Fast Sensing of Hydrogen Cyanide (HCN) Vapors Using a Hand-Held Ion Mobility Spectrometer with Nonradioactive Ionization Source.

Sensitive real-time detection of vapors produced by toxic industrial chemicals (TICs) always represents a stringent priority. Hydrogen cyanide (HCN) is definitely a TIC, being widely used in various industries and as an insecticide; it is a reactive, very flammable, and highly toxic compound that affects the central nervous system, cardiovascular system, eyes, nose, throat, and also has systemic effects. Moreover, HCN is considered a blood chemical warfare agent. This study was focused toward quick detection and quantification of HCN in air using time-of-flight ion mobility spectrometry (ToF IMS). Results obtained clearly indicate that IMS can rapidly detect HCN at sub-ppmv levels in air. Ion mobility spectrometric response was obtained in the negative ion mode and presented one single distinct product ion, at reduced ion mobility K0 of 2.38 cm2 V-1 s-1. Our study demonstrated that by using a miniaturized commercial IMS system with nonradioactive ionization source model LCD-3.2E (Smiths Detection Ltd., London, UK), one can easily measure HCN at concentrations of 0.1 ppmv (0.11 mg m-3) in negative ion mode, which is far below the OSHA PEL-TWA value of 10 ppmv. Measurement range was from 0.1 to 10 ppmv and the estimated limit of detection LoD was ca. 20 ppbv (0.02 mg m-3).

Effects of nitrogen fertilization and drought on hydrocyanic acid accumulation and morpho-physiological parameters of sorghums.

BACKGROUND: Nitrogen fertilization can increase sorghum yield and quality and the hydrocyanic acid (HCN) accumulation in plants, increasing the risk of animal toxicity, particularly under drought conditions. In this study, plants of three sorghum genotypes (sweet sorghum, sudangrass and hybrid sorghum) were supplemented with nitrogen (0, 60, 90 and 120 kg N ha-1 ) under well-watered and drought-stressed conditions, aiming to investigate the responses of morpho-physiological parameters and HCN accumulation to drought and nitrogen fertilization. RESULTS: Drought caused a decline in growth and photosynthesis. Average HCN content increased by 27.85% in drought-stressed plants when compared with those in well-watered plants. Drought increased the proline and soluble protein content, the content of O2 - , H2 O2 and malondialdehyde (MDA), and the activities of antioxidant enzymes in leaves of all three genotypes. Maximum plant growth and higher plant nutrient content (nitrogen and phosphorus) were observed at 120 kg N ha-1 , followed by 90 and 60 kg N ha-1 . However, a sharp increase in HCN content and a decrease in antioxidant enzyme activities were observed when nitrogen rates increased from 90 to 120 kg N ha-1 , suggesting that 90 kg N ha-1 might be better for sorghums under drought conditions. CONCLUSION: These results suggest that optimum nitrogen application on sorghum under drought conditions could achieve a balance between plant defense and food safety, attributed to the reduced MDA, O2 - and H2 O2 accumulation, the improvement in photosynthesis parameters, the increase in soluble protein and proline content, and the increase in antioxidant enzyme activities. © 2020 Society of Chemical Industry.

An in vitro collagen perfusion wound biofilm model; with applications for antimicrobial studies and microbial metabolomics.

