Methylene blue

“ The chief ingredient was found to be a blue dye stuff of the oxazine or thiazine group, much resembling methylene blue (which is the only member of these groups ordinarily used in medicine) , but differing from it in solubility and in its behaviour with certain reagents. This constituted [Pg 119] the greater part of the sediment, and a portion of the dye was also in solution. The liquid further contained a dissolved gum and a trace of terebene; these, with a little magnesium carbonate, were all the ingredients present. No trace of any alkaloid was found, and the solvent was water. ”

“ If hydrogen sulphide is passed through a solution of methylene blue the dye is very quickly reduced and becomes colorless. If the H2S is driven off by boiling the colorless methylene-blue solution, the blue color again returns on cooling. Oxyluciferin can also be reduced by H2S.
If one adds some Mg powder to oxyluciferin and then dilute acetic acid in successive additions as the acetic acid is used up in formation of Mg acetate, the oxyluciferin will be reduced relatively quickly. Nascent hydrogen is produced in the reaction and is no doubt the active reducing agent. ”

“ Here again we find scientific research reacting on technology. A few words of chemical explanation will make this manufacture intelligible. By the action of reducing agents on nitro and nitroso-compounds, the nitro and nitroso-group become converted into the amido-group. Thus when nitrobenzene is reduced by iron and an acid we get aniline; similarly when nitrosodimethylaniline is reduced by zinc and an acid we get amidodimethylaniline, and this is the base used in the preparation of methylene blue. By oxidizing this base in the presence of sulphuretted hydrogen, the colouring-matter is formed. ”

“ Aspirate the (upper) organic layer to waste. Exercise care to not remove any of the aqueous layer. 9.
Extraction of analytes into methylene chloride: a. Add 1-2 drops (20-50 μL) of the mixed pH indicator (phenolphthalein + bromothymol blue) solution to each sample. The color of the samples should be yellow, which indicates that the samples are sufficiently acidic for desorption of the analytes from the wipe samples. b. Add 0.5 mL of 10 M sodium hydroxide to each sample. ”

“ Now these products—dimethylaniline, diethylaniline, and diphenylamine—are derived from aniline, and they are all sources of colouring-matters. Methyl-violet is obtained by the oxidation of dimethylaniline by means of a gentle oxidizer; a mixture of bases is not necessary as in the case of the magenta formation. Then in 1866 diphenylamine was shown by Girard and De Laire to be capable of yielding a fine blue by heating it with oxalic acid, and this blue, on account of the purity of its shade, is still an article of commerce. ”

“ They are now to be removed, and after rapid rinsing in methylated spirit to remove all superfluous colour, they must be placed in a blue staining fluid made by dissolving half a grain of aniline blue in one drachm of distilled water, adding ten 74minims of dilute nitric acid and afterwards sufficient methylated spirit to make two fluid ounces. ”

“ Methyl iodide and methyl bromide.—Methyl iodide (CH3I) , a volatile fluid, is obtained by distillation of wood spirit with amorphous phosphorus and iodine; it is used in the production of methylated tar colours and for the production of various methylene compounds. ”

“ If there are natural colouring-matters which are fast and which are æsthetically orthodox, these are rivalled by tar-products which fulfil the same conditions. Such dyes as aniline black, alizarin blue, anthracene brown, tartrazine, some of the azo-reds and naphthol green resist the influence of light as well as, if not better than, any natural colouring-matter. The artificial yellow dyes are as a whole faster than the natural yellows. There are at the present time some three hundred coal-tar colouring-matters made, and about one-tenth of that number of natural dyes are in use. ”

“ It is advisable to use methyl orange indicator in these titrations as phenolphthalein is affected by the carbon dioxide generated when an acid reacts with a carbonate and does not give the proper end point, unless the solution is boiled to expel the carbon dioxide. Litmus may also be used as the indicator, but here again it is necessary to boil as carbon dioxide also affects this substance. As an aid to the action of these common indicators the following table may be helpful: [Pg 136]
It may be further stated that methyl orange at the neutral point is orange in color. ”

“ A review of the scientific literature concerning CS agent has located no estimates of the concentration of methylene chloride which would prove harmful or lethal to humans. The only estimates which do exist are with respect to mice and rats. For example, the concentration that would prove lethal to 50 percent of a rat population is estimated to be 2,640,000 mgs-min/m^3. ”

