Sensitizers crystal violet

Carbonless Copy Paper. In carbonless copy paper, also referred to as pressure-sensitive record sheet, an acid-sensitive dye precursor, such as crystal violet lactone or /V-hen2oy11eucomethy1ene blue, is microencapsulated with a high boiling solvent or oil within a cross-linked gelatin (76,83,84) or in synthetic mononuclear microcapsules. Microcapsules that have a starch binder are coated onto the back of the top sheet. This is referred to as a coated-back (CB) sheet. The sheet intended to receive the image is treated on the front (coated-front (CF)) with an acid. When the top sheet is mechanically impacted, the dye capsules mpture and the dye solution is transferred to the receiving sheet where the acid developer activates the dye. 

In this work hybrid method is suggested to determine anionic surfactants in waters. It is based on preconcentration of anionic surfactants as their ion associates with cationic dyes on the membrane filter and measurement of colour intensity by solid-phase spectrophotometry method. Effect of different basic dyes, nature and hydrophobicity of anionic surfactants, size of membrane filter pores, filtration rate on sensitivity of their determination was studied. Various cationic dyes, such as Methylene Blue, Crystal Violet, Malachite Green, Rhodamine 6G, Safranin T, Acridine Yellow were used as counter ions. The difference in reflection between the blank and the sample was significant when Crystal Violet or Rhodamine 6G or Acridine Yellow were used. 

Benzoyl leuco Methylene Blue (1), which is a phenothiazine leuco dye, has been known since 1900. The material was developed to extend the range of hues and colors obtainable in such applications as pressure-sensitive carbonless paper and to complement other classes of leuco dyes such as triarylmethanes, crystal violet lactone, and fluorans. Benzoyl leuco Basic Blue 3 (2), which is a phenoxazine leuco dye, is a more recent development. 

Sensitivity to the lethal effects of the high-molecular-weight dye crystal violet for those strains carrying the rfaE mutation ... 

Nonchelating dyes include basic triphenylmethane dyes (e.g., Brilliant Green, Malachite Green, Crystal Violet), xanthene dyes (e.g., Rhodamine B, Rhodamine 6G), azine dyes (e.g., Methylene Blue), and acid dyes (e.g., Eosin, Erythrosin). These are intensely colored and when paired with an oppositely charged analyte ion lead to high sensitivities. 

Instead of MV2+ (in the photo-oxidation of leuco crystal violet (LCV)), a neutral species is sensitized by pyrene containing polymers and the Coulombic effect is not as drastic as in the case of MV2+. As shown in Figure 8, the cationic polymer is more effective than the neutral or anionic polymer. This is attributed to the Coulombic repulsion between LCV- and Py assisted by the cationic environment of the polycation. However, the Coulombic effect occurs only after forward electron transfer. 

In the presence of the dye the photocurrent at both semiconductors is observed in the visible region of the spectrum, i.e., in that region where crystal violet absorbs light. Thus, sensitization is observed. Photoprocesses that take place at zinc oxide and gallium phosphide can be represented by schemes of Figs. 23c and 23b, respectively. 

Lopez Garcia et al. [2] have described a rapid and sensitive spectrophotometric method for the determination of boron complex anions in plant extracts and waters which is based on the formation of a blue complex at pH 1 - 2 between the anionic complex of boric acid with 2,6-dihydroxybenzoic acid and crystal violet. The colour is stabilised with polyvinyl alcohol. At 600 nm the calibration graph is linear in the range 0.3-4.5 xg boron per 25 ml of final solution, with a relative standard deviation of 2.6% for xg/l of boron. In this procedure to determine borate in plant tissues, the dried tissue is treated with calcium hydroxide, then ashed at 400 °C. The ash is digested with 1N sulfuric acid and heated to 80 °C, neutralized with cadmium hydroxide and then treated with acidic 2,6-dihydroxybenzoic acid and crystal violet, and the colour evaluated spectrophotometrically at 600 nm. Most of the ions present in natural waters or plant extracts do not interfere in the determination of boron complex anions by this procedure. Recoveries of boron from water samples and plant extracts were in the range of 97 -102%. 

