Quantitative Analysis of Trifluoroacetate in the Urine and Blood by Isotachophoresis

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Abstract
Trifluoroacetate (TFA), the major metabolite of halothane, was assayed by a newly developed isotachophoretic technique. This technique has several advantages over the presently used methods of analysis. It requires no special preparation of [human] urine or blood samples. The sample volume is small (5-100 .mu.l) and the analysis time is short (30-90 min/sample). The method provides an analysis that is both qualitative and quantitative over a wide range of concentrations (from 2 nmol in 200 .mu.l to 200 nmol in 5 .mu.l). In this study, the assay was performed using HCl (0.01 M) in 1% Triton X-100, titrated with .beta.-alanine to a pH value of 3.6-3.9 as the leading electrolyte and n-caproic acid (0.01 M) as the terminal electrolyte (50-100 .mu.A migration current). Using this technique, daily urinary TFA excretion of 7 patients was measured during halothane anesthesia and for 14 days postoperatively. The TFA values were highest on the 2nd postoperative day (317-1259 mg). The mean values of the urinary TFA excreted during the entire study (2501 .+-. 493 mg, mean .+-. SEM [standard error of the mean]) were much higher than those reported previously. The isotachophoretic technique provides a sensitive assay for future research into the biotransformation of halothane.
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