Dear Colleagues! How correct and appropriate is it to conduct forensic toxicological and food examination of volatile substances (ethanol, methanol, propanol, ethyl glycol, etc.) in blood and liquid materials on one GC-Headspace device?
Anna... Headspace GC is a practical technique for volatile components like halo-hydrocarbons that boils much below the water boiling water. It was originally designed for such halo compounds in drinking water as a result of the reaction of chlorine with water for disinfection as byproducts from reaction of Cl2 with the trace organic pollutants. To analyze for ethanol, methanol, etc.. you need to try placing a small amount of the sample in a capped bottle and shaking the bottle for enough time to ensure evaporation. You also need to run standards to be sure that your analyzed vapor contain these alcohols. We may have further discussion after your trial.. Regards
Same issue with the column. Headspace chromotography is a primary method for GC and GCMS anslysis of drugs and for alcohol. Different columns are used for the alcohol and the temperature profiles are different. If you are in a locale with an alcohol testing program, you can try to get a copy their protocol. AS LONG AS THE HEADSPACE DEVICE IS KEPT CHEMICALLY CLEAN, YOU SHOULD BE ABLE TO DO THE ANALYSES ON DIFFERENT TIMES AND WITH THE DIFFERENT COLUMNS. IF YHOU USE ALCOHOL BASED SOLVENTS FOR THE FOOD ANALYSES, YOU WOULD WANT TO RUN SEVERAL WASH SOLVENTS THROUGH THE HEADSPACE AND THEN CONFIRM WITH TWO OR THREE BLANK RUNS BEFORE RUNNING THE ALCHOHOL SAMPLES; LIKEWISE DO THE SAME AFTER REPLACING THE FOOD COLUMN. HEATED HEADSPACE SHOULD CLEAR OUT THE ALCOHOLS, BUT BETTER SAFE THAN SORRY.
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