In the ongoing fight for clean drinking water, there are many contaminants that need to be monitored. One such contaminant is hexavalent chromium, also known as chromium-6 or Cr(VI). This hazardous substance infiltrates drinking water through various industrial processes and poses significant health risks, including cancer and damage to vital organs. Until recently, drinking water regulations primarily focused on total chromium, which includes both chromium-3 (an essential nutrient) and chromium-6. However, California took a crucial step in addressing this issue by announcing the nation’s first rule that specifically targets chromium-6. This new limit, which is scheduled to be implemented on Oct. 1, 2024, requires a limit of 10 µg/L hexavalent chromium. While this limit is still above the public health goal of 0.02 µg/L, it marks a positive stride toward safeguarding our communities.
Advanced testing methods needed
To meet these new requirements for hexavalent chromium, advanced testing methods are necessary. Fortunately, a highly effective method that targets hexavalent chromium has already been developed. US EPA Method 218.7, which was developed through a direct collaboration with Thermo Fisher Scientific and the EPA, provides guidelines for utilizing ion chromatography (IC) with a variable wavelength detector to accurately measure hexavalent chromium levels in drinking water. This direct injection IC method is highly accurate and can detect hexavalent chromium as low as 0.003 µg/L, significantly below the California public health goal of 0.02 µg/L.
Following US EPA Method 218.7, the Thermo Scientific Dionex Inuvion IC system and Thermo Scientific Dionex AS-DV autosampler with the Thermo Scientific Dionex™ IonPac AS7 column set can achieve a method detection limit of 0.0056 ug/L hexavalent chromium (AP002416). For higher sample throughput, the Thermo Scientific Dionex ICS-6000 HPIC system and Thermo Scientific Dionex AS-AP autosampler with the same column set can also be utilized (AU179). This setup offers the same methodology with increased productivity because of the dual-channel configuration. The Figure 1 demonstrates this method in A) DI water blank, B) 0.007 ug/L, and C) Sunnyvale, CA tap water.
Direct injection IC helps ensure regulatory compliance
With the establishment of a new drinking water limit for hexavalent chromium, California is taking a significant step in safeguarding public health. Advanced testing methods, such as direct injection IC, provide the necessary tools to accurately measure hexavalent chromium levels in drinking water. By employing these techniques, laboratories can ensure compliance with regulatory standards and contribute to the ongoing battle against hexavalent chromium contamination. Together, we can continue working toward cleaner and safer drinking water for all.
Interested in learning more?
Download our application notes to learn how you can implement this method using Thermo Scientific Dionex ion chromatography systems to perform sensitive determination of Cr(VI) in drinking water.
- Dionex Inuvion IC system method: Sensitive determinations of hexavalent chromium in drinking water using a compact IC system (AP002416)
- Dionex ICS-6000 HPIC system method: Sensitive determination of hexavalent chromium in drinking water (AU179)
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