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Screening for Ricinoleic Acid as a Chemical Marker for Secale cornutum in Rye by High-Performance Thin-Layer Chromatography with Fluorescence Detection
- Oellig, Claudia
- Journal of agricultural and food chemistry 2016 v.64 no.43 pp. 8246-8253
- Secale, cyclohexanes, detection limit, fluorescence, formic acid, gas chromatography, oils, ricinoleic acid, rye, screening, silica gel, solid phase extraction, statistical analysis, thin layer chromatography, transesterification
- Ricinoleic acid as the characteristic fatty acid of Secale cornutum oil is a good marker for Secale cornutum impurities in cereal. The presented screening for ricinoleic acid in rye by high-performance thin-layer chromatography with fluorescence detection (HPTLC–FLD) offers a selective and sensitive method for the determination of Secale cornutum and is very different from existing gas chromatographic analyses. Lipid extraction was followed by transesterification and solid-phase extraction cleanup; thereafter, extracts were selectively derivatized with 2-naphthoyl chloride and analyzed by HPTLC–FLD with silica gel plates and cyclohexane/diisopropyl ether/formic acid (86:14:1, v/v/v) as mobile phase. For quantitation, the enhanced fluorescence was scanned at 280/>340 nm. Limits of detection and quantitation of 0.1 and 0.4 mg ricinoleic acid/kg of rye were obtained, which enables the determination of Secale cornutum far below the maximum admitted level. With near-100% recoveries and low standard deviations at relevant spiking levels, reliable results were guaranteed.