Computer‐controlled apparatus forautomated development of continuous flow methods

Abstract

An automated apparatus to assist in the development of analytical continuous flow methods is described. The system is capable of controlling and monitoring a variety of pumps, valves, and detectors through an IBM PC-AT compatible computer. System components consist of two types of peristaltic pumps (including a multiple pump unit), syringe pumps, electrically and pneumatically actuated valves, and an assortment of spectrophotometric and electrochemical detectors. Details of the interface circuitry are given where appropriate. To demonstrate the utility of the system, an automatically generated response surface is presented for the flow injection determination of iron(II) by its reaction with 1,10-phenanthroline.

Spectrophotometric determination of peroxydisulphate with o-dianisidine by flow injection

“…The automated flow injection analyzer used was the same as in previous methods development (16,17) and is discussed in detail elsewhere (13). The options used in this work included a custom-built variable speed peristaltic pump unit containing five independent pump heads, a high precision variable speed peristaltic pump (Models C-4V or C-6V, Alitea USA, Seattle, WA), and a six-port air-driven solenoid-actuated injection valve (Rheodyne 5020P, Cotati, CA) equipped with a 100 pL sample loop.…”

“…), via an IEEE-488 instrumentation interface. All the other units were controlled by the same microcomputer as described elsewhere (13). For the flow injection studies, a 30 pL, 1 cm path length quartz flow cell was used.…”

“…Simplex optimization was chosen as an optimization procedure because it rapidly optimizes chemical and flow conditions in flow injection systems (12). While this approach adequately locates the maximum, it gives little information about the global nature of the response surface (13). Some workers have advocated carrying out an additional set of experiments around the best conditions found by an experimental optimization to confirm that the true optimum has indeed been located and establish the effect of changes in experimental variables in this region (21).…”

“…The present work has been carried out on an automated flow injection methods development system, which has been reported elsewhere (13). Such computer-controlled units have much to offer analytical chemistry.…”

“…Simplex optimization (14)(15)(16) and automated response surface mapping (13,17) have been implemented on these systems. The former provides a rapid means to find the optimum conditions for analvsis.…”