UV spectrophotometric studies

The optimum dosage of coagulant corresponds to the lowest residual turbidity or the lowest TSS content in the supernatant. However, the use of turbidity is not always appropriate (see Chapter 6), and TSS measurement is time consuming and therefore too slow to be used for process control. The UV spectrophotometric study enables the control of the effect of ferric chloride dosage. A decrease in absorbance is observed all along the spectrum, especially between 230 and 350 nm where colloids and TSS are responsible for a diffuse absorbance. 

Cochineal extract (Colour Index 75470, E 120)is the final alcohol-free material obtained after aqueous ethanolic extraction of the dried bodies of the female scale insect Dactylopius coccus Costa which lives on cacti such as Opuntia or Nopalea coccinellifera a species indigenous to Peru and Mexico, although also found in the Canary Islands. In practice a simpler procedure consists of aqueous alkaline extraction. The colourant principle is carminic acid which is more well-known in the form of carmine, an aluminium chelate of carminic acid, a material insoluble in water and stable on the acidic side. A uv spectrophotometric study has been made (ref. 21). Thin layer chromatography of cochineal has been examined on acetylated cellulose with the solvent system, ethyl acetate-tetrahydrofuran-water (6 35 47) in which the Rf was 0.94 (refs.22,23). The history of the chemistry of cochineal has been discussed (ref.24). 

Visible and UV spectrophotometric techniques are most convenient for studying the polymer and various oxidation states of plutonium. The spectra of the plutonium states and the procedure for resolution of the concentrations were previously described (9 ). Changes in the relative concentrations of the oxidation states and of the polymer generally are determined from corresponding changes in the spectra and a comparison of the changes to standard spectra of the various states. These techniques have been used exclusively for studying the photochemistry of aqueous plutonium. 

We passed then to a particular olefin, adamantylideneadamantane, whose reaction with Br2 had been shown to stop at the stage of bromonium ion formation because of steric hindrance to backside nucleophilic attack. An UV-Vis spectrophotometric study (ref. 10) has shown that the complicated equilibrium reported in Scheme 4 is immediately established on mixing the olefin and Br2 in DCE. Equilibrium (1) could be isolated by working at low Br2 and ten to hundred fold higher olefin concentrations. A Scott plot followed by a NLLSQ refinement of the data gave a Kf = 2.89 x 10 (4.0) M-l. It is worth noting that conductimetric measurements showed the non-ionic nature of the 1 1 adduct, consistent with a CTC intermediate, but not with a bromonium-bromide species. 

Quantitative information about the equilibrium between olefin and Br2 on the one hand and CTC s and bromonium ion species on the other (Scheme 4) has been obtained by the already mentioned UV-Vis spectrophotometric study of the adamantylideneadamantane Br2 system (ref. 10). The spectrophotometric UV-Vis data of a large set of solutions of different reagents concentrations have been used to dissect, using a program based on NLLSQ fitting procedures, the complex spectra in those of the single species present at the equilibrium, as shown in Figure 5. 

Tewari SN, Sharma IC. 1978. Study of the distribution of chlorinated organic pesticides in different autopsy materials of human poisoning cases using TLC and UV spectrophotometric techniques. Chemical Era 215-218. 

The aim of this study to investigate the effects of Cu(II) ion and PVP concentrations on the oxidation kinetics of H A in aerated and acetate buffered solution, at 25°C, using direct UV spectrophotometric method [14, 15]. 

The amorphous state of the lyophilized solids was verified by powder X-ray diffractometry (Rigaku Denki Co., Ltd., Danvers, MA), and their Ca/P04 ratios after dissolution in HCl were determined by atomic absorption (AAS, Perkin Elmer, Norwalk, CT) and UV spectrophotometric [6] (Varian Analytical Instruments, Palo Alto, CA) measurements of Ca + and PO4, respectively. Dissolution of the ACP fillers was studied by kinetically following the changes in Ca + and PO4 concentrations in continuously stirred HEPES-buffered (pH = 7.4) solutions adjusted to 240 mOsm/kg with NaCl at 37°C. All solutions initially contained 0.8 mg/mL of the ACP filler. 

Rizk et al. developed a sensitive and selective derivative UV-spectrophotometric method for the determination of three fluoroquinolone compounds, including ciprofloxacin, in formulations and spiked biological fluids (7]. The method depends on the complexation of Cu(II) with the studied compounds in an aqueous medium. A linear correlation was established between the amplitude of the peak and the drug concentration over the range of 35-120 ng/mL. The detection limit was reported as 1.3 ng/mL. The method was used for the determination of the ciprofloxacin bulk drug substance and its tablet formulation, with an overall percentage recovery of 99.22 0.55 to 100.33 1.60. 

The ultraviolet (UV) and visible spectra of some phenothiazines were recorded for analytical purposes (characterization, identification, and dosage). Spectrophotometric studies on the colored... 

