A GLC procedure for determining sub-nanogram levels of indol-3-yl acetic acid

Analytical History of Auxin

“…Of course, procedures where endogenous methyl-IAA may remain in the sample need to be dealt with using either a stable isotope-labeled derivatization reagent or using diazoethane as an alternative to diazomethane. The third category, which is often combined with the second (Bittner and Even-Chen 1975;Epstein and Cohen 1981), consists of reagents that halogenate auxin at the indole nitrogen (trifluoroacetyl, heptafluorobutanoyl, pentafluoropropionyl derivatives; Table 2), which improves the sensitivity of the system to indole compounds (summarized in Rivier 1986). The improvement in sensitivity is due to the fact that alkyl halides are one of the few classes of compounds that readily form negative ions; therefore, if the MS is operated in negative ion mode, the halogenated indole compounds produced through derivatization may be some of the few compounds in the mixture to ionize, which will thus decrease noise in the spectrum and enhance sensitivity to auxin and related compounds.…”

“…In studies of auxin, GC has been coupled to a variety of detectors, including flame ionization detectors (where detector response is well correlated to the amount of material detected, but lacks specificity; Bandurski and Schulze 1974;DeYoe and Zaerr 1976), electron capture detectors (after derivatization with a halogen-containing group; Bittner and Even-Chen 1975;Seeley and Powell 1974), and thermionic specific detectors (TSD; which is specific for nitrogen and phosphorous-containing hydrocarbons; Cohen and Schulze 1981;Martin and others 1980). The first GC-MS couplings were developed in the mid to late 1950s (reviewed in Gohlke and McLafferty 1993;Holmes and Morrell 1957), only a few years after the first GC system was invented Martin 1952, 1954).…”