TLC determination of dyes in various matrices

Because of the relatively low sensitivity of TLC methods they have not been frequently applied for the analysis of samples containing trace amounts of synthetic dyes. However, TLC techniques have been proven to be a rapid, reliable and valuable tool for the easy following of synthetic procedures for the preparation of new dyes. Thus, the synthesis of some bifunctional reactive triazine dyes has been monitored by TLC. The synthetic pathways a and b are shown in Fig. 3.12. The purity of intermediates was controlled by TLC using a silica stationary phase (Rp value of 2-allylamino-4,6-chloro-l,3,5-triazine = 0.48 

2 Amidoblack 4-Amino-5-hydroxy-3-[4-nitrophenyl)azo]-6-(phenylazo)-2,7-naphtalenedisulphonic acid disodium salt 

4 Bengal Rose 3,4,5,7-Tetrachloro-3, 6 -dihydroxy-spiro[isobenzofuran-l(3H), 9 -[9H]xanthen]-3-one] disodium salt 

5 Brilliant Green N-[4-[[-(Diethylamino)phenyl]phenylmethylethylene]- 2,5 -cyclohexadien-1 -yhdene] -N-ethylethanaminium sulphate 

6 Bromthymol Blue 4,4 -(3H-2,l-Benzoxathiol-3-ylidene)bis[2-bromo-3-methyl-6-(1-methylethyl) phenol]S,S-dioxide 

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