II Acetate Basic Reagent

Dipping solution Basic lead(II) acetate solution (lead content 17.5—19%). Storage 

The reagent solution may be stored over a longer period of time, providing it is tightly stoppered. 

Lead(II) acetate yields colored lead salts with flavonoids and thiourea derivatives. 

The chromatogram is freed from mobile phase in a stream of warm air, immersed in the reagent solution for 1 s or homogeneously sprayed with it until the layer starts to be transparent and heated to 50 —80 C for 5 — 20 min. 

Chromatogram zones of various colors sometimes appear even before heating, these fluoresce under long-wavelength UV light (A = 365 nm) in the case of some substances. 

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The cobalt complex is usually formed in a hot acetate-acetic acid medium. After the formation of the cobalt colour, hydrochloric acid or nitric acid is added to decompose the complexes of most of the other heavy metals present. Iron, copper, cerium(IV), chromium(III and VI), nickel, vanadyl vanadium, and copper interfere when present in appreciable quantities. Excess of the reagent minimises the interference of iron(II) iron(III) can be removed by diethyl ether extraction from a hydrochloric acid solution. Most of the interferences can be eliminated by treatment with potassium bromate, followed by the addition of an alkali fluoride. Cobalt may also be isolated by dithizone extraction from a basic medium after copper has been removed (if necessary) from acidic solution. An alumina column may also be used to adsorb the cobalt nitroso-R-chelate anion in the presence of perchloric acid, the other elements are eluted with warm 1M nitric acid, and finally the cobalt complex with 1M sulphuric acid, and the absorbance measured at 500 nm. 

In the first step tin(II) chloride in acetic acid solution reduces the aromatic nitro grot to amino groups. The aromatic amines produced then react with fluorescamine weakly basic medium to yield fluorescent derivatives (cf. reagent monograph Flui escamine Reagent , Volume la). 

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