solution was transferred into a 25-ml calibrated flask and 0.02 g
aluminum metal was added in order to reduce Sn(IV) to Sn(II).
After adding the other reagents according to the general proce-
dure, the fluorescence intensity was measured.
2.4.2. Fish sample
Approximately 2.0 g of the fishwas dried and ashed at 600 ◦C.
After that the ash was dissolved with 10ml of concentrated HCl
and diluted to 50ml with distilled water and 1mol l
−1 NaOH
so that the final pH was ca 1. For the analysis, 0.5ml of the
obtained solution was transferred into a 25-ml calibrated flask
and 0.02 g aluminum metal was added in order to reduce Sn(IV)
to Sn(II).After adding the other reagents according to the general
procedure, the fluorescence intensity was measured.
The recovery assay was carried out using the same procedure
but adding known amount of tin.