Factorial design for optimization of flow-injection preconcentration procedure for copper(II) determination in natural waters, using 2-aminomethylpyridine grafted silica gel as adsorbent and spectrophotometric detection

The 2-aminomethylpyridine anchored silica gel (AMPSG) was successfully used as a sorbent in a simple spectrophotometric flow system for Cu2+ preconcentration in natural water samples, using sodium diethyldithiocarbamate as chromogenic agent (460nm). The system was optimized using a full factorial design 2 5 to determine better analytical conditions to determine copper in the natural water samples such as those from river, tap, stream, spring, well, waste, synthetic brackish water and a water reference material (NIST-1640). The better conditions used were: 180s loading; 30s elation; 30s regeneration of the column; loading flow rate 6.6 mL min(-1); buffer solution for the preconcentration and regeneration of the column-acetate buffer pH 5.75; elation flow rate 1.6 mL min(-1); eluent composition 0.20 mol L-1 HNO3. Under these conditions, the preconcentration factor obtained was 77, and the detection limit achieved was 3.0 ng mL(-1). The recovery of spiked water samples ranged from 95.2 to 104.7%.