Use of 1,3-diaminepropane-3-propyl grafted onto a silica gel as a sorbent for flow-injection spectrophotometric determination of copper (II) in digests of biological materials and natural waters

The 1,3-diaminepropane-3-propyl-anchored silica gel (DAPPS) was successfully employed as a sorbent in a spectrophotometric flow system for the preconcentration of Cu 2+ in digests of biological materials (maize powder, soybean, citrus leaves, corn stalks) as well as water samples (river, stream, streamlet, springwater and well). The system presented a minicolumn packed with DAPPS, where the sample solution was passed through it for a period of time, and subsequently, an eluent solution, stripped-out the retained analyte which was further determined with DDTC at 460 nm. The better preconcentration conditions utilized were: 120 s loading, 60 s elution, 30 s regeneration of the column, loading flow rate 6.5 ml min −1, buffer solution for the preconcentration and regeneration of the column-borate buffer pH 8.5, elution flow rate 2.3 ml min −1, time of elution 60 s, eluent composition, 0.4 mol l −1 HNO 3. Under these conditions, the preconcentration factor obtained was 36, and the detection limit achieved was 8.4 ng ml −1 in water samples and 0.84 μg g −1 in biological material. The maximum adsorption capacity of DAPPS to Cu 2+ was 0.49 mmol g −1 (31.1 mg g −1) obtained in a batch system. The recovery of copper in the water samples ranged from 96.9 to 102.4% and in the biological materials ranged from 97.0 to 102.6%.