Determination of trace concentrations of copper by FIA-FAAS after preconcentration on chelating sorbents

Abstract

A FIA-FAAS apparatus containing a six-channel sorption equipment with five 3 x 26 mm microcolumns packed with Spheron Oxin 1 000, Ostsorb Oxin and Ostsorb DTTA was set up. Combined with sorption from 0.002M acetate buffer at pH 4.2 and desorption with 2M-HCl, copper can be determined at concentrations up to 100, 150 and 200 μg l^-1, respectively. For sample and eluent flow rates of 5.0 and 4.0 ml min^-1, respectively, and a sample injection time of 5 min, the limit of copper determination is L_Q = 0.3 μg l^-1, repeatability s_r is better than 2% and recovery is R = 100 ± 2%. The enrichment factor is on the order of 10² and is a linear function of time (volume) of sample injection up to 5 min and of the sample injection flow rate up to 11 ml min^-1 for Spheron Oxin 1 000 and Ostsorb DTTA. For times of sorption of 60 and 300 s, the sampling frequency is 70 and 35 samples/h, respectively. The parameters of the FIA-FAAS determination (acetylene-air flame) are comparable to or better than those achieved by ETA AAS. The method was applied to the determination of traces of copper in high-purity water.