Sampling Protocol

In this section we will consider some precautions necessary for the sampling of various materials before analysis. In general, samples should be representative of the bulk samples from which they were taken.

It is shown that the variation associated with field sampling is 5 to 10 times greater than that associated with laboratory procedure. It would therefore be better to increase the number of core samples taken from the field than try to improve the accuracy of the analytical methods if the precision of the results from our field experiments is to be improved.

(Allen and Whitfield, 1964).

Enough core samples should be taken throughout the field or mass of material to give a representative bulk sample. This may weigh several kilograms, so should be thoroughly mixed and sub-sampled, perhaps on site, to obtain a truly homogeneous sample of a size suitable for processing.

Galvanized sampling tools should not be used for trace element analysis. Usually from 20 to 25 cores are taken in a 'W' pattern across the whole area. An alternative approach is to traverse the whole area in a zig-zag manner, sampling at random along different sections of the area (Scott et al., 1971). The cores should be broken up and mixed well in a bucket, then about 200 g retained in a labelled polythene bag.

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