Cupferron as a Reagent in Qualitative Analysis Cupierron (nitrosophenylhydroxylamine,NH4+salt) is proposed a?a reagent to be used for the removal of Cu(I1) from a solution containing both Cu(I1) and Cd(I1) in preparation for carrying out the eonfirmstory test for the latter in qualitative analysis. I t reacls with Cu(I1) to form a chelate which is extractable into chloroform. According to Feigl ["Chemistry of Specific, Selective, and Sensitive Reactions," Academic Press, Inc., 1949, pp. 262-61, the equation for the reaction is
+
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MI,+
-0 A procedure which has been carried out successfully is as follows. A 10-drop ammoniactll solution containing both Cu(I1) and Cd(I1) is just acidified by the dropwise addition of acetic acid, treated with 5 drops of saturated aqueous solution of cupferron, then 1-1.5 ml of chloroform is introduced. The test tube is stoppered, and the contents are agitated until t,he non-aqueous layer is saturated. After the two phases have separated, the aqueous phase is pipeted off, and the non-aqueous phase is discarded. The sample is subjected to repeated entract,ion in the same manner until no blue color is extracted nor is any color left in the aqueous sample. About four such extractions are ususlly required. Finally, the sample is made ammoniacal, treated with 5 % thioaeetamide solution,and heated in a water bath. Cd(I1) is confirmed by the preeipitation of the yellow cadmium sulfide. Slight traces of Cu(I1) may cause the precipitate to be somewhat golden in color. This procedure introduces the technique of extraction of inorganic ions into non-aqueous solvents as well as yielding dependable res~dts. A. 0. PARKS BETSYDUBOSR
TEXASSTATEUNIVERSITY SOUTHWE~T SANMARCOB, 78666
768
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Journol of Chemical Education