“ The red substance is not produced at every temperature; 300° C. is the most favourable. On washing sodium chloride is dissolved; the washed violet is free from chlorine, but has taken up water, which is expelled on heating, when the violet turns to blue. A similar brownish-red body is formed when sulphur trioxide is led over heated ultramarine blue, and when sulphur chloride acts on warm ultramarine blue. When the brownish-red chlorine compound is introduced into absolute alcohol, a reddish-violet compound is produced, containing organic matter. ”

“ Methyl orange (helianthin, gold orange, Mandarin orange) , (CH3) 2N·C6H4·N2·C6H4SO3Na, is the sodium salt of para-dimethylaminobenzene-azo-benzene sulphonic acid. It is an orange crystalline powder which is soluble in water, forming a yellow solution. The free acid is intensely red in colour. Methyl orange is used largely as an indicator. The constitution of methyl orange follows from the fact that on reduction by stannous chloride in hydrochloric acid solution it yields sulphanilic acid and para-aminodimethyl aniline. ”

“ He testified that "in some sense [methylene chloride] acts like an inhibitor." [17] He further testified that he conducted experiments using methylene chloride as a "wetting" agent by depositing it on wood, paper, and other flammable objects that might have been found in the structure in an effort to determine whether the methylene chloride might have burned along with these items. As a result of these experiments, he concluded "that the methylene chloride had no enhancement effect on the fires spread over the room furnishings and other things that burned in the compound." ”

“ Assuming that all of the CS inserted by the CEV's during one phase was inserted at a single moment, and that approximately \1/4\ of the Ferret round projectiles used during the entire operation also entering the building at that same time (thus adding an additional 3,300 grams of methylene chloride in each phase [68] ) , and that the Davidian residence was airtight, the concentration of methylene chloride during each of the first two phases would have been 548 ppm. [69] At this concentration, studies have shown no observable effects in humans. ”

“ For example, if you want a violet of a very blue shade, and you take Methyl Violet and dissolve it in water and then add Aniline Blue also in solution, you find that precipitation of the colour takes place in flocks. A colouring matter which requires, as some do, to be applied in an acid bath, ought not to be applied simultaneously with one that dyes best in a neutral bath. ”

“ Another blue, of quite a different tint, may be produced by letting a few drops of a solution of ammonia fall into one of sulphate of copper, when a precipitate of a light blue falls down, which is dissolved by an additional quantity of the ammonia, and forms a transparent solution of the most splendid rich blue color. ”

“ Among the reds there is great variation in properties, generally they are not fast to light, standing washing and soaping well and resisting weak alkalies; some of them, such as the Benzo purpurines and Congo reds are very sensitive to acids, being turned blue with very weak acids, but on washing or soaping the original colour comes back; others, like the Titan reds, Diamine reds and Delta purpurines are not so sensitive, but these are affected by moderately strong acids; there are one or two reds like Benzo fast scarlet 4 B S and Purpuramine D H, which are fast to acids. ”

“ It is a dark-blue solid substance, somewhat like indigo, assumes a metallic fiery lustre on friction, and varies in tint from copper to golden. It is void of taste and smell, not volatile; carbonizes at a high heat without emitting an ammoniacal smell; is soluble or rather very diffusible in water; gives a green solution with a cast of crimson, in sulphuric acid, with a cast of red blue, in muriatic acid, and with a cast of aurora red, in acetic acid. It is insoluble in alkalis. It dyes a fast blue upon linen and cotton goods, with tin and aluminous mordants. ”

“ It is used both as a dye for wool and as a pigment. It may be mentioned here that other nitroso-derivatives of phenols, such as those of resorcinol and the naphthols, under the name of “gambines,” are largely used for dyeing purposes, owing to the facility with which they combine with metallic mordants to form coloured salts in the fibre. In this same year, 1879, it was found that by heating nitrosodimethylaniline with beta-naphthol in an appropriate solvent, a violet colouring-matter was formed. ”