BACKGROUND: The majority of in vitro studies of medically relevant biofilms involve the development of biofilm on an inanimate solid surface. However, infection in vivo consists of biofilm growth on, or suspended within, the semi-solid matrix of the tissue, whereby current models do not effectively simulate the nature of the in vivo environment. This paper describes development of an in vitro method for culturing wound associated microorganisms in a system that combines a semi-solid collagen gel matrix with continuous flow of simulated wound fluid. This enables culture of wound associated reproducible steady state biofilms under conditions that more closely simulate the dynamic wound environment. To demonstrate the use of this model the antimicrobial kinetics of ceftazidime, against both mature and developing Pseudomonas aeruginosa biofilms, was assessed. In addition, we have shown the potential application of this model system for investigating microbial metabolomics by employing selected ion flow tube mass spectrometry (SIFT-MS) to monitor ammonia and hydrogen cyanide production by Pseudomonas aeruginosa biofilms in real-time. RESULTS: The collagen wound biofilm model facilitates growth of steady-state reproducible Pseudomonas aeruginosa biofilms under wound like conditions. A maximum biofilm density of 1010 cfu slide- 1 was achieved by 30 h of continuous culture and maintained throughout the remainder of the experiment. Treatment with ceftazidime at a clinically relevant dose resulted in a 1.2-1.6 log reduction in biofilm density at 72 h compared to untreated controls. Treatment resulted in loss of complex biofilm architecture and morphological changes to bacterial cells, visualised using confocal microscopy. When monitoring the biofilms using SIFT-MS, ammonia and hydrogen cyanide levels peaked at 12 h at 2273 ppb (±826.4) and 138 ppb (±49.1) respectively and were detectable throughout experimentation. CONCLUSIONS: The collagen wound biofilm model has been developed to facilitate growth of reproducible biofilms under wound-like conditions. We have successfully used this method to: (1) evaluate antimicrobial efficacy and kinetics, clearly demonstrating the development of antimicrobial tolerance in biofilm cultures; (2) characterise volatile metabolite production by P. aeruginosa biofilms, demonstrating the potential use of this method in metabolomics studies.

Isocyanates and hydrogen cyanide in fumes from heated proteins and protein-rich foods.

Toxic compounds in cooking fumes could cause respiratory problems. In the present study, the formation of isocyanic acid (ICA), methyl isocyanate (MIC), and hydrogen cyanide (HCN) was studied during the heating of proteins or frying of protein-rich foods. Heating was performed in an experimental setup using a tube oven set at 200-500°C and in a kitchen when foods with different protein content were fried at a temperature around 300°C. ICA, MIC, and HCN were all generated when protein or meat was heated. Individual amino acids were also heated, and there was a significant positive correlation between their respective nitrogen content and the formation of the measured compounds. Gas from heated protein or meat also caused carbamylation in albumin. ICA, MIC, and HCN were also present in fumes generated when meat, egg, and halloumi were fried in a kitchen pan. The levels of ICA were here twice that of the Swedish occupational exposure limit. If ICA, MIC, and HCN in fumes from heated protein-rich foods could contribute to the risk of airway dysfunction among those exposed is not clear, but it is important to avoid inhaling frying and grilling fumes and to equip kitchens with good exhaust ventilation.

User-oriented independent analysis of the toxic load model's ability to predict the effects of time-varying toxic inhalation exposures.

Toxic industrial chemicals and chemical warfare agents present an acute inhalation hazard to exposed populations. The hazardous materials consequence assessment modeling community requires toxicity models to estimate these hazards. One popular phenomenological toxicity model is the toxic load model. Although this model is only well-defined for constant-concentration exposures, several generalizations have been proposed for the case of time-varying exposures. None of them, however, were validated by experimental evidence at the time they were proposed. Accordingly, the Defense Threat Reduction Agency (DTRA) sponsored experiments to explore the effects of time-varying inhalation exposures of hydrogen cyanide (HCN) and carbon monoxide (CO) gas on rats. The experiments were designed and executed by the U.S. Army's Edgewood Chemical and Biological Center (ECBC) and the Naval Medical Research Unit Dayton (NAMRU-D) between 2012 and 2015. We conducted an independent analysis of the toxic load model's ability to predict the ECBC/NAMRU-D experimental data using an analytical methodology oriented toward hazard prediction model users. We found that although some of the proposed extensions of the toxic load model perform better than others, all of them have difficulty reproducing the experimental data. The toxic load model also has difficulty reproducing even the constant-concentration data for HCN exposures under 10 min.

