Page 384 - Tandem Techniques

Page 368

Van Breeman et al., examined the ginseng root powder by extracting the powdered root with aqueous
methanol, evaporating to dryness, dissolving the residue in water, and passing the solution through a
solid-phase extraction tube. The retained material was displaced with butanol, evaporated to dryness,
and redissolved in methanol. Samples of the methanol solution were placed on a carbohydrate analysis
column (aminopropyl bonded to silica) and separated using a water/acetonitrile gradient. As the ion
monitored was an adduct of sodium (M+Na)+, the mobile phase also carried 100 µ M sodium chloride.
The column eluent was monitored by a standard Hewlett-Packard 5989B MS engine quadrupole mass
spectrometer, and the spectra that were obtained for a specific ginsenoside are shown in Figure 9.28.

It is seen that the standard sample, injected directly into the mass spectrometer, gave the expected
sodium adduct ion, (M+Na)+ at an m/z value of 970. The same peak appears when the standard is
chromatographed and passed through the electrospray interface. However, it is seen that two new peaks
appears at m/z values of 1067 and 1085. When the root extract is separated and monitored under the
same conditions, there is no peak at 907 m/z and the peaks at m/z values of 1067 and 1085 have
become much bigger, and that at 1085 is now the major peak. Although all standard ginsenoside sample
produced both the sodium adduct ion and the [M+138]+ ion, the natural products only gave the
[M+138] +. It was also found, that the 138 adduct to the ginsenoside was most likely to be the
protonated adduct,(3-aminopropyl)-trihydroxysilane, [NH3(CH2)3Si(OH)3]+ which was present either
as a reagent contaminant in the bonded phase or was produced by the decomposition of the stationary
phase. The 1067 ion appeared to be produced by the removal of water from the [M+138]+ ion. The
spectra represented only 100 pmol of ginsenoside and so the appearance of the (3-aminopropyl)-
trihydroxysilane adducts might be a function of the sample size and if larger charges were employed the
sodium adduct might again appear.

The various penicillins, particularly penicillin G, are widely used in veterinary medicine and to prevent
antibiotic residues from entering the human food chain, their levels in animal products for human
consumption