Errors in estimating ethanol concentration in plasma by using the "osmolal gap".

Electroimmunoassay-Laurell “rockets” (1)-is a simple technique for determining the concentration of a specific protein in a protein mixture. The technique is ideally suited for both routine and research use. A major disadvantage is the need to place small volumes of sample solution, typically 3 pL, into a row of wells in an agarose plate. if the wells are incorrectly cut or imprecisely loaded, large errors can occur. To improve precision, we have modified the method to include the use of an internal standard in samples and standards. We put bovine albumin in the sample diluent, and both anti-bovine antiserum and the specific protein antiserum in the gel. When calculating the sample concentrations, we adjust the peak heights of samples and standards, using the bovine albumin internal standard peak heights, to account for variations in loading. We add 50mg of bovine albumin per liter of electrophoresis buffer (Tris-glycine-barbital, pH 8.8, ionic strength 0.08) for diluting samples and standards. The rocket plate is made by mixing rabbit antisera to the specific protein and to bovine albumin (Dakopatts als, Denmark) with 25 mL of a 10 g/L solution of agarose in electrophoresis buffer. After loading, the plate is electrophoresed, pressed, dried, and stained. The concentration of the samples is determined by a semi-automated method involving a Suxnmergraphics “Bit Pad One” digitizer interfaced to an Intertec “Superbrain” microcomputer. The top of the well and the rocket heights of the specific protein and bovine albumin are digitized consecutively. The peak heights of the specific protein (samples and standards) are then adjusted for any variation in loading by comparing the individual bovine albumin peak with the average of the bovine albumin peak heights. We then calculate the concentration of the specific protein samples, using the corrected sample peak heights.