Adsorption isotherms, degradation kinetics, and leaching behaviors of cyanogen and hydrogen cyanide in eight texturally different agricultural soils from China.

Cyanogen (C2N2) is a new and effective alternative soil fumigant to methyl bromide. The effects of soil properties on the fate of C2N2 and its degradation products, including hydrogen cyanide (HCN), are not fully understood. The objectives of this study were to determine the adsorption kinetics, adsorption isotherms, and degradation kinetics of C2N2 and HCN in texturally different soils and evaluate their leaching potentials using soil columns. Eight agricultural soils were collected throughout China: Luvisols (Hebei Province), Phaeozems (Heilongjiang Province), Gleysols (Sichuan Province), Anthrosols (Zhejiang Province), Ferralsols (Jiangxi Province), Lixisols (Hubei Province), Alisols (Shandong Province), and Plinthosols (Hainan Province). The adsorptions of C2N2 and HCN in C2N2-fumigated soils were positively correlated with organic matter and clay contents. For a C2N2 dose of 100 mg kg-1, the adsorptions of C2N2 and HCN were highest in Phaeozems and lowest in Gleysols according to their adsorption coefficients (15.744 and 3.119, respectively). No significant difference in the half-life of C2N2 and HCN was observed between sterilized and unsterilized soils, indicating that abiotic degradation was predominant in the degradation of C2N2 and HCN. After leaching, the residual C2N2, HCN, NH4+-N, and NO3--N concentrations in C2N2-fumigated Phaeozems were highest within 15 cm of the soil surface (30, 20, 19.68, and 10.41 mg kg-1 soil, respectively). The results indicate that C2N2 and HCN have short lifetimes and low leaching potentials in agricultural soils, even under heavy rainfall conditions. The findings demonstrate that C2N2 and HCN resulting from fumigation will not accumulate in the soil and are not likely to contaminate groundwater.

Exposures to air contaminants in compartment fire behavior training (CFBT) using particleboard fuel.

Firefighters are exposed to a variety of combustion products during operational fires but also during live-fire training. As part of an on-going project investigating firefighter operational and training environments, this study measured the atmospheric concentrations of volatile organic compounds and acid gases outside and inside the structural firefighting ensembles worn by instructors during compartment fire behavior training using particleboard as a fuel. Atmospheric concentrations of benzene, formaldehyde, and hydrogen cyanide within the firefighting environment were observed to exceed Australian workplace exposure standards; although, the use of self-contained breathing apparatus throughout the training meant that atmospheric concentrations measured were not representative of firefighter inhalation exposures. Concentrations of air contaminants inside the structural firefighting ensembles during compartment fire behavior training were substantially lower than outside the ensembles, and much lower than those documented as potentially causing acute toxic effects in humans by dermal absorption from vapor. Although this study is focused on the generation of air contaminants in compartment fires, dermal absorption in these types of training environments may still constitute a potential route of low-level exposure to some combustion products.

Understanding airborne contaminants produced by different fuel packages during training fires.

Fire training may expose firefighters and instructors to hazardous airborne chemicals that vary by the training fuel. We conducted area and personal air sampling during three instructional scenarios per day involving the burning of two types (designated as alpha and bravo) of oriented strand board (OSB), pallet and straw, or the use of simulated smoke, over a period of 5 days. Twenty-four firefighters and ten instructors participated. Firefighters participated in each scenario once (separated by about 48 hr) and instructors supervised three training exercise per scenarios (completed in 1 day). Personal air samples were analyzed for polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), and hydrogen cyanide during live-fire scenarios (excluding simulated smoke). Area air samples were analyzed for acid gases, aldehydes, isocyanates, and VOCs for all scenarios. For the live-fire scenarios, median personal air concentrations of benzene and PAHs exceeded applicable short-term exposure limits and were higher among firefighters than instructors. When comparing results by type of fuel, personal air concentrations of benzene and PAHs were higher for bravo OSB compared to other fuels. Median area air concentrations of aldehydes and isocyanates were also highest during the bravo OSB scenario, while pallet and straw produced the highest median concentrations of certain VOCs and acid gases. These results suggest usage of self-contained breathing apparatus (SCBA) by both instructors and firefighters is essential during training fires to reduce potential inhalation exposure. Efforts should be taken to clean skin and clothing as soon as possible after live-fire training to limit dermal absorption as well.

