TRIAL MEASUREMENTS IN FLOW-ANALYSIS

Trial measurements allow analytical results to be obtained by matching the sample volume with the dynamic range of the detector. In flow ana lysis, implementation of this approach can be accomplished by carrying out sequential injections or using concentration gradients. Trial mea surements are performed using an increasing concentration sequence and the results are compared with a previously set threshold value. Once this value is surpassed, the remainder of the sample by-passes the det ector and goes to waste. The potential and limitations in unsegmented and monosegmented flow systems are discussed. Improved systems for the automated determination of manganese in rocks by atomic absorption sp ectrometry are proposed. The typical measurement precision of flow inj ection was maintained and no baseline drift was observed. Results were in agreement with those obtained by inductively coupled plasma atomic emission spectrometry.