Determination of cyanides by continuous distillation and flow analysis with cylindrical amperometric electrodes

Cyanide and Cyanogenic Compounds-Toxicity, Molecular Targets, and Therapeutic Agents

Cyanide (CN) is a well-known mitochondrial poison. CN poisoning may result from acute or long-term exposure to a number of CN compounds. Recent insight into the chemical affinities of the CN anion has increased our understanding of its toxicity and the mechanisms of antidotal actions, which, together with information on various exposure sources, are reviewed in the present article. A literature search in Scopus, Embase, Web of Science, PubMed, and Google Scholar for the period 2001-2024 revealed that the CN anion after exposure or degradation of CN compounds is distributed to vulnerable copper and iron-containing targets, especially in mitochondria, thus blocking the electron transport chain. Intake of cyanogenic compounds may exert subacute or chronic toxic effects, also because of the interaction with cobalt in vitamin B12. Antidotal agents exert their effects through the affinity of CN for cobalt- or iron-containing compounds. Research on CN interactions with metalloproteins may increase our insight into CN toxicity and efficient antidotal regimens.

A novel method for cyanide quantification in human whole blood using ion chromatography with amperometric detection and its application to cyanide intoxication cases

Cyanide is a highly toxic agent that has been frequently used for suicide in South Korea. It is also used in various industrial fields, such as metal plating, in which many accidental cyanide intoxications have occurred. To overcome the disadvantages of conventional cyanide analysis methods, a simple and fast method for the analysis of cyanide in whole blood using ion chromatography (IC) with amperometric detection was developed in this study. Whole blood samples were deproteinized, diluted, and analyzed using an IC-amperometric detection system. The limits of detection and quantitation were 0.1 and 0.2 mg/L, respectively. The method showed good linearity in the range of 0.2 to 50 mg/L with R²  > 0.99. The intra- and inter-assay precision and accuracy values were <10%. The established method was successfully applied to analyze whole blood samples from three cyanide intoxication cases.

An improved method for direct estimation of free cyanide in drinking water by Ion Chromatography-Pulsed Amperometry Detection (IC-PAD) on gold working electrode

In the present work a fast, reliable and safe Ion Exchange Chromatography-Pulsed Amperometry Detection (IC-PAD) method for direct determination of free cyanide in drinking water has been reported. To the best of our knowledge for the first time we are reporting the application of Gold working electrode for detection of free cyanide in a chromatography system. The system shows a wide linear range up to 8000µg/L. The electrode was found to have improved sensitivity and selectivity in the presence of interfering ions. The detection limit of the system was calculated to be 2µg/L. Long term evaluation of the electrode was found to be stable. Reproducible results were obtained from analysis of drinking water samples with recoveries of 98.3-101.2% and Relative Standard Deviations (RSD) of <2%. This study proves the potential application of the newly developed method for the analysis of free cyanide in drinking water.

Ligand displacement, headspace single-drop microextraction, and capillary electrophoresis for the determination of weak acid dissociable cyanide

A new method involving ligand displacement, headspace single-drop microextraction (SDME) with in-drop derivatization and capillary electrophoresis (CE) was developed for the determination of weak acid dissociable (WAD) cyanide. WAD metal-cyanide complexes (Ag(CN)(2)(-), Cd(CN)(4)(2-), Cu(CN)(3)(2-), Hg(CN)(2), Hg(CN)(4)(2-), Ni(CN)(4)(2-) and Zn(CN)(4)(2-)) are decomposed with ligand-displacing reagent and the released hydrogen cyanide is extracted from neutral solution (pH 6.5) with an aqueous microdrop (5 microl) containing Ni(II)-NH(3) as derivatization agent. The hydrogen cyanide extracted reacts with Ni(2+) to form a stable and highly UV absorbing tetracyanonickelate anion which is then determined by CE. Among the three different ligand-displacing reagents (i.e., ethylenediamine, dithizone and polyethileneimine) studied none of the reagents used alone releases cyanide completely from all WAD cyanide complexes. Complete recoveries were obtained by the extraction of WAD cyanide from 0.4 mol l(-1) ethylenediamine chloride buffer (pH 6.5) containing 0.001% (wt) dithizone. Proposed system was applied to determine WAD cyanide in industrial wastewater and river waters samples with spiked recoveries in the range of 95.8-104.7%.

Separation and determination of metallocyanide complexes of Fe(II), Ni(II) and Co(III) by ion-interaction chromatography with membrane suppressed conductivity detection applied to analysis of oil refinery streams (sour water)

A separation and determination method for the analysis of cyanometallic complexes of Fe(II), Ni(II) and Co(III) was developed to be applied to the analysis of petroleum refinery streams (sour water). Ion-interaction chromatography was used employing an analytical column IonPac NS1 10 microm and a chromatographic system ICS 2500 equipped with a membrane conductivity suppression ASRS ultra 4mm, both supplied by Dionex Corporation. The mobile phase was composed of 2 mmol l(-1) TBAOH, 1 mmol l(-1) Na(2)CO(3), 0.1 mol l(-1) NaCN and ACN (77:23, v/v), flowing at 0.7 ml min(-1). At the optimized conditions, detection limits estimated by the calibration curve parameters and relative standard deviation were: 0.002 mg CNl(-1) and 3.1% for Fe(CN)(6)(4-); 0.003 mg CNl(-1) and 2.5% for Ni(CN)(4)(2-) and 0.003 mg CNl(-1) and 2.8% for Co(CN)(6)(3-). Sour water samples without any pretreatment (except membrane filtration) from a petroleum refinery in Brazil were analyzed successfully by external calibration method.

Ion chromatographic determination of sulfide and cyanide in real matrices by using pulsed amperometric detection on a silver electrode

The determination of free sulfide and cyanide by pulsed amperometric detection (PAD) at a silver-working electrode was improved through a deep de-oxygenation (at least 10 min) of both standard and real solutions containing the two analytes and adopting a two-potential waveform able to eliminate Ag working electrode fouling. The waveform stepped around the oxidation of Ag in the presence of 0.1-0.4 M hydroxyl ion, from -0.1 to 0.1 V versus saturated calomel electrode (SCE). The eluent composition (0.4 M NaOH plus 7.5 mM oxalate solution) allowed a very good column efficiency and selectivity. The presence of a polysulfide species was hypothesized in sulfide solutions that had not been de-oxygenated and aged. The polysulfide eluted just before sulfide and was confirmed by a chemical test with SO3(2-) producing the elimination of the polysulfide peak. Detection limits, according to the Hubaux-Vos method, were 1.0 and 2.0 microg/l for S2- and CN , respectively. We demonstrated good performance of the optimized method by repeatedly injecting standard solutions and by analyzing different real matrices. The method exhibited very good accuracy and repeatability (10 microg/l and a 500 microl injection loop, had a repeatability better than 3% for sulfide and 100 microg/l had a repeatability better than 1% for cyanide). The two-potential waveform ensured long-term stability of the electrode surface that required no manual polishing procedure for at least 1 month (20 analysis per day).

Flow injection analysis: A new approach to pharmaceutical determinations

A review is presented in which the fundamental principles, instrumentation and practical aspects of flow injection analysis (FIA) are discussed. A particular focus is put on applications in pharmaceutical chemistry, which offers a wide scope to the new technique.