UCT Inc., is known around the world as the premier manufacturer of Solid Phase Extraction (SPE) sorbents. It’s support for analysts performing testing in the field of environmental sample testing for public protection has been a core activity for over thirty years. In a recent paper published in Environmental Science Water Research & Technology ((2016), 2, 502) by D.L.McCurry et al., UCT’s Enviro Clean® activated carbon SPE columns were employed to extract and analyze NMDA from water.
Water utilities practicing chlorination of poorly nitrified wastewater effluents for non-potable reuse, or of ammonia-containing, wastewater-impacted source waters during de facto reuse may form NDMA by reactions between wastewater-derived NDMA precursors and inorganic chloramines formed in situ. Treatment with moderate doses (186 mJ/cm germicidal fluence) of UV from medium pressure mercury lamps (MPUV) upstream of chloramination minimize NDMA formation by destroying ambient NDMA (i.e., the NDMA occurring in wastewater) by >70% and deactivating chloramine-reactive NDMA precursors by 46%. UV from low pressure mercury lamps (LPUV) was less effective for NDMA precursor deactivation.
In the study, water samples were extracted on UCT Enviro Clean®coconut shell activated carbon SPE cartridges , and eluted with 12 mL of dichloromethane. This was then dried with approximately 1 g magnesium sulfate heptahydrate and envaporated to 1 mL under nitrogen gas. It was found that ozonation does not destroy ambient NDMA and formed significant levels of NDMA from ozone-reactive precursors. For waters with low ammonia concentrations, breakpoint chlorination deactivated NDMA precursors, but does not destroy ambient NDMA, and formed an array of regulated and unregulated halogenated byproducts. Even over a 3 day contact time, application of preformed monochloramine reduced NDMA formation by 39% by minimizing the exposure to inorganic dichloramine, the inorganic chloramine precursor to NDMA. However, the benefit of preformed monochloramine was restricted to waters with low to moderate ammonia concentrations. This article demonstrates why analysts working in the field of public protection turn to UCT for the finest of sorbents and materials. For more information regarding UCT's various Enviro Clean® SPE sorbents visit here.