Nile Blue A

Ostle, A., Holt, J.G., 1982. Nile blue A as a fluorescent stain for poly-b-hydroxybutyrate. 

In the Nile blue spectrophotometric method, 10 ml 2% aqueous hydrofluoric acid is added to a 10 ml sample contained in a polyethylene bottle. The mixture is shaken for about 2h. Aqueous ferrous sulfate 10% 10 ml and 1ml 0.1% aqueous Nile blue A are added, then extracted with o-dichlorobenzene (10 ml and 3x5 ml). The combined organic extracts are diluted to 50 ml with the solvent and the extinction measured at 647 nm. Interference from chloride ions up to 100 mg/1 can be eliminated by precipitation as silver chloride. 

Nile blue A [aminonaphthodiethylamino- 0.406J -0.119 1.4-12.3 Colorless to blue... 

In the case of fluorescence spectra, it is the emission of the radiation from the excited state that is measured, rather than its absorption. This also provides valuable information. As an example, tetraethylorthosilicate (TEOS)-based gels were doped with two optically active organic indicators, thionin and nile blue A. Before trapping in a solgel host, thionin and nile blue A were both evaluated for solvent and protonation effects on their spectral properties. Only extreme pH values provided by HCl, NaOH, and NH4OH produced new absorption and/or fluorescence bands. The absorption and fluorescence spectra revealed a decrease in a pH 11 solution of NH4OH compared to neutral conditions (Krihak et al., 1997). 

Nicotinic acid hydrazide [553-53-7] M 137.1, m 158-159 . Crystd from aqueous EtOH or benzene. Nile Blue A [3625-57-8] M 415.5, m 138 (dec). Crystd from pet ether. 

Figure 13.7 Raman spectra of Nile Blue A on roughened Ag electrode, glassy carbon electrode (GC), and in solution pH = 9.0. Excitation wavelength = 488 nm. Laser power for Ag, 10 mW for GC, 200 mW for solution, 180 mW. Raman shifts in cm 1 shown above peaks. [From Ref. 59.]...

Acids and Bases", and the author has extended the list upwards to include Nile Blue A (pKg. S) and Rhodamine B(pKari<10-ll). ... 

In another approach, optical absorbance detection was achieved in an injection-molded PMMA flow cell consisting of 1800 pillars (25 pm high) that were used as diffraction elements. The LOD of Nile blue A perchlorate was determined to be 1.2 pM [713],... 

Figure 6. Variation of E° with pH for (A) Nile Blue A adsorbed on graphite ( ), Nile Blue A adsorbed on Ag ( ), and Nile Blue A dissolved...

Figure 7. Structural formulae of 3-j3-naphthoyl-Nile Blue A and its imino form.

The oxazine dyes are Nile blue A perchlorate (NB) and oxazine 1 perchlorate (0X1), which are ionic dyes, and coumarin 102 is chosen as a fluorescent probe molecule in the dynamic Stokes shift measurements. The electron donating solvents are aniline (AN) and N,N-dimethylaniline (DMA). 

Among oxazine dyes are Capri Blue (formula 4.31), Nile Blue A (formula 4.32) and Mendola s Blue. Safranine T [75] represents a phenazine dye (formula 4.33). The absorption spectra of the three azine dyes are presented in Fig. 4.3. 

Besides the Methylene Blue, other spectrophotometric methods, based on ion-associates of anionic boron complexes with basic dyes are used. Extractable associates with BF4 are obtained with Nile Blue A (formula 4.32) [7,36,37], Capri Blue (formula 4.31) [38], Malachite Green (formula 4.26, with Me instead of Et), Chrompyrazole II (CHCI3, e = 6.7-10 at 595 nm) [40], etc. 

Methods based on extraction of Ge(IV) complexes with 3,5-dinitropyrocatechol or 4-nitropyrocatechol, associated with Brilliant Green (CCI4, e =1.4-10 ), Nile Blue A (CHCI3, e =1.3-10 ), and Methylene Blue (benzene, e =1.0-10 ), have been recommended [45,46]. The anionic complex of Ge with Alizarin Complexone, associated with Rhodamine 6G, is the basis of a sensitive method (e = 2.9-10 ) [1,2]. In another very sensitive method, use has been made of tetrabromofluorescein and Rhodamine 6G [47]. Ge is determined after extraction (with chlorobenzene) with mandelic acid and Malachite Green (e = 1.33-10 ) [48]. 

A large group of extraction-spectrophotometric methods, similar to the Rhodamine B method, is based on extraction of ion associates of AuCU with various basic dyes, such as Brilliant Green (toluene) [47 9], Methylene Blue (chloroform) [50-53], Nile Blue A [54], Chrompyrazole I (an antipyrine dye, formula 23.1) (toluene, e = 6.5-10 at 580 nm) [55]. 

