Electronic absorption spectrophotometry

Second-derivative electronic absorption spectrophotometry, which is a method applied without any separation procedure, was used to determine the partition coefficients of three N-monodemethylated phenothiazine drugs, such as CPZ, triflupromazine and promazine, between the phosphatidylcholine bilayers of small unilamellar vesicles (SUVs) and water, in order to evaluate their affinity to biomembranes. The second-derivative spectra exhibited distinct isobestic points, confirming the entire elimination of the residual background signal effects of the SUVs which were observed in the conventional absorption spectra [161]. 

Macrocycles. The influence of solvents and added solute molecules on the nature of associative species observed in solutions of the sodium salt of cobalt(ii)tetrasulpho-phthalocyanine has been investigated by electronic absorption spectrophotometry. Isolation of LCo2Br2,MeOH [LH2 = macrocyclic tetrakis SchifT base (10)] and its oxidation by Br2 to form LCo2Br3,2H20 has been reported. The crystal structure of the LCo2Br2,MeOH complex consists of a dinuclear unit with the two cobalts separated by 3.158(2) A and each cobalt is in an identical pseudo-square-pyramidal... 

Fig. 4.4. Block diagram of optical system for electronic absorption spectrophotometry. L, L, biconvex silica lenses M, Mi, multiple reflexion cell (eight traversals shown) N, deuterium arc P, Hakuto R106 photomultiplier cell Q, wavelength drum and marker (R) S, recorder T, Vibron electrometer amplifier, U, grating. (After ref. 60.)...

Usually, titration methods are used to calibrate spectrometrically determined radical concentrations in absolute terms. Most kinetic studies of radicals have used either e.p.r. spectrometry or electronic absorption spectrophotometry. A survey of these methods has been given in section 4.2 of this article selected examples will be discussed later in this section. 

Del Greco and Kaufman established the mechanism of the decay reaction of OH, using time-resolved electronic absorption spectrophotometry with an OH lamp. Rapid bimolecular disproportionation of 20H occurs, leading to oxygen atoms. 

However, the CIO radical was also formed in the products of the reactions O -b OCIO (excess), and Br -b OCIO, which latter reaction also gave BrO. The IO(X n) radical in both vibrational levels j = 0 and v" = was detected as a product of the reaction I( Ps/2) + O3 -> 10 -b O2, and limited kinetic data on this species were obtained. Detection of all three radicals, CIO, BrO and lO was by means of multiple traversal electronic absorption spectrophotometry of the intense ultraviolet A I1 -<-X n band systems. ... 

Some of the better treatments of electronic absorption spectrophotometry are located in unobvious places. Coggeshall s Spectroscopic Functional Group Analysis in the Petroleum Industry appears in the series. Organic Analysis. We highly recommend it. 

The one-electron reduction of thiazole in aqueous solution has been studied by the technique of pulse radiolysis and kinetic absorption spectrophotometry (514). The acetone ketyl radical (CH ljCOH and the solvated electron e were used as one-electron reducing agents. The reaction rate constant of with thiazole determined at pH 8.0 is fe = 2.1 X 10 mole sec in agreement with 2.5 x 10 mole sec" , the value given by the National Bureau of Standards (513). It is considerably higher than that for thiophene (6.5 x 10" mole" sec" ) (513) and pyrrole (6.0 X10 mole sec ) (513). The reaction rate constant of acetone ketyl radical with thiazolium ion determined at pH 0.8 is lc = 6.2=10 mole sec" . Relatively strong transient absorption spectra are observed from these one-electron reactions they show (nm) and e... 

This technique links several others, especially mass spectrometry and UV absorption spectrophotometry, and its results often illuminate them. A relatively new technique, it has been used extensively to probe the electronic structure of furan and its allies a general review is available (80PAC1509). 

Following are selected refs on absorption spectroscopy, absorption spectrophotometry, electronic spectroscopy, etc l)F.Twyman C.B.Allsop, "The Practice of Absorption Spectrophotometry, Adam Hilger,London(1934) 2)H.Mohler, "Absorptionsspektrum der chemi-schen Bindung,"reproduced by Edwards Bros, Ann Arbor, Mich(1943) 3)L.PaulingfOSRD Rept5953(1945) "Absorption Spectra of Explosives and Other Compounds of Interest in the Study of Smokeless Powder (Conf)(not used for this dictionary) 4)G.R.Harrison, R.C.Lord J.R.Loofbourow, "Practical... 

Many alternative techniques, both qualitative and quantitative, have been investigated either for screening purposes or as primary methods. Such techniques include atomic absorption spectrophotometry, molecular luminescence, electron spin resonance spectrometry, X-ray analysis methods, and electro analytical methods. Flameless atomic absorption spectrophotometry (FAAS) is the technique that has almost completely replaced NAA. 

The analysis of corrosion scale or product may be done by wet chemical methods such as spectrophotometry or atomic absorption spectrophotometry in cases where the removal of corrosion scale is permitted, or by surface analytical techniques such as X-ray photoelectron spectroscopy, Auger electron spectroscopy, electron microprobe analysis, by energy dispersive X-ray analysis in the case of samples which need to be preserved. 

Following are selected refs on absorption spectroscopy, absorption spectrophotometry, electronic spectroscopy, etc l)F.Twyman ... 

R15. Rousselet, F., and Girard, M. L., Apparatus for vaporisation by electron bombardment and application to atomic absorption spectrophotometry. Method. Phys. Anal. 6, 167-168 (1970). 

AAS = atomic absorption spectrophotometry EPA = Environmental Protection Agency GC/ECD = gas chromatography/electron capture detector GC/FPD = gas chromatography/flame photometric detector GC/HECD = gas chromatography/ Hall s electrolytic conductivity detector GC/MS = gas chromatography/mass spectrometry GC/PID = gas chromatography/photoionization detector ILS = isotopically labelled standard NR = not reported SCD = Sievers chemiluminescence detector... 

Nicked circular PM2 DNA (0.02 mg/mL) was incubated in NaClOt (10 mM) with platinum compounds at 20 C in the dark for 8 d. After dialysis against NaClOt (10 mM) and platinum determination by atomic absorption spectrophotometry, the complexes were absorbed on carbon-coated copper grids and observed using a Philips 301 electron microscope. The average length of control DNA (Ldsa) and of platinum-DNA complexes (Ldna pO were determined from an observation of at least 60 molecules. 

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