Ethanol analysis in blood with Headspace sampler and GC

Abstract

In this paper, based on Panyu self-developed automatic headspace sampler HS-25, as well as Panna GC 1949 for the analysis of ethanol in the blood, using FID detector, linearity, detection limits, standard recovery rate are in line with the relevant requirements.The following is a detailed description of the establishment of standard curve, method verification and other contents.

Introduction

According to the Letter of Opinions on the Applicable Standards for the Determination of Blood Alcohol Content of Vehicle Drivers issued by the Judicial Appraisal Administration of the Ministry of Justice on May 3, 2018, the applicable standards for the determination of blood alcohol content of vehicle drivers have been uniformly stipulated. When the judicial appraisal institutions test the blood alcohol content of vehicle drivers, GA/T 1073 or GA/T 842 shall be adopted in accordance with the requirements of the national standard GB19522.

The Ministry of Public Security issued the standard for the public security industry, "Method for Testing Blood Alcohol Content" (GA/T 842-2019).It was promulgated on April 19, 2019 and implemented on May 1, 2019. The previous version is GA/T842-2009.This standard provides for Headspace - GC for the determination of blood alcohol content and is applicable to the qualitative and quantitative analysis of alcohol in the blood of persons engaged in road traffic enforcement activities.

In this paper, using Panyu headspace sampler HS-25 and Panna GC 1949(equipped with split/ splitless inlet and hydrogen flame ionization detector), according to "GA/T 842-2019 test method for blood alcohol content", the establishment of tert-butanol as an internal standard for the analysis of alcohol content in blood analysis method.

Principle of method

The sample is placed in a closed headspace bottle. Under a certain temperature and pressure, the volatile components of the sample in the headspace bottle volatiliize to the liquid space, resulting in vapor pressure, and the gas-liquid phase reaches thermodynamic dynamic equilibrium. Within a certain concentration range, the concentration of the substance to be measured in the gas phase is proportional to the concentration in the water phase.Quantitative extraction of the gas phase part with GC separation, hydrogen flame ionization detector detection, according to the retention time qualitative, standard curve internal standard method quantitative.

Instruments and reagents

GC: PANNA Model 1949 GC with FID detector

Channel 1 column: -innowax capillary column 30m x 0.32mm x 0.25µm

Column for Channel 2: PLOT Q Capillary column 30m x 0.32mm x 20µm

Headspace device: Automatic headspace sampler HS-25 (Changzhou Panyu Instrument Co., LTD.)

Standard product:

Ethanol (99.9%), tert-butanol (99.5%)

General laboratory commonly used equipment, reagents

Analysis steps

1. Analysis conditions:

Headspace: Heating balance temperature 65℃, valve/quantitative ring temperature 80℃, transmission line 110℃, heating balance time 10min, injection time 1min, Pressurization pressure 15psi, quantitative pressure 4psi,  Flow purge 50ml/min before injection, large flow purge 200ml/min after injection, purge time 1min, Sample plate oscillation grade 0.

GCy:

Channel 1: Column HP-innowax 30m*0.32mm*0.25μm;

Injector at 200℃, constant flow 2ml/min.The column box was kept at a constant temperature of 40℃ for 6min.Shunt sampling, shunt ratio 10:1, detector :250℃, hydrogen:30ml/min, air:300ml/min, make up gas:25ml/min.

Channel 2: Column HP-PLOT Q 30m*0.32mm*20μm

Injection port 200℃, constant current 4ml/min.The column box is kept at a constant temperature of 130℃ for 20min.Shunt sampling, split ratio 10:1, detector 250℃, hydrogen:30ml/min, air:300ml/min, make up gas:25ml/min.

2. Standard configuration and test results:

Ethanol standard working solution: Mix 99.9% anhydrous ethanol with water to form a 1000 mg/100 mL ethanol stock solution.

Tert-butanol internal standard working solution: Prepare 99.5% tert butanol standard with water to form a 4 mg/100 mL tert-butanol internal standard working solution

   Absorb 0.5ml, 2ml, 4ml, 8ml, 10ml and 20ml ethanol reserve solution into 100ml volumetric bottle to make a series of standard products. And the concentrations were 5mg/100ml, 20mg/100ml, 40mg/100ml, 80mg/100ml, 100mg/100ml and 200mg/100ml respectively to make calibration curves.In addition, 0.1ml of ethanol reserve liquid is absorbed and put into a 100ml volumetric bottle to make the standard concentration of 1mg/100ml.

Add 0.10mL of 6 series standard concentrations and 0.50mL of tert-butanol internal standard working solution into the sample bottle, cover with silicone rubber pad, seal the aluminum cap with sealing pliers, and mix well.The samples were determined in accordance with the foregoing analytical conditions.

The typical spectra of channel 1 obtained are as follows:

Figure 1  100mg/100mml spectrum of channel 1(Innowax column)

Calibration curve for channel 1

Figure 2  Calibration curve for channel 1（Innowax）

Repeatability spectrum of channel 1

Figure 3  Channel 1 (Innowax) 20mg/100ml repeatability spectrum

The typical spectra of channel 2 obtained are as follows:

Figure 4 100mg/100mml spectrum of Channel 2 (PLOT Q column)

Calibration curve for channel 2

Figure 5  Calibration curve for channel 2（PLOT Q）

Repeatability spectrum of channel 2

Figure 8  Channel 2 (PLOT Q) 20mg/100ml repeatability spectrum