Effect of sucrose on continuous-flow analyzers

In connection with the estimation of protein and of enzymes releasing p-nitrophenol or phenolphthalein, manifolds for continuous-flow analyses have been developed and tested. The “protein” manifold includes facilitities for the preliminary digestion of the sample with NaOH. The performance of the manifolds has been assessed by measurement of the half wash time for the rising and falling section of the peak. The results indicate that less than 5% cross-contamination will be encountered at a sampling rate of 40/hr and less than 2% at 30/hr. The effect of sucrose on the functioning of the manifolds was examined. Besides interfering in a way that is also encountered when the assays are done by discrete methods, the sucrose interfered with the functioning of the flow system. The half wash time on the descending part of the peak was increased by about 50% when 1.8 M sucrose was present in the sample. Such an increase corresponds to a more than twofold increase in the amount of cross-contamination between adjacent samples. The rising part of the peak, on the other hand, was somewhat sharpened.