Enzyme immunoassay and gas--liquid chromatography compared for determination of lidocaine in serum

Lidocaine, an anti-arrhythmic drug, was quantitated in serum by a commercially supplied enzyme immunoassay procedure. Replicate analyses of serum controls resulted in a within-assay coefficient of variation of less than 5.0 and a between-assay coefficient of variation of less than 6.5. Regression analysis of 87 serum samples analyzed by this technique (y) and by gas-liquid chromatography (x) gave the equation y = 0.96x - 0.03 (r = 0.99). Clinical evaluation of the results indicates the enzyme immunoassay technique to be highly specific and sensitive for lidocaine.