GB1392490A - Analytical process - Google Patents

Abstract

1392490 Rotary photometric analyzers UNION CARBIDE CORP 8 Dec 1972 [9 Dec 1971] 56891/72 Heading G1A In a multiple sample photometric analyzer of the type in which the rotation of a rotor causes reagents and samples originally placed in separate radially aligned chambers to be mixed and transferred to analysis chambers, measurements are made of the mixed reagent and sample before any substantial reaction has occurred to provide reference levels which are stored in a memory and subtracted from the corresponding measurements made after the reaction is completed. As shown, Fig. 3, light from a lamp 50 passes through the cuvettes of a rotor 35 the rotation of which produces output pulses from a photomultiplier 60, the amplitude of each pulse depending on the optical density of the respective sample. The output pulses are applied via a logarithmic amplifier 61 to a peak detector 62 which is reset between pulses. The rotor is loaded with samples and reagents and then spun so that they are mixed and transferred to the peripheral cuvettes. Before any reaction can occur the optical density of each mixed sample is measured, converted to digital form and stored in a memory unit 68 to provide a reference level. After a suitable length of time during which the reaction occurs a further set of measurements are taken and the corresponding values stored in a memory unit 72. The reference level of each sample is subtracted from the corresponding measurement after the reaction and the resulting value recorded by a printer 77. A specific example relates to the determination of glucose in blood serum, the composition of the reagent being given.