Airborne contaminants during controlled residential fires.

In this study, we characterize the area and personal air concentrations of combustion byproducts produced during controlled residential fires with furnishings common in 21st century single family structures. Area air measurements were collected from the structure during active fire and overhaul (post suppression) and on the fireground where personnel were operating without any respiratory protection. Personal air measurements were collected from firefighters assigned to fire attack, victim search, overhaul, outside ventilation, and command/pump operator positions. Two different fire attack tactics were conducted for the fires (6 interior and 6 transitional) and exposures were compared between the tactics. For each of the 12 fires, firefighters were paired up to conduct each job assignment, except for overhaul that was conducted by 4 firefighters. Sampled compounds included polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs, e.g., benzene), hydrogen cyanide (HCN), and particulate (area air sampling only). Median personal air concentrations for the attack and search firefighters were generally well above applicable short-term occupational exposure limits, with the exception of HCN measured from search firefighters. Area air concentrations of all measured compounds decreased after suppression. Personal air concentrations of total PAHs and benzene measured from some overhaul firefighters exceeded exposure limits. Median personal air concentrations of HCN (16,300 ppb) exceeded the exposure limit for outside vent firefighters, with maximum levels (72,900 ppb) higher than the immediately dangerous to life and health (IDLH) level. Median air concentrations on the fireground (including particle count) were above background levels and highest when collected downwind of the structure and when ground-level smoke was the heaviest. No statistically significant differences in personal air concentrations were found between the 2 attack tactics. The results underscore the importance of wearing self-contained breathing apparatus when conducting overhaul or outside ventilation activities. Firefighters should also try to establish command upwind of the structure fire, and if this cannot be done, respiratory protection should be considered.

A free cyanohydrin as arms and armour of Marasmius oreades.

Cyanogenic plants and fungi are widespread in nature. Although the origin of hydrocyanic acid in plants has been studied in detail, little is known about its origin in fungi. Here, we report the identification of the cyanohydrin of glyoxylic acid as the precursor of hydrocyanic acid in the fungus Marasmius oreades and several other cyanogenic fungi. Moreover, a feeding experiment revealed glycine as biosynthetic precursor of the cyanohydrin of glyoxylic acid. Thus, the cyanogenesis of M. oreades and other fungi is fundamentally different from cyanogenesis in plants.

Breath metabolite response to major upper gastrointestinal surgery.

BACKGROUND: Esophagectomy and gastrectomy are associated with profound metabolic changes and significant postoperative morbidity. The aim of this prospective clinical study was to determine whether breath analysis can offer novel insight into the surgical metabolic response and identify biomarkers of postoperative complications, including lung injury. METHODS: Breath samples were collected preoperatively and at 24, 48, 72, 96 and 168 h after esophagectomy (n = 25) and gastrectomy (n = 15). Targeted analysis of four prominent breath metabolites was performed by selected ion flow-tube mass spectrometry. Patients with nonsurgical lung injury (community-acquired pneumonia) were recruited as positive controls. RESULTS: Perioperative starvation and subsequent reintroduction of nutritional input were associated with significant changes in breath acetone levels. Breath acetone levels fell after esophagectomy (P = 0.008) and were significantly lower than in gastrectomy patients at postoperative time points 48 (P < 0.001) and 72 h (P < 0.001). In contrast, concentrations of isoprene increased significantly after esophagectomy (P = 0.014). Pneumonia was the most frequently observed postoperative complication (esophagectomy 36% and gastrectomy 7%). The concentration of hydrogen cyanide was significantly lower in the breath of patients who developed pneumonia, 72 h after surgery (P = 0.008). Exhaled hydrogen cyanide (P = 0.001) and isoprene (P = 0.014) were also reduced in patients with community-acquired pneumonia compared with healthy controls. CONCLUSIONS: Selected ion flow-tube mass spectrometry can be used as a totally noninvasive resource to monitor multiple aspects of metabolic alterations in the postoperative period. Exhaled concentrations of several prominent metabolites are significantly altered after major upper gastrointestinal surgery and in response to pneumonia.

