Benzoin as a Fluorescent Reagent for the Detection of Germanium

RECENTLY, we 1 have described a fluorometric method for the detection and determination of germanium, making use of resacetophenone in sulphuric acid or phosphoric acid medium. The test is quite specific, except for the interference of boron. In view of the similarity of the germanic and boric acids thus found, we have investigated the use of other reagents which form fluorescent compounds with boric acid. The reagents described in the literature are flavonols 2 , 1-amino-4-hydroxy anthraquinone 3 , O-hydroxy carbonyl compounds 4 and benzoin 5 . Among the many compounds tested by us the following have been found to be definitely useful: (1) ω-methoxy resacetophenone, phloro-acetophenone, 4- methoxy-2-hydroxy-benzaldehyde, β-resorcylic aldehyde and salicylaldehyde, which give a greenish-yellow fluorescence; (2) 2-methoxy-3 : 6 dihydroxy acetophenone, 2-benzoyl-phloroglucinaldehyde and 4-methoxy-2-hydroxy-benzoic acid, which give a yellow fluorescence; (3) β-resorcylic acid, orsellinic acid and ethyl orsellinate, which give a violet fluorescence with germanic acid in concentrated sulphuric acid medium.