A RAPID METHOD FOR MEASUREMENT OF ETHYLENE-GLYCOL

It has been reported that ethylene glycol produces a positive interfer ence in the triglyceride assay on the DuPont aca discrete analyzer. Th e sensitivity of this method for ethylene glycol was exploited to deve lop a rapid and convenient method for detecting and quantitating ethyl ene glycol in serum by the use of a ''triglyceride gap.'' This method is based on the difference between two different enzymatic triglycerid e measurements; the DuPont aca triglyceride measurement, which uses li pase and glycerol dehydrogenase, and a Boehringer Mannheim method, whi ch uses lipase, glycerol kinase, glycerolphosphate oxidase, and peroxi dase. Serum pools were spiked with increasing concentrations of ethyle ne glycol to construct a standard curve (linear to 25 mmol/L). Patient specimens and control sera were analyzed using a one point calibratio n. Within-run and between-run coefficients of variation (CV) of 1.5, 2 .8, 5.8, and 3.2%; 3.4%; and 12.6% were obtained at ethylene glycol co ncentrations of 20.13, 8.37, and 2.18 mmol/L, respectively. The sensit ivity of this method is 1.0 mmol/L. Methanol, ethanol, n-propanol, iso propanel, and acetone at 100 mmol/L; 20 mmol/L 1,3-propanediol; and 10 mmol/L glycolic acid, oxalic acid, glyoxylic acid, and lactic acid di d not interfere in the quantitation of ethylene glycol. High levels (1 0 mmol/L) of beta-hydroxybutyrate and glycerol showed a slight positiv e interference on the quantitation of ethylene glycol, whereas 10 mmol /L glycoaldehyde caused a substantial overestimation of serum ethylene glycol. The presence of propylene glycol, at levels ranging from 5 to 50 mmol/L, resulted in an underestimation of serum ethylene glycol. R esults obtained by our method showed excellent correlation with a gas chromatographic method (n = 56; y = 1.05x - 0.2; r(2) = 0.984). These results suggest that this method can provide a rapid and convenient al ternative to measuring ethylene glycol concentrations by gas chromatog raphy.