Correlation of chemical compositions of cassava varieties to their resistance to Prostephanus truncatus Horn (Coleoptera: Bostrichidae).

The preference of cassava as a major host by Prostephanus truncatus Horn is a major constraint to ample production of cassava, Manihot esculenta Crantz and storage. This study analyzed the nutritional and secondary metabolite compositions in 15 cassava varieties, evaluated levels of damage and reproduction by P. truncatus, and assessed their resistance to attack. One hundred grams of dried cassava chips in 250-ml Kilner jars were infested with 10 adult larger grain borerof 0-10 days old and held for 3 months. The nutritional and secondary metabolites compositions of the dry cassava chips were determined using the method of Association of Analytical Chemists . Chip perforation rates in the cassava varieties ranged from 17.7 to 71.6%. The weight of cassava powder varied by about threefold. The final number of larger grain borer in the cassava varieties varied by about sixfold with 63 in 01/0040 and 379 in 01/1368. Hydrocyanic acid content content varied by over 10-fold and correlated negatively with number of larger grain borer. Flavonoid content varied by ∼10%. Tannins and saponin content of the cassava negatively correlated with number of adult P. truncatus. The cassava varieties 95/0166, 92/0326, 01/0040, 05/0024, and 34 91934 had selection index <0.8 and were classified as resistant to larger grain borer damage, while others with selection index >0.8 were classified as susceptible. The resistance to high damage in the resistant varieties was conferred by secondary metabolites such as tannins, saponins, alkaloids, and hydrocyanic acid content. The genetic variation in cassava varieties could be explored to breed resistant cassava varieties for use in larger grain borer-endemic areas.

Structural Fire Fighting Ensembles: Accumulation and Off-gassing of Combustion Products.

Firefighters may be exposed to toxic combustion products not only during fire fighting operations and training, but also afterwards as a result of contact with contaminated structural fire fighting ensembles. This study characterized the deposition of polycyclic aromatic hydrocarbons (PAHs) onto structural fire fighting ensembles and off-gassing of combustion products from ensembles after multiple exposures to hostile structural attack fire environments. A variety of PAHs were deposited onto the outer layer of structural fire fighting ensembles, with no variation in deposition flux between new ensembles and already contaminated ensembles. Contaminants released from ensembles after use included volatile organic compounds, carbonyl compounds, low molecular weight PAHs, and hydrogen cyanide. Air samples collected in a similar manner after laundering of ensembles according to manufacturer specifications indicated that laundering returns off-gassing concentrations of most of the investigated compounds to pre-exposure levels. These findings suggest that contamination of firefighter protective clothing increases with use, and that storage of unlaundered structural fire fighting ensembles in small, unventilated spaces immediately after use may create a source of future exposure to toxic combustion products for fire fighting personnel.

Emission factors for gases and particle-bound substances produced by firing lead-free small-caliber ammunition.

