Application of sequential injection analysis as process analyzers

Abstract

The use of chemical analyzers in the process control strategy represents a significant shift in the thinking of many process control engineers. Increasing pressure on the chemical manufacturing industry to produce higher quality products, in an economically viable and environmentally acceptable manner, increases the requirement to maintain strict control of plant conditions throughout the production process. The sophisticated instrumentation of laboratory facilities is unlikely to be suitable for manufacturing environments and hence dedicated systems offering long-term dependability must be developed. The simplicity of the sequential injection (SI) manifold and its low need for maintenance makes it an ideal tool in process analysis. Having established the manifold design principles, sequential injection analysis (SIA) is evaluated as an approach to sample manipulation. Methods for use in pharmaceutical companies and hospitals (determination of calcium) and for environmental monitoring (determination of sulphate, phosphate and ammonia) are proposed. The usefulness and advantages of sequential injection analysis over conventional flow injection analysis (FIA) is demonstrated.