Abstract: An automated injection and dilution system (details given) based on the flow injection principle provided the delivery of a uniform and highly reproducible dilute sample to the plasma. Through-put rates of 80 samples h-1 were routinely achieved, and errors due to variations in viscosity were negligible. The method was applied to the determination of 21 elements in lubricating oils, with use of organometallic standards for calibration. The short-term coefficient of variation was 1 to 2%, and multi-operator long-term coefficient of variation averaged 3.1%; drift during the long-term test was negligible. Recoveries averaged 102%.

Abstract: The system comprises, inter alia, a Zymark laboratory robot, a balance, a hotplate, an SC-110 automatic sample changer, a FIAtron model SHS-300 microprocessor-controlled flow injection solution-handling system (FIAtron Systems, Oconomowoc, WI), an ICP emission spectrometer controlled by a PDP-11/34 minicomputer, and an IBM/XT personal computer. The personal computer co-ordinates the activities of the microprocessor and the PDP-11/34 (used for data acquisition, background correction and calculation of results) corrects for spectral interference, displays the results on a printer and stores them on floppy disc, and, with the approval of the operator, transmits them to a laboratory information-management computer. The robot is programmed to perform the various sample-preparation steps (heating at ~70°C for 35 min, dilution with xylene, and weighing). The precision of the transient signal integration was at least an order of magnitude better than for conventional steady-state integration, and results by the two types of measurement were equivalent.