New fuchsine

In a variation of this method, isolation of the ben2hydrol derivative is not required. The methane base undergoes oxidative condensation in the presence of acid with the same or a different arylamine direcdy to the dye. New fuchsine [3248-91 -7] Cl Basic Violet 2 (16), is prepared by condensation of two moles of o-toluidine with formaldehyde in nitrobenzene in the presence of iron salts to give the corresponding substituted diphenylmethane base. This base is also not isolated, but undergoes an oxidative condensation with another mole of o-toluidine to produce the dye. 

Measurements show some variation depending upon the staining solution used and the method of application. In dried and fixed smears, the cell wall and slime layer do not stain with weakly staining dyes such as methylene blue but do stain with the intensely staining pararosaniline, new fuchsin, crystal violet, and methyl violet. The great majority of bacteria have been measured in fixed and stained preparations. In some instances dried, negatively stained smears have been used. Therefore, the method employed should be specified when measurements of bacteria are reported otherwise the results will be of doubtful v alue. 

These compounds are triphenylmethane pigments. Strictly speaking, they should be referred to as triaminophenylmethane derivatives. The parent structure is known as reddish violet parafuchsin (118) or its anhydro base pararosaniline (119). The parent compound may bear between one and three methyl substituents (fuchsin, new fuchsin). 

The technically important new fuchsine synthesis from a primary aromatic amine and formaldehyde falls, in the case of aniline, into the above reaction scheme since the formation of the intermediate product, p-diaminodiphenylmethane, is readily intelligible. 

Develop the chromogeuic reaction of the second sequence using AEC/H2O2 development for IPO or naphthol phosphate/Fast Blue, Fast Red, or New Fuchsin for lAP development as detailed in Subheading 3.3. (see Note 15 for triple labeling). 

The wide range of chromogenic-substrate systems available allows one to obtain excellent color contrast for double/multiple antigen detection. Chromo-genie reactions resulting in black (IGSS), yellow-brown (IPO/DAB), red-brown (IPO/AEC), blue (lAP/Fast Blue, or 5-bromo-4-chloro-3-indolyl phosphate/ nitroblue tetrazolium [BCIP-NBT]), and purple (lAP/Fast Red or New Fuchsin) can be used in different combinations (see Chapter 23). For development of these products, the following protocols are provided (see Note 16). 

Mix 1 drop New Fuchsin (vial c) with 1 drop sodium nitrite (vial d). After 2 min, mix this chromogen solution to the buffer-substrate solution, shake, and cover the sections with this solution. A purple product will form in 5-15 min. 

Since 1973, the U.S. International Trade Commission has reported the manufacture and sales of dyes by application class only. In 1972, the last year for which statistics are available by chemical class, 3900 metric tons of triarylmethane dyes were manufactured, which represents approximately 4% of total dyestuff production in the United States. At that time, there were 185 triarylmethane dyes Us ted in the Colour Index. From the latter half of the 1970s through the 1980s, annual dye production in the United States, including triarylmethane dyes, changed very litde. In 1981, methyl violet, with an annual production of 725 t, was the only triarylmethane dye for which production statistics were available. Some triarylmethane dyes were imported, eg, malachite green (163 t in 1981), methyl violet (40 t), new fuchsine (30 t), and other dyes totalling less than 15 t. 

This also gives a red end product. Unlike Fast Red TR and Fast Blue BB, the color produced by New Fuchsin is insoluble in alcohol and other organic solvents, allowing for the specimens to be dehydrated before coverslipping. The staining intensity obtained by use of New Fuchsin is greater than that obtained with Fast Red TR or Fast Blue BB. 

New Fuchsin Substrate Solution (recommended for tissue sections)... 

New Fuchsin Incubate the slides for 10 min. The product is red and stable in xylene and alcohols. Counterstain with hemalum and mount in DPX. 

Amino-3-methylphenyI) 4-imino 3-methyl-2,5-cyclohexadien-l-ylidene)methyI -2-methylhenzenamine, 9CI. New fuchsin. C.I. 42520. Astrazon fuchsine GN. Leather ruby HF. Magenta ABN. New fuchsine G crystal. New magenta. Remacryl magenta B. Numerous other proprietary names... 

In experiments of Freundlick on the coarsening of HgS after it had been coagulated with a dye-stuff like new fuchsin, the desorption of the flocculating ion was very marked. The sol of HgS could be flocculated by new fuchsin in such quantities that the supernatant liquid remained practically uncoloured (equivalent flocculation). 

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