological risks of synthetic coolants in electronic nicotine delivery systems (ENDS) have not been thoroughly studied. We identified the synthetic coolant menthone 1,2-glycerol ketal (MGK) in a menthol-flavored e-liquid at a concentration of ∼170 µg/mL. We also detected MGK in aerosols resulting from heating the e-liquid with an electronic waterpipe. MGK was initially detected in the e-liquid by two-dimensional gas chromatography-time-of-flight mass spectrometry. To avoid potential analytical artifacts that could result from heating samples in the injection port of the gas chromatograph, quantitation of MGK in the e-liquid was accomplished using a liquid chromatography-tandem mass spectrometry method. Following recent reports identifying other synthetic coolants in e-liquids, these results add knowledge about inhalation exposures from ENDS use and suggest the importance of future research to study the potential inhalation toxicity related to the use of MGK-containing e-liquids in ENDS devices. Furthermore, the results demonstrate the ability to quantify ketals in e-liquids using liquid chromatography methods.

A procedure to detect and identify specific chemicals of potential inhalation toxicity concern in aerosols.

OBJECTIVE: Understanding the potential inhalation toxicity of poorly characterized aerosols is challenging both because aerosols may contain numerous chemicals and because it is difficult to predict which chemicals may present significant inhalation toxicity concerns at the observed levels. We have developed a novel systematic procedure to address these challenges through non-targeted chemical analysis by two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOFMS) and assessment of the results using publicly available toxicity data to prioritize the tentatively identified detected chemicals according to potential inhalation toxicity. MATERIALS AND METHODS: The procedure involves non-targeted chemical analysis of aerosol samples utilizing GC × GC-TOFMS, which is selected because it is an effective technique for detecting chemicals in complex samples and assigning tentative identities according to the mass spectra. For data evaluation, existing toxicity data (e.g. from the U.S. Environmental Protection Agency CompTox Chemicals Dashboard) are used to calculate multiple toxicity metrics that can be compared among the tentatively identified chemicals. These metrics include hazard quotient, incremental lifetime cancer risk, and metrics analogous to hazard quotient that we designated as exposure-(toxicology endpoint) ratios. RESULTS AND DISCUSSION: We demonstrated the utility of our procedure by detecting, identifying, and prioritizing specific chemicals of potential inhalation toxicity concern in the mainstream smoke generated from the machine-smoking of marijuana blunts. CONCLUSION: By designing a systematic approach for detecting and identifying numerous chemicals in complex aerosol samples and prioritizing the chemicals in relation to different inhalation toxicology endpoints, we have developed an effective approach to elucidate the potential inhalation toxicity of aerosols.

Chemical characterization of marijuana blunt smoke by non-targeted chemical analysis.

Background: Marijuana blunts, which are tobacco cigar wrappers filled with marijuana, are commonly smoked in the US as a means of cannabis use. The use of marijuana blunts presents toxicity concerns because the smoke contains both marijuana-related and tobacco-related chemicals. Thus, it is important to understand the chemical composition of mainstream smoke (MSS) from marijuana blunts. This study demonstrates the ability to detect and identify chemical constituents exclusively associated with blunt MSS in contrast to tobacco cigar MSS (designated as 'new exposures') through non-targeted chemical analysis.Methods: Samples collected separately from blunt MSS and tobacco cigar MSS were analyzed using two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOFMS).Results and Discussion: Two new exposures, which likely represent only a subset of all new exposures, were identified by evaluating the data from thousands of detected signals and then confirming selected compound identities in analyses using authentic chemical standards. The two confirmed new exposures, mellein and 2-phenyl-2-oxazoline, are not cannabinoids and, to the best of our knowledge, have not been previously reported in association with cannabis, tobacco, or smoke of any kind. In addition, we detected and quantified three phenols (2-, 3-, and 4-ethylphenol) in blunt MSS. Given the toxicity of phenols, quantifying the levels of other phenols could be pursued in future research on blunt MSS.Conclusion: This study shows the power and utility of GC × GC-TOFMS as a methodology for non-targeted chemical analysis to identify new chemical exposures in blunt MSS and to provide data to guide further investigations of blunt MSS.