“ Significant heat is generated when the desorbing solution is added to the charcoal. To minimize sample loss, chill the desorbing solution before adding to the charcoal [4] . 7. Allow to stand 30 min with occasional agitation to aid desorption.
CALIBRATION AND QUALITY CONTROL: 8. Calibrate daily with at least six working standards over the range of interest. Three standards (in duplicate) should cover the range from the LOD to LOQ. a. Add known amounts of methylene chloride to CS 2 in 10-mL volumetric flasks and dilute to the mark. ”

“ As methyl orange is not affected by carbonic acid, bicarbonates of alkaline earths have an alkaline reaction, and may be estimated in solution by standard acid like the alkalies themselves. 100 c.c., or in soft waters 200 c.c., of the water is measured into a beaker, a drop or two of solution of methyl orange added, and decinormal hydrochloric or sulphuric acid run in from the burette with constant stirring till the colour just changes to pink. ”

“ If a solution of methyl green be allowed to fall drop by drop into a solution of an acid dye, for instance orange g., a coarse precipitate first results, which dissolves completely on the further addition of the orange. No more orange should be added than is necessary for complete solution. This is the type of a simple neutral staining fluid. ”

“ The conversion of acetylene into ethylene, and the synthesis of alcohol were also important reactions. Acetylene polymerizes, under the influence of the electric spark, into benzene, and many of its derivations were formed by Berthelot. He also formed methane by passing the vapour of carbon disulphide and sulphuretted hydrogen over hot copper; and by the action of carbon monoxide on a hot solution of caustic potash, potassium formate was produced, the formate yielding formic acid on distillation with hydrochloric acid. ”

“ Other possible effects of methylene chloride used with CS at Waco While the subcommittees conclude that the levels of methylene chloride did not reach lethal toxic levels, the subcommittees also considered whether the levels of methylene chloride may have affected the Davidians in other ways. At levels over 1,000 parts per million (ppm) anaesthetic effects begin to occur in humans. [65] At levels above 2,300 ppm, exposure to methylene chloride may cause dizziness. ”

“ About a dozen distinct compounds producing different shades of pink, crimson and red, and all derived from fluoresceïn, are at present in the market, and a few other phthaleïns formed by heating phthalic anhydride with other phenolic compounds instead of resorcinol or pyrogallol (e.g. diethylamidophenol) , are also of industrial importance. ”

“ Blue.—Alkali blue, soluble blue, opal blue, methyl blue, Höchst new blue, patent blue, ketone blue, cyanine, thiocarmine, fast blue, induline, violamine 3 B, azo acid blue, wool blue, indigo extract, erio glaucine, erio cyanine, erio blue, lanacyl blue, sulphon-azurine, sulphon-cyanine. ”

“ The first of these colouring-matters derived from the naphthols, was introduced in 1876-77 by Roussin and Poirrier, and by O. N. Witt. They were prepared by converting aniline into a sulpho-acid (sulphanilic acid) , diazotising this and combining the diazo-compound with alpha- or beta-naphthol. The compounds formed are brilliant orange dyes, the latter being still largely consumed [Pg 151] as “naphthol orange.” Other dye-stuffs of a similar nature were introduced by Caro about the same time, and were prepared from the diazotised sulpho-acid of alpha-naphthylamine combined with the naphthols. ”

“ Carbon disulfide is toxic and a serious fire and explosion hazard (flash point = -30 C) . Methylene chloride is a suspected carcinogen. Wear appropriate protective clothing and work with these compounds in a well ventilated hood.
SAMPLING: 1. Calibrate each personal sampling pump with a representative sampler in line. 2. Break ends of sampling tubes immediately before sampling. Attach sampler train to personal sampling pump with flexible tubing. 3. Sample at an accurately known flow rate between 0.01 and 0.2 L/min for total a sample size of 0.5 to 2.5 L. 4. ”

“ Samples of methylal in dry air were generated using a three-neck round-bottom generator flask containing the liquid methylal. An accurately measured flow of nitrogen gas was used to sweep the vapors out of the flask. Overall precision, s r, was 0.060 with average recovery of 104%. Desorption efficiency was 78, 81, and 88%, respectively, at 3.1, 6.2, and 12.3 mg methylal taken per sample. Breakthrough (5% on back section) occurred at 20 min when sampling an atmosphere containing 6250 mg/m 3 methylal at 0.183 L/min at 0% RH. Breakthrough at high humidity was not tested, nor was sample stability. ”