The Technical Support Staff is called upon for analysis of a wide variety of sample types many of which have little sample history. However, it is usually necessary to account for all elements present. For these reasons, x-ray fluorescence spectrometry (XRF) has been a useful tool. Unfortunately, XRF requires the use of a range of standards for each element, the preparation of which could become so time consuming that the advantages of XRF would soon be diluted. Consequently, the utility of the J. W. Criss fundamental parameters computer program was evaluated for samples in which only one standard per element was used and where the standard matrix did not strictly resemble the unknown matrix. Some of the results of these tests on environmental assessment samples are reported here.