Use of Comprehensive Two-Dimensional Gas Chromatography with Time-of-Flight Mass Spectrometric Detection and Random Forest Pattern Recognition Techniques for Classifying Chemical Threat Agents and Detecting Chemical Attribution Signatures.

In this proof of concept study, chemical threat agent (CTA) samples were classified to their sources with accuracies of 87-100% by applying a random forest statistical pattern recognition technique to analytical data acquired by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detection (GC × GC-TOFMS). Three organophosphate pesticides, chlorpyrifos, dichlorvos, and dicrotophos, were used as the model CTAs, with data collected for 4-6 sources per CTA and 7-10 replicate analyses per source. The analytical data were also evaluated to determine tentatively identified chemical attribution signatures for the CTAs by comparing samples from different sources according to either the presence/absence of peaks or the relative responses of peaks. These results demonstrate that GC × GC-TOFMS analysis in combination with a random forest technique can be useful in sample classification and signature identification for pesticides. Furthermore, the results suggest that this combination of analytical chemistry and statistical approaches can be applied to forensic analysis of other chemicals for similar purposes.

Identification of New and Distinctive Exposures from Little Cigars.

Little cigar mainstream smoke is less well-characterized than cigarette mainstream smoke in terms of chemical composition. This study compared four popular little cigar products against four popular cigarette products to determine compounds that are either unique to or more abundant in little cigars. These compounds are categorized as new or distinctive exposures, respectively. Total particulate matter samples collected from machine-generated mainstream smoke were extracted with methylene chloride, and the extracts were analyzed using two-dimensional gas chromatography-time-of-flight mass spectrometry. The data were evaluated using novel data-processing algorithms that account for characteristics specific to the selected analytical technique and variability associated with replicate sample analyses. Among more than 25 000 components detected across the complete data set, ambrox was confirmed as a new exposure, and 3-methylbutanenitrile and 4-methylimidazole were confirmed as distinctive exposures. Concentrations of these compounds for the little cigar mainstream smoke were estimated at approximately 0.4, 0.7, and 12 µg/rod, respectively. In achieving these results, this study has demonstrated the capability of a powerful analytical approach to identify previously uncharacterized tobacco-related exposures from little cigars. The same approach could also be applied to other samples to characterize constituents associated with tobacco product classes or specific tobacco products of interest. Such analyses are critical in identifying tobacco-related exposures that may affect public health.

Fish tissue quality in near-coastal areas of the Gulf of Mexico receiving point source discharges.

The objective of this study was to determine inorganic and organic contaminant concentrations in edible tissue of fish collected from eight coastal areas receiving wastewater discharges and from two reference locations. Trace metal residues were statistically similar regardless of the collection site. Zinc (100% detection in all samples), total mercury (100%), total arsenic (92%), copper (92%), and selenium (88%) were the more commonly detected trace metals. Mercury concentrations exceeded the Florida health-based standard of 0.5 microg/g for limited fish consumption in 30% of the total samples and averaged 0.40 (+/- 1 S.D. = 0.22, range < or = 0.08 to 0.85) microg/g wet weight. The average total PAH concentrations were 1.79 (+/- 1.60) ng/g (reference areas) and 2.17 (+/- 3.29) ng/g (wastewater-impacted areas). Pyrene was detected most frequently (63% of the total samples) and averaged 0.74 (+/- 0.35) ng/g wet wt. The average total PCB concentrations were 4.8 (+/- 7.1) ng/g (reference areas) and 31.6 (+/- 31.3) ng/g (wastewater-impacted areas) Concentrations of dieldrin and cis-chlordane were approximately eight times greater, respectively, in fish collected from wastewater receiving waters, whereas total DDT and total pesticide concentrations were not elevated in the same areas. Concentrations of total PCBs and all chlorinated pesticides were below US health-based standards. The lack of a published reference data base for fish tissue quality in near-coastal areas of the Gulf of Mexico restricts an assessment of the environmental significance of results from this and similar studies investigating the fate of point source contaminants.