Solid phase spectrophotometry

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. 

Among the many, such combination method, which allows to combine the sorption concentration and the subsequent photometrical determination in solid phase, as solid-phase spectrophotometry (SPS), proves to be very effective in the analysis. 

Derivative spectrophotometric ratio spectrum-zero crossing Solid phase spectrophotometry... 

Solid phase spectrophotometry proved to be an appropriate technique for the determination of colorants in foods dne to its simplicity, selectivity, reasonable cost, low detection limits, and use of conventional instrnmentation. This simple, sensitive, and inexpensive method allowed simnltaneons determinations of Snnset Yellow FCF (SY), Quinoline Yellow, and their nnsnlfonated derivatives [Sndan I (SUD) and Quinoline Yellow Spirit Soluble (QYSS)] in mixtnres. Mixtnres of food colorants containing Tartrazine, Sunset Yellow, Ponceau 4R, Amaranth, and Brilliant Blue were simultaneously analyzed with Vis spectrophotometry without previous chemical separation. ... 

Capitan, F. et ah. Determination of colorant matters mixtures in foods by solid-phase spectrophotometry, AmZ. Chim. Acta, 331, 141, 1996. 

Capitan-Vallvey, L.F. et al.. Simultaneous determination of the colorants tartrazine, ponceau 4R and sunset yellow FCF in foodstuffs by solid phase spectrophotometry using partial least square multivariate calibration, Talanta, 47, 861, 1998. 

Capitan et al. [326] determined down to 0.1 ng/1 thiabend azole residues in seawater using solid phase spectrophotometry. 

Bosque-Sendra JM, Valencia C, Boudra S. 1994. Determination of trace amounts of aluminum in water by solid-phase spectrophotometry. Anal Lett 27 1579-1594. 

Ruiz-Medina, A., Fernandez-de Cordova, M. L., and Molina-Diaz, A. A very simple resolution of the mixture paracetamol and salicylamide hy flow injection-solid phase spectrophotometry. Anal. Chim. Acta 394(2-3) 149-158, 1999. 

Teixeira, L. S. G., Rocha, F. R. P., Korn, M., Boaventura, F. Reis, Sergio, L. C. Ferreira, and Antonio, C. S. Costa. Flow-injection solid-phase spectrophotometry for the determination of zinc in pharmaceutical preparations. Anal. Chim. Acta, 383(3) 309—315,1999. 

Solid-phase extraction of various analyte complexes on e.g. microcrystalline naphthalene (Ni [23] and Cu [24] with nitroso-R salt and tetradecyldimethylbenzylammonium chloride), ammonium tetraphenylborate-naphthalene (U with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol) [25], chitin column (Cr(VI) with 1,5-diphenylcarbazide) [26], strong anion-exchange cartridge (Cr(VI) at pH 8) [27], Cig cartridge (CL-azo dye) [28] and minicolumn (As with ammonium diethyl dithiophosphate) [29], silica modified chemically with A-allyl- or A-phenyl-TV -propylthiourea (OSO4) [30] and Sephadex DEAE A-25 (chloride form) (V with Eriochrome Cyanine R) [31] prior to the spectrophotometric determination has recently been reported. The application of solid-phase spectrophotometry to determine nitrite and nitrate in water samples has recently been described [32]. 

Collection of Fe(II) on a nitrocellulose membrane filter in the form of ion associate with ferrozine and a cation surfactant was applied to the determination of Fe(II) in river and sea water samples [14]. Solid-phase spectrophotometry using ascorbic acid and ferrozine was employed to determine Fe in water, waste water, wine, soil extract, digested vegetal tissues, drugs and human hair [15]. 

A complex formed with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol included on cyclodextrin polymer makes a basis of the determination of trace amounts of manganese in black rice and tea by solid-phase spectrophotometry [2]. 

Spectrophotometric methods applicable to speciation analysis for V in different oxidation states have been reviewed [12]. Attempts to speciation of V(IV) and V(V) with Eriochrome Cyanine R in natural waters by solid-phase spectrophotometry has been described... 

Complexation with PAN immobilized on a Dowex 50Wx4 cation exchanger makes a basis of the determination of Zn in human hair, natural water and pharmaceutical and cosmetic formulations [11]. Flow-injection solid-phase spectrophotometry using TAN immobilized on silica gel was proposed for the determination of Zn in pharmaceutical preparations [12]. Adsorption of the complex with PAR on Sephadex anion exchanger makes a basis of solid phase spectrophotometric method for the determination of Zn in environmental samples [13]. 

L.S.G. Teixeira, E.S. Leao, A.F. Dantas, H.L.C. Pinheiro, A.C.S. Costa, J.B. Andrade, Determination of formaldehyde in Brazilian alcohol fuels by flow-injection solid phase spectrophotometry, Talanta 64 (2004) 711. 

F.S. Oliveira, M. Korn, Employment of a single standard solution for analytical curves in flow injection analysis system coupled to solid phase spectrophotometry, Quim. Nova 26 (2003) 470. 

Other strategies for presenting the handled sample to the detector, involving the use of beads for solid phase spectrophotometry or hanging drop approach for measurements without a flow cell, are discussed in the Sections 4.1.1.4 and 2.6. 

UV—Vis = spectrophotometry CL = chemiluminescence SPS = solid phase spectrophotometry. Analytical range or detection limit given in original units. 

