Page 374 - Tandem Techniques
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the residue taken up in 200 µl of the mobile phase. This solution was used for the LC/MS analysis. 50
µl samples were placed on a Li-Chrospher 60RP-select B column 12.5 cm long, 4 mm I.D. packed with
5 µm particles. The mass spectrometer was the Hewlett-Packard 5989A MS engine with thermospray.
Single ion chromatograms obtained from the analysis are shown in Figure 9.21.
Figure 9.21
Single Ion Chromatograms of Levamisole
Extracted form Liver Tissue (ref.18)
It is seen that again by single ion monitoring the peak of interest is picked out with only one other
appearing in the chromatogram. The limit of detection was found to be about 5 ng/g and it was
calculated that the mean recovery for liver, kidney and muscle tissue was 93%, 85% and 79%
respectively. This method is now used as the standard assay for levamisole in eats.
Blanchflower and Kennedy [19], developed a similar procedure utilizing LC/MS with a thermospray
interface for the assay of Nitroxynil in meats. A modified extraction procedure for the specific material
was developed
