Automated measurement of urinary proteins

We have investigated the automation of the trichloroacetic acid turbidometric method for the estimation of urinary proteins using a standard centrifugal analyser. Conditions of temperature, trichloroacetic acid concentration, sample and reagent volumes have been examined. The method requires 10 microliter of urine sample and results have been shown to be linear to 2.0 g per litre with undiluted specimens; higher levels of protein require dilution of the urine samples to obtain greater accuracy. The coefficient of variation at a level of 0.5 g per litre is 3.5% and at 1.0 g per litre is 1.3%; recoveries ranged from 98.9 to 108%. The estimation of urinary protein in 29 samples may be carried out in 5 min.