1.1 This Recommendation provides requirements for defining, testing and verifying the performance of portable and transportable X-ray fluorescence (XRF) spectrometers which may be used for legal measurements of hazardous elemental pollutants found in various media, especially soil and waste water. This Recommendation applies only to energy-dispersive X-ray spectrometers, but does not intend to exclude any other equivalent means of analysis. Portable and transportable instruments are self-contained or integrated compact assemblies which can be used to carry out a complete analysis on site. The portable instruments usually operate on battery (DC) power, and the transportable instruments usually operate on mains or generator (AC) power. The major components specified in this Recommendation reflect examples of current technology and are not intended to exclude new developments. Laboratorybased instruments are not covered in this Recommendation. 1.2 Instruments that meet the requirements of this Recommendation have flexibility in some major components depending on their specific applications. 1.2.1 Essential instrument components are an excitation source, a means of providing reproducible presentation of the sample being measured, a detector, and a data processing system. 1.2.2 The excitation source may be either an X-ray tube with or without secondary targets or radioactive source(s). The principle X-ray fluorescence energies of the target elements of interest is from approximately 1 keV to 14 keV. Appropriate detectors currently available are gas-filled proportional detectors and semiconductor detectors. 1.3 Instrument performance better than the criteria prescribed in these applications may be achieved by optimizing the performance of each major component of the measuring system as well as new technological developments. In such cases, success may depend on the knowledge, skill and experience of the operator. 1.4 Sampling plans, sample preparation and measurement methods are beyond the scope of this Recommendation. 1.5 This Recommendation does not address safety requirements and tests necessary for personnel protection. Manufacturers and users should therefore determine that the instruments meet intrinsic safety and labeling requirements according to national regulations.