The chapter is divided into five sections. In Sec. Ill, we discuss how the molecular structure of crystal violet (CV), which is one of TPM dyes selected, is sensitive to its surrounding solvent molecules in solution. Recently, subtle structural differences in the ground state of CV was identified in alcohols by means of a femtosecond spectral hole-burning technique [19-21], Two key points of these studies are (1) proposal of a novel class of isomers, which are differentiated from one another by solvation and (2) conclusive decision of a long-run dispute over 50 years on whether the ground-state conformational isomers exist. 

Color formers are very sensitive to the addition of acids and solvents. In acid, crystal violet lactone (6) is only partially converted to the colored carboxylic acid (7) with opening of the lactone ring nax (log e) = 603 nm (4.41) in methanol / acetic acid (1/1)]. 

M in concentration. This is in the range required for single-molecule detection. These sensitivity levels have been obtained on colloidal clusters at near-infrared excitation. Figure 10.3 is a schematic representation of a single-molecule experiment performed in a gold or silver colloidal solution. The analyte is provided as a solution at concentrations smaller than 10-11 M, Table 10.1 lists the anti-Stokes/Stokes intensity ratios for crystal violet (CY) at 1174 cm-1 using 830-nm near-infrared radiation well away from the resonance absorption of CY with a power of 106 W/cm2 [34]. CV is attached to various colloidal clusters as indicated in the table. Raman cross sections of 10-16 cm2/molecule or an enhancement factor of 1014 can be inferred from the data. 

Procedure Transfer about 300 mg of the test article (accurately weighed) to a 150-mL beaker, dissolve in 1.5 mL of anhydrous formic acid, and add 60 mL of glacial acetic acid. Add crystal violet Test Solution, and immediately titrate with 0.1 N HCIO4 to a green endpoint. Perform a blank determination, and make any necessary correction. Each milliliter of 0.1 N HCIO4 is equivalent to 29.43 mg of aspartame. The method description cautions that a blank titration exceeding 0.1 mL may be due to excessive water content, and may cause loss of visual endpoint sensitivity. 

The author showed, that only UV light was active and that a polar solvent was required and described the reaction as a benzylic heterolysis. This and related photochemical reactions with the leuco derivatives of crystal violet and malachite green were later studied in detail in their mechanism [3-9] and were among the first compounds proposed as chemical actinometers [10-12], although in the event these were found to be less suited than other derivatives, since the high sensitivity was counterbalanced by the high absorption of the photoproducts in the UV. 

The sensitization effect is not limited to the above mentioned dyes. For example, Terrel98 studied charge carrier generation and injection processes in the crystal violet/PVK system. Meier et al.124 extended the spectral response of PVK to over 600 nm by pinacyanol. Okamoto et al.12s sensitized PVK into the visible region by Malachite Green, etc. 

Selective photosensitized oxidation of some amino acids present in proteins can be also utilized for specific labeling with a chosen sensitizer (methylene blue and hematoporphyrin for methionine, crystal violet or cresol red for cysteine, proflavine for tryptophan, etc.). This topic is described by Scoffone et al. 

The antibody-coated red cells are prepared as previously described. It is particularly important for this procedure that the indicator red cells are absolutely free of clumps. The sensitivity of coated cells can be assayed by reverse passive hemagglutination if, as in the model under consideration, the antigen is available in soluble form. The cells under study are washed in suitable tissue culture medium or other buffered solution and suspended at a concentration of 10 per milliliter in the same diluent to which serum has been added (usually 1% fetal calf serum). A small volume (50-100 /U.1) of the cell suspension is placed in a 10 x 75 mm disposable tube. The addition of an equal volume of 1% coated red cells results in a mixture that contains about 25 red cells per lymphocyte. Linkage of antibody on the red cells to the corresponding antigen determinant on the surface of the lymphocyte results in the formation of a rosette or lymphocyte surrounded by red cells. The mixing of cells and incubation for at least 1 hr are done in an ice bath. The tubes are then centrifuged very briefly (1 min at 1000 g), and a drop of dye is added to tint the lymphocytes (e.g., crystal violet or brilliant cresyl blue). The mixture is then aspirated four or five times with a Pasteur pipette and examined in a hemacytometer chamber at about 400 x. A cell is scored as a rosette if it is surrounded by three or more adherent erythrocytes, and usually 300 cells are counted. 

