Sample handling and storage for the quantitative analysis of volatile compounds in blood: the determination of toluene by headspace gas chromatography

Serum levels of methyl methacrylate following inhalational exposure to polymethylmethacrylate bone cement

Teratogenic effects of polymethylmethacrylate cement at levels used during routine orthopaedic procedures have never been reported, however the hypothetical risk remains a major concern among female surgeons. Our aim was to determine if methyl methacrylate is detectible in the serum during routine cement exposure.

METHODS

Twenty healthy volunteers were exposed during the mixing of polymethylmethacrylate cement in a simulated operating room environment. Forty serum samples were obtained during the expected peak inhalational exposure and levels of methyl methacrylate were assessed utilizing headspace gas chromatography mass spectrometry.

RESULTS

Methyl methacrylate was not detected in any of the forty experimental specimens.

CONCLUSIONS

With a detection level of 0.5 ppm, methyl methacrylate is undetectable in the serum during routine mixing of polymethylmethacrylate cement.

A pilot study on the stability of toluene in blood from workers

Background

Biological monitoring is used to assess toluene exposure in medical examinations. The American Conference of Industrial Hygienists, Japanese Society for Occupational Health and Deutsche Forschungsgemeinschaft have proposed various biological exposure determinants, such as toluene in blood and urine, and o-cresol in urine. Toluene in blood is a common biomarker among them. Toluene is a volatile organic solvent; therefore, sample preservation under appropriate conditions before measurement is necessary. However, little study has been done on the stability of toluene in workers’ blood samples under conditions simulating those of a medical examination.

Finding

We carried out a pilot study on the stability of toluene in blood from humans, according to different methods of sample preservation. Toluene in blood was analyzed by head space-gas chromatography/mass spectrometry. The sealing performance of the vial was examined by using toluene-added blood and the stability of toluene in blood according to the preservation period was examined by using blood from toluene-handling workers, which was collected with vacuum blood tubes. The sealing performance of the headspace vial used in this study was good for three days and toluene in blood in tubes from workers was stable at least within 8 hours up to blood packing at 4°C.

Conclusion

We could propose that the collected blood need only be transferred into headspace vials on the collection day and analyzed within a few days, if the samples are preserved at 4°C. Our data size is limited; however, it may be considered basic information for biological monitoring in medical examinations.

Toluene-impaired drivers: behavioral observations, impairment assessment, and toxicological findings

Toluene is an aromatic hydrocarbon solvent frequently abused for its euphoric and intoxicating properties. This report describes a series of six cases involving drivers arrested for driving under the influence who subsequently tested positive for toluene. Case data including driving behavior, physiological signs and symptoms, evidence of impairment, and toxicology findings were reviewed. Blood toluene concentrations in the drivers ranged from 12 to 45 mg/L (median 23 mg/L, mean 25 mg/L, SD 12.1 mg/L). All drivers were determined to be intoxicated, and displayed symptoms including balance problems, confusion and disorientation, loss of coordination, and inability to follow instructions. They also displayed horizontal but not vertical nystagmus, elevated pulse and blood pressure, and lower body temperature. These findings are consistent with prior reports that subjects with blood toluene concentrations above 10 mg/L are invariably under the influence and their driving skills are affected.

Stabilizing Drug Molecules in Biological Samples

Stability is one of the basic parameters, along with accuracy, precision, selectivity, and sensitivity, for bioanalytic method validation in nonhuman and clinical pharmacology/toxicology, bioavailability (BA), bioequivalence (BE), and other studies related to the drug approval process. In the drug development stage where stability evaluation is obligatory, instability of drug candidates in biologic samples will seriously complicate assay validation. In this article, we review the general strategies and methodologies such as temperature adjustment, pH control, derivatization, and addition of inhibitors and oxidant that are commonly employed to stabilize pharmaceuticals that might be unstable in biologic samples.

