An evaluation of the Gilford 3400 automatic enzyme analyser

An assessment of the Gilford Automatic Enzyme Analyser was conducted over a period of one year. The optics of the instrument were satisfactory with regard to accuracy of wavelength selection and linearity of absorbance response. Excellent precision was obtained for both absorbance readings and operation of the dispenser pump. Carry-over within the microflow-cell was low. The method of operation recommended by the manufacturers for enzyme determinations failed to take account of endogenous blank reactions which could lead to significant error. When revised methods utilising a pre-incubation stage and initiation with a single substrate were employed, the results correlated well with those obtained with standard automatic (LKB 8600) and manual (Pye Unicam SP 800) kinetic systems for aspartate and alanine aminotransferase, creatine phosphokinase and alpha-hydroxybutyrate dehydrogenase, and the precision at all activity levels was satisfactory. Acceptable precision could not be obtained over the clinical range for enzyme assays requiring a blank determination on each sample (5'-nucleotidase and adenosine deaminase) and those with very low normal serum activities (isocitrate dehydrogenase and glutamate dehydrogenase). These limitations appeared to be due to relative insensitivity of the transducer response and liability to optical disturbance. This apart, the instrument has many advantages over alternative equipment.