Use of the Du Pont "Automatic Clinical Analyzer" in Direct Determination of Lactic Acid in Plasma Stabilized with Sodium Fluoride

Abstract

Abstract We have studied the determination of lactic acid with the Du Pont ACA and the suitability of plasma as a sample. Blood collected in sodium fluoride/ potassium oxalate Vacutainers and separated in 15 min provided acceptably stable plasma. With a 40-µl sample of plasma, results are linearly related to concentration to 20 mmol/ liter. Standard deviations were 0.16-0.22 mmol/ liter for day-to-day precision. When lactate was added to 53 samples, an average of 99.11% was recovered analytically. Results for plasma lactate (y-axis) agreed with those on plasma filtrates by the Calbiochem "Rapid Lactate" method (n, 92; slope, 1.025; y intercept, -0.086 mmol/liter; standard error, 0.23 mmol/liter). Perchloric acid filtrates can also be analyzed, but fluoride-stabilized plasma is simpler to use.