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High accuracy determination of organochlorine and organophosphorus pesticides in tomato certified reference material

D.G. Burke, S. Askew, J. Cuthbertson, R. Myors, J. Richardson, D. Saxby, N. Sousou, P. Taylor, and L. Mackay

National Measurement Institute, Sydney, Australia


Accurate measurement of microgram quantities of pesticides in food is needed to enforce Australian Food Standards Code regulations and to protect our food exporting industries. The National Measurement Institute provides materials which enable achievement of accurate measurements; a tomato puree reference material with certified values for nine pesticides at the maximum residue level has been prepared for food analysts.

The accuracy of the values for the certified reference material was further confirmed by development of a high accuracy methods for five of the pesticides, of which four used isotope dilution mass spectrometry. This method provides traceability to the International System of Units (SI) when it is appropriately applied and all potential biases are assessed. This is the first time a fresh frozen vegetable matrix certified reference material has been prepared that contains both organophosphorus and organochlorine pesticides and for which assignment of certified values has been confirmed in this way. The compounds, the values and uncertainties determined by our method are tabulated below.

This paper describes the development of our high accuracy method of analysis, the identification and quantification of potential sources of bias and measurement of these compounds in the tomato puree reference material.

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