Drugs and Poisons in Humans - A Handbook of Practical Analysis (Part 14)

Introduction:Alcohol usually means ethanol/ethyl alcohol. It has a long history for the human being, and gives euphoric effects and sometimes improves the human relationship. In contrast, there are many cases of violence, injuries, homicides and traffic accidents with drinking; close relation can be observed between ethanol and crimes/accidents. When forensic autopsies are performed, ethanol concentrations in blood and urine are routinely measured. GC analysis of ethanol using the conventional packed columns is described in many of literature [1, 2]. In this chapter, a quantitative method is presented for GC analysis of ethanol in blood and urine using headspace extraction...
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Drugs and Poisons in Humans - A Handbook of Practical Analysis (Part 14) 1.5II.1.5 Ethanol by Kanako WatanabeIntroductionAlcohol usually means ethanol/ethyl alcohol. It has a long history for the human being, andgives euphoric effects and sometimes improves the human relationship. In contrast, there aremany cases of violence, injuries, homicides and traffic accidents with drinking; close relationcan be observed between ethanol and crimes/accidents. When forensic autopsies are per-formed, ethanol concentrations in blood and urine are routinely measured. GC analysis of ethanol using the conventional packed columns is described in many ofliterature [1, 2]. In this chapter, a quantitative method is presented for GC analysis of ethanol inblood and urine using headspace extraction and wide-bore capillary columns; an ultra-sensi-tive analysis of breath ethanol is also given.Determination of ethanol in blood and urineReagents and their preparation• 10 µL of ethanol is dissolved in 10 mL distilled water (0.1 %, v/v).• 10 µL of n-propanol a is dissolved in 10 mL of distilled water (0.1 %, v/v).• 10 µL of tert-butanol (internal standard, IS) b is dissolved in 10 mL of distilled water (0.1 %, v/v). All above chemicals can be of reagent grade.GC conditionsGC columns: a DB-1 fused silica wide-bore capillary column (30 m × 0.53 mm i. d., film thick-ness 5 µm, J&W Scientific, Folsom, CA, USA), and a Rtx-BAC2 fused silica wide-bore capillarycolumn (30 m × 0.53 mm i. d., film thickness 2.0 µm, Restek: Bellefonte, PA, USA). GC conditions [3]: an HP6890 Series gas chromatograph c (Agilent Technologies: PaloAlto, CA, USA) equipped with FID. Conditions for the DB-1 column are: Column (oven) temperature: 40 °C (isothermal); injection port and detector temperature:170 °C; carrier gas: helium; its flow rate: 20 mL/min. Conditions for the Rtx-BAC2 column are: Column (oven) temperature: 40 °C→ 5 °C/min→ 70 °C (5 min)→ 20 °C/min→ 280 °C; injec-tion port and detector temperature: 170 °C; carrier gas: helium; its flow rate: 5 mL/min.© Springer-Verlag Berlin Heidelberg 2005136 Ethanol Procedure i. 0.5 mL of a specimen (whole blood or urine) is placed in a 4 mL volume test tube d with a rubber cap, followed by the addition of 0.2 mL IS solution and 0.2 mL distilled water, and sealed with the rubber cap. ii. In another test tube (standard solution), 0.5 ml of 0.1 % ethanol, 0.2 mL of IS solution and 0.2 mL of 0.1 % n-propanol are placed, and sealed with the rubber cap. iii. Both test tubes are heated at 55 °C for 15 min on an aluminum block heater or in a water bath. During the above heating, a glass syringe to be used is also put on the heater to heat it simultaneously; the syringe is a 1 mL volume gas-tight grass syringe with a 23 G needle e. After heating, 0.1 mL of the headspace vapor is withdrawn into the syringe and injected to GC swiftly. Calculation: P(ethanol)s : peak area of ethanol in the specimen P(IS)s : peak area of IS in the specimen P(ethanol)ss : peak area of ethanol in the standard solution P(IS)ss : peak area of IS in the standard solution. Assessment and some comments on the method > Figure 5.1 shows gas chromatogram for a whole blood specimen containing 0.1 % ethanol. With the DB-1 column [3], peaks of ethanol and IS appeared at short retention times at 40 °C; the Rtx-BAC2 column [4] had been developed for analysis of ethanol, and gives good shapes of the peak and high sensitivity. The detection limits of the method are 20–50 μg/mL whole blood with the DB-1 wide-bore capillary column, and about 10 μg/mL whole blood with the Rtx-BAC2 wide-bore capillary column. For actual measurements of blood ethanol after drinking, the GC method is sufficiently sensitive with either of the capillary columns, because blood ethanol concentrations in blood after drinking is usually 0.3–0.4 mg/mL. The headspace method for GC analysis of ethanol gives clean background and almost no interfering peaks. The postmortem production of ethanol a due to putrefaction should be kept in mind in case of non-fresh specimens; in such cases the appearance of n-propanol is an indicator of the con- comitant postmortem production of ethanol. Even without drinking, so-called “endogenous ethanol” is present, which is probably due to food and enteric bacteria; its level was reported to be as low as 0.180 ± 0.117 μg/mL [5], and thus does not interfere with the ethanol determination after drinking. After fresh blood is sampled into a test tube and sealed ...