Pre-treatment of serum samples for immunonephelometric analysis by precipitation with polyethylene glycol

A pre-treatment schedule for plasma samples to be analysed with immunonephelometry has been worked out using polyethylene glycol 6000 for precipitating the lipoproteins. The pre-treatment conditions have been studied in detail. By decreasing the blanks in immunonephelometric analysis a greater sensitivity of the method was gained. This was shown by performing analyses of S-β2-micro-globulin to concentrations below 1 mg/l. Another advantage with such a pretreatment is that blank determinations can be omitted for S-transferrin analysis and probably other analyses since the blanks in different samples are reduced to almost the same level.