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: 120s loading, 60s elution, 30s 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 60s, 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 microg 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%.