Quantification of albumin in urine by a new method: zone immuno-electrophoresis assay (ZIA)

Albumin in urine was determined by a new procedure called zone immunoelectrophoresis assay. A special apparatus was used with 20 vertical glass tubes (diameter 2 mm) which were filled up to 2 cm below their upper orifices with agarose gel containing antibodies against albumin. The samples were pipetted on top of each gel. Albumin was transported by electrophoresis into the agarose gels, in which zones of immunoprecipitates were formed. The amount of albumin in a sample was directly proportional to the distance from the gel surface to the front of the zone. The coefficient of variation was 8.8% within-day and 9.6% between days. The recovery of albumin added to urines was about 101%. The normal range for 40 adult persons was 2--23 mg/l with a mean and a median of 9.9 and 9.5 mg/l, respectively. The detection limit was well below the lowest value. The method was simple to use and the antiserum needed was only 0.5 microliter per test.