Narcissus and Daffodil

288 N.P.D. Nanayakkara and J.K. Bastos
In many instances, the separation method can be simplified based on the selectivity
of the detection mode. In studies where highly specific detection techniques
(e.g., immunoassay) were used, minimum sample processing was necessary (Tanahashi
et al., 1990; Poulev et al., 1993).
QUANTITATIVE ANALYSIS OF AMARYLLIDACEAE ALKALOIDS
Gas chromatography
Packed column-gas chromatography (PC-GC)
In early studies, the feasibility of gas chromatography for the analysis of alkaloids
was explored using packed columns. Lloyd et al. (1960) analysed several underivatised
Amaryllidaceae alkaloids by PC-GC, and single component sharp peaks for
these compounds were observed in chromatograms. Yamaguchi et al. (1962)
reported the detection of galanthamine, lycoramine and tazettine by PC-GC
under similar conditions. However, this method was not applicable to non-volatile
alkaloids, such as lycorine, and other hydroxylated alkaloids showed significant
peak tailing, especially with polar liquid surfaces.
Takagi et al. (1968a) described the GC analysis of twelve Amaryllidaceae alkaloids,
using several commercially available polar and non-polar stationary phases.
The test compounds were converted to their trimethylsilyl derivatives prior to
analysis. The trimethylsilyl derivatives of these compounds showed symmetrical
and relatively sharp peaks, even for non-volatile alkaloids such as lycorine.
Multiple peaks for lycorenine were observed under these conditions, presumably
due to decomposition. These authors later applied this method to determine the
quantitative changes in lycoramine and galanthamine content in Lycoris radiata
through a period of one year (Takagi et al., 1968b). In a subsequent study (Takagi
et al., 1969), the lycorenine content in L. radiata was determined quantitatively by
converting it into tetrahydrohomolycorenine and analysing the trimethylsilyl
ether derivative by PC-GC.
Packed column-gas chromatography-mass spectrometry (PC-GC-MS)
Millington et al. (1972) analysed the alkaloid fraction of Crinum glaucum after trimethylsilyl
derivatisation by PC-GC-MS in electron impact mode. In addition to the
identification of ambeline and lycorine, several new alkaloids were recognised. In a
subsequent report (Onyiriuka and Jackson, 1978), the same group used PC-GC-MS
in electron impact mode, in combination with other mass spectral data and
nuclear magnetic resonance (NMR) spectroscopic information, to detect and
propose chemical structures for several new compounds in alkaloid fractions of
Crinum ornatum and C. natans.
Capillary gas chromatography (CGC)
A CGC method coupled with nitrogen phosphorus detection was also used for
the quantitative analysis of Amaryllidaceae alkaloids in plant extracts (Bastos
et al., 1996). In this study, baseline resolution for eleven reference alkaloids