Variable recovery of polar compounds is a potential pitfall in the on-line extraction-reversed-phase HPLC analysis of
lipoxygenase products. Therefore, the addition of a polar internal standard to
biological samples, which permits the assessment of the recovery of the polar components in individual samples, appears to be essential. 19-Hydroxyprostaglandin (PG) B2 was found to be a suitable compound for this application. It was easily prepared from deproteinized human semen by base-catalyzed
dehydration of
19-hydroxy-PGE2, and purified in a single step by reversed-phase HPLC. Similarly to
PGB2, already used as internal in HPLC,
19-hydroxy-PGB2 has excellent chemical stability and carries a strong uv chromophore that enables detection at 280 nm. Most importantly, it is eluted just prior to the polar
arachidonic acid metabolites 20-hydroxy- and
20-carboxy-leukotriene B4, 12-oxo-dodecatrienoic
acid and the lipoxines A and B. The measurement of the ratio of
PGB2 and
19-hydroxy-PGB2 used in combination as internal standards in HPLC analysis of
lipoxygenase products, provides a simple and reliable way to assess sample to sample recovery of the polar components when using on-line extraction procedures.