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PubMed1990

Surveillance of urinary thiocyanate concentration after epidemic spastic paraparesis in Mozambique.

A large epidemic of spastic paraparesis in Mozambique during a drought was attributed to cyanide exposure from cassava. Active surveillance in one of the villages most affected by the epidemic detected four new cases in the first year after the epidemic, and none in the second year. In apparently healthy schoolchildren in the same village, surveillance of urinary thiocyanate concentration, an indicator of cyanide exposure, showed high peak values of 1175 and 673 mumols l-1 in succeeding years, with a gradual return to near-normal values in the third year. A marked seasonal variation in thiocyanate concentration was present, with the highest value coinciding with the dry season, the period of the epidemic, and the cassava harvest. Lower values were found in the neighbouring unaffected semi-urban centre. As cassava cultivation increases in many drought-affected countries, we recommend monitoring urinary thiocyanate concentration to estimate cyanide exposure and identify populations at risk for spastic paraparesis epidemics.

Child↗

PubMedDate not supplied

Standardisation of methods for the estimation of thiocyanate and iodine in foodstuff.

Thiocyanate content in vegetables has been estimated by passing the water extract of vegetables through an alumina column. The thiocyanate content in the eluate has been measured according to Johnston and Jones. Iodine content in the vegetables has been estimated according to a modified method of Acland. The results show the primarily the Cruciferae family vegetables contain higher concentration of thiocyanate.

Animals↗

PubMed1986

[Verification of smoking habits in group studies by anamnesis or determination of serum thiocyanate level?].

In an unselected series of 336 patients of our clinic for occupational diseases a standardized questionnaire on respiratory symptoms and measurements of lung function (spirometry, body plethysmography, flow-volume-curve) were used to study the relations of these results to smoking habits evaluated by questionnaire or thiocyanate level. Statistical elaboration revealed closer connections between anamnestic data on smoking habits and respiratory impairment than between the latter and thiocyanate level. In conclusion anamnestic data on smoking habits are more reliable than thiocyanate measurements in occupational field studies.

Adult↗

PubMed1986

Anti-sickling effect of dietary thiocyanate in prophylactic control of sickle cell anemia.

As a clinical entity, sickle cell anemia (SCA) is known to be relatively rarer in Africans than in the African-American population of the United States. Paradoxically, sickle cell trait (SCT), the non-anemic, heterozygous condition, is about three times more common among indigenous Africans than in African-Americans. The ratio of SCA to SCT is 1:50 for African-Americans, and less than 1:1,000 for tropical Africans. This etiological disparity is attributed to an anti-sickling agent, thiocyanate, (SCN-) found abundantly in staple African foods, such as the African yam (Dioscorea sp) and cassava (Manihot utilissima). Staple American foods have negligible SCN-concentrations. Nonstaple foods in the American diet, such as carrots, cabbage, and radishes, have SCN- levels far below the African yam and cassava. This finding explains the high incidence of SCA among African-Americans and its rarity in Africans.The author concludes that SCA is a congenital deficiency anemia, ameliorable by prophylactic diets of foods with high SCN- contents. Thus, "thiocyanate deficiency anemia" is nutritionally a more correct clinical status for those born with the homozygous sickle hemoglobin genome. Just as any iron undernourished person can suffer from iron deficiency anemia, sickle hemoglobin homozygotes suffer from "thiocyanate deficiency anemia" when they subsist on SCN-deficient foods. This article reviews the role of dietary SCN- in SCA control.

Anemia, Sickle Cell↗

PubMed1979

[Evaluation of smoke consumption by the determination of serum thiocyanate (author's transl)].

The method of Butts and Coll. for determination of serum thiocyanate--parameter correlated to smoke assumption--has been modified in order to improve sensibility and has been characterized as regards precision and accuracy. The improved method has been successively utilized for determination of serum thiocyanate of 493 subjects during a screening for prevention from coronary heart disease. A linear correlation (r = 0,916) between the number of smoked cigarettes and serum thiocyanate has been found. Assuming 40 mumol/l as a cut-off point to distinguish cigarette smokers and non smokers, 1,8% false positive and 5% false negative resulted.

Adult↗

PubMed1980

A technique of silver impregnation for nervous tissues with some thiocyanates.

Taking advantage of some properties of thiocyanates, a technique of silver impregnation for nerve fibres in the human central nervous system is described. The following procedure is suggested: frozen sections 25-35 micrometer thick, 5-10% aqueous solution of ammonium thiocyanate or potassium thiocyanate, 10% aqueous solution of silver nitrate, ammoniacal silver solution, reduction in 20% formalin, gold toning, dehydrating and mounting. By this procedure, fine fibres appear in the color range from purple to dark purple on the almost colorless background.