Quantification of propane in biological materials by head-space GC

Propane was measured in specimens taken from two persons who died from a LPG explosion in an apartment using head-space-GC/FID. Because of the variation of instrument performance and sample injection, the internal standard pentane was used. Calibration standards were prepared by injecting each calculated volume of pure propane gas into capped vials containing 2 ml of blood and 5 microl of internal standard. The calibration curve revealed good linearity from 0.09 microg/ml to at least 90 microg/ml. The method validation data also included repeatability and recovery. The propane quantities in blood, fat and brain tissue were between 0.27 and 71 microg/ml (microg/g) with the highest concentration observed in fat. The confirmation of propane was conducted by the means of solid phase micro-extraction and mass spectrometry.

Volatile substance abuse—post-mortem diagnosis

A substantial number of children and adolescents world-wide abuse volatile substances with the intention to experience an euphoric state of consciousness. Although the ratio of deaths to nonfatal inhalation escapades is low, it is an important and preventable cause of death in young people. In the analytical investigation of volatile substances proper sample collection, storage and handling are important in view of the volatile nature of the compounds. Volatile organic compounds in post-mortem matrices such as blood, urine and tissues are generally determined by gas chromatography after extracting the compounds with methods such as static and dynamic headspace or even with pulse-heating and solvent extraction. In post-mortem cases, metabolites in urine seem less relevant, however, trichloroethanol and trichloroacetic acid were determined in several cases. When interpreting qualitative and quantitative results, researchers should be aware of false conclusions. The main reason why scepticism is necessary is the occurrence of losses of analytes during sampling, sample handling and storage, which results in false quantitation.

Stability of toluene and reduction of acetone to 2-propanol in homogenates of the human liver, brain and lungs

The homogenates of the livers, lungs and brains collected from five different cadavers were placed in the desiccator filled with vapours of rubber glue solvents and the concentrations of toluene, acetone and 2-propanol were determined during the 28-day storage at +25, +4 and -20 degrees C. It was demonstrated that only freezing of the material stabilised the initial concentration of these three xenobiotics while cooling to +4 degrees C resulted in limited conversion of acetone to 2-propanol and additionally reduced the biodegradation of toluene in the brain homogenates. Moreover, it was showed that at +25 degrees C the loss of acetone was almost equimolarly balanced by the 2-propanol increase, which allowed to estimate the initial concentration of acetone with the mean error of about 10%.

Toluene itself as the best urinary marker of toluene exposure

Head-space gas chromatography (GC) and high-performance liquid chromatography (HPLC) (with fluorescence detectors) methods were developed for toluene (TOL-U) and o-cresol (CR-U) in urine, respectively. In order to identify the most sensitive urinary indicator of occupational exposure to toluene vapor (TOL-A) among TOL-U, CR-U, and hippuric acid in urine (HA-U), the two methods together with an HPLC (with untraviolet detectors) method for determination of HA-U were applied in the analysis of end-of-shift urine samples from 115 solvent-exposed workers (exposed to toluene at 4 ppm as geometric mean). Regression analysis showed that TOL-U correlated with TOL-A with a significantly higher correlation coefficient than did HA-U or CR-U. With regard to the TOL-A concentrations at which the exposed subjects could be separated from the nonexposed by the analyte, TOL-U achieved separation at < 10 ppm TOL-A, whereas both HA-U and CR-U did so only when TOL-A was 30 ppm or even higher. The ratio of the analyte concentrations at 50 ppm TOL-A to those at 0 ppm TOL-A was also highest for TOL-U. Overall, the results suggest that TOL-U is a better marker of exposure to toluene vapor than HA-U or CR-U.

A simple analysis of 5 thinner components in human body fluids by headspace solid-phase microextraction (SPME)

A simple method for the extraction of 5 thinner components from human whole blood and urine, using the headspace solid-phase microextraction (SPME) method is presented. After heating a vial containing the samples with 5 compounds (toluene, benzene, n-butyl acetate, n-butanol and n-isoamyl acetate) at 80 degrees C, a polydimethylsiloxane-coated SPME fiber was exposed to the headspace of the vial to allow adsorption of the compounds. The fiber needle was then injected into a capillary gas chromatography (GC) port. The headspace SPME-GC gave intense peaks for each compound and a low level of background noise was seen only for whole blood. Recovery rates of the 5 compounds by use of the headspace SPME-GC were 50-70%. Reproducibility for headspace SPME-GC data were excellent for both body fluids. The calibration curves showed linearity in the range 2-100 ng/0.5 ml whole blood or urine. The detection limits of each compound were 1.1-2.4 ng/0.5 ml sample. The present results on the analysis of 5 thinner components by headspace SPME-GC suggest its applicability to a number of other volatile compounds in forensic toxicology.

