The UniCel DxC 660i Chemistry analyzer, by Beckman Coulter Chemistry analyzers measure substances within bodily fluids to establish a pattern of abnormalities. The wide range of tests can be grouped under several categories such as electrolytes, enzymes, blood sugar, metabolites, thyroids, hormones, lipids, therapeutic drug monitoring, and drugs of abuse monitoring. This analysis can be conducted on blood (either whole, serum or plasma), urine, semen or cerebrospinal fluids Chemistry analysis begins with patient sample placed in separate capsules, test tubes, slides or sample cups that are transported on a conveyor with sample racks or in a carousel in a reagent tray. Specimens are sampled and then mixed automatically together with diluents and reagents in a reaction cuvette. The reagents are pulled from a reagent carousel, which is typically refrigerated to keep the reagents shelf life longer. The reactive cuvette is stored and processed in the Reaction carousel. The Reaction carousel holds the mixing station (which mixes samples and reagents) and wash station (which rinses the cuvettes). Dependent on the manufacturer, the cuvette is either made of glass or plastic, but must be optically clear so that light may pass through without any intervention from scratches or blemish. Chemistry analysis is calculated through the absorbance of the specific wavelengths as light is passed through the specimen. All chemistry analyzers possess a photometer (either filter photometer or spectrophotometer) that conducts the measurement of the light absorbance of the specimen, and results are calculated. Filter photometers use glass filters, on a rotating filter wheel, coated with colored material while spectrophotometers use prisms or gratings, to isolate these wavelengths from the scanner beam. In both cases, a lamp (typically halogen) is the light source. Spectrophotometry is a more commonly used method than Filter photometry, which is currently only used in J&J, Roche Cobas and Siemens Dimension systems. Spectraphometry is used in most other systems including Abbott, Beckman and Roche Hitachi systems. The process to attain the results from the absorbance tests are classified either as End Point or Kinetic. End point method incubates the reaction mixture for a predetermined amount of time to reach the end point, or equilibrium of the reaction. Kinetic method, as the reagents and the sample are mixed, the reaction is monitored, the rate of change in absorbance is then determined and related to analyte concentration. As such, Kinetic is a faster method than End Point.