Methods for the analysis of the saffron metabolites crocin, crocetins, picrocrocin and safranal for the determination of the quality of the spice using thin-layer chromatography, high-performance liquid chromatography and gas chromatography

Abstract

Saffron spice is the dry stigmata of Crocus sativus L. Methods have been developed for the determination of the quality of the spice using thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC) and gas chromatography (GC). TLC and HPLC gave comparable results for crocin and crocetins (colour principles), picrocrocin (bitter substance) and safranal (flavour). Similarly, the determination of safranal by GC was in agreement with analysis by TLC and HPLC. Separation of the constituents was achieved by silica gel G TLC using an n-butanol-acetic acid-water (4:1:1) system. The resolution of crocin, crocetins and picrocrocin by HPLC was obtained using a Shimadzu 15-cm CLC-ODS column with 20–80% acetonitrile in water as the eluent; for safranal an isocratic run with 76% acetonitrile in water was suitable. GC was adopted only for the determination of safranal using a Shimadzu 5% SE-30 column. HPLC was most suitable for the detection of adulterants and was simpler and more efficient for quality analysis. The TLC method was time-consuming and also gave an overestimation of the colour principles.