Re-analysis of suspected DWI blood samples for ethanol: A Texas case study.

The gradual loss of ethanol over time in stored blood specimens under a variety of conditions has been well documented. An analysis of over 160 blood specimens from suspected impaired drivers was recently accomplished with the knowledge that the samples had previously been analyzed. These two analyses were performed independently, using different methods and instrumentation and by different individuals. Although in most cases there were two tubes available in each case, the tube used for the initial analysis was also used for the second analysis. Reported results from both laboratories were obtained and evaluated retrospectively. Over an average interval of approximately 13 months (range 34-1002 days), the average change of ethanol concentrations was a loss of 0.006 g/dL, with a maximum loss of 0.023 g/dL, and a maximum increase of 0.004 g/dL. The median difference was a loss of 0.005 g/dL. The percentage of samples that reported second concentrations equal to or less than the original reported concentrations (to the thousandths decimal place) was 96.4%. No correlation was observed between the net loss and the initial BAC value, but the amount of time between analyses did impact the extent of the loss of ethanol as determined by the second analysis. Our results indicate a smaller loss of ethanol, and hence stronger correlation between analytical events, than what has been experienced in similar work. Based on our analysis and review of previously opened and analyzed blood specimens, a previously opened blood tube can yield a strong correlation to the original analysis and may therefore be appropriate if a second tube is not available or compromised in some way.

A rapid quantitative method of carisoprodol and meprobamate by liquid chromatography-tandem mass spectrometry.

The identification and quantitation of carisoprodol (Soma) and its chief metabolite meprobamate, which is also a clinically prescribed drug, remains a challenge for forensic toxicology laboratories. Carisoprodol and meprobamate are notable for their widespread use as muscle relaxants and their frequent identification in the blood of impaired drivers. Routine screening is possible in both an acidic/neutral pH screen and a traditional basic screen. An improvement in directed testing quantitations was desirable over the current options of an underivatized acidic/neutral extraction or a basic screen, neither of which used ideal internal standards. A new method was developed that utilized a simple protein precipitation, deuterated internal standards and a short 2-min isocratic liquid chromatography separation, followed by multiple reaction monitoring with tandem mass spectrometry. The linear quantitative range for carisoprodol was determined to be 1-35mg/L and for meprobamate was 0.5-50mg/L. The method was validated for specificity and selectivity, matrix effects, and accuracy and precision.

Mouse breathalyzer.

BACKGROUND: The development of a relatively simple, noninvasive method for estimating blood ethanol concentrations in mice will be useful in behavioral studies related to alcoholism. This study validated such a method. METHODS: The apparatus consists of a body chamber fitted with a head stock through which the mouse head protrudes. This was fitted against a water-jacketed head-space chamber surrounding the mouse's head. Rebreathed air maintained at 37 degrees C in the head-space chamber was removed using a peristaltic pump and loaded into a 1-ml injection loop. Ethanol in the sample was quantified using gas chromatography. To validate this method, ethanol levels in breath samples were compared against those in tail blood samples collected immediately after the breath samples. Breath samples were collected at 5, 10, 20, 40, 80, 120, and 160 minutes after ethanol (0.4, 0.8, 1.2, 1.6, 2.4, and 3.2 g/kg) was administered to male C57BL/6J mice. RESULTS: Breath and blood ethanol levels were well correlated (r(2) = 0.96) across time points on the descending ethanol-time curve at doses below 2.4 g/kg. Correlation for these doses on the ascending portion of the curve had greater variance, but was still well correlated (r(2) = 0.92). CONCLUSIONS: The mouse breathalyzer is an accurate, convenient, noninvasive and well-tolerated method for estimating blood ethanol concentrations in mice across a range of behaviorally relevant concentrations below 2.4 g/kg, especially on the descending limb of the ethanol-time curve. Although this procedure requires a gas chromatograph in the animal facility, the ability to estimate ethanol concentrations quickly and easily will be especially useful in behavioral studies where repeated blood sampling is not feasible.