SIMULTANEOUS DETERMINATION OF ETHYLENE-GLYCOL AND ITS MAJOR TOXIC METABOLITE, GLYCOLIC ACID, IN SERUM BY GAS-CHROMATOGRAPHY

We developed a gas-chromatographic procedure for the simultaneous dete rmination of ethylene glycol (EG) and its major toxic metabolite, glyc olic acid (GA), suitable for clinical use in instances of EG intoxicat ion, After serum protein precipitation with acetonitrile (containing i nternal standard), the supernate is treated with 2,2-dimethoxypropane (containing dimethylformamide) to remove water, and the volume is then reduced by evaporation to <100 mu L of dimethylformamide (but not to dryness). After trimethylsilyl derivatization, the resulting derivativ es are analyzed by capillary column gas chromatography, Only 100 mu L of serum is required and the entire determination, including calibrato rs and controls, takes <2 h, The method gives a linear response to at least 10 g/L EG and 5 g/L GA and has a limit of detection <10 mg/L. In traassay CV is less than or equal to 2.8% for EG (100 and 1000 mg/L) a nd GA (100 and 500 mg/L); between-day CV is less than or equal to 6.5% . The absolute recovery from serum was 91% for EG and 77-82% for GA (2 00 and 2000 mg/L each), Relative to calibrators prepared bovine serum albumin (70 g/L), the recovery was 99-104% for EG (100-5000 mg/L) and 95-105% for GA (50-2500 mg/L). No clinically important interference wa s detected for >60 exogenous or endogenous compounds and drugs.