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Contamination of heparin by histamine: measurement and characterization by high‐performance liquid chromatography and radioimmunoassay

Plasma samples which were collected in the presence of heparin contained 12.83 ± 0.34 ng/ml histamine‐immunoreactive material (n= 10). In contrast, histamine‐immunoreactive material in plasma samples which were collected in the presence of EDTA/phenanthroline contained 0.32 ± 0.01 ng/ml (n= 10). Histamine‐immunoreactive material was found as a contaminant in three different heparin formulations with unrelated batch numbers. The concentrations of the histamine‐like material were 32.82, 81.93, and 280.23 ng/ml, respectively. Octadecasilyl‐silica (ODS) cartridges were used to purify histamine from other constituents in the heparin preparations. The histamine‐immunoreactive material in the three preparations could be characterized as histamine with cation‐exchange high‐performance liquid chromatography (HPLC) on a TSK SP‐5 PW column with NaH2PO4, pH5.0, as a mobile phase and gradient elution. For the accurate measurement of histamine in plasma samples with heparin as an anticoagulant, one should be aware of a possible contamination of heparin formulations by histamine.