Determination of the histamine metabolite tele-methylimidazoleacetic acid and of creatinine in urine by the same HPLC system.
OBJECTIVE
To develop an HPLC method with UV detection for determination of tele-methylimidazoleacetic acid (t-MelmAA) in urine of man or animals, which is reliable, simple and less expensive than existing GC/MS techniques.


METHODS
The elaborated procedure enables separation of t-MelmAA from its pros-isomer (p-MelmAA) as well as from imidazoleacetic acid. As an internal standard tele-ethylimidazoleacetic acid (t-EtlmAA) is used. The acids, after being converted to their stable isopropylesters, are extracted at pH 6.0-6.5. The further separation prior to HPLC utilises a small cellulose phosphate column. The HPLC system is isocratic with a C18 column and mobile phase consisting of an aqueous solution of SDS at pH 3.5 mixed with acetonitrile (65:35). An advantage of this system is that it can be used to determine the urine creatinine concentration to express excreted t-MelmAA in mmol/mol creatinine.


CONCLUSIONS
The method applicability is demonstrated in repeated studies in mastocytosis patients. The broad range of excretion values, from normal up to a high level (0.9 to 30 mmol/mol creatinine), indicates that it can be satisfactorily used for evaluation of histamine turnover under various clinical conditions. The method appears to be a good alternative to GC/MS based ones.
Granerus
G
G
Department of Medicine and Care, University Hospital, Linköping, Sweden. goran.granerus@nuk.us.lio.se
Lönnqvist
B
B
Wass
U
U
D000328:Adult; D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D003404:Creatinine / Q000652:urine*; D006801:Humans; D007093:Imidazoles / Q000652:urine*
D007093:Imidazoles; C002667:methylimidazoleacetic acid; D003404:Creatinine