One-step extraction and quantitation of toxic alcohols and ethylene glycol in plasma by capillary gas chromatography (GC) with flame ionization detection (FID)

• This method combines ethylene glycol and volatile alcohol analyses into one run.
• The method shows clean background, good sensitivity, and high reproducibility.
• The method employs low cost liquid injection and flame ionization detection.
• Rapid and simple extraction is easily adaptable to other clinical laboratories.
• The method is validated according to CLSI guidelines for clinical application.

ObjectivesClinical analysis of volatile alcohols (i.e. methanol, ethanol, isopropanol, and metabolite acetone) and ethylene glycol (EG) generally employs separate gas chromatography (GC) methods for analysis. Here, a method for combined analysis of volatile alcohols and EG is described.Design and MethodsVolatile alcohols and EG were extracted with 2:1 (v:v) acetonitrile containing internal standards (IS) 1,2 butanediol (for EG) and n-propanol (for alcohols). Samples were analyzed on an Agilent 6890 GC FID. The method was evaluated for precision, accuracy, reproducibility, linearity, selectivity and limit of quantitation (LOQ), followed by correlation to existing GC methods using patient samples, Bio-Rad QC, and in-house prepared QC material.ResultsInter-day precision was from 6.5–11.3% CV, and linearity was verified from down to 0.6 mmol/L up to 150 mmol/L for each analyte. The method showed good recovery (~ 100%) and the LOQ was calculated to be between 0.25 and 0.44 mmol/L. Patient correlation against current GC methods showed good agreement (slopes from 1.03–1.12, and y-intercepts from 0 to 0.85 mmol/L; R2 > 0.98; N = 35). Carryover was negligible for volatile alcohols in the measuring range, and of the potential interferences tested, only toluene and 1,3 propanediol interfered. The method was able to resolve 2,3 butanediol, diethylene glycol, and propylene glycol in addition to the peaks quantified.ConclusionsHere we describe a simple procedure for simultaneous analysis of EG and volatile alcohols that comes at low cost and with a simple liquid–liquid extraction requiring no derivitization to obtain adequate sensitivity for clinical specimens.

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