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Cottonseed oil estimation by pulsed nuclear magnetic resonance technique
Author(s) -
Srinivasan V. T.,
Singh B. B.,
Chidambareswaran P. K.,
Sundaram V.
Publication year - 1985
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/bf02935706
Subject(s) - cottonseed , free induction decay , nuclear magnetic resonance , pulse sequence , pulse (music) , chemistry , analytical chemistry (journal) , relaxation (psychology) , yield (engineering) , spin echo , signal (programming language) , chromatography , magnetic resonance imaging , physics , biology , thermodynamics , food science , medicine , neuroscience , detector , computer science , optics , radiology , programming language
Seed asymmetry and moisture associated with the seeds are known to affect seed oil estimation by pulsed nuclear magnetic resonance (NMR) technique employing free induction decay or single spin echo (SE) pulse sequence. Using Gossypium (cottonseeds) as experimental material, it is shown that transverse relaxation times (T 2 ) of seed oil, in different varieties of seeds, measured in vivo, are not the same. The mean T 2 value of tetraploid seeds is found to be significantly higher than that of diploids. The effect of T 2 variation and other problems on oil estimation by the free induction decay and SE methods can be avoided by using the Carr‐Purcell‐Meiboom‐Gill (CPMG) pulse sequence to monitor the signal intensities of a certain number of selected echoes and processing them to yield the extrapolated signal intensity at zero time. The oil content values thus estimated are found to agree well with those obtained by Soxhlet method. The agreement between the two methods might depend upon the presence of gossypol and other pigments present in the samples. Neither delinting nor dehydrating the seeds is necessary in the present method. Even with the CPMG sequence, use of individual echoes is not recommended, as the T 2 variations give rise to erroneous values.