Application of comprehensive two-dimensional gas chromatography for the detection and speciation of volatile organic phosphorus compounds in petroleum samples

Phosphate esters from residual fracturing fluid gellants have been implicated in numerous refinery shutdowns costing millions of dollars in lost productivity and maintenance. Current methodologies for the analysis of alkyl phosphates have a relatively poor detection limit (0.5 +/- 1.0 mug mL-1) and provide no speciation information: only a total phosphorus concentration. A method that permits the detection and speciation of alkyl phosphates in petroleum samples at trace levels is described. The technique relies on the derivatization of dialkyl phosphate esters followed by a comprehensive two-dimensional gas chromatographic (GCxGC) separation with selective detection by a time-of-flight mass spectrometer (TOFMS). For the model alkyl phosphates, the average minimum detectable concentration was 0.08 mug·mL -1. Preliminary classification, quantification and speciation of alkyl phosphate contaminants was conducted on a series of industrial petroleum samples.