A method for determination of sodium isoascorbate (see 2) in boiler feed water, where it is used for deoxygenation, consists of following the reaction kinetics of Rhodamine B (13) in the presence of KBrOs, measuring at 555 nm. A linear correlation exists between the catalytic effect of the analyte on the reaction rate and its concentration Fe(III), Ca(II) and Mg(II) in the 5-200 ppm range interfere with the analysis . The effects of solvents, pH, surfactants, metal ions and other food additives on the absorbance were studied for the micelle-enhanced UV spectrophotometric determination of the food preservative sodium D-isoascorbate. The optimal conditions were using water at pH 7-8 as solvent and polyvinyl alcohol as surfactant, which causes an up to 3-fold increase of the UV absorbance. ... 

Another study on aromatic amines from azo dye reduction gives a complete overview on the use of direct UV spectrophotometric detection in textile industry wastewater [34],... 

Fluorometric and spectrophotometric studies of filipin-cholesterol interaction showed that the stoichiometry of the interaction was 1 1 [150] or 1 1.5 [146,147]. UV spectrophotometry changes have been used to monitor the stoichiometry of the interaction between filipin and free or liposome-bound cholesterol. Analysis of aqueous dispersions suggested that the stoichiometry was 1 1 [171]. Lecithin, dicetyl phosphate-cholesterol liposomes only produced maximal spectral changes of filipin when the sterol polyene ratio was 1 1 [172]. Filipin released trapped ion markers from sterol—phospholipid liposomes. The rate of release was dependent upon cholesterol content of the liposome membrane (maximum at sterol phospholipid ratio of 1 1) and upon the molar fllipin sterol ratio (maximum at fllipin sterol ratio of 1 1). 

This is one of the most important uses of UV-VlS spectrophotometry. Impurities in a compound can be detected very easily by spectrophotometric studies by experimentally verifying whether the given compound shows an absorption maxima not characteristic of it. Thus carhon disulphide impurity in carbon tetrachloride can be detected Ccisify by measuring absorbance at 318 nm where carbon disulphide absorbs. Similarly benzene impurity in commercial absolute alcohol can be detected by measuring absorbance at 280 nm where alcohol (210 nm) does not absorb. A lot many commercial solutions are routinely tested for purity spectrophotometriealty. 

Pereira L, Pereira R, Oliveira CS, Alves MM (2013) UV/Ti02 photocatalytic degradation of xanthene dyes. Photochem Photobiol, 2013,89 33-50. doi 10.1111/j.l751-1097.2012.01208.x Perez F (2001) Spectrophotometric study of industrial effluents - application in parameters estimation. PhD thesis, Universite d Aix-Marseille II Pielesz A (1999) The process of the reduction of azo dyes used in dyeing textiles on the basis of infrared spectroscopy analysis. J Mol Struct 337-344. http //www.doi.oig/10.1016/ S0022-2860(99)00176-3... 

The kinetics of this reaction can be very conveniently followed by measuring the volume of carbon dioxide liberated in a given time, and the earlier studies employed this technique, though more recently spectrophotometric (uv) methods have been favoured. Most of the kinetic studies have been directed towards determining whether the SE1 or A-SE2 mechanisms, equilibria (257) and (258) or (259) and (260), respectively,... 

Earlier studies using thermal denaturation analysis and spectrophotomet-ric titration with TxA T and CxC-C" containing DNA triplexes showed that coralyne binds strongly to these triplexes by intercalation and does not exhibit a significant sequence-selectivity [222]. In a later study by Morau Allen et al. [217], employing DNase footprinting, thermal denaturation analysis, UV-visible spectrophotometric titrations, circular dichroism and NMR spectroscopy, showed that coralyne is fully intercalated into TxA T triplex DNA whereas in C GxC triplex, it is partially intercalated due to electrostatic repulsion between the cationic alkaloid and the protonated cytosine [217]. Kepler et al. [223] demonstrated that coralyne intercalated to parallel triplex DNA but did not intercalate to antiparallel triplex DNA. Recently Hud and coworkers [219,224] demonstrated that duplex poly(dA) poly(dT) is trans-... 

RPLC separation with spectrophotometric detection is often applied to the identification of the anthraquinone colour components of cochineal, lac dye and madder. [28,40,41,50 53] In particular the latter, containing many colourants, is the object of many research studies. Due to the large number of anthraquinones isolated from plants of the Rubiaceae family, their unambiguous identification solely by UV-Vis detection is not always possible,... 

Lynen had studied chemistry in Munich under Wieland his skill as a chemist led to the successful synthesis of a number of fatty acyl CoA derivatives which proved to be substrates in the catabolic pathway. Many of these C=0 or C=C compounds had characteristic UV absorption spectra so that enzyme reactions utilizing them could be followed spectrophotometrically. This technique was also used to identify and monitor the flavoprotein and pyridine nucleotide-dependent steps. Independent evidence for the pathway was provided by Barker, Stadtman and their colleagues using Clostridium kluyveri. Once the outline of the degradation had been proposed the individual steps of the reactions were analyzed very rapidly by Lynen, Green, and Ochoa s groups using in the main acetone-dried powders from mitochondria, which, when extracted with dilute salt solutions, contained all the enzymes of the fatty acid oxidation system. 

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