Anthraquinones quinalizarin

Several anthraquinone derivatives have been suggested for the spectrophotometric determination of germanium, namely quinalizarin (extraction of the complex with chloroform in the presence of diphenylguanidine), Purpurin (1,2,4-trihydroxyanthraquinone) [52], and Alizarin Complexone [53]. 

Quinalizarin (0.05% in pyridine). Dissolve 0.01 g quinalizarin (1,2,5,8-tetrahydroxy-anthraquinone) in 2 ml pyridine, and dilute the solution with acetone to 20 ml. 

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