Analysis of hydrazine in smokeless tobacco products by gas chromatography-mass spectrometry

Lignosulfonate-Assisted In Situ Deposition of Palladium Nanoparticles on Carbon Nanotubes for the Electrocatalytic Sensing of Hydrazine

This paper presents a novel modified electrode for an amperometric hydrazine sensor based on multi-walled carbon nanotubes (MWCNTs) modified with lignosulfonate (LS) and decorated with palladium nanoparticles (NPds). The MWCNT/LS/NPd hybrid was characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The electrochemical properties of the electrode material were evaluated using cyclic voltammetry and chronoamperometry. The results showed that GC/MWCNT/LS/NPd possesses potent electrocatalytic properties towards the electro-oxidation of hydrazine. The electrode demonstrated exceptional electrocatalytic activity coupled with a considerable sensitivity of 0.166 μA μM-1 cm-2. The response was linear from 3.0 to 100 µM L-1 and 100 to 10,000 µM L-1, and the LOD was quantified to 0.80 µM L-1. The efficacy of the modified electrode as an electrochemical sensor was corroborated in a study of hydrazine determination in water samples.

Point-of-Care and Dual-Response Detection of Hydrazine/Hypochlorite-Based on a Smart Hydrogel Sensor and Applications in Information Security and Bioimaging

A novel dual-response fluorescence probe (XBT-CN) was developed by using a fluorescence priming strategy for quantitative monitoring and visualization of hydrazine (N₂H₄) and hypochlorite (ClO^-). With the addition of N₂H₄/ClO^-, the cleavage reaction of C=C bond initiated by N₂H₄/ClO^- was transformed into corresponding hydrazone and aldehyde derivatives, inducing the probe XBT-CN appeared a fluorescence "off-on" response, which was verified by DFT calculation. HRMS spectra were also conducted to confirm the sensitive mechanism of XBT-CN to N₂H₄ and ClO^-. The probe XBT-CN had an obvious fluorescence response to N₂H₄ and ClO^-, which caused a significant color change in unprotected eyes. In addition, the detection limits of XBT-CN for N₂H₄ and ClO^- were 27 nM and 34 nM, respectively. Interference tests showed that other competitive analytes could hardly interfere with the detection of N₂H₄ and ClO^- in a complex environment. In order to realize the point-of-care detection of N₂H₄ and ClO^-, an XBT-CN@hydrogel test kit combined with a portable smartphone was developed. Furthermore, the portable test kit has been applied to the detection of N₂H₄ and ClO^- in a real-world environment and food samples, and a series of good results have been achieved. Attractively, we demonstrated that XBT-CN@hydrogel was successfully applied as an encryption ink in the field of information security. Finally, the probe can also be used to monitor and distinguish N₂H₄ and ClO^- in living cells, exhibiting excellent biocompatibility and low cytotoxicity.

Determination of hydrazine in air by liquid chromatography/tandem mass spectrometry combined with precolumn derivatization

In this study, we developed a determination method for hydrazine in the air. Hydrazine was derivatized with p-dimethyl amino benzaldehyde (DBA) to yield p-dimethylaminobenzalazine, which was subjected to liquid chromatography-electrospray tandem mass spectrometry (LC/MS/MS) analysis. The derivative exhibited good sensitivity in the LC/MS/MS analysis, and its instrument detection limit and instrument quantification limit were 0.003 and 0.008 ng/mL, respectively. The air sample was collected using an air sampler equipped with a peristaltic pump at 0.2 L/min for 8 h. We demonstrated that a silica cartridge impregnated with DBA and 1,2-bis(4-pyridyl) ethylene can collect hydrazine in the air stably. The mean recovery rates in outdoor and indoor locations were 97.6% and 92.4%, respectively. Further, the method detection and quantification limits were 0.1 and 0.4 ng/m³, respectively. The proposed method does not require any pretreatment and/or concentration step, enabling high-throughput analyses.

