Separation and identification of Group IIB cations on the semimicro scale

12 SEPARATION AND IDENTIFICATION OF GROUP IIB CATIONS ON THE SEMIMICRO SCALE For this separation the centrifugate from Group IIA is used. The separation scheme outlined in Table VI. 14 is therefore linked directly to Table VI in Section VI.11. If the ammonium polysulphide method has been adopted for the separation of Groups IIA and IIB, the student should scale down the scheme given in Table V.18 (Section V.12) to semimicro scale. 

May contain HgS and As2S3. If yellow, only As2S3 present. Wash residue with S drops of water discard washings. Treat residue with 0-5 ml dilute NH3, stir well, and centrifuge. 

Or - To 2 drops of the solution on a spot plate, add a minute crystal of NaN02, stir, and add 2 drops of Rhodamine-B reagent. 

Or - Treat 0- 2-0-3 ml of the solution with 5-10 mg of Mg powder, add 2 drops of FeCl3 solution, 2-3 drops of 5 % tartaric acid solution, 1-2 drops of dimethylglyoxime reagent, and then dil. NH3 solution until basic. 

Notes to Table V.14 1. If Group IIA absent, commence here. 

---