QUANTITATIVE CAPILLARY ELECTROPHORESIS ION-SPRAY TANDEM MASS-SPECTROMETRY DETERMINATION OF EDTA IN HUMAN PLASMA AND URINE

A quantitative method has been developed for the determination of EDTA in human plasma and urine, The samples are prepared with automated an ion-exchange solid-phase extraction using 100 mu L of human plasma. Th e extracts are analyzed by capillary electrophoresis/mass spectrometry using selected reaction monitoring in the negative ion mode. Lace-vol ume injections (10% of the CE capillary volume) are used to improve th e concentration level of detection via field-amplified sample injectio n. The first reported validation of a CE/MS/MS technique was carried o ut for this method. Using a C-13 stable-label isotope for the internal standard, the lower level of detection and lower level of quantitatio n were determined to be 7.3 and 14.6 ng/mL EDTA in human plasma, respe ctively. The injection precision had a relative standard deviation (RS D) of 6.1%. The intra-assay precision was less than 15% RSD, The intra -assay accuracy was less than +/-12% bias from the nominal concentrati on, The interassay precision was less than 18% RSD and the interassay accuracy was less than +/-9% bias from the nominal concentration.