Role of Hydrazine-Related Chemicals in Cancer and Neurodegenerative Disease

Hydrazine-related chemicals (HRCs) with carcinogenic and neurotoxic potential are found in certain mushrooms and plants used for food and in products employed in various industries, including aerospace. Their propensity to induce DNA damage (mostly O⁶-, N⁷- and 8-oxo-guanine lesions) resulting in multiple downstream effects is linked with both cancer and neurological disease. For cycling cells, unrepaired DNA damage leads to mutation and uncontrolled mitosis. By contrast, postmitotic neurons attempt to re-enter the cell cycle but undergo apoptosis or nonapoptotic cell death. Biomarkers of exposure to HRCs can be used to explore whether these substances are risk factors for sporadic amyotrophic laterals sclerosis and other noninherited neurodegenerative diseases, which is the focus of this paper.

Diethyl Malonate-Based Turn-On Chemical Probe for Detecting Hydrazine and Its Bio-Imaging and Environmental Applications With Large Stokes Shift

Diethyl malonate-based fluorescent probe NE-N₂H₄ was constructed for monitoring hydrazine (N₂H₄). The novel probe NE-N₂H₄ exhibits good properties, such as large Stokes shift (about 125 nm), good selectivity, and low cytotoxicity. This sensing probe NE-N₂H₄ can be operated to detect hydrazine in living HeLa cells. Especially after soaking in probe solution, the thin-layer chromatography (TLC) plate could detect the vapor of hydrazine. Therefore, the probe NE-N₂H₄ might be used to monitor hydrazine in biosamples and environmental problem.

Chemical Classification of Explosives

This work comprehensively reviews some fundamental concepts about explosives and their two commonly used classifications based on either their velocity of detonation or their application. These classifications are highly useful in the military/legal field, but completely useless for the chemical determination of explosives. Because of this reason, a classification of explosives based on their chemical composition is comprehensively revised, discussed and updated. This classification seeks to merge those dispersed chemical classifications of explosives found in literature into a unique general classification, which might be useful for every researcher dealing with the analytical chemical identification of explosives. In the knowledge of the chemical composition of explosives, the most adequate analytical techniques to determine them are finally discussed.

A Combined Study of Headspace Volatiles using Human Sensory, Mass Spectrometry and Chemometrics

Smokeless tobacco products (STPs) are widely used in certain parts of the world, yet there is limited understanding of how they are consumed, particularly the impact of chemosensory characteristics on their use. In order to develop an understanding of the drivers of STP use and product acceptability we conducted both human sensory panel testing and chemical analyses on a range of STPs. Free-sorting paired odour testing using sensory panellists identified similarities and clear differences between eleven different STPs. Headspace volatiles, analysed by headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS), identified 20 to 70 components depending upon the STP. Key differences in headspace volatiles were found between STPs. For example, the headspace of Skoal Bandits Wintergreen was dominated by methyl salicylate, while Marlboro Spice consists of a more complex profile including pinene, nicotine, eugenol and cymene. Chemometric Target Factor Analysis (TFA) and Hierarchical Cluster Analysis (HCA) of chemistry and sensory data was used to deduce chemical drivers of sensory perceptions. The chemometric strategy used showed that headspace analysis is a complementary screening tool to sensory analysis in classification studies. This study is generic with applications across various product sectors that require routine human sensory panel evaluation.

A Sensitive and Quantitative Isotope-Dilution LC-MS/MS Method for Analysis of Hydrazine in Tobacco Smoke

A new isotope dilution liquid chromatography/tandem mass spectrometric method was developed for the analysis of potential hydrazine present in tobacco smoke. The sample preparation was performed via an optimized derivatization method using an aqueous buffer:methanol solution of 2-nitrobenzaldehyde (10 g/L) used as a derivatizing agent. The mainstream smoke of cigarettes was passed through a glass fiber filter pad followed by a trapping solution containing an isotopically labeled 15N2-hydrazine used as internal standard. After smoking, the filter pad was extracted with the trapping solution and then incubated for 30 minutes at 35°C. An aliquot of the extract was centrifuged and the resultant hydrazone was quantified by liquid chromatography tandem mass spectrometry (LC-MS/MS). The isotope dilution standard calibration curve demonstrated good linearity (R2 > 0.999) from 0.079 to 248 ng/mL, with limits of quantification in mainstream smoke of 0.2 and 0.4 ng/cig for ISO and Canadian Intense smoking regimens, respectively. The method recovery was assessed using samples spiked with solutions of known amounts of hydrazine. The results showed good accuracy with recoveries ranging from 98 to 111%. Although there were no detectable levels of hydrazine in the reference cigarettes used in the validation (KR3R4F), the method precision was estimated to be ~10% based on the variability observed in the spiked samples. Trapping efficiencies were assessed using a hydrazine permeation tube providing a known amount of hydrazine vapor such that the distribution between the vapor phase and particulate phase of mainstream smoke could be determined.

