Disinfection Byproduct Recovery during Extraction and Concentration in Preparation for Chemical Analyses or Toxicity Assays

Over 700 disinfection byproducts (DBPs) have been identified, but they account for only similar to 30% of total organic halogen (TOX). Extracting disinfected water is necessary to assess the overall toxicity of both known and unknown DBPs. Commonly used DBP extraction methods include liquid-liquid extraction (LLE) and solid-phase extraction (SPE), which may use either XAD resins or other polymeric sorbents. With few exceptions, DBP recoveries have not been quantified. We compared recoveries by LLE, XAD resins, and a mixture of Phenomenex Sepra SPE sorbents (hereafter SPE) for (semi-)volatile DBPs and nonvolatile model compounds at the 1-L scale. We scaled up the three methods to extract DBPs in 10 L of chlorinated creek waters. For (semi)volatile DBPs, XAD resulted in lower recoveries than LLE and SPE at both 1- and 10-L scales. At the 10-L scale, recovery of certain trihalomethanes and trihalogenated haloacetic acids by XAD was negligible, while recovery of other (semi-)volatile DBPs extracted by XAD (<30%) was lower than by SPE or LLE (30-60%). TOX recovery at the 10-L scale was generally similar by the three extraction methods. The low TOX recovery (<30%) indicates that the toxicity assessed by bioassays predominantly reflects the contribution of the nonvolatile, hydrophobic fraction of DBPs.

Automated summary

This study compared the recovery rates of different DBP extraction methods at 1-L and 10-L scales, finding that XAD resin extraction resulted in lower recovery rates for (semi-)volatile DBPs, while TOX recovery rates were generally similar across the three extraction methods.