Determination of urinary albumin using high-performance immunoaffinity chromatography and flow injection analysis

The detection of low levels of albumin in urine can be an important aid in the early diagnosis of kidney disease. In this study, an automated system for urine analysis was developed that could simultaneously measure both albumin and creatinine, an indicator of urine output and volume. Albumin was determined by use of a column that contained immobilized anti-albumin antibodies. An on-line flow injection analysis system was used to measure creatinine as this solute eluted nonretained from the antibody column. The total analysis time of the system was 5 min per injection. Limits of detection for albumin and creatinine in a 20 microL sample (at S/N = 2) were 3 and 5 mg/L, respectively. The response for these compounds covered the range of clinical interest. Within-run precision for both analytes was +/- 1-2% at normal urine concentrations. The results of this method showed good agreement with those obtained by reference techniques. This approach can be adapted for the detection of other urine components by changing the type of antibody column used in the system.