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but the LC/MS analysis was almost identical. Nitroxynil is used in animals to control liver fluke and
consequently the amount ingested when consuming meats from such animals needs to be continuously
monitored. Single ion monitoring was again used and a low detection limit of 2 ng/g was reported. The
average recover of the drug from a range of different tissues was found to be 82%

The choice of the most effective LC interface is complicated by the fact that the majority of LC
separations are carried out employing reversed phase chromatographic distribution systems. This means
that an aqueous mixture of polar solvents must be used as the mobile phase. Unfortunately, this renders
the electrospray interface (which will be discussed next) more useful than the thermospray. It would
appear from contemporary literature that the majority of LC/MS tandem systems now utilize the
electrospray interface, and far fewer applications employing the thermospray interface are now being
reported.

The Electrospray Interface

One of the earlier reports describing the electrospray interface was that of Whitehouse et al. [20] and
this device is probably the most commonly used interface in modern LC/MS tandem instruments today.
A diagram of the elctrospray interface is shown in Figure 20.

Figure 9.20
The Electrospray Interface