Lawrence Ritchie

Quantitative immunoassay for determining polyaromatic hydrocarbons in electrical insulating oils

Abstract The development and application of a combined sample extraction and immunoassay protocol for the quantification of polyaromatic hydrocarbons (PAHs) in transformer oils is reported. Tests were performed on 12 different used transformer oils from three major manufacturers. The removal of matrix interferents was achieved by loading oil fractions onto silica solid phase extraction cartridges and eluting with non-polar solvent prior to evaporation and reconstitution in a more polar medium. Extracts were immunoassayed using two commercially available PAH test kits either having broad specificity towards priority PAHs or enhanced binding specificity toward more carcinogenic PAHs. The total and carcinogenic PAH test kits yielded PAH levels in the oil extracts 5.86-fold and 126-fold lower than the industry-standard IP346 method. The latter method, widely used by the industry, since it correlates with biological carcinogenicity tests, grossly over-estimates PAH levels in oils since it is a non-specific gravimetric solvent extraction approach. The assay was found to be unaffected by the extract sample matrix and was capable of determining PAHs at the nanogram per millilitre level. The assay protocol was simple, low-cost and rapid (

Quantification of polynuclear aromatic hydrocarbons in transformer oils by enzyme immunoassay.

Many polynuclear aromatic hydrocarbons (PAHs) are either known or suspected carcinogens and are a common constituent of mineral oils. Due to the large number of possible PAH structures, standard quantification methods fail since they either lack specificity or are too complex, requiring individual fractionation, identification, and quantification. A rapid, low-cost, novel analytical screening method, incorporating a silica-based solid-phase extraction (SPE) method linked to co-solvent dilution and quantification of total and carcinogenic PAH levels by immunoassay, is reported here. The method yielded high extraction efficiencies and minimal matrix effects. This novel approach yielded total and carcinogenic PAH levels × 5.7 and × 126, respectively, lower than that recorded by the industry-recognised BS2000 Pt. 346 (IP346) method which estimates the polyaromatic carbon (PAC) content of oils by gravimetry. The method is expected to be of benefit where an indication of PAH levels in oils is important for purchasing, management or disposal purposes and also for risk assessment and for appropriate labelling of oils in line with current legislation.

The development of a sub-surface monitoring system for organic contamination in soils and groundwater.

A major problem when dealing with environmental contamination is the early detection and subsequent surveillance of the contamination. This paper describes the potential of sub-surface sensor technology for the early detection of organic contaminants in contaminated soils, sediments, and landfill sites. Rugged, low-power hydrocarbon sensors have been developed, along with a data-logging system, for the early detection of phase hydrocarbons in soil. Through laboratory-based evaluation, the ability of this system to monitor organic contamination in water-based systems is being evaluated. When used in conjunction with specific immunoassays, this can provide a sensitive and low-cost solution for long-term monitoring and analysis, applicable to a wide range of field applications.