TIME-BASED INJECTION APPROACH FOR MONOSEGMENTED CONTINUOUS-FLOW SYSTEMS AND RELATED TECHNIQUES

A time-based injection module for monosegmented continuous flow system s and related techniques, which uses three independently controlled so lenoid valves, is described. A timer circuit employing three I.C. 555s and three TIP-121 transistors was constructed to control the injectio n module valves. The injection device was tested with non-reacting che mical systems (for example with a spectrophotometric standard and calc ium flame emission) and with reacting conditions (for example the dete rmination of Cr(VI), using diphenylcarbazide as colour reagent, and ac id-base titration). The performance of this injection module demonstra tes its suitability for everyday use.