A set of data collected over the time period November 1993 to October 1994 is discussed in this paper. Although they are not a continuous data set, the FT-IR spectra were collected on 127 days during the year for a total 4463 spectra. These have all been analyzed for N2O, CH4, CO, O3, and C2H4. Ethylene was measured on only a few occasions during the year and was only once substantially above the detection limit. The goal of this work was to determine whether any of the first four gases named above could be used as surrogate standards for precision and accuracy measurements for the FT-IR technique. This work shows that the daily variability of CO and O3 is to high for these gases to be used for QA/QC purposes, whereas N2O can be used. Under certain circumstances CH4 can also be used, but only with great care, and in the presence of a local, varying source, it should not be used.