An assessment of the performance of the Chemispek J200 in a hospital laboratory

(1) The sampler is electronically variable for both wash and sample time. The 60-position sample plate is removable. (2) Each pump and gear-box serves a pair of analytical platforms. Each pump has four speeds. There is one operating speed (5 rev./min.), one fast and two slow speeds. (3) The reagent valves have three positions, reagent, wash and a clamped position to prevent reagents running back. Each analytical platform is controlled by its own set of reagent valves. (4) There is an analytical platform for each chemistry, except sodium and potassium. The platform contains a special block to facilitate the introduction ofair bubbles into the liquid phase in a uniform manner. Mixing coils, dialysers, heating bath and connecting tubing are all located on the platform. The waste from the flow cell drains away under the platform where it is piped into a central drain. (5) The twin-channel photometer incorporates a quartz iodine light-source and an interference filter for each channel. Each channel has its own circuitry to allow for normal or inverse chemistry, blank correction mode and curve regeneration. The photometer uses a special 5mm flow cell which has angled reflective glass surfaces at each end. This enables the photometer to use an energy gating system to measure the optical density of the liquid phase without the need to debubble. (6) A flame photometer with integral diluter (Corning 455) is connected to the microprocessor via a digital analogue converter. The sample is obtained using a split-stream connector connected to the sample line. (7) A Bryans Southern six-pen recorder is used to monitor the six channels (1/6 full-scale deflection or full-scale deflection). Each channel can be controlled independently for scale deflection. (8) A 16-channel microprocessor is used to monitor the signals from all photometers. Each chemistry is assigned its own microprocessor channel which standardizes, calculates and corrects for carry-over and drift. The results for each channel are then printed out