Urinary methylchloroform rather than urinary metabolites as an indicator of occupational exposure to methylchloroform

In order to compare methylchloroform (MC, or 1,1,1-trichloroethane) per se and its metabolites in urine as indicators of occupational exposure to this solvent, 50 male solvent workers were studied in the second half of a working week to evaluate the exposure-excretion relationship. The time-weighted average intensity of solvent exposure of individuals during an 8-h shift was monitored by personal diffusive sampling. Urine samples were collected near the end of the shift and were analyzed for MC and its metabolites [i.e., trichloroacetic acid (TCA), trichloroethanol (TCE) and total trichloro-compounds (TTC; the sum of TCA and TCE)] by head-space gas chromatography. MC per se, TCA, TCE, and TTC in urine correlated significantly (P < 0.01) with MC in ambient air, and among the four the correlation coefficient was highest for MC. The same result were obtained by multiple regression analysis in which ambient air MC was taken as the dependent variable and either the three indicators urinary MC, TCA, and TCE or the two indicators urinary MC and TTC were taken as independent variables. Taking the specificity and selectivity of the analyte as well as the simple and hazardous chemical-free procedure of analysis into consideration, it is concluded that MC is the analyte of choice as an indicator of occupational exposure to MC, when urine is selected as a specimen available by noninvasive sampling.

Toluene in blood as a marker of choice for low-level exposure to toluene

The validity of two new biological exposure markers of toluene in blood (TOL-B) and toluene in urine (TOL-U) was examined in comparison with that of the traditional marker of hippuric acid in urine (HA-U) in 294 male workers exposed to toluene in workroom air (TOL-A), mostly at low levels. The exposure was such that the geometric mean for toluene was 2.3 ppm with a maximum of 132 ppm; the workers were also exposed to other solvents such as hexane, ethyl acetate, styrene, and methanol, but at lower levels. The chance of cutaneous absorption was remote. Higher correlation with TOL-A and better sensitivity in separating the exposed workers from the nonexposed subjects were taken as selection criteria. When workers exposed to TOL-A at lower concentrations (< 50 ppm, < 10 ppm, < 2 ppm, etc.) were selected with correlation with TOL-A was examined, TOL-B showed the largest correlation coefficient which was significant even at TOL-A of < 1 ppm, whereas correlation of HA-U was no longer significant when TOL-A was < 10 ppm. TOL-U was between the two extremes. The sensitivities of TOL-B and TOL-U were comparable; HA-U showed the lowest sensitivity. Thus, it was concluded that TOL-B is the indicator of choice for detecting toluene exposure at low levels.

Reference values for blood toluene in the occupationally nonexposed general population

Blood toluene was measured by gas chromatography--mass spectrometry in 232 occupationally nonexposed subjects, consisting of 126 rural and 106 urban workers, and 37 chemical workers. Mean blood toluene was significantly lower in rural (698 ng/l) and urban workers (984 ng/l) than in chemical workers (2789 ng/l). Blood toluene was not significantly different between the rural and urban workers or among the urban workers with different jobs. Smokers had significantly higher levels (median 606 ng/l) than nonsmokers (median 424 ng/l). Subjects who had smoked at least one cigarette in the last 2 h before blood sampling had significantly higher blood toluene (median 1170 ng/l) than those who had not smoked during this time (median 693 ng/l), for whom the level was not significantly different from that in nonsmokers. Blood toluene in the total population was less than 2863 ng/l in 95% cases.

