APPLICATION OF WAVELET TRANSFORMS TO DETERMINE PEAK SHAPE-PARAMETERS FOR INTERFERENCE DETECTION IN GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY

A procedure to quantify the shape of the absorbance-time profile, obta ined during graphite furnace atomic absorption spectrometry, has been used to detect interference effects caused by the presence of a concom itant salt. The quantification of the absorption profile is achieved t hrough the use of the Lipschitz regularity, alpha(0), Obtained from th e wavelet transform of the absorbance-time profile. The temporal posit ion of certain features and their associated values of alpha(0) provid e a unique description of the shape of the absorbance-time profile. Ch anges to the position or values of alpha(0) between standard and sampl e atomizations may be indicative of uncorrected interference effects. A weak, but linear, dependence was found of the value of alpha(0) upon the analyte concentration for Cr and Cu. The ability of the Lipschitz regularity to detect interference effects was illustrated for Pb, Se and Cu. For Pb, the lowest concentration of NaCl added, 0.005% m/v, ch anged both the values of alpha(0) and the peak height absorbance. For Se, no change in the peak height and peak area absorbance signals was detected up to a NaCl concentration of 0.25% m/v. The values of the as sociated Lipschitz regularities were found to be invariant to NaCl con centration up to this value. For Cu, a concentration of 0.05% m/v NaCl reduced the peak height and peak area absorbance signals by approxima tely 25% and significantly altered the values of alpha(0). (C) 1998 El sevier Science B.V. All rights reserved.