Field Screening of Waterborne Petroleum Hydrocarbons by Thickness Shear-Mode Resonator Measurements

Abstract

An inexpensive, field-portable sensor for direct, aggregate determination of aqueous petroleum hydrocarbons (PH) down to sub-ppm levels was developed. The basis of this sensor was an unusual, highly nongravimetric frequency response of 10 MHz (series fundamental) AT-cut quartz crystals when coated with rubbery silicone films. The response depended linearly and reliably on the total concentration of dissolved hydrocarbons over a range of 0.01-100 mg x L(-1) or up to aqueous solubility limits. Calibration sensitivities were measured individually for laboratory-prepared solutions of BTEX (benzene, toluene, ethylbenzene, and xylene isomers) and C6-C8 aliphatic components. Each component demonstrated a method detection limit (MDL) in the low-to sub-ppm range (benzene 10 mg x L(-1), n-hexane 0.54 mg x L(-1)) for light coatings of a commercially available poly-(dimethylsiloxane) gum (OV-1, > 10(6) g x mol(-1)) and lower MDLs for heavier coatings. Pairwise responses for the aliphatic and benzenoid standards were additive, indicating that aggregate determinations of mixtures (especially light fuels) were possible. Natural matrix interferences caused by sample turbidity and ionic strength were overcome by simple preparative methods. Fuel-spiked natural waters were determined with respect to standards and verified by gas chromatography. A 0.19 mg x L(-1) MDL for gasoline was obtained for heavy OV-1 films. Field determinations of groundwater surrounding a leaking underground fuel tank demonstrated that the sensor and method were useful for on-site PH screening. Large differences between the equilibration times of aliphatic and benzenoid components also indicated one avenue for BTEX speciation with the device.

Quantifying BTEX in aqueous solutions with potentially interfering hydrocarbons using a partially selective sensor array

“…† Partially selective sensor arrays have started to show limits of detection at the 100 μg L −1 level, 5,19 but work has only been relatively clean systems that are free of possibly interfering compounds until now. Applebee et al 6 used thickness shear mode resonator sensors to examine petroleum hydrocarbons in water with a variety of possibly interfering compounds.…”

“…Partially selective sensor arrays may become an attractive alternative to monitor groundwater. There are several partially selective sensing platforms that have been used to directly detect petroleum products in soil and water: fluorescent DNAbased chemosensors, 2 bacterial bioreporting assay sensors, 3 luminescence monitoring of interpenetrating metal organic frameworks (MOF), 4 preconcentration and chemicapacitive polymer detectors, 5 polymer coated thickness shear-mode resonators, 6,7 polymer coated surface acoustic wave (SAW) sensors, 8,9 siloxane clad optical fibre sensors, 10 polymer chemiresistors, 11 and graphene, carbon nanotube or gold nanoparticle chemiresistors. 12,13 These partially selective sensors must be deployed in arrays to discriminate and quantify the chemicals that they detect.…”

A survey of the 2001 to 2005 quartz crystal microbalance biosensor literature: applications of acoustic physics to the analysis of biomolecular interactions

“…Other examples for small molecule detection, in particular environmental contaminants include petroleum hydrocarbons (Fahnrich et al, 2002;Applebee et al, 2004), Cr 6þ , Cr 3þ , Cd 3þ , Cu 2þ and other ions (Howie and Hoagland, 2002;Mirmohseni and Oladegaragoze, 2002;Tani and Umezawa, 2003;Sung and Shih, 2005), estrogenic compounds (Murata et al, 2003;Luck et al, 2004), aliphatic amines (Mirmohseni and Oladegaragoze, 2003), phenol (Mirmohseni and Oladegaragoze, 2004), sulfur dioxide (Palenzuela et al, 2005), NO x (Seh et al, 2005), enantiomers , pesticides , doxorubicin (Serpe et al, 2005), cholesterol (Ram et al, 2001), limonene (Fietzek et al, 2001), alcohols (Loergen et al, 2005), dioxins Kurosawa et al, 2003) and cisplatinum drugs .…”

Model Bacterial Extracellular Polysaccharide Adsorption onto Silica and Alumina: Quartz Crystal Microbalance with Dissipation Monitoring of Dextran Adsorption

“…QCM can quantify relatively low levels of adsorption (e.g., ng/cm 2 ) with real-time monitoring (see refs 15 and 16 for review). Recently, this QCM technique has been used in environmental studies to detect specific organic compounds mainly due to the high sensitivity on adsorbed mass ( , ).…”