A basic need for a protein-based dosimeter is a purified protein. In this communication we present an isolation protocol and an HPLC-based assay which allows one to determine the purity of the isolated albumin. A total of 168 human blood samples were collected from workers of a benzene processing plant and from nearby countryside at Kohtla-Järve, Estonia. Albumin was isolated from plasma by sequential precipitation and the purity was determined by HPLC. The amount of albumin present in plasma varied between the individuals, being 147 +/- 26 mg/5 ml (n = 168), which is about 59% of plasma albumin. However, the isolated albumin was highly pure (100.9 +/- 8.2%, n = 5). All albumin samples analyzed demonstrate two peaks in HPLC analysis. The two peaks detected were collected and subjected to MS analysis, which demonstrates a difference of 120 mass units between the two albumin products isolated. We have developed an assay, which is easy to carry out and is not too labor intense. The HPLC analysis can be applied to confirm the purity of the isolated albumin as well as to confirm the quantity of the albumin in samples.