Thiocyanates analysis

A major advance was devised by Pehr Edman (University of Lund Sweden) that has become the standard method for N terminal residue analysis The Edman degrada tion IS based on the chemistry shown m Figure 27 12 A peptide reacts with phenyl iso thiocyanate to give a phenylthwcarbamoyl (PTC) denvative as shown m the first step This PTC derivative is then treated with an acid m an anhydrous medium (Edman used mtromethane saturated with hydrogen chloride) to cleave the amide bond between the N terminal ammo acid and the remainder of the peptide No other peptide bonds are cleaved m this step as amide bond hydrolysis requires water When the PTC derivative IS treated with acid m an anhydrous medium the sulfur atom of the C=S unit acts as... 

A simple example of a titration is an analysis for Ag+ using thiocyanate, SCN , as a titrant. 

Analysis. The abiUty of silver ion to form sparingly soluble precipitates with many anions has been appHed to their quantitative deterrnination. Bromide, chloride, iodide, thiocyanate, and borate are determined by the titration of solutions containing these anions using standardized silver nitrate solutions in the presence of a suitable indicator. These titrations use fluorescein, tartrazine, rhodamine 6-G, and phenosafranine as indicators (50). 

Manufacture, Shipment, and Analysis. In the United States, sodium and potassium thiocyanates are made by adding caustic soda or potash to ammonium thiocyanate, followed by evaporation of the ammonia and water. The products are sold either as 50—55 wt % aqueous solutions, in the case of sodium thiocyanate, or as the crystalline soHds with one grade containing 5 wt % water and a higher assay grade containing a maximum of 2 wt % water. In Europe, the thiocyanates may be made by direct sulfurization of the corresponding cyanide. The acute LD q (rat, oral) of sodium thiocyanate is 764 mg/kg, accompanied by convulsions and respiratory failure LD q (mouse, oral) is 362 mg/kg. The lowest pubhshed toxic dose for potassium thiocyanate is 80—428 mg/kg, with hallucinations, convulsions, or muscular weakness. The acute LD q (rat, oral) for potassium thiocyanate is 854 mg/kg, with convulsions and respiratory failure. 

Shipping, analysis, and safety factors are similar to those of ammonium thiocyanate, except that the alkaU thiocyanates are more thermally stable. Sodium thiocyanate is best handled in 316 stainless steel. At room temperature where some iron contamination can be tolerated, type 304 can be used. Aluminum corrodes more rapidly than stainless steel, but some alloys can be used below 60°C. Some but not all mbber equipment is satisfactory. 

For colorimetric or gravimetric determination l-nitroso-2-naphthol can be used. For chromatographic ion exchange (qv), cobalt is isolated as the nitroso-(R)-salt complex. The cyanate complex is used for photometric determination and the thiocyanate for colorimetry. A rapid chemical analysis of... 

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. ... 

Ammonium sulfide, 3, n Ammonium thiocyanate, 7, 48 Ammonolysis, 4, 3 7, 16 o-Amyl alcohol, 1, 4, 10 Amyl alcohol, active, 7, 77 mo-Amyl Bromide, 1,1, 2, 4, 10 w-Amyl Methyl Ketone, 7, do -Amyl propiolic acid, 7, 62 Analysis of Benzoylhydroperoxide, 8,32 Analysis of Benzoylperoxide, 8, 31 Anhydro-o-Hydroxymercoribenzoic Acid, 7, 3... 

Tri-n-butyl phosphate, ( -C4H9)3P04. This solvent is useful for the extraction of metal thiocyanate complexes, of nitrates from nitric acid solution (e.g. cerium, thallium, and uranium), of chloride complexes, and of acetic acid from aqueous solution. In the analysis of steel, iron(III) may be removed as the soluble iron(III) thiocyanate . The solvent is non-volatile, non-flammable, and rapid in its action. 

Fluoride ion, and weak acids and bases do not interfere, but nitrate, nitrite, perchlorate, thiocyanate, chromate, chlorate, iodide, and bromide do. Since analysis of almost all boron-containing compounds requires a preliminary treatment which ultimately results in an aqueous boric acid sample, this procedure may be regarded as a gravimetric determination of boron. 

Cirunwald-Winstein analysis, 1,505 thiocyanates, 3, 729 thiourea, 3, 755 tricyanomethides, 3, 709 triethylenetetramine, 3, 722 tripod ligands tetradentate, 3,734... 

One-phase titration methods have also been developed. These methods are not truly one-phase titrations but the term is used to indicate the absence of a second organic phase. One of these methods, applied to the analysis of sodium and triethanolamine lauryl sulfates and lauryl ether sulfates, use a quaternary amine as a titrant and cobalt(II) thiocyanate as indicator. Centrimide was found to avoid the use of chloroform which was not possible with other titrants examined, such as domiphen bromide and oxyphenonium bromide. The pink color of the indicator changes to violet as an excess of titrant forms a complex with the indicator [238]. 

