Assay for N tau-methylimidazoleacetic acid, a major metabolite of histamine, in urine and plasma using capillary column gas chromatography-negative ion mass spectrometry

Assay and biological relevance of endogenous histamine and its metabolites: application of microseparation techniques

This review provides an overview of the assay methods used to determine the presence of endogenous histamine (HA) including its metabolites, and also discusses their biological significance. Firstly, this review briefly summarizes the biological significance of HA and its biological pathways. Next, the assay methods with microseparation techniques, such as gas-chromatography (GC), liquid-chromatography (LC), capillary electrophoresis (CE) and capillary electrochromatography (CEC) are looked at from a developmental viewpoint. Finally, the use of these methods, including flow cytometry techniques, for the determination of HA and its metabolites in biological samples, such as blood, urine, brain and cells, is described. The merits and demerits associated with each of these various methods are also discussed, along with their applications.

Determination of 1-methylhistamine and 1-methylimidazoleacetic acid in human urine as a tool for the diagnosis of mastocytosis

The determination of the metabolites of histamine, 1-methylhistamine (MHIS) and 1-methylimidazoleacetic acid (MIIA), in human urine is a useful tool for the diagnosis of mastocytosis. MHIS was extracted under basic conditions with chloroform and derivatized with trifluoroacetic acid anhydride, MIIA was derivatized with pentafluorobenzylbromide prior to extraction under basic conditions and the derivative was extracted with chloroform. The samples were assayed by gas chromatography-mass spectrometry. Normal concentrations of MHIS (2.01 micromol l(-1)) and MIIA (21.3 micromol l(-1)) in healthy volunteers' urine samples are clearly detectable with coefficients of variation of 7.0 and 8.9%. Pathological concentrations of 10.1 and 113 micromol l(-1) for MHIS and MIIA, respectively, are quantifiable with coefficients of variation of 6.6 and 4.8%.

Combined assay for phenacetin and paracetamol in plasma using capillary column gas chromatography-negative-ion mass spectrometry

A gas chromatographic-mass spectrometric assay has been developed for the measurement of phenacetin and its major metabolite paracetamol in plasma. Phenacetin and unconjugated paracetamol are analysed in a single chromatographic run while total paracetamol is measured separately after enzymatic hydrolysis. The two compounds, and the deuterated analogues used as internal standards, are analysed as their trifluoroacetyl derivatives and the mass spectrometer is operated in the electron-capture negative-ion chemical ionisation mode. The negative-ion mass spectra of the derivatives contain fragment ions, formed by loss of an acetyl group from the respective molecular ions, which are the base peaks in the spectra. When these ions are specifically monitored, amounts of derivative equivalent to 1 pg of parent compound can be detected. This allowed the development of an assay for phenacetin, unconjugated paracetamol and total paracetamol in plasma having a precision of 2.6, 1.4 and 2.4%, respectively, and preliminary results for a subject given a 100-mg oral dose of phenacetin are reported.