Next Article in Journal
Application of Carbon Nanotubes Modified Coatings for the Determination of Amphetamines by In-Tube Solid-Phase Microextraction and Capillary Liquid Chromatography
Previous Article in Journal
Quantification of Temozolomide in Nonhuman Primate Fluids by Isocratic Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry to Study Brain Tissue Penetration Following Intranasal or Intravenous Delivery
Article Menu

Export Article

Open AccessArticle
Separations 2016, 3(1), 5; doi:10.3390/chromatography3010005

Comparison of Spot and Time Weighted Averaging (TWA) Sampling with SPME-GC/MS Methods for Trihalomethane (THM) Analysis

Environmental Chemistry, Grenfell Campus, Memorial University of Newfoundland, Corner Brook, NL A2H 5G4, Canada
*
Author to whom correspondence should be addressed.
Academic Editor: Frank L. Dorman
Received: 3 November 2015 / Accepted: 15 January 2016 / Published: 4 February 2016
View Full-Text   |   Download PDF [2691 KB, uploaded 31 March 2016]   |  

Abstract

Water samples were collected and analyzed for conductivity, pH, temperature and trihalomethanes (THMs) during the fall of 2014 at two monitored municipal drinking water source ponds. Both spot (or grab) and time weighted average (TWA) sampling methods were assessed over the same two day sampling time period. For spot sampling, replicate samples were taken at each site and analyzed within 12 h of sampling by both Headspace (HS)- and direct (DI)- solid phase microextraction (SPME) sampling/extraction methods followed by Gas Chromatography/Mass Spectrometry (GC/MS). For TWA, a two day passive on-site TWA sampling was carried out at the same sampling points in the ponds. All SPME sampling methods undertaken used a 65-µm PDMS/DVB SPME fiber, which was found optimal for THM sampling. Sampling conditions were optimized in the laboratory using calibration standards of chloroform, bromoform, bromodichloromethane, dibromochloromethane, 1,2-dibromoethane and 1,2-dichloroethane, prepared in aqueous solutions from analytical grade samples. Calibration curves for all methods with R2 values ranging from 0.985–0.998 (N = 5) over the quantitation linear range of 3–800 ppb were achieved. The different sampling methods were compared for quantification of the water samples, and results showed that DI- and TWA- sampling methods gave better data and analytical metrics. Addition of 10% wt./vol. of (NH4)2SO4 salt to the sampling vial was found to aid extraction of THMs by increasing GC peaks areas by about 10%, which resulted in lower detection limits for all techniques studied. However, for on-site TWA analysis of THMs in natural waters, the calibration standard(s) ionic strength conditions, must be carefully matched to natural water conditions to properly quantitate THM concentrations. The data obtained from the TWA method may better reflect actual natural water conditions. View Full-Text
Keywords: THMs; haloalkanes; direct (DI)- and headspace (HS)- solid phase microextraction (SPME) sampling; spot and TWA SPME sampling; GC/MS analysis THMs; haloalkanes; direct (DI)- and headspace (HS)- solid phase microextraction (SPME) sampling; spot and TWA SPME sampling; GC/MS analysis
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Scifeed alert for new publications

Never miss any articles matching your research from any publisher
  • Get alerts for new papers matching your research
  • Find out the new papers from selected authors
  • Updated daily for 49'000+ journals and 6000+ publishers
  • Define your Scifeed now

SciFeed Share & Cite This Article

MDPI and ACS Style

Parkinson, D.-R.; Barter, D.; Gaultois, R. Comparison of Spot and Time Weighted Averaging (TWA) Sampling with SPME-GC/MS Methods for Trihalomethane (THM) Analysis. Separations 2016, 3, 5.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Separations EISSN 2297-8739 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top