Methylene blue confirmation

These findings lead to (he conclusion that the reduction of MHb by its reductase requires a natural cofactor, which is abolished during the purification procedure and can be replaced by methylene blue (G5, H22, H23, K8, K14). Since methylene blue and the other effective dyes are redox intermediates, it is obvious that the postulated cofactor interacts in the electron transport sequence of the MHbR reaction (H23). This is confirmed by the finding that oxygen and cytochrome c serve as well as terminal electron acceptor as does MHb (H22, H23, K14). Nevertheless, it had been possible to separate a cytochrome c reductase from MHbR in yeast extracts (A6). 

Methylene blue and other reducible dyes were shown to enhance the activity of NADPHa-linked MHbR (K8, K9). This is confirmed by the finding that intravenous injections of methylene blue in methemo-globinemic patients result in a striking decrease of MHb levels (e.g., B14, K9, K10). This seems to be paradoxical, since methylene blue is capable of reacting with Hb with formation of MHb, but the dye reacts much more effectively as an artificial electron carrier in the NADPH2-MHbR Systran (B14). It has been stated (K10) that methemoglobin reduction is associated with the formation of pyruvate in equivalent amounts, but that in reactions accelerated by reducible dyes no correlation between pyruvate formation and MHb reduction could be found. 

The charge transfer kinetics of azobenzene at the mercury electrode is slower than that of methylene blue, thus the frequency interval provided by modem instra-mentation (10 < //Hz < 2000) allows variation of the electrochemical reversibility of the electrode reaction over a wide range [79]. The quasireversible maxima measured by the reduction of azobenzene in media at different pH ate shown in Fig. 2.47 in the previous Sect. 2.5.1. The position of the quasireversible maximum depends on pH hence the estimated standard rate constant obeys the following dependence A sur = (62-12pH) S- for pH < 4. These results confirm the quasite-versible maximum can be experimentally observed for a single electrode reaction by varying the frequency, as predicted by analysis in Fig. 2.75. 

Although the leucometabolite of methylene blue has been repeatedly detected (75, 76), recent research (77) cannot confirm its presence in milk various metabolites at different stages of demethylation, in addition to a methylene blue complex, are found instead. Among these metabolites, a trimethyl derivative called azure A, a dimethyl derivative called azure B, a monomethyl derivative called azure C, and completely demethylated thionin have been positively identified. Further investigation demonstrated that the methylene blue complex was a protein-thionin conjugate, whereas thionin was the residue with the longest residence time in milk (78). 

LAS Treatability and Environmental Concentrations. The removal of LAS during sewage treatment was confirmed by monitoring studies in both the United States and Europe. Numerous studies reported anionic surfactant concentrations in surface waters measured by nonspecific analytical techniques such as methylene blue active substance (MBAS). However, the correlation between MBAS and LAS concentrations determined by spe-... 

An example of the results for such an approach is shown in Fig. 2.5 (from Ref [1]), which we now discuss. Methylene Blue (MB) is used here as a probe molecule and is transferred onto gold NP arrays by dipping them into a 10 // M MB solution for 5 minutes. The arrays are plasma-cleaned before any dipping, to ensure that no contaminants are previously adsorbed on the NPs. The MB molecules are therefore adsorbed directly onto the gold surfaces, with possibly some molecules further away from the surface if several monolayers are present. Three NP arrays are used with distinct LSP resonances at 612 nm (array Al), 667 nm (A2) and 713 nm (A3), as evidenced in the extinction spectra of Fig. 2.5(b). The resonance of A2 is close to the peak absorption and fluorescence of MB and would be considered as the standard situation for most MEF experiments (except for the direct adsorption onto the metal). Al and A3 have resonances much further away on either side of the MB fluorescence spectrum. The MEF spectra (corrected for the ITO background), shown in Fig. 2.5(c), exhibit a broad spectrum underneath the SERS (Raman) peaks. The SERS peaks clearly confirm the presence of MB on the NPs surface. The accompanying broad signal is attributed to the modified MB fluorescence (MEF), initially for two reasons ... 

Cationic surfactants can also be tested using methylene blue solution. First add 2 drops of a known anionic surfactant solution to a mixture of 5 ml methylene blue solution and 5 ml chloroform, shake well and leave to stand until the chloroform layer shows as blue. Then add a few drops of the sample solution, shake well and leave for layers to form. If the blue colour in the chloroform layer becomes lighter or colourless, the existence of cationic surfactants in the sample solution can be confirmed. 

The test is conducted as in Section 4.3.1, acidic methylene blue test. If the aqueous layer is emulsified to a milk-like state, or both layers have the same colour, the existence of non-ionic surfactants can be confirmed. 

The appearance of aerobic lactose-splitting colonies on Endo or eosin methylene blue plates made from a lactose broth fermentation tube in which gas has formed, confirms to a considerable extent the presumption that gas-formation in the fermentation tube was due to the presence of members of the B. coli group. 

Make one or more Endo or eosin methylene blue plates from the tube which, after 48 hours incubation, showB gas formation from the emallest amount of water tested. (For example, if the water has been tested in amounts to 10 cc., 1 cc., and 0.1 cc and gas is formed in 10 cc. and 1 cc. not in 0.1 cc., the test need be confirmed only in the 1 cc. amount)... 

LC-PB-MS has been investigated as a potential confirmatory method for the determination of malachite green in incurred catfish tissue, " and cephapirin, furo-semide, and methylene blue in milk, kidney, and muscle tissue, respectively. LC-PB-MS has also been investigated for the analysis of ivermectin residues in bovine hver and milk. The specificity required for regulatory confirmation was obtained by monitoring the molecular... 

Confirmed test Second stage of testing for coliforms in multiple-tube fermentation in which samples from the highest dilution showing gas production are streaked into eosin methylene blue agar. 

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