Procentdelen af 13CO2 i prøver af udåndingsluft bestemmes ved hjælp af isotopforholdsmassespektrometri (IRMS) eller en anden passende valideret metode, udført af et
The proportion of 13CO2 in the breath samples may be determined by isotope-ratio-mass spectrometry (IRMS) or by another suitably-validated method carried out by any qualified laboratory, and stated as an absolute difference (excess) in the value between the pre-urea and post-urea breath samples (see section 6.6).