Methylene blue method

The spectophotometric methylene blue method for anionic surfactants has been applied to seawater. In one version, the surfactants are collected in ethyl acetate. The solvent is then evaporated, the surfactants put back in solution in water, and the standard spectrophotometric methylene blue method is applied to this solution. In this manner, the salt error introduced by seawater is eliminated [195]. A similar method, with the methylene blue-surfactant complex extracted into chloroform, and measured directly was proposed by Hagihara [192]. 

Total sulfide can be measured photometrically by the methylene blue method (Cline, 1969 Standard Methods for the Examination of Water and Wastewater, 1998). Reliable sensors exist for the measurement of hydrogen sulfide in air. 

Wang, L.K. Modified methylene blue method for estimating the MBAS concentration. J. Am. Water Works Assoc. 1975, 67 (7), 19-21. 

Reduced Sulfur Compounds in Marine Sediments. To determine the applicability of the bimane-HPLC technique to measure reduced sulfur compounds in sediment porewater samples, we compared the results of the methylene blue method of Cline (26). the DTNB procedure of Ellman (28) and the bimane-HPLC procedure outlined above. Cores included came from a Spartina foliosa marsh in Mission Bay (near San Diego, California), and an evaporation pond for the production of salt in south San Diego Bay (Table I). 

Fogo, J. K. and M. Popowsky Spectrophotometric determination of hydrogen sulfide, methylene blue method. Anal. Chem. 21, 732—734 (1949). 

The consumption of cyanide is accurately determined by argentometric titration. The method was found to apply both to oxidized starch [439] as well as to cellulose [418], The method is accurate and recently the coefficient of variance and standard deviation for an oxidized cellulose containing 5.60 mmol per 100 g of ketone groups, were found to be 0.0046 and 0.0068, respectively. The corresponding values for the carboxyl groups by the methylene blue method of the same samples were 0.001 and 0.031 [440]. 

Methylene Blue Method for Measuring Thiosulfate and Silver Densitometric Method for Measuring Residual Chemicals in Films, Plates, and Papers... 

The affinity of variously oxidized cellulosic materials for certain basic dyes, notably methylene blue, has long been known. Kenyon and coworkers have recently shown that in the case of nitrogen dioxide oxycelluloses, the methylene blue absorption is a function of the carboxyl group content. Application of the reversible methylene blue method to the determination of carboxyl groups in purified cellulose has been made by Davidson and by Weber, who was able to show good agreement with the cation-exchange methods previously considered as well as with viscosity and osmotic pressure measurements. 

L. K. Wang, Evaluation of two methylene blue methods for analyzing MBAS concentrations in aqueous solutions. J. Am. Water Works Assoc. 67(4), 182-184 (1975). 

The method for the determination of sulfur in phosgene is based on the absorption or hydrolysis of sulfur compounds in an excess of sodium hydroxide solution, followed by reduction to H S using hydriodic acid and subsequent determination of sulfide ion by the methylene blue method. 

The Methylene Blue method has been utilized in determinations of boron in biological materials [33], soils and rocks [68], steels [32], silicon [7,69], copper and its alloys [34,35], and various chemical materials [70,71]. 

Of the methods for separating sulphur, those based on distillation are the most important. Oxy-compounds of sulphur are reduced to hydrogen sulphide, which is carried in an inert gas stream (e.g., nitrogen) to a receiver containing Zn or Cd ions [1-5] (see the Methylene Blue method). When S(-II) is determined, the H2S is distilled after acidification of the sample. 

Various forms of sulphur have been determined. Two particularly sensitive methods are discussed below. In the Methylene Blue method sulphur is first converted into hydrogen sulphide, and in the pararosaniline method SO2 is the reacting species. The classical turbidimetric (BaS04) method is also discussed. All these methods are highly selective. Spectrophotometric (and other) methods for S determination have been reviewed [13]. 

The Methylene (and Ethylene) Blue method has been applied in determinations of sulphur in plants [86], biological materials [87], waters [12,88], air [5,12,16,20], hydrocarbons [89], iron alloys [90,91], cobalt and zirconium [91], titanium [92], thallium and its halides [93], arsenic [94], selenium [95], and various reagents (including barium chloride) [14]. Flow-injection analysis has been applied in the determination of sulphur by the Methylene Blue method [96]. 

D. J. Leggett, N. H. Chen, and D. S. Mahadevappa, Flow Injection Method for Sulfide Determination by the Methylene Blue Method. Anal. Chim. Acta, 128 (1981) 163. 

Kawase et. al.[24] determined anionic surfactants using liquid-liquid extraction based on the methylene blue method at an early stage of development. Sahlestrom and Karl-berg [25] used the same reaction to determine anionic surfactants using a microconduit extraction system. The methods were not intended for very low concentration levels. 

Results showed good agreement with those obtained by a batch Methylene Blue method... 

Table 2.3 Determination of bromate in Evian water and in three types of ozonated matrices comparison between the reference technique (IC/CD) and the methylene blue method (after Ingrand et at, 2002). Reprinted from Trends in Analytical Chemistry, Vol. 21, No. 1, Ingrand et at, Determination of bromate... , pp. 1-12, 2002, with permission from Elsevier...

This method allows determination of bromate at coneentration levels from 4 to 50 ag/L, with divergenee between results obtained with both IC/CD (referenee method) and methylene blue methods lower than 20 %. The high level of interferenee from hypoehlorite ions has been demonstrated but it ean be overeome by pre-treating samples with hydroxylamine hydrochloride. Such pre-treatment should be adapted to the matrix analysed on site (Ingrand et al, 2002). 

Zhang, G., Y. Luo, and X. Deng. 2002. Determination of surface area of red mud and beringite using methylene blue method. Pedosphere 12, no. 2 189-192. 

The determination of hydrogen sulphide as methylene blue (3,7-bis(dimethylamino)phe-nothiazine-5-onium chloride) was introduced by Fischer (1883) and has been used for seawater in many investigations. Cline (1969) has closely reviewed and tested the methylene blue method and has suggested several improvements. 

Accurate results were also obtained using the methylene blue method as described by Meier et al. (20). However, as it is the case for most of the photometric methods critical examination is required to avoid errors due to small alterations in the operational conditions (8). Also the correction for blanks can be a problem, especially when the method is used near its detection limit. This was demonstrated within the above BCR round robin a first result of (0.30 0.12) g/g was obtained for the same aluminium as above. When a purer aluminium sample, accurately characterized with charged particle activation analysis, was used to determine the blank, a value of (1.27 + 0.08) tig/g was obtained. 

Emission spectrometry with plasma excitation is based on chemical separation of boron by wet chemistry and is matrix and form independent. The sensitivity is good (0.01 to 0.02 Mg/g) but the method requires several difficult manipulations, thus highly skilled operators. The latter also applies to photometry which was used under different forms the methylene blue method, with varying BF formation times and with and without reextraction of fluorine, and the curcumine method. Under optimal conditions, these methods allow precisions and accuracies of + 10 % at the 0.5 to 1 /ig/g level. 

D2725 Test Method for Hydrogen Sulfide in Natural Gas (Methylene Blue Method) ... 

The separation is performed on a column of Amberlite CG-50, 25 x 400 mm, mixed Na" and H form, thermostatted at 35-C. An eluent of 30 70 2-PrOH/0.5 M NaCl solution is used, with the column effluent checked batchwise by the methylene blue method to detect... 

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