Development and Testing of a Field Screening Method Based on Bubbling Extraction and Photoionization Detection for Measurement of Benzene and Total VOCs

Abstract

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.2008), high-resolution site characterization (USEPA 2013) among other initiatives; as ways of streamlining site assessment activities. The triad approach involves three elements: systematic project planning, dynamic work plan strategies, and real-time measurement technologies (ITRC 2007). Development of innovative field screening tools for site assessment falls into the real-time measurement technology element and also influences the dynamic work element. USEPA also recognizes that new technologies and methods need to be evaluated promptly to quickly ascertain whether the new technique is suitable for the site in terms of data quality objectives, cost and effectiveness (USEPA 2008).The increase in the use of innovative field screening tools for real-time assessment of chemical contamination for rapid vertical and horizontal source zone or dissolved plume delineation has led to less reliance on laboratory testing as evidenced by the use of direct-push tools to characterize the subsurface (membrane interface probe [MIP], laser-induced fluorescence, and others). Field screening tools bypass the wait for traditional laboratory analytical results in favor of nearly real-time results that facilitate quick decisions, for example, on monitoring well placement or areas requiring further characterization. Semi-quantitative methods, as defined by USEPA, provide order of magnitude estimations of contamination (e.g., 10s, 100s and 1000s of micrograms per liter [µg/L]); semi-quantitative methods can be used for defining the location of known types of contamination (USEPA 1997). MIP is an example of a semi-quantitative Abstract A field screening method was developed for rapid measurement of benzene and gasoline range total petroleum hydrocarbons (TPHg) concentrations in groundwater. The method is based on collecting photoionization detector (PID) measurements from vapor samples. The vapor samples are collected by bubbling air through groundwater samples (air sparging) with a constant volume, temperature and sparging rate. The level of accuracy, sensitivity, precision, and statistical significance of the estimated concentrations, derived from the screening method, are comparable to conventional laboratory analytical results at concentrations equal to or greater than 150 µg/L for benzene and greater than 50 µg/L for TPHg. The method's concentration estimations can assist in making real-time decisions regarding location of dissolved plumes and light nonaqueous phase liquid (LNAPL) source zones at many fuel release sites. The screening method was tested in the laboratory and in the field with 208 and 107 samples, respectively. The study concludes that the screening method can be used as a tool to aid in completing a site conceptual model as well as analyz...

Online Scavenging of Trace Analytes in Complex Matrices for Fast Analysis by Carbon Dioxide Bubbling Extraction Coupled with Gas Chromatography–Mass Spectrometry

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Correlations between on-site screening methods and laboratory analyses of oil-contaminated fuelling station sites

“…Li (2007) indicated that the drop in correlation is caused by the increase in water content and volatile solids in soil samples. Devine et al (2014) also suggested that high humidity tends to decrease the detector response of PID because the water vapour can absorb and diffuse the light that is trying to ionise the compounds. The low test kit on-site readings may also be engendered by the inappropriate settings of the turbidity meter.…”

BTEX Assessment among Informal Charcoal-Burning Food Traders for Cleaner and Sustainable Environment

“…The PID lamp absorbed the chemicals emitted and then ionized the chemical to provide an ionization response, which was then displayed as the concentration of the chemical as "ppm" (parts per million). The PID had an internal sampling draw pump that was calibrated using a standard reference gas, Isobutylene gas, and can also be calibrated using by two-point field zero [15,16]. Charged particles migrated to the electric field towards the respective electrodes, generating a current that was indicative of the number of formed ions + electron pairs, regardless of the compounds present in the chamber [17].…”