Cell Nucleus↗

PubMed1983

Lactoperoxidase and thiocyanate protect cultured mammalian cells against hydrogen peroxide toxicity.

The toxicity of various combinations of lactoperoxidase-thiocyanate-hydrogen peroxide was tested on a cell line of human epidermoid carcinoma of the cervix (HeLa), a Chinese hamster ovary cell line (CHO), and human gingival fibroblasts. The capacity of the cells to proliferate, to exclude trypan blue and to produce acids from glucose was evaluated. There was no significant difference between the three cell types in their reactions to the various test combinations. A 1 h exposure of the cells to 10 microM hydrogen peroxide reduced their capacity to proliferate. After a 1 h exposure to 100 microM hydrogen peroxide the cells were damaged to such an extent that none survived. In the presence of lactoperoxidase and thiocyanate the cells were protected from the toxic effects of hydrogen peroxide as disclosed by their capacity to proliferate and exclude trypan blue. The rate of acid production of the cells in the presence of glucose was inhibited, however, by the combination lactoperoxidase-thiocyanate-hydrogen peroxide.

Animals↗

PubMed1981

[Gas chromatographic determination of thiocyanate in vegetable and animal foods and in human serum following paper chromatographic separation (author's transl)].

Paper chromatographic separation of thiocyanate is the first step in determining non-bound thiocyanate in homogenized animal and vegetable foods and in human serum. The thiocyanate eluated from the paper chromatogram is brominated and then determined as cyanogen bromide using a gas chromatograph equipped with an electron-capture detector. Interfering substances (mainly ethanol-unprecipitable protein components, amino acids and cyanide from glycosidic precursors) are eliminated by this procedure.

Chromatography, Paper↗

PubMed1980

[Autoradiographic distribution of 14C after administering tracer-marked nitroprusside, cyanide and thiocyanate to pregnant mice and rats (author's transl)].

Doses of ca. 2--3 mg/kg of nitroprusside, cyanide and thiocyanate, tracer-marked with 14C, were applied i.v. to pregnant mice and rats. Autoradiograms of the whole animal were taken 1 min, 10 min and 60 min after administration. After administering nitroprusside two phases of the tracer pattern could be distinguished: the phase of removal of the cyanide poisoning with tracer-markings predominant in the liver and the lungs, followed by the phase of thiocyanate excretion, with tracer-markings predominantly in the stomach and urinary system. Tracer-markings in the foetuses were observed during the thiocyanate phase, but not during the cyanide phase. The therapeutic consequences are discussed.

Animals↗

PubMed1979

Blood cyanide and thiocyanate concentrations after administration of sodium nitroprusside as hypotensive agent in neurosurgery.

In a group of 50 neurosurgical patients receiving sodium nitroprusside as a hypotensive agent, in doses of 50--2131 microgram/kg body weight, whole blood cyanide was estimated before infusion of drug, during infusion, immediately after infusion, and 1 and 3 h later. Cyanide values increased significantly, reaching the maximum in a sample taken immediately after infusion (mean value, 333; highest value, 1800 microgram/liter). Values correlated closely with both dose and rate of infusion. Blood thiocyanate, estimated before, immediately after, and 3 h after the infusion, showed no significant changes in thiocyanate concentration. In any case, no signs or symptoms of cyanide or thiocyanate poisoning were observed. We conclude that sodium nitroprusside, in the proper dose and given at the proper rate, does not precipitate cyanide poisoning.

Adolescent↗

PubMed1993

Determination of thiocyanate metabolite of sodium nitroprusside in serum by spectrophotometry.

A sensitive, reproducible and rapid method for the spectrophotometric determination of thiocyanate, the metabolite of sodium nitroprusside, was developed. Acetonitrile was used to remove protein in the serum. Uniform design technique was used in arranging the experiments and choosing the reaction conditions between thiocyanate and ferric nitrate reagent. The wavelength of maximum absorption was 456 nm, the calibration curve of SCN- was linear in the range of 1.68-13.4 micrograms/ml (r = 0.9999), the relative average recovery of thiocyanate was 94.0%. The day-to-day and within-day relative standard deviations were less than 4.0% (n = 8) and 3.2% (n = 10) respectively. The limit of determination was 0.3 microgram/ml. Drugs such as lidocaine, etc. presented no interference on the determination.

Aged↗

PubMed1995

Spectrophotometric determination of plasma thiocyanate by formation of an ion-pair with methylene blue.

We describe a sensitive method for measuring thiocyanate in 500 microliters plasma samples. This technique, although slower than the standard method, improves sensitivity. It requires the extraction in chloroform of an ion-pair formed between thiocyanate ions and methylene blue in acidic medium. Within-day precision had a coefficient of variation of 2.5% and between-day precision a CV of 4.75%. The results were well-correlated (r = 0.997). For 30 non-smokers, the mean thiocyanate level was < 55 mumol/l, and for 30 smokers 90 mumol/l (SD = 20). The method was successfully applied to seven fire smoke victims treated with hydroxocobalamin.

