Direct Brown

Azo-stilbene dyes formed by diazotization of a condensation product containing primary amino groups and coupling with azo dye coupling components, eg. Direct Brown 29 (Cl 40505) (6) ... 

Two important browns, other than benzidine derivatives, are of azo chemical composition. Direct Brown 30 [6222-60-2] (82) (Cl 17630) is produced by coupling Primuline [30133-37-2] (Cl 49000) to N-phenylgamma acid under alkaline conditions. Direct Brown 44 [6252-62-6] (Cl 35005-35010) is produced by coupling two moles of sulfanilic acid to Bismark Brown [10114-58-6] (Basic Brown 1) (Cl 21000) forming a heterogeneous product with a significant component (83). 

DHEW/NIOSH/NCI, Joiat Intelligence Bulletin No. 24, Direct Black 38, Direct Blue 6, and Direct Brown 95," Ben dine DerivedDjes, NIOSH Pubhcation No. 78—148, Dept, of Health, Education, and Welfare, Washington, D.C., 1978. 

Sludge Reactive Black 5, Direct Brown 2, glucose Escherichia coli, Pseudomonas sp. [135]... 

Reactive Black 5 and Direct Brown 2 Granulated anaerobic sludge mixed culture Decolorization and substrate removal were achieved under test conditions but ultimate removal of azo dyes and substrate were not observed at high dye concentrations. Aromatic amine and volatile fatty acid accumulation observed proportionally at higher azo dye concentration [135]... 

Ghodake G, Jadhav S, Dawkar V, Govindwar S (2009) Biodegradation of diazo dye Direct brown MR by Acinelobacler calcoaceticus NCIM 2890. Int Biodeter Biodegr. doi 10.1016/j. ibiod.2008.12.002... 

Consortium Reactive black 5 direct brown 2 Shaked bottles Batch... 

Reactive black 5 Direct brown 2 Consortium - B rdye = 1.2 x I0 3 DyeL rdye = 6.8 x 10 4 DyeL... 

Isik M, Sponza DT (2004) A batch kinetic study on decolorization and inhibition of Reactive Black 5 and Direct Brown 2 in an anaerobic mixed culture. Chemosphere 55 119-128... 

Direct Yellow 12 Direct Green 6 Direct Brown 2 Direct Black 38 Direct Blue 15 Direct Red 23 Congo Red Direct Orange 26 Tartrazine P. chrysosporium ZrOCl2-activated pumice [54]... 

It is in the direct dye class that the more complex polyazo dyes come into their own, and trisazo structures such as Cl Direct Blue 78 (4.64), Cl Direct Brown 222 (4-65) and Cl Direct Black 38 (4.66) are classic examples of this type of dye. The last-named dye is now known to be carcinogenic [72]. Generally, the A—>M2— E type (such as 4-64) afford reasonably bright blue shades whilst dyes prepared according to other sequences, such as the E<—D— Z<—A type (examples 4.65 and 4-66) yield drab shades. 

Fig. 3.105. HPLC chromatograms for enzymatic reduction, (a) Xylidine ponceau-2R (1 = 2,4-xyli-dine, 2 = 2,6-xylidine, 3 = 2,4,5-trimethylaniline). (b) Direct black-38 (1 = benzidine, 2 = 4-aminophenyl). (c) Direct brown-1 (1 = benzidine, 2 = 4-aminobiphenyl). Conditions mobile phase, acetonitrile (A) and water (B) flow rate, 0.7 ml/min 25°C injection volume, 10 p gradient elution 0 min, A 23 per cent, B 77 per cent 0-21 min, A 34 per cent and B 66 per cent 21-30 min, A 60 per cent and B 40 per cent 30-34 min, A 70 per cent and B 30 per cent 34-37 min, A 90 per cent and B 10 per cent and 37—40 min, A 23 per cent and B 77 per cent. Detection at 280 nm. Reprinted with permission from M. Bhaskar et al. [159].

DHHS (NIOSH) Publication No. 78-148, Direct Blue 6, Direct Black 38 and Direct Brown 95 Benzidine Derived Dyes, Washington, DC, 1978. 

Direct Black 38 (see also Benzidine-based dyes) Direct Blue 6 (see also Benzidine-based dyes) Direct Brown 95 (see also Benzidine-based dyes) Disperse Blue 1 Disperse Yellow 3... 

F. Blue 2B 250% (C.I. Direct Blue 6, C.I. No. 22610), Direct Brown BRL 200% (C.I. Direct Brown 95, C.I. No. 30145) Fabricolor Inc. Evans Blue (C.I. Direct Blue 53, C.I. No. 23860), Benzo Azurine G (C.I. Direct Blue 8, C.I. No. 24140) Pfaltz and Bauer Inc. Benzidine was obtained from Sigma Chemical Co., o-tolidine from Fisher Scientific Corp. and 3,3 -dimethoxybenzidine (o-dianisidine) from Eastman Kodak Company. Aniline, -aminophenol, -phenylenediamine and -nitroaniline used in the interference study were obtained from Chem Service Inc. 

C.I. Direct Black 38, C.I. Direct Brown 95 and C.I. Direct Blue 6 were studied individually in the visible spectrum. A baseline was recorded using the phosphate reduction buffer in both cells. Subsequent additions of known amounts of dye and scanning allowed absorption maxima and molar absorptivity to be determined. Then 3 mg of sodium hydrosulfite was added to the dye-containing cell. The concentration of dye remaining after reduction was calculated using Beer s Law. The remaining dye varied from 0 to 6% of the original amount of dye added (Table I). Reduction was complete within 30 minutes. 

C.I. Direct Blue 6 C.I. Direct Brown 95 C.I. Direct Black 38... 

Three of the dyes (C.I. Direct Blue 8, C.I. Direct Black 38 and C.I. Direct Brown 95) had been analyzed for residual benzidine content during previous work (21 ). None of the dyes contained sufficient quantities of residual benzidine to require a correction to be made to the total amount of benzidine found in the reduced dye samples. 

The repeatability and stability studies were done at concentration levels which preliminary evidence on liquid samples had shown to be reproducible within 10% CV. However, this was not the case for three of the dyes (C.I. Direct Red 28, C.I. Direct Brown 95, and C.I. Direct Black 38). In this situation, the lowest analytically quantifiable limit (LAQL) had to be redefined. From the results of the repeatability study, the second highest level was the logical choice for this redefined LAQL. A second abbreviated stability study was conducted with C.I. Direct Red 28, C.I. Direct Black 38, and... 

C.I. Direct Brown 95 at this new LAQL. Because of the problems encountered with the midget impinger humidification system, changes were made to incorporate one large impinger and supply the humidified air to the filter cassettes at atmospheric and not reduced pressure. Again, 60 L of humidified air were pulled through each cassette. The results of this study are shown in Table V. Recoveries of C.I. Direct Black 38 and C.I. Direct Brown 95 were approximately 90%. 

This method has been used to analyze both symmetrical (C.I. Direct Red 28 and C.I. Direct Blue 6) and unsymmetrical (C.I. Direct Black 38 and C.I. Direct Brown 95) benzidine-based dyes. Based on this work, the application of the method to other benzidine-based dyes should be straightforward. When field samples are submitted for benzidine-based dye analysis, bulk samples of the dyes present in the sample also should be submitted. With these bulk samples, the analyst should be able to determine if this method is applicable to the various dyes submitted and if any interferences are present. The method presently has not been tested on field samples. An existing sampling method (J 3) for azo dyes and diazonium salts should be directly applicable to this method with a change from a cellulose ester to a Teflon filter. This change is necessary to insure quantitative recovery of the sample from the filter. 

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