Raman spectroscopic analysis of cyanogenic glucosides in plants: development of a flow injection surface-enhanced Raman scatter (FI-SERS) method for determination of cyanide.
Cyanogenic glucosides were studied using Raman spectroscopy. Spectra of the crystal forms of linamarin, linustatin, neolinustatin, amygdalin, sambunigrin, and dhurrin were obtained using a Raman spectrograph microscope equipped with a 532 nm laser. The position of the signal from the C identical with N triple bond of the cyanohydrin group was influenced by the nature of the side group and was above 2240 cm(-1) for the three cyanogenic glucosides that contain a neighboring aromatic ring, and below or partially below 2240 cm(-1) for the non-aromatic cyanoglucosides. Signals from the CN bond of linamarin/lotaustralin in leaves and roots from a medium cyanogenic cassava variety were obtained in situ using a Fourier transform near-infrared (FT-NIR) Raman interferometer with a 1064 nm laser, but the signal was very weak and difficult to obtain. A spectrum containing a signal from the CN bond of dhurrin in a freeze-dried sorghum leaf was also obtained using this instrument. Surface-enhanced Raman Spectroscopy (SERS) was demonstrated to be a more sensitive method that enabled determination of the cyanogenic potential of plant tissue. The SERS method was optimized by flow injection (FI) using a colloidal gold dispersion as effluent. Potential problems and pitfalls of the method are discussed.
Centre for Advanced Food Studies, Department of Dairy and Food Science, Food Technology, The Royal Veterinary and Agricultural University, 30 Rolighedsvej, DK-1958 Frederiksberg C, Denmark.
Lisbeth Garbrecht
LG
Thygesen
Kirsten
K
Jørgensen
Birger Lindberg
BL
Møller
Søren Balling
SB
Engelsen
D003486:Cyanides / Q000032:analysis*; D005960:Glucosides / Q000032:analysis; D006027:Glycosides / Q000737:chemistry*; D002365:Manihot / Q000737:chemistry*; D009570:Nitriles / Q000032:analysis; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D010945:Plants, Edible / Q000737:chemistry*; D045868:Sorghum / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*
D003486:Cyanides; D005960:Glucosides; D006027:Glycosides; D009570:Nitriles; C005091:linamarin; C001556:lotaustralin