PROJECT ILSAP - AN INTER-LABORATORY STUDY ON ACCURACY AND PRECISION IN ISOTACHOPHORESIS

In a collaborative study by seventeen laboratories, six aqueous sample solutions also containing 0.9% (w/v) NaCl were analysed for lactate a nd creatinine using isotachophoresis. A split-level study was carried out with three levels of the order of 3, 10 and 30 mmol/l, two subleve ls and without blind duplicates. A calibration graph was constructed a t five concentrations, using citrate and Tris as internal standards, a dded on a mass basis. The concentrations in the sample were determined in singular. After elimination of a few outliers using the Grubbs tes t at a 1% confidence level, data were treated according to ISO 5725. F or low, medium and high concentration levels, the repeatability values r were 0.41, 0.40 and 1.67 mmol/l, respectively, for lactate and 0.63 , 0.53 and 1.43 mmol/l, respectively, for creatinine. The reproducibil ity values R were 0.59, 1.12 and 2.05 mmol/l, respectively, for lactat e and 1.33, 0.88 and 2.66 mmol/l, respectively, for creatinine.