DIRECT INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRIC DETERMINATION OFCADMIUM IN URINE WITH SPECIAL ATTENTION TO MATRIX EFFECT CORRECTION

In the direct ICP-MS determination of Cd in urine, nonspectral matrix effects caused by high concentrations of sodium chloride can play an i mportant role, In the present study, matrix effects were reduced by an optimum choice of the instrumental conditions and of the internal sta ndard element, in this ease Rh, Residual matrix effects were corrected with two procedures: the first was based on the signal of Cl-35 and t he second on the matrix effect experienced by the internal standard el ement. Average recovery with either procedure both of a Cd spike added to the samples and of the concentration found for a certified referen ce material was between 99 and 101% with a relative standard deviation of 2.3%. The correction factors in the correction equations were calc ulated from the recoveries of a limited number of recovery experiments . Sample preparation consisted of a 10-fold dilution of the sample wit h 1% HNO3. Cd-114 was found to be the best isotope with a detection li mit of 8 ng l(-1) in a nondiluted urine sample. The Rh matrix effect-b ased procedure can most probably also be used to correct for matrix ef fects in other sample types.