Thiocyanate absorption

Procedure A standard calibration curve is plotted by thoroughly mixing together about 10% (w/w) of the analyte with the KBr-KSCN mixture and then grinding the same intimately. Now, the ratio of the thiocyanate absorption at 2125 cm-1 to a selected band absorption of the analyte is plotted against the percent concentration of the sample. Likewise, an identical disc is prepared with the unknown sample and the same KBr-KSCN mixture. Finally, its absorbance ratio is determined and the concentration (of unknown sample) is read off directly from the standard calibration curve. 

Infrared, nuclear magnetic resonance, ultraviolet, optical rotary dispersion and circular dichroism measurements have been used for the spectral analysis of thiiranes. A few steroidal thiiranes have been reported to possess infrared absorption in the range from 580 to 700 cm The intermediate thiocyanate derivatives (RSCN) have a strong sharp peak at 2130-2160 cm the isomeric isothiocyanate (RNCS) shows a much stronger but broad band at 2040-2180 cm. ... 

The inhibitor should not decompose during the life of the pickle nor decrease the rate of scale removal appreciably. Some highly efficient inhibitors, however, do reduce pickling speed a little. It would be expected that since the hydrogen evolution is reduced the amount of hydrogen absorption and embrittlement would also be reduced. This is not always the case thiocyanate inhibitors, for example, actually increase the absorption of hydrogen. 

Discussion. Molybdenum(VI) in acid solution when treated with tin(II) chloride [best in the presence of a little iron(II) ion] is converted largely into molybdenum(V) this forms a complex with thiocyanate ion, probably largely Mo(SCN)5, which is red in colour. The latter may be extracted with solvents possessing donor oxygen atoms (3-methylbutanol is preferred). The colour depends upon the acid concentration (optimum concentration 1M) and the concentration of the thiocyanate ion (1 per cent, but colour intensity is constant in the range 2-10 per cent) it is little influenced by excess of tin(II) chloride. The molybdenum complex has maximum absorption at 465 nm. 

The amount of reddish-purple acid-chloranilate ion liberated is proportional to the chloride ion concentration. Methyl cellosolve (2-methoxyethanol) is added to lower the solubility of mercury(II) chloranilate and to suppress the dissociation of the mercury(II) chloride nitric acid is added (concentration 0.05M) to give the maximum absorption. Measurements are made at 530nm in the visible or 305 nm in the ultraviolet region. Bromide, iodide, iodate, thiocyanate, fluoride, and phosphate interfere, but sulphate, acetate, oxalate, and citrate have little effect at the 25 mg L 1 level. The limit of detection is 0.2 mg L 1 of chloride ion the upper limit is about 120 mg L . Most cations, but not ammonium ion, interfere and must be removed. 

To use KBr discs for quantitative measurements it is best to employ an internal standard procedure in which a substance possessing a prominent isolated infrared absorption band is mixed with the potassium bromide. The substance most commonly used is potassium thiocyanate, KSCN, which is intimately mixed and ground to give a uniform concentration, usually 0.1-0.2 per cent, in the potassium bromide. A KBr/KSCN disc will give a characteristic absorption band at 2125 cm 1. Before quantitative measurements can be carried out it is necessary to prepare a calibration curve from a series of standards made using different amounts of the pure organic compound with the KBr/KSCN. A practical application of this is given in Section 19.9. 

It is expected, therefore, that the cyclic hexamer also exhibits a characteristic tendency to complex with cations. In fact, the addition of an acetonitrile solution of metal thiocyanates to a solution of the cyclic hexamer in the same solvent shifted the carbonyl absorption to a lower wave number46,52 The shift values depended upon the kind of metal ions present, and the largest shift value of 40 cm-1 was observed for barium thiocyanate (molar ratio of Ba2+/hexamer = 10). In addition to the shift of the carbonyl absorption, the intensities of the C—O-C stretching vibrations around 1200 cm-1 varied appreciably. 

In a 1 litre round-bottomed flask provided with an efficient double surface condenser, place 40 g. (39 ml.) of aniline, 50 g. (40 ml.) of carbon sulphide CAUTION inflammable) (1), and 60 g. (63-6 ml.) of absolute ethyl alcohol (2). Set up the apparatus in the fume cupboard or attach an absorption device to the top of the condenser (see Fig. II, 8, 1) to absorb the hydrogen sulphide which is evolved. Heat upon an electrically-heated water bath or upon a steam bath for 8 hours or until the contents of the flask sohdify. When the reaction is complete, arrange the condenser for downward distillation (Fig. II, 13, 3), and remove the excess of carbon disulphide and alcohol (CAUTION inflammable there must be no flame near the receiver). Shake the residue in the flask with excess of dilute hydrochloric acid (1 10) to remove any aniline present, filter at the pump, wash with water, and drain well. Dry in the steam oven. The yield of crude product, which is quite satisfactory for the preparation of phenyl wo-thiocyanate (Section IV,95), is 40-46 g. RecrystaUise the crude thiocarbanihde by dissolving it, under reflux, in boiling rectified spirit (filter through a hot water funnel if the solution is not clear), and add hot water until the solution just becomes cloudy and allow to cool. Pure sym.-diphenylthiourea separates in colourless needles, m.p. 154°. 

