Tetramethyl benzidine

Tetramethyl-benzidine flMB) 1 M Sulfuric Acid (H2SO4) Yellow/450 nm... 

Tetramethyl benzidine. Incubate for 15 min. The product is blue, and stable in xylene and alcohols. Counterstain with methyl green, and mount in DPX. 

The enzymes commonly used are pure and have a high turnover number (48). They include horseradish peroxidase (with o-phenylene diamine as substrate which yields a yellow colored product, 2,2 azino-(3ethyl)-benzo-sulphonic acid gives green colored product, or tetramethyl benzidine gives a blue product) and alkaline phosphatase (with p-nitro phenyl phosphate as substrate to give a yellow /orange colored product). 

Horseradish peroxidase (HPP), choline oxidase and acetylcholineesterase A three enzyme layered assembly on Au electrodes or Au quartz crystal, consisting of HRP, ChO and AChE is used to sense ACh by the HRP-mediated oxidation of 3,3, 5,5 -tetramethyl benzidine (1) by H202 and the formation of the insoluble product (2) on the respective transducers. Acetylcholine is hydrolyzed by AChE to choline that is oxidized by ChO and 02 to yield the respective betaine and H202. The amount of generated H202 and the resulting insoluble product on the transducer correlates with the concentration of acetylcholine in the samples. 

Crude tetryl commonly contains a small quantity of amorphous-appearing, buff-colored material of high melting point which is insoluble in benzene. The amount of this material is increased by the presence of larger amounts of water in the nitrating acid. Michler and Pattinson found that tetramethyl-benzidine is produced when dimethylaniline is heated with concentrated sulfuric acid. The same material is evidently formed during the preparation of tetryl and gives rise to the three substances indicated below, which constitute the benzene-insoluble impurity. 

A similar mechanism could also be proposed for the 9-methylcarbazole-sensitized C—O bond cleavage of the picolinium esters (142-144) (Scheme 21)251. The formation of Af-methyl-4-picolyl radical 145 is verified by the observation of IV-methylpicolinium ion (146) in the presence of 1,4-cyclohexadiene, a good H-atom donor. Other anilines such ALALW. /V -tetramethyl benzidine and triphenylamine are also efficient sensitizers in this reaction. 

Peroxidase Horseradish 40000 5-7 2,2 -Azino-di(3-ethyl-benzthiazoline sulfonic acid-6) (ABTS)/H202 3,3 -5,5 -Tetramethyl-benzidine (TMB)/H202 o-Phenylendiamine (0PD)/H202 p -Hy droxyphenyl-acetic acid p -Hy droxyphenyl-propionic acid Luminol... 

Several alternative assay format variants have been reported, including an EPBA whereby sample extracts and standards are incubated with a streptavi-din-peroxidase conjugate, and dispensed in microtitre wells coated with biotin-albumin conjugate. After 30 minutes incubation, 3,3, 5,5 -tetramethyl benzidine (TMB) in acidic solution both stop the reaction and create a yellow colour that is measureable at 450 nm. 

One promising lead was the discovery (Colloid Science, Vol. 3, p. 268) that photoionization processes are facilitated in micelles. In the case of tetramethyl-benzidine (118) photolysis in anionic micelles leads to a radical cation that is stable for days. Concomitant with this is expulsion of an electron from the micelle, which reacts stoicheiometrically to produce 0.5 moles of hydrogen and hydroxide ion. Many further examples are now available. Flash photolysis of chloropromazine (119) and its analogues in oxygenated anionic micelles gives efficient photoionization, and a radical cation whose lifetime is >10 longer in the micelle than in water. Laser-induced photoionization of pyrene may be... 

In another study of the phase behavior of Schiff base donor compounds, with 4,4 -dinitro- or 4,4 -dicyanobiphenyl as electron acceptors, or of A,A,A, A -tetramethyl-benzidine as an electron donor with suitable Schiff base acceptors, similar mesophase inductions/stabilizations are reported [11] (see Table 1). Even p-substituted derivatives of nitrobenzene and benzonitrile, respectively, are able to induce or stabilize smectic mesophases (SmA and/or SmB) in mixtures with, for example, the mesogen N-(4-propyloxybenzylidene)-4-hexylaniline [12]. However, in these systems a dipolar mechanism for the enhanced molecular aggregation seems more likely. 

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