A seminaphthorhodafluor-based near-infrared fluorescent probe for hydrazine and its bioimaging in living systems

Hydrazine (N₂H₄) has been classified as a potential carcinogen with its high toxicity, which can be readily absorbed through the skin or via breathing directly. Although some fluorescent probes have been developed for imaging of N₂H₄, very little can be used for imaging of N₂H₄ in vivo because of its short emission wavelength. In this study, a new colorimetric and near-infrared (NIR) fluorescent probe CF-1 based on a seminaphthorhodafluor dye was successfully designed and used for hydrazine determination. Upon reaction with N₂H₄, probe CF-1 showed obvious off-on NIR emission spectrum centered at 657 nm, as well as a distinct color change that can be distinguished by the naked eye. The results of fluorescence spectrum experiments indicated that probe CF-1 has high selectivity and low detection limitation (40.6 nM in the solution). Probe CF-1 has low cytotoxicity and was applied to imaging hydrazine in mitochondria of HeLa cells and in zebrafish.

SLTChemDB: A database of chemical compounds present in Smokeless tobacco products

Smokeless tobacco (SLT), a cause of potentially preventable diseases, has a diverse chemical composition encompassing toxicants as well as potent carcinogens. Though the chemical profile of SLT products has been analyzed earlier, this information is not available in a comprehensive and easily accessible format. Hence, there is an imperative felt need to develop a one-stop information source providing inclusive information on SLT products. SLTChemDB is the first such database that makes available detailed information on various properties of chemical compounds identified across different brands of SLT products. The primary information for the database was extracted through extensive literature search, which was further curated from popular chemical web servers and databases. At present, SLTChemDB contains comprehensive information on 233 unique chemical compounds and 82 SLT products. The database has been made user-friendly with facility for systematic search and filters. SLTChemDB would provide the initial data on chemical compounds in SLT products to various tobacco testing laboratories. The database also highlights research gaps and thus, would be a guide for researchers interested in chemistry and toxicology of SLT products. With regular update of information in the database, it shall be a valuable evidence base for policymakers to formulate stringent policies for SLT control.

The composition of contemporary American and Swedish smokeless tobacco products

The major components of 70 brands of smokeless tobacco products (STPs) from Sweden and the US were determined to provide greater understanding of the general chemical composition of these products. Various styles of STPs were examined: loose and portion snus from Sweden, and chewing tobacco, dry snuff, moist snuff, hard pellet, soft pellet and plug from the US. The components analysed were major STP components such as water, nicotine, sugars, humectants, sodium ions, chloride ions and ash. The relative quantities of the components varied significantly between different styles of STP. The major component of moist snuff and Swedish loose snus is water. With Swedish portion snus water and pouch material comprise more than half of the product mass; with chewing tobaccos water and sugars comprise around 60% of the products. With these STPs, tobacco was a minor component (30–35%) of the product mass. By way of contrast, tobacco comprised the majority (around 70–90%) of the product mass with dry snuff, hard pellet and soft pellet products. Additives such as sugars, propylene glycol, glycerol, and sodium chloride comprised up to around 12% of the STPs, except for plug and chewing tobaccos where sugars comprised 15–30% by mass of the STP on average. Significant disagreements were found amongst alternative methods of determining water/moisture content for STPs. In particular the oven method, commonly used to determine moisture in tobacco, gave significantly higher values than the Karl Fischer water method when propylene glycol was present. Smaller but similar differences were found using the Near-Infrared method. Choice of measurement technique has important consequences for accuracy of toxicant levels when reporting on a dry-weight basis, a commonly used parameter in smokeless tobacco research and emerging regulatory standards. Conversion to a DWB was also found to produce a preferential bias between and within different STP categories in favour of drier products. These data provide greater understanding of differences in the compositions of contemporary smokeless tobacco products, and demonstrate challenges associated with conversion of actual product contents to dry weight basis values.