Lead-free ammunition is becoming increasingly popular because of the environmental and human health issues associated with the use of leaded ammunition. However, there is a lack of data on the emissions produced by firing such ammunition. We report emission factors for toxic gases and particle-bound compounds produced by firing lead-free ammunition in a test chamber. Carbon monoxide, ammonia, and hydrogen cyanide levels within the chamber were analysed by Fourier transform infrared spectroscopy, while total suspended particles and respirable particles were determined gravimetrically. The metal content of the particulate emissions was determined and the associated organic compounds were characterized in detail using a method based on thermal desorption coupled to gas chromatography and mass spectrometry. The particulate matter (∼30 mg/round) consisted primarily of metals such as Cu, Zn, and Fe along with soot arising from incomplete combustion. Nitrogen-containing heterocyclic aromatic compounds such as carbazole, quinolone, and phenazine were responsible for some of the 25 most significant chromatographic peaks, together with PAHs, diphenylamine, and phthalates. Emission factors were determined for PAHs and oxygenated PAHs; the latter were less abundant in the gun smoke particles than in domestic dust and diesel combustion smoke. This may be due to the oxygen-deficient conditions that occur when the gun is fired. By using an electrical low pressure impactor, it was demonstrated that more than 90% of the particles produced immediately after firing the weapon had diameters of less than 30 nm, and so most of the gun smoke particles belonged to the nanoparticle regime.

A pilot study to determine medical laser generated air contaminant emission rates for a simulated surgical procedure.

The U.S. Occupational Safety and Health Administration (OSHA) estimates that half a million health-care workers are exposed to laser surgical smoke each year. The purpose of this study was to establish a methodology to (1) estimate emission rates of laser-generated air contaminants (LGACs) using an emission chamber, and to (2) perform a screening study to differentiate the effects of three laser operational parameters. An emission chamber was designed, fabricated, and assessed for performance to estimate the emission rates of gases and particles associated with LGACs during a simulated surgical procedure. Two medical lasers (Holmium Yttrium Aluminum Garnet [Ho:YAG] and carbon dioxide [CO2]) were set to a range of plausible medical laser operational parameters in a simulated surgery to pyrolyze porcine skin generating plume in the emission chamber. Power, pulse repetition frequency (PRF), and beam diameter were evaluated to determine the effect of each operational parameter on emission rate using a fractional factorial design. The plume was sampled for particulate matter and seven gas phase combustion byproduct contaminants (benzene, ethylbenzene, toluene, formaldehyde, hydrogen cyanide, carbon dioxide, and carbon monoxide): the gas phase emission results are presented here. Most of the measured concentrations of gas phase contaminants were below their limit of detection (LOD), but detectable measurements enabled us to determine laser operation parameter influence on CO2 emissions. Confined to the experimental conditions of this screening study, results indicated that beam diameter was statistically significantly influential and power was marginally statistically significant to emission rates of CO2 when using the Ho:YAG laser but not with the carbon dioxide laser; PRF was not influential vis-a-vis emission rates of these gas phase contaminants.

Determination of the two-compartment model parameters of exhaled HCN by fast negative photoionization mass spectrometry.

Breath exhaled hydrogen cyanide (HCN) has been identified to be associated with several respiratory diseases. Accurately distinguishing the concentration and release rate of different HCN sources is of great value in clinical research. However, there are still significant challenges due to the high adsorption and low concentration characteristics of exhaled HCN. In this study, a two-compartment kinetic model method based on negative photoionization mass spectrometry was developed to simultaneously determine the kinetic parameters including concentrations and release rates in the airways and alveoli. The influences of the sampling line diameter, length, and temperature on the response time of the sampling system were studied and optimized, achieving a response time of 0.2 s. The negative influence of oral cavity-released HCN was reduced by employing a strategy based on anatomical lung volume calculation. The calibration for HCN in the dynamic range of 0.5-100 ppbv and limit of detection (LOD) at 0.3 ppbv were achieved. Subsequently, the experiments of smoking, short-term passive smoking, and intake of bitter almonds were performed to examine the influences of endogenous and exogenous factors on the dynamic parameters of the model method. The results indicate that compared with steady-state concentration measurements, the kinetic parameters obtained using this model method can accurately and significantly reflect the changes in different HCN sources, highlighting its potential for HCN-related disease research.

Evaluation of exposure to cyanogenic glycosides and potential hydrogen cyanide release in commercially available foods among the Korean population.