Some analytical procedures exploiting e.g., chemiluminescence, fluo-rimetry and solid-phase spectrophotometry (see 4.1.1.4) require quantification of the product immediately after its formation. The analyte concentration/separation step should then be incorporated as close and possible to the detector, as exemplified by the speciation of iron in natural waters [239]. 

Another option is to place the filtration unit inside the flow cell, as demonstrated in the spectrophotometric flow injection determination of hydrogen peroxide [297]. The analyte interacted with titanium(IV) and 2-((5-bromopyridyl)azo)-5-(N-propyl-N-sulfopropylamino) phenol (PAPS) yielding a red-purple complex. After ion pairing with CTAB, the complex was adsorbed and concentrated on a very small area of the membrane filter positioned inside the flow cell. The analyte was quantified directly in the membrane by solid-phase spectrophotometry (see 4.1.1.4). Thereafter, ethanol was injected in order to solubilise the complex and transport it to waste. 

Teixeira L. S. G. and Rocha F. R. P. (2007) A green analytical procedure for sensitive and selective determination of iron in water samples by flow-injection solid phase spectrophotometry. Talanta, 71,1507-1511. 

In a technique called solid-phase spectrophotometry absorption of a colour complex of the analyte sorbed on a solid support is measured without subsequent stripping of the chromogenic species. Solid-phase spectrophotometry offers the advantage of in situ preconcentration of the analyte. Therefore, it is (several) orders of magnitude more sensitive than the corresponding conventional spec-trophotometric methods [11]. UV microscopy (cfr. Chp. 5.3.2) may find application in studies aiming at the study of the physical distribution of additives UV microspectroscopy is discussed in Chp. 5.6.1. For UVA IS reflectance, cfr. ref. [12]. 

Flow injection methods have excellent potential in almost all areas of analysis since they provide high-throughput analysis (increase of analytical frequency) and the possibility of automation. However, the application of analytical methods based on flow analysis for food analysis has still received little attention, due to the complexity of food matrices (Lopez-Fernandez et al., 1995). Therefore, the development of automated methods for the determination of additives, such as synthetic antioxidants (e.g., BHA, BHT, and TBHQ), is a promising area of investigation. Flow injection solid-phase spectrophotometry was used for the determination of BHA and PC in fatty food (dehydrated chicken soup, chicken cream, bull calf, and chicken broth) and cosmetics, providing greater selectivity to the conventional spectrophotometric technique. After extraction with petroleum either for food and with hexane for cosmetics, the two antioxidants were separated by... 

Capitan-Vallvey, L. F., M. C. Valencia, and E. Arana Nicolas. 2003. Simple resolution of butylated hydroxyanisole and w-propyl gallate in fatty foods and cosmetics samples by flow-injection solid-phase spectrophotometry. J. Food Sci. 68(5) 1595-1599. 

SP (Vis) Copper(II) contained on a solid-phase reactor was reduced by AA, and then detected as its chelate produced with bathocuproine. X - 480 nm SP (Vis) Fe(III) was reduced by AA, and then determined by using ferrozine as chromogenic reagent. X = 562 nm SP (Vis) Fe(III) contained on a solid-phase reactor was reduced by AA, and then detected as its chelate produced with 1,10-phenanthroline. A, = 510 nm SP (UV) A column packed with modified silica was used for interfering retention. X = 265 nm SP (UV) AA was determined by a continuous flow-through solid-phase spectrophotometry. The system was based on the measurement of its intrinsic absorbance at 261 nm when retained on a Sephadex QAE A-25 anion exchanger gel layer... 

Capitan-Vallvey et al. [92] proposed an integrated solid-phase spectrophotometry FIA method for the simultaneous determination of the mixture of saccharin and aspartame. The procedure is based on online preconcentration of aspartame on a Cjj silica gel minicolumn and separation from saccharin, followed by measurement at 210 nm of the absorbance of saccharin, which is transiently retained on the adsorbent Sephadex G-25 placed in the flow-through cell of a monochannel FIA setup using pH 3.0 orthophospho-ric acid-dihydrogen phosphate buffer, 3.75 x 10 M, as carrier. Subsequent desorption of aspartame with methanol enables its determination at 205 nm. 

Valencia et al. developed an integrated solid-phase spectrophotometry-FIA method for the determination of Sunset Yellow in drinks in the presence of its unsulfonated derivative Sudan I [43]. The procedure is based on the retention and the preconcentration of the low level Sudan I in the upper zone of a silica gel packed cell, while Sunset Yellow is not retained and its optical signal at 487 nm is read directly over the packed cell. The applicable concentration range and detection limit for Sunset Yellow were 0.5-20.0 mg/L and 0.2 mg/L, respectively. 

Capitan Vallvey, L. F., M. D. Fernandez, I. de Orbe, J. L. Vilchez, and R. Avidad. 1997. Simultaneous determination of the colorants sunset yellow FCF and quinoline yellow by solid-phase spectrophotometry using partial least squares multivariate calibration. Analyst 122(4) 351-354. 

Flow-injection solid phase spectrophotometry by use of TAN immobilized on C j-bonded silica (A = 595 nm)... 

Determination of the 2 1 green complex in acid medium which is fixed on a dextran-type anion-exchange resin (Sephadex QAEA-25) by first-derivative solid-phase spectrophotometry (A = 674 nm)... 

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