New Analytical Method Posted for Hexavalent Chromium

EPA has recently posted an updated analytical method for hexavalent chromium on their website. The new method, EPA 218.7, improves upon an existing method and is designed to assure the stability of samples in storage while they await analysis as well as provide greater confidence in analytical results at very low levels of hexavalent chromium.

Hexavalent chromium (also referred to as Chrome +6) has been in the news over the last year or so since an environmental advocacy group identified hexavalent chromiuim in a number of water systems across the country. They believed some lower levels of hexavalent chromium posed a risk to public health. EPA is currently reviewing the health risks of chromium, but in response to this new information, they initiated a voluntary monitoring program for water systems. At that time, there was some concern that hexavalent chromium could be converted to trivalent chromium during sample storage causing invalid results. Also, there were questions about whether the existing analytical method (EPA 218.6) could reliably detect hexavalent chromium at low enough levels to indicate whether there could be a public health impact. The updated method addresses these concerns and improves the consistency and accuracy of the methods so it is possible to achieve minimum reporting levels in the range of 20–50 parts per trillion.

The new method is available for download here.