Amin and Issa [15] described an indirect atomic absorption spectrometric method for the determination of primaquine and other antimalarials. The method is based on the formation of their ion-associates with [Cd2+, Co2+, Mn2+, and Zn2+1] thiocyanate, ammonium reineckate, and/or sodium cobaltinitrate. 

Hassan et al [65] used a method for the determination of primaquine and other antimalarials, through ternary complex formation. The analytical aspects of the reaction between the widely used antimalarial drugs with cobalt and thiocyanate to form ternary complexes are described. Alternatively, determination of the cobalt content of the nitrobenzene extract using atomic absorption spectroscopy provided an indirect method for the determination of the drugs. Both methods are applied to the analysis of pharmaceutical preparation and the results obtained agreed well with those obtained with official methods. 

Oxidative stress Lipid oxidation Oxygen absorption Manometric, polarographic Diene conjugation HPLC, spectrophotometry (234 nm) Lipid hydroperoxides HPLC, GC-MS, chemiluminescence, spectrophotometry Iodine liberation Titration Thiocyanate Spectrophotometry (500 nm) Hydrocarbons GC Cytotoxic aldehydes LPO-586, HPLC, GC, GC-MS Hexanal and related end products Sensory, physicochemical, Cu(II) induction method, GC TBARS Spectrophotometry (532-535 nm), HPLC Rancimat Conductivity F2-iP GC/MS, HPLC/MS, immunoassays... 

The pH, EC and Fe3+ were used as control parameters. The first two were measured with an Orion probe combined pH/ATC electrode Triode and a conductivity cell DuraProbe ref. 0133030. Fe3+ was determined by molecular absorption (thiocyanate method). Mineralogical composition of the precipitates was determined by X-ray powder diffraction (XRD). Scanning electron microscopy, combined with an energy dispersive system (SEM-EDS), allowed the observation of morphological and compositional aspects of the precipitates. 

Charge-transfer spectra represent one of the most important classes of spectra for analytical chemistry since the molar absorptivities tend to be very large. Charge-transfer can occur in substances, usually complexes that have one moiety that can be an electron donor and another that can be an electron acceptor. Both the donor and acceptor must have a small difference in their energy levels so that the electron can be readily transferred from the donor to the acceptor orbitals and back again. One example is the well-known, deep-red color of the iron (III) thiocyanate ion. The process appears to be... 

Erythrocyte suspension Sample purged absorption of hydrogen cyanide in sodium hydroxide conversion of thiocyanate to cyanide by potassium permanganate oxidation Spectrophotometry (thiocyanate- cyanide determination) No data 93-97 McMillan and Svoboda 1982... 

Thiocyanate Human serum, urine, saliva Extraction of buffered (pH 7) 2-benzoyl pyridine thiosemi-carbazone and sample with isoamyl acetate Flame atomic absorption spectrometry 4 ng/mL 96-102 Chattaraj and Das 1992... 

Chattaraj S, Das AK. 1992. Indirect determination of thiocyanate in biological fluids using atomic absorption spectrometry. Spectrochica Acta 47(5) 675-680. 

PECH did not react with potassium cyanate but reacted with equimolar potassium thiocyanate in DMF (90°Ci.16 h) to give the thiocyanated polymer (2g, IR, 2180 cm 1) in 53% of DS. Comparing the IR spectrum with those of model compounds, Me2CHCH2SCljl (2180 cm-1) and Me2CHCH2NCS (2200., 2125 cm-1), the isothiocyanate moieties are scarcely existed in the polymer 0. Since the -SCN is a protecting form of thiol likewise the -SCI, the polymer 20 are insolubilized with aqueous alkali presumably due to the S-S crosslinking (23.). Further, absorption at 2180 cm in 20 was completely disappeared treating it with two equivalents of triethyl phosphite at 90°C for 16 h in DMF probably due to the formation of phosphonate structure ( ,). ... 

Flash excitation of solutions of 3,5-dinitroanisole in the presence of nucleophiles produces a short-lived species with an absorption maximum at 550-570 nm (Figure 11, curve a). Decay of this species follows first order kinetics. The lifetime varies rather strongly with the nature of the nucleophile, from 40 ms with hydroxide ion to 0 1 ms with thiocyanate (Table 4). The absorption spectrum is independent of the reagent used. 

The observation of a strong infrared absorption at below 2,000 cm for the dinuclear complex of (185) incorporating manganese thiocyanate was taken as indicating that rare (single atom) N-bound NCS bridges occur in this manganese(II) species." " ... 

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