The instrumental approach to the determination of elements through annihilation radiation demands a high degree of specificity
which has not been fully met by the high resolution Ge(Li) or the two detector (180°) coincidence spectrometry. The triple
coincident measurement of the three gamma quanta resulting from the triplet state annihilation of e−−e+ system provides enhanced specificity, although at a loss of sensitivity. The development of this approach for the measurement
of annihilation radiation is decribed with the determination of copper in orchard leaves as an illustrative example.