The determination of each trace element is carried out on the aliquot portions indicated in the method for each individual trace element.

Methods 26e, 26f, 26g, 26i and 26j cannot be used to determine elements present in a chelated or complexed form. In such cases Method 26c must be used prior to the determination.

In the case of determinations by atomic absorption spectrometry (Methods 26h and 26k) such treatment may not be necessary.