 The study aimed to analyze the reproducibility of off-axis integrated cavity output spectroscopy, OAICOS, derived Delta IIH and Delta 180 measurements on a set of 35 water samples by comparing the performance of four laser spectroscopes with that of a conventional mass spectrometer under typical laboratory conditions. The results demonstrated an overall agreement between OAICOS-based and mass spectrometry-based measurements for the entire dataset, but there was a certain degree of variability in precision and accuracy between the four instruments. Analytical precision ranged from plus or minus 0.56 and per mil to plus or minus 1.80 and per mil for Delta IIH and from plus or minus 0.10 and per mil to plus or minus 0.27 and per mil for Delta 180 measurements with a marked variability among the four instruments. The overall capability of laser instruments to reproduce stable results with repeated measurements of the same sample was acceptable, and averaging the measurements of three identical samples led to a higher degree of accuracy and eliminated the potential for random deviations. This article was authored by Mbonaza, BMC Fisher, MBORGA, and others. We are article.tv, links in the description below.