Measurement of fuel oxygenates in tap water using solid-phase microextraction gas chromatography-mass spectrometry.

The presence of alkyl ether fuel oxygenates in drinking water supplies has raised public health concerns because of possible adverse health effects from chronic exposure to these compounds. To enable large exposure studies exploring possible relationships between chronic exposure to alkyl ether fuel oxygenates and health effects, we developed an improved analytical method, using headspace solid-phase microextraction coupled with capillary gas chromatography and mass spectrometry. This method quantifies trace levels of methyl tertiary-butyl ether, ethyl tertiary-butyl ether, di-isopropyl ether, and tertiary-amyl methyl ether in tap water. The method achieves detection limits of less than 0.025 microg/L for all analytes and linear ranges of three orders of magnitude in the measurement of the alkyl ether fuel oxygenates in 5-mL tap water samples. The relative percentage of recoveries of the alkyl ether fuel oxygenates ranged from 97% to 105%. The relative standard deviation ranged from 2% to 6%. Methyl tertiary-butyl ether was detected in samples of tap water taken from geographically diverse regions of the United States. The improved throughput and sensitivity of this method will enable large epidemiologic field studies of the prevalence and magnitude of exposure to alkyl ether fuel oxygenates in the general population.

Quantification of 31 volatile organic compounds in whole blood using solid-phase microextraction and gas chromatography-mass spectrometry.

The prevalence of exposure to volatile organic compounds (VOCs) has raised concern about possible health effects resulting from chronic human exposure. To support studies exploring the relation between VOC exposure and health effects, we developed an automated analytical method using solid-phase microextraction (SPME), capillary gas chromatography (GC), and quadrupole mass spectrometry (MS). This method quantifies trace levels (low parts per trillion) of 14 halogenated alkanes, 5 halogenated alkenes, 10 aromatic compounds, and 2 other VOCs in human blood. Detection limits for the SPME-GC-MS method range from 0.005 to 0.12 microg/L, with linear calibration curves spanning three orders of magnitude. The improved throughput of this method will enable us to expand biomonitoring efforts to assess nonoccupational VOC exposure in large epidemiological studies.

Measurement of trihalomethanes and methyl tertiary-butyl ether in tap water using solid-phase microextraction GC-MS.

The prevalence of water disinfection byproducts in drinking water supplies has raised concerns about possible health effects from chronic exposure to these compounds. To support studies exploring the relation between exposure to trihalomethanes (THMs) and health effects, we have developed an automated analytical method using headspace solid-phase microextraction coupled with capillary gas chromatography and mass spectrometry. This method quantitates trace levels of THMs (chloroform, bromodichloromethane, dibromochloromethane, and bromoform) and methyl tertiary-butyl ether in tap water. Detection limits of less than 100 ng/L for all analytes and linear ranges of three orders of magnitude are adequate for measuring the THMs in tap water samples tested from across the United States. THMs are stable for extended periods in tap water samples after quenching of residual chlorine and buffering to pH 6.5, thus enabling larger epidemiologic field studies with simplified sample collection protocols.

The development and testing of a dermal exposure system for pharmacokinetic studies of administered and ambient water contaminants.

INTRODUCTION: In order to investigate the pharmacokinetics of water-borne chemicals while eliminating exposures by other routes, a dermal exposure system was developed to expose the hand and forearm of human subjects. METHODS: The goal was, primarily, to study the dermal pharmacokinetics of methyl tertiary butyl ether (MTBE), a water contaminant, and, secondarily, the ambient disinfection byproducts (DBPs). MTBE is used as a fuel oxygenate and DBPs result from chlorination of drinking water. The DBPs measured in the water and blood of the subjects were chloroform, bromodichloromethane, and dibromochloromethane. The dermal exposure system was constructed of inert and impervious materials. The interface between the glass and Teflon exposure tank and the subject was custom-made of clear Tedlar (polyvinylfluoride) so that the depth of the arm in the media could be monitored. RESULTS: Sampling of the water concentration of the test chemical, MTBE, demonstrated stability over the duration of the exposure. A temperature loss of about 1.5 degrees C occurred over the course of the 1-h exposure. Blood concentrations taken from 14 human subjects before, during, and after the 1-h exposure demonstrated that measurable MTBE and DBPs were absorbed. DISCUSSION: This system has the advantages of maintaining contaminant concentration and exposing an anatomically distinct body region, and the convenience of blood sampling.