The use of holding coils to facilitate long incubation times in unsegmented flow analysis : Determination of serum prostatic acid phosphatase

Conventional unsegmented flow analysis is best suited to determinations involving rapid chemical reactions. Analyses requiring relatively long reaction times necessitate stopping the flow to allow sufficient reaction product to accumulate, which significantly decreases sampling frequency. An automated distribution valve is described which directs samples into one of four holding coils where they remain for a predetermined time. Because one parallel coil may be filled with a sample while the others hold other samples for reaction, thoroughput is increased fourfold compared with a comparable single tube system. This technique is applied to the determination of prostatic acid phosphatase in human blood sera. The method is compared with a manual procedure.