Humans↗

PubMed2001

Diverse heteroleptic ytterbium(III) thiocyanate complexes by oxidation from bis(thiocyanato)ytterbium(II).

The new ytterbium(II) thiocyanate complex [Yb(NCS)2(thf)2] (1), synthesised by redox transmetallation between [Hg(SCN)2] and ytterbium metal in THF at room temperature, gave monomeric, eight coordinate [Yb-(NCS)2(dme)3] (2, dme = 1,2-dimethoxyethane) on crystallisation from DME, and is a powerful, synthetically useful reductant. Thus, oxidation of 1 with Hg(SCN)2, Hg(C6F5)2/HOdpp (HOdpp = 2,6-diphenylphenol), TlCp (Cp = C5H5 or CH3C5H4), Tl(Ph2pz) (Ph2pz = 3,5-diphenylpyrazolate) and CCl3CCl3 in THF yielded the ytterbium(II) complexes [Yb(NCS)3(thf)4] (3), [Yb-(NCS)2(Odpp)(thf)3](4), [Yb(NCS)2Cp-(thf)3] (Cp = C5H5 (5), CH3C5H4 (6)), [Yb(NCS)2(Ph2pz)(thf)4] (7) and [Yb(NCS)2Cl(thf)4] (8). In the solid state, complexes 4, 6 and 7 were shown by X-ray crystallography to be six, eight and eight coordinate monomers, respectively. Exclusively terminal, N-bound transoid thiocyanate bonding is observed with eta1-Odpp (4), eta5/-C5H4Me (6) and eta2-Ph2Pz (7) ligands attached approximately perpendicular to the N...N vector. The chloride complex 8 is not a molecular species, but consists of discrete, seven coordinate [YbCl2(thf)5] cations and [Yb(NCS)4(thf)3] anions. By contrast, oxidation of 1 with TlO2CPh gave a mixture of [[Yb(NCS)-(O2CPh)2(thf)2]2] (9) and 3 through rearrangement of an initially formed [Yb(NCS)2(O2CPh)] species. The X-ray structure of 9 indicates a dimeric complex with a (Yb(mu-O2CPh)4Yb] core that contains both bridging bidentate and bridging tridentate benzoate groups, and with a terminal N-bound thiocyanate and two THF ligands on each ytterbium. Reduction of Ph2CO with 1 in THF yielded the dinuclear complex [[Yb(NCS)2(thf)3]2(mu-OC(Ph)2C(Ph)2O)] (10), in which two octahedral Yb centres are bridged by a 1,1,2,2-tetraphenylethane-1,2-diolate ligand, derived from reductive coupling of the benzophenone reagent.

Journal Article↗

PubMed2003

Study of a bis-furaldehyde Schiff base copper(II) complex as carrier for preparation of highly selective thiocyanate electrodes.

A new highly selective thiocyanate electrode based on N,N'-bis-(furaldehyde)-1,2-phenylenediamine-dipicolyl copper(II) complex [Cu(II)-BFPD] as neutral carrier is described. The electrode has an anti-Hofmeister selectivity sequence: SCN->I->Sal->ClO4->Br->NO2->Cl->NO3->SO4(2-)>SO3(2-)>H2PO4- and a near-Nernstian potential linear range for thiocyanate from 1.0x10(-1) to 5.0x10(-6) mol L(-1) with a detection limit 2.0x10(-6) mol L(-1) and a slope of 57.5 mV decade(-1) in pH 5.0 of phosphate buffer solution at 20 degrees C. The response mechanism is discussed on the basis of results from A.C. impedance measurement and UV spectroscopy. The anti-Hofmeister behavior of the electrode results from a direct interaction between the central metal and the analyte ion and a steric effect associated with the structure of the carrier. The electrode has the advantages of simplicity, fast response, fair stability and reproducibility, and low detection limit. The selectivity of electrodes based on [Cu(II)-BFPD] exceeds that of classical anion-sensitive membrane electrodes based on ion exchangers such as lipophilic quaternary ammonium or phosphonium salts. Application of the electrode for determination of thiocyanate in waste water samples from a laboratory and a gas factory, and in human urine samples, is reported. The results obtained were fair agreement with the results obtained by HPLC.

Journal Article↗

PubMed2006

A novel thiocyanate-selective electrode based on a zinc-phthalocyanine complex.