Analysis of coumarin and angelica lactones in smokeless tobacco products

Differences in health risks between different styles of smokeless tobacco products (STPs) have prompted interest in their relative levels of toxic chemicals. We report here the development of methods for the analysis of STPs for coumarin and for α-angelica lactone (α-AL), both of which have been included in various published lists of tobacco toxicants. We have also determined the concentrations of these lactones in commercial STPs from the US and Sweden, representing 80–90% of the 2010 market share for all the major STP categories in these two countries: 65 products (plus two reference products) for coumarin and 66 commercial products for α-AL. For coumarin, methanol extracts of the STPs were analysed by HPLC/MS/MS. The lower limit of quantification (LOQ) and limit of detection (LOD) were, respectively, 100 and 30 ng coumarin/g of STP on a wet weight basis (WWB). Alpha-AL was determined via direct headspace GC/MS. The LOQ and LOD were 65 and 30 ng/g WWB respectively. Coumarin was detected In 3/33 Swedish snus, 5/13 US chewing tobaccos, 16/16 moist snuffs and 5/6 dry snuffs. Concentrations in those samples with quantifiable coumarin contents ranged from 186 to 1656 ng/g WWB. Concentrations of coumarin measured in this study were consistent with levels naturally found in tobacco. None of the STPs analysed would significantly contribute to coumarin exposure in consumers compared with dietary sources, and estimated exposure levels were 1000× lower than the European Food Safety Authority Tolerable Daily Intake. Hence the relevance of coumarin to the toxicity of STPs and its inclusion in the FDA’s list of harmful and potentially harmful compounds list is questionable. Measurements of α-AL in these STPs found that the majority did not have quantifiable contents, however, for three STPs concentrations of α-AL were above the LOQ (116–140 ng/g WWB) and for four other STPs concentrations of α-AL could be estimated between the LOD and LOQ. Beta-angelica lactone was tentatively identified in three of the STPs but the levels could not be reliably quantified. The levels of α-AL in tobacco products are reported here for the first time, but the relevance of α-AL to the toxicity of STPs is also highly questionable given that it has GRAS status as a permitted food additive.

Ethyl carbamate in Swedish and American smokeless tobacco products and some factors affecting its concentration

BACKGROUND

We are interested in comparing the levels of harmful or potentially harmful constituents in Swedish and American smokeless tobacco products (STPs). We report here the concentrations of the IARC Group 2 A (probable human) carcinogen ethyl carbamate (EC) in seventy commercial STPs from the US and Sweden, representing 80-90% of the market share of the major STP categories in these countries. We also examine the effects of various additives, processing and storage conditions on EC concentrations in experimental snus samples.

RESULTS

EC was determined from aqueous extracts of the STPs using ultra performance liquid chromatography tandem mass spectrometry (UPLC/MS/MS). EC was undetectable (< 20 ng/g wet weight basis WWB) in 60% of the commercial STPs, including all the chewing tobacco (CT), dry snuff (DS), hard pellet (HP), soft pellet (SP), and plug products. Measurable levels of EC were found in 11/16 (69%) of the moist snuff (MS) samples (average 154 ng/g in those samples containing EC) and 19/32 (59%) of the Swedish snus samples (average 35 ng/g). For the experimental snus samples, EC was only observed in ethanol treated samples. EC concentrations increased significantly with ethanol concentrations (0-4%) and with storage time (up to 24 weeks) and temperature (8 °C vs 20 °C). EC concentrations were lower at lower pHs but were unaffected by adding nitrogenous precursors identified from food studies (citrulline and urea), increasing water content or by pasteurisation. Added EC was stable in the STP matrix, but evaporative losses were significant when samples were stored for several weeks in open containers at 8 °C.

CONCLUSIONS

EC was found in measurable amounts only in some moist STPs i.e. pasteurised Swedish snus and unpasteurised US MS; it is not a ubiquitous contaminant of STPs. The presence of ethanol contributed significantly to the presence of EC in experimental snus samples, more significantly at higher pH levels. Sample age also was a key determinant of EC content. In contrast, pasteurisation and fermentation do not appear to directly influence EC levels. Using published consumption rates and mouth level exposures, on average STP consumers are exposed to lower EC levels from STP use than from food consumption.

