Gray Environmental, Inc.

X-Ray Fluorescence (XRF) Testing for Lead-Based Paint

Portable X-ray Fluorescence (XRF) - The X-ray fluorescence technique utilizes the physics of the interaction of gamma rays (from the excitation source) with electrons in the target element (lead). Depending on the size of the source and the efficiency of the detector and electronics, the XRF instrument causes lead to fluoresce (emit X-rays), and measures the amount of fluorescence. Portable XRF instruments differ in design and performance. Some instruments are generally accepted to be more accurate and precise.

Gray Environmental, Inc. conducts lead surveys with a Niton XL portable spectrum analyzer, proven to have both outstanding accuracy as well as precision without a need for substrate correction which can bias the sampling results generated by other instruments.

Gray Environmental, Inc. minimizes the sources of instrument, operator and measurement error by adhering to a strict field sampling protocol.

XRF field sampling protocol includes:

  1. Documentation of each sampling plan in the form of dwelling floor plans (documents the minimum sampling model for the dwelling which yields statistically valid data, according to HUD Guidelines);

  2. Calibration of the instrument at regular intervals (calibration verifies that instrument is working properly, and contributes to the quality of the test data); and

  3. High density sampling (i.e."high frequency") provides for statistically valid results. Sample results are recorded by the instrument's computer and downloaded into a data log, thereby avoiding errors associated with manual recording, transcribing, and reporting.

  4. Sampling of all types of substrates (building materials are not all homogeneous, therefore sampling of similar substrates, as well as dissimilar substrates will be conducted).

Cost Effective "Real-Time" Testing

Portable XRF instruments are less expensive and easier to use than laboratory instruments, therefore testing costs per sample are much lower than laboratory methods. This allows for onsite, real-time analysis that can give you lead content reading within seconds.

Non-destructive

A major advantage in using a portable XRF spectrum analyzer, is that higher density (high frequency) sampling is possible as it is not necessary to take chips out of painted structures. Chip sampling is time consuming, involves costly analysis, not always accurate and the sample site is expensive to repair.

Because of the usually unknown nature of the methods of paint application and renovation history found in a large percentage of pre-1978 structures, as well as the high variability of lead concentrations that can be found in paint films, testing plans which utilize a combination of high density sampling (e.g. XRF sampling), and incorporate quality control or verification sampling analysis (e.g. chip sampling) results in the most accurate overall assessments.