Cuprous test paper prodn. by impregnation with cupric salt - followed by reduction, allows prodn. in aq. medium

摘要

Prodn. of Cu(I) test paper involves producing the active component, esp. Cu2I2 or Cu(I) pseudohalide, in or on the paper fibre by consecutive chemical treatment. This is achieved by (a) impregnation with a Cu (II) salt then (b) converting this to a Cu (I) cpd and preventing the formation of free I2. In an example paper was impregnated with conc. aq CuSO4 soln. and then with a soln. of KI and ascorbic acid in water so that Cu2I2 was deposited on the fibres. The test paper forms fluorescent cpds. with free organic N bases and NH3, the fluorescent colour often changing on changing the temp. e.g. cooling in liquid N2. It can be used in qualitative spot analysis and also in electrophoresis and paper and thin layer chromatography. Impregnation is carried out entirely in an aq. system avoiding the use of organic solvents, e.g. MeCN used in the parent patent, and a much higher Cu2I2 concn. can be obtd. than is the case when MeCN is used. The process is simple, safe and cheap.