FEASIBILITY OF ANALYZING [C-13]UREA BREATH TESTS FOR HELICOBACTER-PYLORI BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY IN THE SELECTED-ION MONITORING MODE

Background: The [C-13]urea breath test for Helicobacter pylori is nonr adioactive, as well as noninvasive, but few clinical laboratories have the expensive isotope ratio mass spectrometer used for analysis. Meth ods: To demonstrate the feasibility of analysing [C-13]urea breath tes ts with a gas chromatograph-mass spectrometer routinely used for drug testing, (CO2)-C-13 standards for breath tests and breath samples from patients in a multiple-blind study were analysed. The breath samples were also analysed by isotope ratio mass spectrometry, and the diagnos es were compared with biopsy results. Results: The precision of the en richment measurements by gas chromatography-mass spectrometry was 1.1 parts per thousand, and the calculated differences in enrichment betwe en standard gases equaled the certified values. The sensitivity (94%), specificity (94%), and percentage agreement (94%) for diagnosis of He licobacter pylori (n = 34) were as high or higher than for analysis of replicate breath samples by isotope ratio mass spectrometry and compa rable to the values reported for diagnosis of the bacterium by other c urrently accepted tests.Conclusions: The study demonstrates that a gas chromatograph-mass spectrometer can be used to analyse [C-13]urea bre ath tests, thus potentially lowering the cost of the test and increasi ng the number of laboratories that can perform the test.