with a Flllorometric Detector

IAA in plant tissues has been analyzed by a number of physico-chernical methods. GC-MS has been used for both qualitative and quantitative analyses with deuterium-labeled IAA as the internal standard (Caruso et al. 1978, Magnus et al. 1980, Pengelly et al. 1981). This GC-MS method however, requires extensive purification of the plant extract and additional procedures for the preparation of volatile IAA derivatives. Furthermore, the instrument is expensive and has a high running cost; thus, it can not be used in all laboratories for the routine analysis of IAA (Sweetser and Swartzfager 1978). Because of these dithculties, a new, simplified device for the determinatien of endogenous IAA is needed. HPLC has been used fbr the purification of IAA and recently fbr the quantitative analysis of IAA combined with a spectrofluorometer as the versatile HPLC detector (Sweetser and Swartzfager 1978, Crozier et al. 1980, Sandberg 1981), Since IAA has natural fluerescence when excited at 280 nm, this method ofanalysis does not require the derivatization ofIAA. In the fluorometric determination, however, the IAA fraction is purified by chromatographic procedures such as Sephadex G-25 and DEAE-Sephadex A-25 (Sweetser and Swartzfager 1978); "-Spherogel (Crozier et al, 1980); PVP, Sephadex LH-20 and TLC (Sandberg 1981) before HPLC. These methods are time consuming and, in some cases, have low recovery rates (McDougall and Hillman 1978). In contrast, the C-18 SEP-PAK cartridge recently has been