Leuco-malachite green

Thus, simple deproteinization of plasma with trichloroacetic acid, perchloric acid, phosphoric acid, or acetonitrile, followed by centrifugation and direct injection of the supernatants, yielded low recoveries of malachite green and leuco-malachite green, probably due to insufficient debinding of the analytes (495). Acidification or alkalinization of plasma and subsequent extraction with ethyl acetate also resulted in poor recoveries. In contrast, protein denaturation with a mixture of either acetonitrile or methanol and citric acid could substantially improve Ute recovery of the analytes, possibly due to the pairing-ion function of Ure citrate ions. 

Fig. 29.15.1 Representative chromatograms of (a) blank rainbow trout sample, (b) 100 ppb malachite green standard, (c) rainbow trout sample fortified at 50 ppb with malachite green and leuco malachite green, and (d) 50 ppb leuco malachite green standard. (From Ref. 506.).

A leuco compound is also obtained when a benzaldehyde derivative is treated with 2 molar equivalents of an aniline derivative. Leuco malachite green (17) is thus formed from benzaldehyde (15) and dimethylaniline (16). 

Lead peroxide is used for oxidising leuco-bodies. For example, leuco-malachite green (obtained by condensing benzaldehyde with dimethyl-aniline) is converted to the base of malachite greon by heating with PbOa ... 

This dyestuff, which is obtained by sulphonation of leuco-malachite green, and subsequent oxidation, is the oldest of its class j but is not much used at present, as its acid properties are only slightly developed. 

Leuco malachite green from benzaldehyde and dimethylaniline. 299... 

Leuco-malachite green (3.3 g) is dissolved in hot N-hydrochloric acid (40 ml), which is then diluted with water (300 ml), cooled, and treated with a suspension of lead dioxide (2.4 g) in water (20 ml) gradually, within 5 min, with vigorous shaking. The mixture is shaken for a further 5 min on the water-bath, then treated with a clear solution of zinc chloride (4 g). The zinc chloride double salt of the dye salt is then salted out by addition of saturated sodium chloride solution, collected, dissolved again in hot water, and again salted out (yield ca. 3 g). 

J. Olafsson, The Semi-Automated Determination of Manganese in Sea Water with Leuco-Malachite Green. Sci. Total Environ., 49 (1986) 101. 

Two dyes were separately absorbed at the expanded inner surfaces of a gel. One surface contained the photosensitizer adsorbate, and the other surface the acceptor sorbate. When mixed, the particles are in contact with one another, but the sensitizer and the acceptor are not. The critical experiment for the detection of diffusable, activated oxygen involved irradiating the sensitizer dye, and observing photochemical bleaching of the acceptor dye. The sensitizer was trypaflavine and the acceptor was leuco-malachite green. 

In fact, the earliest application of kinetic methods was to determine trace levels of substances exerting catalytic activity in oxidation-reduction reactions involving multiple electron transfers (1885-trace level V on its catalysis of the oxidation of aniline). For example, the reduced form of many triphenylmethane dyes is colorless , and loses two electrons on oxidation to the dye. The rate of reaction with such oxidants as 104 is relatively slow, but can be catalyzed by trace levels of transition metal ions which involve single electron transfer in their own redox steps. Thus, trace levels of manganese can be determined by the proportionality of the rate of oxidation of leuco-malachite green by iodate at less than micromolar concentrations. Similarly, trace levels of Cu ", < 10 M, can be determined from the catalytic effect on the atmospheric oxidation of ascorbic acid. Such systems can be written as a generalized redox reaction... 

Gj reactions are in effect Gj, processes in which the two radical sites have very different electronegativities. A typical example is the photochemical conversion of colorless leuco Malachite Green cyanide to the... 

Other tests for cerium v compounds [a) Leuco malachite green is oxidized to malachite green by Ce(OH)4, which is formed from Ce(OH)8 by autoxidation. Interference due to Mn(OH)2, Co(OH)2, Tl(OH)a and AgaO, which react in the same way, may be prevented... 

Leuco malachite green Ammonium naphthoate, anthra- 0.03 175... 

Dissolve 0.20 g of alcohol recrystallized leuco-malachite green in 250 ml of pure acetone. This solution is stable but should not be allowed to evaporate. The development of a slight green colouration does no harm. 

Phenylmethylene)bis[N, -dimethylbenzenamine], 9CI. 4,4 -Benzylidenebis[N,l> -dimethylanilme], SCI. 4,4 -Tetramethyldiaminotriphenylmethane. Leuco-malachite green. 4,4 -Di dimethylamino)tritane. C.I. Basic green 4 leuco base [129-73-7]... 

Leucine A -carboxyanhydride, see M-00261 Leuco-berbelin blue I, see B-00322 Leuco-malachite green, see B-00327 Leuco-methylene blue, see B-00316 Leucoquinizarin, see A-00381 Leucylalanine, L-00005 iV-L-Leucyl-D-alanine, in L-00005 Leucyl-p-nitroanilide, L-00006 Levamfetamine, in P-00172 Levamfetamine succinate, in P-00172 Levamphetamine, in P-00172... 

Pinacryptol yellow, modified Dragendorff reagent, ninhydrin, iodine, leuco-malachite green, molyb-dophosphoric acid, cobalt thiocyanate, and supres-sion of fluorescence of the F-254 plates... 

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