The release of hydrogen cyanide (HCN) after food ingestion can pose a serious health risk to consumers. This study aimed to simultaneously quantify four cyanogenic glycosides (lotaustralin, prunasin, taxiphyllin, and dhurrin) using liquid chromatography-tandem mass spectrometry. The analysis scope extended beyond agricultural products to various consumer foods to estimate dietary exposure to cyanogenic glycosides and assess its risk levels. The major exposure sources are cassava chips (lotaustralin), apples (seeds) (prunasin and dhurrin), and Prunus mume axis (taxiphyllin). In addition to quantifying specific cyanogenic glycosides, this study proposed the development of a preliminary risk assessment framework based on the dietary exposure assessment and the calculation of theoretical levels of HCN derived from cyanogenic glycoside concentrations. In the absence of established guidelines for the permissible intake of foods containing cyanogenic glycosides, this study provides initial guidance for assessing the risks associated with a range of commonly consumed foods.

Is hydrogen cyanide a marker of Burkholderia cepacia complex?

Biofilm cultures of Burkholderia cepacia complex (BCC) infection have been found to generate the nonvolatile cyanide ion. We investigated if gaseous hydrogen cyanide (HCN) was a marker of BCC infection. Selected ion flow tube mass spectrometry analysis showed HCN was not elevated in the headspace of planktonic or biofilm cultures or in the exhaled breath of adult cystic fibrosis patients with chronic BCC infection. HCN is therefore not an in vitro or in vivo marker of BCC.

A comprehensive evaluation of the toxicology of experimental, non-filtered cigarettes manufactured with different circumferences.

CONTEXT: Historical work indicates that cigarette circumference may affect the toxicological profile of experimental cigarettes. OBJECTIVE: Studies were conducted to examine the effect of different cigarette circumferences on (1) selected mainstream smoke constituents including concentrations of tobacco specific nitrosamines (TSNA) in smoke and (2) mutagenicity and cytotoxicity of cigarette smoke condensate. MATERIALS AND METHODS: Analytical chemistry, Salmonella mutagenicity and cytotoxicity assays were used to evaluate the composition and biological activity of mainstream smoke from experimental, non-filtered cigarettes manufactured with four different circumferences (17.0-27.1 mm). RESULTS: Most smoke constituents, including TSNA, decreased with decreasing cigarette circumference; however, amounts of hydrogen cyanide increased in a non-circumference dependent manner. Mutagenicity and cytotoxicity also decreased slightly with decreasing cigarette circumference. CONCLUSION: Cigarette circumference may have a minor role in the toxicological profile of experimental cigarettes, with a so-far-unidentified mechanism.

Drying and processing protocols affect the quantification of cyanogenic glucosides in forage sorghum.

BACKGROUND: Cyanogenic glucosides are common bioactive products that break down to release toxic hydrogen cyanide (HCN) when combined with specific ß-glucosidases. In forage sorghum, high concentrations of the cyanogenic glucoside dhurrin lead to reduced productivity and sometimes death of grazing animals, especially in times of drought, when the dhurrin content of stunted crops is often higher. The aim of this study was to develop harvesting protocols suitable for sampling in remote areas. RESULTS: Dhurrin concentration in air- and oven-dried leaves was the same as in fresh leaves, with no subsequent losses during storage. Dhurrin concentration was halved when leaves were freeze-dried, although activity of the endogenous dhurrinase was preserved. Direct measurement of dhurrin concentration in methanolic extracts using liquid chromatography/mass spectrometry (LC/MS) gave similar results to methods that captured evolved cyanide. A single freezing event was as effective as fine grinding in facilitating complete conversion of dhurrin to cyanide. CONCLUSION: Direct measurement of dhurrin using LC/MS is accurate but expensive and not appropriate for fieldwork. Air drying provides an accurate, low-cost method for preparing tissue for dhurrin analysis, so long as the specific ß-glucosidase is added. It is recommended that comparative studies like the one presented here be extended to other cyanogenic species.