CIPAC STATUS REPORT

30/01/2008

0342 Oxamyl

Allocated to US

CIPAC methods published in :

CIPAC

CIPAC 50th meeting, June 2006 in Geneva

Mrs Q. Wu presented the results of a full collaborative trial on the determination of oxamyl in technical material, 5G, 10G and 10L formulations, using reversed phase HPLC with UV detection at 240 nm and internal standardisation (acetanilide). To the question of the necessity of using internal standard Mrs Wu answered that it is needed to have a good precision. Mr Bura pointed out that Laboratory 5 did not use internal standard, and produced one of the best results. He questioned the necessity of using an internal standard and wondered if the results can be recalculated without the internal standard. CIPAC proposed long ago not to use internal standards in HPLC. Mr. Hill made a general remark that performing a SST might be a general requirement for all methods. Mr Müller mentioned that SST is included with the expression “or equivalent”, and underlined that this is the point one has to rely on the expertise of the chemist. It is expected that the chemists are checking the performance of the system. Mr. W. Bontoyan noted that this philosophy would not stand in the courts in the US. Seventeen laboratories submitted results. For Oxamyl 10G dry granule samples, the statistical analysis of the study results shows the between-lab %RSDR closely approximates the limits calculated (%RSDR(Hor)) using the Horwitz equation, after removing selected outliers. Moreover, for Oxamyl 10G samples, Laboratory 1 was also removed as an outlier. It was proposed that the method be accepted as a provisional CIPAC method.

This was declared to be a provisional CIPAC method with internal standard, provided that the company provides CIPAC next year a small presentation based on the comparison of raw data produced with and without the use of the internal standard. This is to demonstrate whether or not the internal standard is really needed. Then if the presentation is satisfactory, it is proposed that the method can go to the full CIPAC method.

Decision The reversed phase HPLC method (CIPAC/4494) for the determination of oxamyl in TC, SL and GR formulations was accepted as provisional CIPAC method requesting the company to clarify the necessity of using the internal standard.

CIPAC 51th meeting, June 2007 in Umhlanga Rocks, South Africa

Decision The reversed phase HPLC method (CIPAC/4494) for the determination of oxamyl in TC, SL and GR formulations was accepted as full CIPAC method, with a note that the method can be used without an internal standard (IS), but the validation data have been generated with IS.

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