Abstract
Camalexin is the key phytoalexin in Arabidopsis thaliana and crops such as Camelina sativa. It is typically quantified by liquid chromatographic methods using camalexin dilutions as external standards. Alternatively, 6-fluoroindole-3-carboxaldehyde (6-FICA) is used as an internal standard with the advantage that identical conditions can be used for the analyte and standard, but two detectors are needed (ideally fluorescence for camalexin; UV for 6-FICA). We established an easy method to use readily available, cheap thiabendazole as a novel internal standard, facilitating the use of a fluorescence detector for standard and analyte for fast, reliable camalexin quantification in samples of diverse biological origin.