Cyanides Raman spectroscopy

Raman and infrared vibrations are mutually exclusive and consequently use of both techniques is required in order to obtain a set of vibrational bands for a molecule. The advent of powerful computer-controlled instrumentation has greatly enhanced the sensitivity of these vibrational spectroscopies by the use of Fourier transform (FT) techniques, whereby spectra are recorded at all frequencies simultaneously in the time domain and then Fourier transformed to give conventional plots of absorbance versus frequency. The wide range of applications of FT Raman spectroscopy is discussed by Almond et al. (1990). Specific examples of its use in metal speciation are the observation of the Co-C stretch at 500 cm-1 in methylcobalamin and the shift to lower frequency of the corrin vibrations when cyanide is replaced by the heavier adenosyl in going from cyanocobalamin to adenosylcobalamin (Nie et al., 1990). 

The structure of cyclopropyl cyanide (58) has been examined by microwave spectro-scopy " Raman spectroscopy and theoretical methods and the structure is very similar to cyclopropylacetylene (57). The C-C bond distances (A) determined by the most recent microwave examination for 58 of C(l)-C(2) (1.529), C(2)-C(3) (1.500) and C(l)-C(4) (1.420) are identical within the experimental uncertainty with those for 57 ". The calculated geometry for 58 is also in reasonable agreement with the experimental structure. 

P. Tessier, S. Christesen, K. Ong, E. Clemente, A. Lenhoff, E. Kaler and O. Velev, On-line spectroscopic characterization of sodium cyanide with nanostructured gold surface-enhanced Raman spectroscopy substrates, Appl. Spectrosc. 56, 1524 (2002). 

S. Farquharson, A. Gift, P. Maksymiuk, F. Inscore and W. Smith, pFI dependence of methyl phosphonic acid, dipicohnic acid, and cyanide by surface-enhanced Raman spectroscopy, Proc. SPIE 5269,117 (2004). 

A number of model in situ and on-site apphcations of low resolution, and therefore low cost, Raman spectroscopy have been reported including the quantitative monitoring of synthetic rubber and polystyrene emulsion polymerisations, detection of illicit drugs and explosives and detection of cyanide in wastewater using a surface enhanced Raman system [26]. 

Spectroscopic methods in general and Raman spectroscopy in particular provide further details for silver deposition from cyanide complexes. This will be described in Section 7.8. 

Yellin and Marcus [Ma 74, Ye 72, Ye 74] used Raman spectroscopy to examine interactions of this type. They studied the interactions of cadmium(II) and mercury(II) halides and cyanides with water and with various organic solvents, such as alcohols, acetone, dioxane, acetonitrile, formamide, dimethylformamide, N-ethylacetamide, dimethylacetamide and mixtures of these. 

Of the various methods employed for characterizing complex ions in solution, among the most direct is that of Raman spectroscopy. This method determines the vibrational spectrum of the complex species with a minimum of interference from the solvent and from other species present in the solution. By means of such studies in our laboratories, we have quantitatively characterized the complexes formed in the following aqueous systems the cyanides of... 

Fleischmann, M., Graves, F.R. and Robinson, J. (1985) The Raman spectroscopy of the ferri-cyanide/ferrocyanide system at gold, -palladium hydride and platinum electrodes. Journal of Electroanalytical Chemistry, 182, 87. 

Lacconi, G., Reents, B. and Plieth, W. (1992) Raman spectroscopy of silver plating from a cyanide electrolyte. Journal of Electroanalytical Chemistry, 325,101-1X1. 

Yea GH, Lee S, Kyong JB, Choo J, Lee EK, Joo SW, Lee S (2005) Ultra-Sensitive Trace Analysis of Cyanide Water Pollutant in a PDMS Microfluidic Channel Using Surface-Enhanced Raman Spectroscopy. Analyst 130 1009-1011... 

Clarke et al. [16] has shown that low-resolution Raman spectroscopy (LRRS) can be combined with surface-enhanced Raman spectroscopy (SERS) for the determination of cyanide in water. The enhanced characteristic band of CN at 2134 cm is so prominent and is located in a portion of the spectral band, normally not populated by peaks from other organic compounds. The much lower cost LRRS spectrometer can be used to detect the presence of CN at these trace level concentrations. T e sample consisted of a solution of 2-3 mL of the different sizes of gold colloid (5, 10, and 20 mn. Sigma chemical company) with 1-2 mL of cyanide samples, mixed at room temperature and SERS spectra were recorded from this mixture to detect trace amounts of cyanide. 

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