Methyl violet is gradually turned blue green, and ultimately a pale salmon colour by nitric peroxide. It is much less sensitive than starch iodide. For the test, 2 5 g. of the dried sample, of explosive is placed in a glass tube 29 cm. long and i 5 cm. internal diameter. The sample is pressed down to occupy a depth of 5 cm. and a methyl violet paper is placed in the tube with its lower edge 2 5 cm. above the explosive. The tube is inserted in a bath at 154 to 135 so that about 6 to 7 mm. of the tube projects from the bath. After twenty minutes the tube is partially withdrawn to examine the paper, and this is repeated at intervals of five minutes until the paper becomes salmon-pink. The time of the test should be at least thirty minutes. The papers are prepared by dipping Schleicher and Schiill s filter paper No. S97 in a solution of pure rosaniline acetate (prepared from 0 25 g. basic rosaniline, 0168 g. methyl violet (crystal violet), 4 c.c. glycerine, 30 c.c. water, made up to too c.c. with pure 95 per cent, alcohol. The dried paper is cut into strips 2X7 cm. 

Sensitive extraction spectrophotometric methods for determining Sb have been based on the ion-pair formation between SbCl5 and the basic triphenylmethane dyes [37]. Brilliant Green (e=7.0-10 ) [3,37-46], Crystal Violet [25,37,47-49], Methyl Violet [12,37], Methyl... 

Sensitive methods for determining arsenic are based on ion-associates formed by molybdoarsenate and basic dyes. Flotation-spectrophotometric methods with the use of Crystal Violet (mixture of cyclohexane and toluene as flotation solvent, e=3.210 ) [51] and Malachite Green (flotation with diethyl ether, e=3.2-10 ) [52] have been proposed. The ion-associate with Ethyl Violet is extracted with a mixture of cyclohexane and 4-methylpentanone (1+3) (8=2.810 ) [53]. 

Perchlorate ions form extractable ion-associates with basic dyes such as Brilliant Green (e= 9.4-10 ) [34,35], Malachite Green [36,37], Crystal Violet [38], Methylene Blue [39], and the oxidized form of Variamine Blue [40]. Chloroform, dichloroethane, benzene, nitrobenzene and toluene have been used as extractants. Perchlorate impurities in potassium chlorate have been determined by these sensitive methods [34]. The FIA technique has been applied in the determinations [35]. 

High sensitivity characterizes methods based on the formation of sparingly water-soluble ion-associates of germanomolybdate (Mo-Ge) with basic dyes. The compound with Rhodamine B can be floated and then dissolved in ethanol. The molar absorptivity is -3.7-10 [40]. The Mo-Ge compounds with Methylene Blue, Crystal Violet or Malachite Green, can be centrifuged and then dissolved in acetone. The molar absorptivities are 4.5-10, 4.2-10, and 6.2-10, respectively [41 3]. The ion associate formed by the Mo-Ge anion (reduced with ascorbic acid) with Chrompyrazole II has been floated by shaking with toluene, then dissolved in acetone [44]. 

Mercury(II) forms anionic complexes with F, Br, and CF ions, which react with basic dyes to give ion-associates extractable into organic solvents. Sensitive extractive spectro-photometric methods for determining mercury are based on such reactions with the following dyes Crystal Violet (e = O-IO -IO-IO ) [43 6], Malachite Green and Methyl... 

A very selective variant of these methods has been proposed [52]. Mercury is extracted into benzene as a molecular species, Hgt or HgBr2, which is transformed into a coloured ion-associate by equilibration of the extract with an aqueous basic dye solution also containing iodide or bromide ions. The highest sensitivities have been obtained with Brilliant Green, Crystal Violet and Butylrhodamine B. 

Some methods based on ion-association of thiocyanate anionic complexes with basic dyes are very sensitive. To name a few, they include Crystal Violet (e = 2.3-10 ) [90], Rhodamine B [91,92], and Rhodamine 6G [92,93]. The ion-associate of... 

Flotation-spectrophotometric methods based on ion associates of Brilliant Green and W complex with 3,5-dinitropyrocatechol (e = 1.3-10 ) [148], and of Crystal Violet and thiocyanate complex of W (e = 2.1-10 ) [149] are very sensitive. 

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