Method for measurement of aryl and alkyl phosphates

Status:

completed 01/2011

Aims:

Aryl and alkyl phosphates such as tricresyl phosphate are used as additives in aircraft engine oils. On certain types of aircraft and under certain conditions, they may be carried into the cabins by the ventilation systems. To permit estimation of the exposure, a method for quantitative analysis of aryl and alkyl phosphates was to be developed by the Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA) in response to an initiative by the German Social Accident Insurance institution for the vehicle operating trades.

Activities/Methods:

A filter with downstream silica gel tubes was employed as the sampling medium. The aryl and alkyl phosphates were determined by means of gas chromatography and a nitrogenphosphorus detector (PND).
A range of calibrations and sampling tests were performed in accordance with EN 482, "Workplace atmospheres - General requirements for the performance of procedures for the measurement of chemical agents". A practical trial was also performed of the new prDIN EN 1076, "Workplace exposure - Procedures for measuring gases and vapours using pumped samplers - Requirements and test methods". The objectives included obtaining statistical data (standard deviation of the method), recovery rates for various concentrations, the amenability of the coated sampling media to storage, and the limits of quantitation.
Once all the necessary data had been obtained, standard operation procedure were formulated.

Results:

A method for quantifying the aryl and alkyl phosphates in the room air was developed and validated in the course of the project. Glassfibre filters with downstream silica gel tubes are employed as the sampling medium for determining aryl and alkyl phosphates. 2.5 ml methyl tert-butyl ether is used for desorption. Analysis is performed by means of gas chromatography and phosphorus-selective detectors (GC/PND), with the use of a polar column.
Contrary to expectations, it has not yet been possible to perform workplace measurements except in isolated cases. Owing to the small number of available measured values, no conclusions can be drawn at this stage concerning the exposure of employees to aryl and alkyl phosphates.

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