A robust multisyringe system for process flow analysis . Part I. On-line dilution and single point titration of protolytes

Abstract

A robust multichannel manifold involving a multisyringe piston pump used for performing process flow analysis is proposed. The simultaneous sequential determination of two analytes with a sampling frequency of 97 injections per hour is demonstrated. A robust and rapid continuous flow titration system, including a predilution step, was developed. A quantitative dilution, avoiding the need for diluting the standards too, is achieved in two steps by first splitting the concentrated sample stream and further dilution in a mixing chamber. A wide range of dilution grades (from 80 to 1150) can be easily implemented by software instructions, without the necessity of mechanical reconfiguration of the manifold. The resulting system gives medium or low dispersion peak signals with a sampling frequency of over 75 injections per hour for off-line diluted samples, and more than 33 injections per hour for concentrated samples. The proposed assemblage allows the automation of the single point flow injection titration procedure for the assay of acids and bases in concentrated process solutions. Recoveries of 97.5–103% were found with a maximum RSD value of 5%.