Correction of the alkylnitrite method for the detection of ethanol in blood taking into account toxico-kinetic and anthropometric data

The correction coefficient for the systemic inaccuracy arising during determination of blood ethanol by alkylnitrite gas chromatography and concomitant calibration of aqueous solutions was estimated to equal 0.82; this finding was confirmed by the results of the toxico-kinetic assay for the measurement of total body water (TBW) from the kinetic curve characterizing the time dependence of ethanol concentration in the exhaled air, saliva, capillary and venous blood in combination with 4 anthropometric methods and (in several cases) direct physical detection of TBW. When detecting the blood ethanol level with a correction coefficient of 0.82, the mutual position of the kinetic curves for ethanol concentrations in the blood and the exhaled air (recalculated for the blood level with a coefficient of 2100) as well as in the blood and saliva agreed with that reported in the available literature; it significantly differed from the position of the curves obtained with a correction coefficient of 0.95. The causes accounting for the systematic inaccuracy and erroneous values of the correction coefficients in earlier studies are discussed.     

Estimation of ethanol concentrations in biological media. Comparison of alkylnitrite and direct vapor-phase methods

Ethanol assays in the blood, saliva and urine were made according to two methods: alkylnitrite gas-liquid chromatography and direct vapor-phase method without thermostating. N-propanol was used as an internal standard. For saliva and urine the methods produced similar results. For blood, the direct vapor-phase method detected significantly lower level of ethanol compared to alkylnitrite one (p = 0.001). 24-h storage of the samples in refrigerator does not deviate the results. Recommendations are provided for most effective usage of each method.     

Kinetics of ethanol in biological sections

Ethanol concentration in alveolocapillary blood (ACB), venous blood (VB), capillary blood (CB), saliva and urine was measured in healthy men and women aged 19-45 years 20, 40, 60, 90, 120, 180, 240 and 300 min after a single intake of 20% ethanol solution in soda water in a dose 0.8 g/kg body mass. Two types of kinetic curves were established. Calculations with Vidmark equation for different biomedia were made. Ethanol levels in all BM studied coincided in the resorption phase. In the elimination phase, ethanol concentration forms a sequence: ACB < saliva < VB < urine. Correlations and correlation coefficients of ethanol concentrations in different BM were estimated. The ethanol concentration correlation urine/ACB 1.71 +/- 0.15 and VB/ACB 1.45 +/- 0.07 is proposed for use in tests for alcohol intoxication.     

Correction of the alkylnitrite method for the measurement of ethanol in blood: direct experimental evidence

A coefficient (multiplier) for the correction of a systemic inaccuracy of ethanol detection in the blood by the alkylnitrite method arising from calibration against an aqueous solution has been improved. The experiment was carried out as a multilaboratory study (with the participation of six laboratories). The value of the coefficient was estimated at 0.82 +/- 0.014 (SD) instead of 0.95 computed earlier (CV = 1.7%). The main factor influencing the value of the coefficient turned out to be the time of preparation of the model ethanol-blood mixture for comparison with the aqueous solution. The coefficient of 0.82 was obtained using fresh blood samples that of 0.93 to 0.96 with blood samples previously stored during 3-10 days. The results of the study suggest different ethanol distribution patterns in vivo and in vitro in the aqueous phase of the blood stored for a few days.