FENTIN COMPOUNDS                                JMPR 1972

    Explanation

    Fentin compounds were considered at the Joint Meetings in 1965 and
    1970. In the 1970 evaluation (FAO/WHO, 1971), further information was
    required (1) on analytical methods capable of distinguishing between
    fentin compounds and tricyclohexyltin hydroxide, and (2) on occurrence
    of monophenyltin and diphenyltin compounds in the residues in celery.

    FATE OF RESIDUES

    In plants

    A study (Freitag, 1972) on the terminal residues of 113Sn-labelled
    fentin chloride in sugar beet leaves shows that triphenyltin is
    converted via diphenyltin and monophenyltin to inorganic tin and that
    the terminal residues consist mainly of triphenyltin and inorganic
    tin. The proportion of diphenyltin and monophenyltin can be considered
    insignificant in the terminal residues.

    METHODS OF RESIDUE ANALYSIS

    A colorimetric method (Bürger, 1961) is available which allows the
    determination of triphenyltin in the presence of trihexyltin in the
    residues.

    APPRAISAL

    It has been demonstrated that triphenyltin in sugar beet leaves is
    degraded via diphenyltin and monophenyltin to inorganic tin, and the
    amounts of diphenyltin and monophenyltin are insignificant in the
    terminal residues. The Joint Meeting considered that this information
    applies also to the residues of fentin compounds in celery.

    A colorimetric method is available which is suitable for determination
    of triphenyltin in the presence of trihexyltin in the residues.

    The further information required by the 1970 meeting and made
    available to the 1972 Meeting is considered satisfactory.

    RECOMMENDATIONS

    In addition to the recommendations for tolerances made by the 1970
    Meeting, the following recommendations are made for those crops on
    which fentin compounds are used and where residues have been found to
    be below the limit of determination by the analytical methods.

    TOLERANCES

                                                           ppm

         Pecans (shelled)                                  0.05*

         Rice (in husk), cocoa beans,
         coffee (raw beans)                                0.1*

         * at or about the limit of determination

    FURTHER WORK OR INFORMATION

         None

    REFERENCES

    Bürger, K. (1961) Zur Analytik von Organozinnverbindungen, Z.
    Lebensmittel-Unters.u.-Forschung, 114: 1-10.

    FAO/WHO (1971) 1970 evaluations of some pesticide residues in food
    FAO/AGP/1970/M/12/1; WHO/Food Add./71.42.

    Freitag, K.-D. (1972) Metabolismus und Rückstandsanalytik des
    Triphenylzinnchlorides. Dissertation. Naturwissenschaftliche Fakultät
    der Johannes-Gutenberg - Universität in Mainz.

    CORRIGENDUM

    1970 evaluations of some pesticide residues in food. Fentin Compounds.

    p.350, line 15, for Hoechst 1967 read Hoechst 1968r. p.360,
    after Hoechst 1968g entry add Hoechst Report 43IIIA-45IIIA-46IIA-
    51IIA, dated 5-9-1968. (unpublished)
    

    See Also:
       Toxicological Abbreviations
       Fentin Compounds (AGP:1970/M/12/1)