Glue sniffing deaths in Singapore--volatile aromatic hydrocarbons in post-mortem blood by headspace gas chromatography

Over a period from 1983 to 1991, of a total of 19,000 post-mortems, 33 were found to have at least one aromatic hydrocarbon (benzene, toluene or xylenes) in the blood. Of the 33 deceased, 22 had a history of toluene or petrol abuse while most of the remaining 11 were suspected to be glue sniffers through evidence found at the scene. This number, which represented 0.17 per cent of all the unnatural deaths, is considered small for a nation having a glue sniffing epidemic. The low death rate, as compared to 2.1 per cent through drug and chemical poisoning during the same period, is attributed to the timely intervention by the Government who outlawed glue sniffing and the effectiveness of compulsory rehabilitation. The male gender predominates (81.8 per cent) among the 33 deceased with a mean age of 20.1 years (range 15 to 33). The mean age for the female gender is 17.7 years (range 16 to 20). The blood toluene levels were found to be in the range 0.2 to 92 micrograms per ml blood. The causes of death are: 63.6 per cent due to falling or suicide by jumping; 18.2 per cent drowning; 6.1 per cent hanging; 6.1 per cent homicide; and 6.1 per cent acute toluene poisoning. The high proportion of traumatic deaths are discussed. Headspace gas chromatography with a suitable GC column was used for the analysis. Calibration blood standards were prepared in situ or in bulk stabilized by 10 per cent (v/v) methanol to overcome the hydrophobic and volatile nature of the aromatic hydrocarbons.(ABSTRACT TRUNCATED AT 250 WORDS)

Simultaneous determination of benzene and toluene in the blood using head-space gas chromatography

A head-space method for the simultaneous determination of benzene and toluene in blood using a gas chromatograph equipped with a photoionization detector was developed. Internal standards for benzene and toluene were fluorobenzene and o-xylene, respectively, and the detection limit was 5 nmol/l for both solvents. This method is sensitive enough for needs of biological monitoring of benzene and toluene in exposed workers. With automation it offers a possibility for routine measurements. An application of the method in monitoring exposed workers in the industry is presented.

Diagnosis and treatment of acute poisoning with volatile substances

1. The acute toxicity of many volatile compounds is similar, being more related to physical properties than to chemical structure. 2. Volatile substance abusers experiences euphoria and disinhibition but this may be followed by nausea and vomiting, dizziness, coughing and increased salivation; cardiac arrhythmias, convulsions, coma and death occur in severe cases. 3. Laboratory analysis of blood and urine samples collected up to 24 h post-exposure may be helpful if the diagnosis of volatile substance abuse is in doubt. 4. There is only a weak correlation between blood toluene and 1,1,1-trichloroethane concentrations and the clinical features of toxicity, possibly because of rapid initial tissue distribution and elimination. 5. Recovery normally occurs quickly once exposure has ceased but support for respiratory, renal or hepatic failure may be needed as well as treatment for cardiac arrhythmias. Therapy with intravenous acetylcysteine should be considered in cases of acute carbon tetrachloride poisoning.

An introduction to the practice, prevalence and chemical toxicology of volatile substance abuse

1. Volatile substance abuse is largely a teenage practice; it is estimated that in the UK 3.5-10% of young people have at least experimented and that 0.5-1% are current users. 2. The products abused are many and varied but only about 20 chemical compounds, notably toluene, chlorinated solvents such as 1,1,1-trichloroethane, fuel gases such as butane and aerosol propellants, are commonly encountered. 3. The acute hazard varies with the compound, product and mode of abuse. Mortality in the UK is now about 100 per year, from all social classes, 90% of whom are male. 4. Chronic toxicity is difficult to assess, partly because of the diversity of products abused. However it is clear that some long-term abusers suffer permanent damage to the central nervous system, heart, liver and kidney. 5. Toxicological analysis may be relied upon for confirmation of diagnosis, providing attention is paid to the kinetics of excretion and stability in the sample. 6. Responses include codes of practice for the sale of products and educational strategies; legislation has also been enacted. There is little evidence that any of these measures have made a significant impact on the problem.