A novel thiocyanate (SCN-)-selective PVC membrane electrode based on a zinc-phthalocyanine (ZnPc) complex as neutral carrier is described. The membrane electrode containing ZnPc with 5.1% (w/w) ionophore, 29.2% (w/w) PVC, and 65.7% (w/w) 2-nitrophenyl octyl ether (o-NPOE) as plasticizer displayed an anti-Hofmeister selectivity sequence, SCN- > Sal- > I- > ClO4- > Br- > Cl- > NO3- > NO2- > H2PO4- > SO4(2-)), and exhibited near-Nernstian potential response to thiocyanate ranging from about 1.0 x 10(-1) to 1.0 x 10(-6) mol L(-1) with a detection limit of 7.5 x 10(-7) mol L(-1) and a slope of 58.1+/-0.5 mV per decade in pH 3.0 phosphate buffer solution at 25 degrees C. This preferential response is believed to be associated with the unique coordination between the central metal of the carrier and thiocyanate.

Journal Article↗

PubMed2000

Photokinetic voltammetric method for the determination of thiocyanate.

Thiocyanate traces have a strong inhibitory effect on the oxidation of Neutral Red by potassium bromate under UV irradiation in diluted phosphoric acid. Neutral Red exhibits a sensitive second derivative oscillopolarographic wave at -0.6 V(vs. SCE) in diluted phosphoric acid and sodium acetate solution. The oscillopolarographic behavior of Neutral Red was selected as indicator component for its photo-activated oxidation. The photochemical reaction rate equation was determined. A detection limit of 0.3 ng mL(-1) (3sigma/k) and a linear calibration curve from 2.0-48.0 ng mL(-1) thiocyanate were obtained. The method was applied to the determination of thiocyanate in urine, saliva and serum with satisfactory results.

Journal Article↗

PubMed2000

Separation of trace amounts of palladium (II) with crown ether from hydrochloric acid and potassium thiocyanate media.

A new method for the separation of trace amounts of palladium from hydrochloric acid and potassium thiocyanate media has been established based on the formation of an ion-pair complex of palladium thiocyanate anion Pd(SCN)4(2-) and the cationic potassium complex of dicyclohexyl- 18-crown-6 (DC18C6) in chloroform. The effect of various factors (solvent, crown ether, potassium thiocyanate, hydrochloric acid, reagent concentration, shaking time, phase volume ratio, composition of the extracted species, foreign ions, etc.) on the extraction and back-extraction of palladium has been investigated. The method can be combined with subsequent FAAS determination of palladium. The procedure was applied to determine palladium traces in chloroplatinic acid and rhodium chloride.

Journal Article↗

PubMed2005

Lead(II) thiocyanate complexes with bibracchial lariat ethers: an X-ray and DFT study.

Compounds of formula [Pb(L2)(NCS)2] (1) and [Pb(L4)(SCN)2] (2) (where L2 is the lariat crown ether N,N'-bis(3-aminobenzyl)-4,13-diaza-18-crown-6 and L4 is the Schiff-base lariat crown ether N,N'-bis(3-(salicylaldimino)benzyl)-4,13-diaza-18-crown-6) were isolated and structurally characterized by X-ray diffraction analyses. The X-ray crystal structures of both compounds show the metal ion coordinated to the six donor atoms of the crown moiety, leaving the corresponding pendant arms uncoordinated. The coordination sphere of lead(II) is completed by two thiocyanate groups that coordinate either through their nitrogen (1) or sulfur (2) atoms. The organic receptor adopts a syn conformation in 1, while in 2 it shows an anti conformation. To rationalize these unexpected different conformations of the L2 and L4 receptors in compounds 1 and 2, as well as the different binding modes found for the thiocyanate ligands, we have carried out theoretical calculations at the DFT (B3LYP) level. These calculations predict the syn conformation being the most stable in both 1 and 2 complexes. So, the anti conformation found for 2 in the solid state is tentatively attributed to the presence of intermolecular pi-pi interactions between phenol rings, for which the dihedral angle between the least-squares planes of both rings amounts to 2.6 degrees and the distance between the center of both rings is 3.766 A. On the other hand, the analysis of the electronic structure has revealed that the Pb-ligand bonds present highly ionic character in this family of compounds. They also suggest a greater transfer of electron density from the NCS- ligands when they coordinate through the less electronegative S atom. The Pb-SCN covalent bond formation mainly occurs due to an effective overlap of the occupied 3p z orbitals of the S atoms and the unoccupied 6p z AO of the Pb atom, while the Pb-NCS bonding interaction is primarily due to the overlap of the 6s and 7s AO of Pb with sp(1.10) hybrids of the N donor atoms. Our electronic structure calculations can rationalize the different coordination of the thiocyanate groups in compounds 1 and 2: the simultaneous formation of two Pb-SCN bonds is more favorable for S-Pb-S angles close to 180 degrees , for which the overlap between the occupied 3p z orbitals of the S atoms and the unoccupied 6 pz AO of the Pb atom is maximized.

Journal Article↗