Crompton [21] has reviewed the use of electrochemical methods in the determination of phenolic and amine antioxidants, organic peroxides, organotin heat stabilisers, metallic stearates and some inorganic anions (such as bromide, iodide and thiocyanate) in the 1950s/1960s (Table 8.75). The electrochemical detector is generally operated in tandem with a universal, nonselective detector, so that a more general sample analysis can be obtained than is possible with the electrochemical detector alone. 

To establish the well drainage boundaries and fluid flow patterns within the TFSA-waterflood pilot, an interwell chemical tracer study was conducted. Sodium thiocyanate was selected as the tracer on the basis of its low adsorption characteristics on reservoir rocks (36-38), its low and constant background concentration (0.9 mg/kg) in produced fluids and its ease and accuracy of analysis(39). On July 8, 1986, 500 lb (227 kg) of sodium thiocyanate dissolved in 500 gal (1.89 m3> of injection brine (76700 mg/kg of thiocyanate ion) were injected into Well TU-120. For the next five months, samples of produced fluids were obtained three times per week from each production well. The thiocyanate concentration in the produced brine samples were analyzed in duplicate by the standard ferric nitrate method(39) and in all cases, the precision of the thiocyanate determinations were within 0.3 mg/kg. The concentration of the ion in the produced brine returned to background levels when the sampling and analysis was concluded. 

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. 

After 2 h incubation of the prepared antibody beads with UV-crosslinked extract in a cold room, the beads are washed 4 x with 100 /A RIPA buffer (50 mMTris-HCl pH 7.5, 150 rnMNaCl, 1% NP-40, 0.5% sodium deoxycholate, and 0.1% SDS) and lx with genomic DNA lysis buffer (50 mM Tris, pH 7.4, 10 mM EDTA, 500 mM NaCl, 2.5 mM DTT, 0.5 mM spermidine, 1% Triton X-100). Approximately 300 /(I of PK solution (1 mg/ml proteinase K in genomic DNA lysis buffer and 0.2 U//A RNase inhibitor) is added to the total lysate previously kept on ice and the beads are then incubated at 37° for 30 min. Gently flick the tubes to resuspend the beads every 10 min during the incubation. After removal of the proteinase K solution, 300 /A of RNA extraction solution (4 M guanidine thiocyanate, 0.5% sarkosyl, and 25 mM sodium citrate, pH7) is added to the beads, incubated for 10 min and the supernatant is mixed with 30 fig yeast tRNA (as a carrier) and 30 fil of 3 M sodium acetate. The RNA solution is phenol-chloroform extracted, ethanol-precipitated, and the pellet washed once with 70% ethanol. The dry pellet is used for 1st strand cDNA synthesis, followed by PCR analysis. The removal of proteins... 

Acrylonitrile metabolites have been measured in blood and urine, but, except for measurement of thiocyanate, these methods have not been developed for routine monitoring of exposed humans. Supercritical fluid extraction/chromatography and immunoassay analysis are two areas of intense current activity from which substantial advances in the determination of acrylonitrile and its metabolites in biological samples can be anticipated. The two techniques are complementary because supercritical fluid extraction is especially promising for the removal of analytes from sample material and immunoassay is very analyte-selective and sensitive (Vanderlaan et al. 1988). 

Compound (XIII) exists as a mixture of monomeric and dimeric species at room temperature. The same situation is true for the reaction products from methyl- and isopropyl-thiocyanate, respectively, with triisopropylborane, whereas the iminoborane obtained from reacting methyl-thiocyanate with tri-n-butylborane is dimeric 3 . With the exception of (XIII) these compounds have not been characterized by analysis. 

Thiocyanate solution, in silver quantitative analysis, 22 677 Thiocyanic acid, 23 678-681 Thiodiacids, 23 740 2,2 -Thiodiethanethiol, acid-catalyzed condensation of, 23 732 Thiodiols, 23 744 Thiodipropionic acid... 

It should be noted that the amounts of cyanide or thiocyanate found by chemical analysis are not necessarily the amounts that are bioavailable. 

The values reported for environmental levels of cyanide and thiocyanate must be interpreted with caution. Methods for the analysis of cyanide and thiocyanate have many interferences. In addition, samples containing cyanide and/or thiocyanate may not be stable if the samples are not carefully preserved. It should be noted that the amounts of cyanide or thiocyanate found by chemical analysis are not necessarily the amounts that are bioavailable. 

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