Comprehensive survey of radionuclides in contemporary smokeless tobacco products

There is considerable interest in the chemical composition of smokeless tobacco products (STPs), owing to health concerns associated with their use. Previous studies have documented levels of 210Po, 210Pb and uranium in STP samples. Here, the levels of 13 α-particle and 15 β-radiation emitting radionuclides have been measured in a broad and representative range of contemporary STPs commercially available in the United States and Sweden. For each radionuclide, the level of radioactivity and calculated mass per gram of STP are reported. The results indicate that, among 34 Swedish snus and 44 US STPs, a more complex radionuclide content exists than previously reported for these products. Of the 28 radionuclides examined, 13 were detected and quantified in one or more STPs. The most frequently identified radionuclides in these STPs were 40K, 14C, 210Po and 226Ra. Over half the STPs also contained 228Th, and an additional 8 radionuclides were identified in a small number of STPs. The presence of 14C, 3H and 230Th are reported in tobacco for the first time. The activity of β-emitters was much greater than those of α-emitters, and the β-emitter 40K was present in the STPs with both the greatest radioactivity and mass concentrations. Since the three radionuclides included in the FDA's HPHC list were either not detected (235U), identified in only three of 78 samples (238U), and/or had activity levels over fifty times lower than that of 40K (210Po, 238U), there may be a rationale for reconsidering the radionuclides currently included in the FDA HPHC list, particularly with respect to 40K. Using a model of the physical and biological compartments which must be considered to estimate the exposure of STP users to radionuclides, we conclude that exposure from α-emitters may be minimal to STP users, but 40K in particular may expose the oral cavities of STP users to β-radiation. Although a more comprehensive picture of the radioisotope content of STPs has emerged from this study, epidemiological evidence suggests that the levels of radionuclides measured in this study appear unlikely to present significant risks to STP users.

2-benzothiazoleacetonitrile based two-photon fluorescent probe for hydrazine and its bio-imaging and environmental applications

A novel turn-on two-photon fluorescent probe NS-N 2 H 4 was developed with the 2-benzothiazoleacetonitrile as a new recognition site for the detection of hydrazine (N2H4). The two-photon probe exhibited favorable properties including high selectivity, low cytotoxicity and almost 16-fold fluorescence enhancement in the presence of N2H4 in solution. The probe could be used to image hydrazine in the living cells. Notably, we also used the two-photon fluorescent probe to image hydrazine in the tissue imaging for the first time. Furthermore, by the way of probe-loaded TLC plate, we further monitored vapor of hydrazine. Therefore, the novel two-photon probe is expected to be employed to detect N2H4 in biosamples and environmental pollution and the new recognition site will be widely applied to construct fluorescent probes for the detection of N2H4.

The acrylamide content of smokeless tobacco products

BACKGROUND

There is considerable interest from a regulatory and public health perspective in harmful and potentially harmful constituents in tobacco products, including smokeless tobacco products (STPs). A wide range of commercial STPs from the US and Sweden, representing 80-90 % of the 2010 market share for all the major STP categories in these two countries, were analysed for the IARC Group 2A carcinogen acrylamide. These STPs comprised the following styles: Swedish loose and portion snus, US snus, chewing tobacco, moist snuff, dry snuff, soft pellet, hard pellet and plug.

RESULTS

Acrylamide was detected in all the products tested and quantified in all but one product. Concentrations ranged from 62 to 666 ng/g wet weight basis (WWB). The average levels of acrylamide (WWB) by type of STP were not significantly different (p > 0.05) except for US snus which had, on average, greater levels but with a very wide range of individual levels according to the manufacturer. Acrylamide levels in STPs were significantly and positively correlated with pH, but not with levels of either reducing sugars or ammonia nitrogen. Levels of acrylamide increased by sixfold or more (on a dry weight basis) during manufacture of a snus sample and then decreased during subsequent storage for up to 22 weeks. Acrylamide generation in tobacco generally appears to occur at lower temperatures, but longer time scales than found with food production.

CONCLUSIONS

Acrylamide is a common contaminant of STPs, formed through heat treatment of tobacco. Our data show that exposure to acrylamide from consumption of STPs is small compared with exposure from food consumption or cigarette smoking.