Flow injection determination of chloride ions with spectrophotometric detection

A single-line FIA system with a stream-sample splitting device for chloride determination is presented. The analytical method is based on the Fe3+/Hg(SCN)(2)/Cl- system and the absorbance of the red Fe(SCN)(2+) species monitored spectrophotometrically at 480 nm. Using a stream-sample splitting device, the recorded signal is composed of two merged peaks. Three calibration curves were obtained, once injecting the standard solution series, two using the maximum heights of P-1 and P-2 peaks and one using the height of T trough. The FIA system showed three linear responses to the concentration of chloride in the ranges 10-100 ppm (P-1); 10-500 ppm (P-2) and 20-1000 ppm (T), respectively. Also, it was capable of detecting chloride ions in different types of water with a throughput of 15 samples h(-1) and the RSD for 240 ppm of Cl- (n=10) were 1.67% (P-1); 2.38% (P-2) and 1.23% (T), respectively The interference of several ions (commonly found in water) on the FIA outputs was investigated.