Many other basic dyes besides Methyl Violet have been used in sensitive extraction-spectrophotometric methods for the determination of Ta as the anionic complex TaFe [92]. Mention may be made of Crystal Violet (formula 4.27) (e = 8.5-10" ) [91-93], Brilliant Green (e = 1.2-10 ) [94,95], Malachite Green [96,97], Methyl Green (e = 1.2-10 ) [98], Rhodamine 6G and butylrhodamine B [99], Methylene Blue (e = 9.1-10" ) [98], Nile Blue A [100], Capri Blue (e = I.TIO ) [101], and Victoria Blue B [102]. Ion-associates with these dyes are extractable from acid solutions into benzene, toluene, CHClj, xylene, or dichloroethane. 

Some sensitive spectrophotometric methods for determining nitrate utilize extractable ion-associates of the nitrate ion with the basic dyes Crystal Violet (chlorobenzene, pH 6) [97], Nile Blue A [98], and Methylene Blue (1,2-dichloroethane) [99]. Nitrogen has been determined also by the FIA technique with the use of Malachite Green [ 100]. 

Besides the Rhodamine 6G-SnCl2 flotation-spectrophotometric method described above, similar methods using other basic dyes, e.g., Victoria Blue B, Victoria Blue 4R, Capri Blue [41], Crystal Violet (e = 2.1-10 ) [42], or Nile Blue A [43], have been proposed. An ion-associate of the chloride platinum complex with Methyl Green has been extracted with a mixture of 1,2-dichloroethane and CCI4 (e = 1.45-10 ) [44]. The ion-associate of the Pt-thiocyanate complex with Malachite Green has been extracted with benzene [45], and a thiocyanate- or iodide- Pt complex associated with Crystal Violet has been extracted into xylene or toluene [46]. 

Sensitive extraction-spectrophotometric methods are based on the extractable (into CHCI3, 1,2-diehloroethane, benzene, or toluene) ion-associates of basic dyes and anionic Ag complexes with cyanide [35,36], iodide [37,38], and bromide [39]. In these methods, use has been made of such dyes as Crystal Violet [35,39], Brilliant Green [38,39], Malachite Green [39], Methylene Blue [36], and Nile Blue A [37]. In some of these methods the molar absorptivities are elose to MO [36,39]. A flotation method has been proposed, based on the addition compound [R6G ][Ag(SCN )2] [R6G ][SCN ] which is formed by silver ions (at pH 2-5) in the presence of thiocyanate and Rhodamine 6G (flotation with DIPE, the precipitated compound is washed and dissolved in acetone, e = 1.5-10 ) [40]. The complex Ag(CN)2 , associated with Crystal Violet, has been utilized in another flotation-spectrophotometric method of determining silver [41]. Silver has been determined also in a system comprising thiocyanate and Rhodamine B, as an aqueous pseudo-solution, in the presence of poly(vinyl alcohol) [42]. 

The methods of determining Te with the use of basic dyes are very sensitive. The tellurium bromide complex has been extracted as the ion-associate with Butylrhodamine B [44,45] or Victoria Blue 4R (e = 8.0-10 ) [46]. The halide complexes give also ion-associates, extractable into toluene (e = 3.75-10 ) with Violet Red [47 9]. The TeBr associate with Rhodamine 6G can be floated with benzene, and the separated compound is then dissolved in a mixture of benzene with ethanol (e = 1.7-10 ) [50]. The ion-associate of the iodide complex of Te(IV) with Nile Blue A has been floated with cyclohexane, and the separated compound dissolved in methanol (e = 1.4-10 at 640 nm) [51]. High sensitivity has... 

Tin(ll) can be determined with the use of the ion-associate of SnCl with Crystal Violet (formula 4.27) (4-heptanone, e = 8.5-10 ) [48]. The associates of SnCU with Malachite Green [49] and Butylrhodamine B [50] has been extracted into benzene. Usually, TiCH is used to keep tin as Sn(II). The flotation of the ion-associate of SnCli with Rhodamine 6G by means of DIPE enables the separation and determination of traces of Sn(Il) in tin(IV) chloride [51]. The anionic complex of tin(IV) with 3,5-dinitrocatechol can be associated with Brilliant Green (CCU+CeHe, 8 = 1.75-10 ) and Nile Blue A (8 = 1.3-10 ) [52]. The ion-associate of the Ti(rV)-3-nitroalizarin complex with Brilliant Green (CHCI3, 8 = 2.0-10 ) [53], and the complex with thiocarbamide and Xylenol Orange [54] have also been used for Sn determination. 

While it would be clearly advantageous for a photosensitizer, in fact, any cancer therapeutic agent, to have high affinity for a wide variety of cancers and little uptake or retention in normal tissues, this has rarely, if ever, been achieved. However, certain cationic dyes, for example, oxazines like Nile Blue A (NBA) (Figure 9 1) and similar structures have been reported to be taken up and retained selectively in the mitochondria or in some cases in the lysosomes of carcinoma cells, that is, cancer cells involving soft tissues [27,42]. 

Figure 14-9. Cyclic voltammogram of a graphite electrode modified with P-naphthoyl Nile Blue, a) buffer (pH 8.0) b) after addition of NADH (10 mM). The increase in the anodic current is attributed to electrocatalytic oxidation of NADH at the mediator-modified electrode. - SOO to +300 mV vs. SCE 5 mV s" 0.1 M phosphate buffer (pH 8.0) with 0.5 M NaCl graphite disk electrode, 6.4 mm diameter.

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