Rapid liquid chromatography-tandem mass spectrometry-based method for the analysis of alcohol ethoxylates and alkylphenol ethoxylates in environmental samples.

A sensitive and selective method for the determination of alcohol ethoxylates (AEOs) and alkylphenol ethoxylates (APEOs) using solid-phase extraction (SPE) and LC-MS/MS was developed and applied to the analysis of water samples. All AEO and APEO homologues, a total of 152 analytes, were analyzed within a run time of 11min, and the MS allowed for the detection of ethoxymers containing 2-20 ethoxy units (nEO=2-20). The limits of detection (LOD) were as low as 0.1pg injected, which generally increased as nEO increased (e.g., as high as 300pg for nEO=20). Additionally, the responses of the various ethoxymers varied by orders of magnitude, with ethoxymers with nEO=3-5 being the most sensitive and those with nEO>15 producing the least response in the MS. Absolute extraction recoveries of the analytes ranged from 37% to 69% in ultrapure water (RSD≤20%), with the recovery depending on the length of the alkyl chain. Abiotic stability studies were performed, and C14-18 ethoxylates showed significant degrees of degradation. Water samples from the Colorado River were then analyzed for AEOs and APEOs, with absolute extraction recoveries ranging from 33% to 45% (RSD≤12%). The predominant species observed in most samples were the octylphenol (OP) and nonylphenol (NP) ethoxylates, which contained total concentrations that were greater than 100ng/L APEOs in a couple samples. Other AEO homologues were identified in the river water samples, including C13, C15, C16, and C18 ethoxylates, but these compounds were generally present at much lower levels (i.e., <50ng/L total concentration).

Characterization of liquid chromatography-tandem mass spectrometry method for the determination of acrylamide in complex environmental samples.

This work describes the characterization of a solid-phase extraction (SPE) and liquid-chromatography-tandem mass spectrometry-based method for the analysis of acrylamide (AA) in complex environmental waters. The method involved the SPE of AA using activated carbon, and the AA was detected with tandem mass spectrometry after separating on an ion exclusion high-performance liquid chromatography column. The method incorporated two labeled AA standards for quantification using isotope dilution and to assess absolute extraction recovery. The method was evaluated for inter- and intra-day precision and accuracy. The method was both accurate (i.e., <30 % error) and precise (i.e., <20 % relative standard deviation), with absolute extraction recoveries averaging 37 %. The mass spectrometry provided excellent sensitivity, with instrumental limits of detection and quantitation values of 23 and 75 pg, respectively. The method detection limit was determined to be 0.021 µg/L. The analysis of AA was successfully performed in real-world samples that contained total dissolved solids concentrations ranging from 23,600 to 297,000 mg/L and AA concentrations ranging from 0.082 to 1.0 µg/L.