No abstract

No abstract

Chlorophyll a (Chl a) and chlorophyll b (Chl b) plant pigments, which are important in the food industry and are beneficial as environmental pollution indicators, have been extracted with a novel solvent mixture (1:1 v/v acetone-propanol) not containing chloroform and simultaneously determined by first-derivative spectrophotometry. The results were statistically compared to those obtained by the ordinary absorption spectrophotometric reference utilizing the principle of additivity of absorbances. The testing of the developed method in synthetic mixtures of Chl a and Chl b and in real plant material samples (grass, spinach, chard, purslane, black cabbage, crisp lettuce, rocket, dill and seaweed) proved successful in that the developed extractive derivative spectrophotometric method was both rapid and precise, and was not dependent on the Chl a/b ratio in contrast to the reference method which was adversely affected by the latter parameter.

No abstract

The study was aimed at developing suitable chromatographic conditions and pretreatment methods for reliable trace analysis of cyanide in drinking water and seawater. Separation of CNˉ (as CNOˉ), Fˉ, Clˉ, NO 2ˉ, Brˉ, NO 3ˉ, CO 3 2ˉ, SO 4 2ˉ, PO 4 3ˉ was carried on a Dionex IonPac AS20 column. Two different methods were developed for different samples. LOD and LOQ values were 7.2 µg L −1 and 24.0 µg L −1 for method I and were 15.4 µg L −1 and 51.3 µg L −1 for method II, respectively. Our results did not indicate the presence of cyanide in drinking water samples commercially supplied from Istanbul markets. By the addition of 250, 500, and 1000 µg L −1 to drinking water, cyanide recoveries were found 100.1 %, 104.5 % and 106.9 %, respectively by employing method I. Method II was applied to an artificial and real seawater sample obtained from the Marmara Sea, Istanbul, where a 50 µg L −1 cyanide spike gave a recovery of 100.1 %. Interferences from excessive amounts of salts in seawater were removed by using strongly acidic cation-exchange resin and melamine-formaldehyde resin. The proposed pre-treatment method (II) and chromatographic conditions provided low LOD's for Downloaded by [Georgetown University] at 01:57 25 August 20152 cyanide in seawater (well below acute toxicity limits), since dilution errors and matrix effects were eliminated.

The first aim of this study was to develop a selective, sensitive and reliable method for direct simultaneous determination of cyanate, thiocyanate and hexavalent chromium by ion chromatography with conductivity detection. The other target was to successfully determine cyanides by utilizing same chromatographic system. Yet, since cyanides can not be detected by the direct method, free cyanide ions were converted into cyanate with chloramine-T at alkaline pH. In addition, strongly complexed metal cyanides were converted into cyanate by using photo-oxidation following chloramine-T. Total cyanate ion obtained from developed methods were analysed with IC. The chromatographic separations on anion exchange column were accomplished by optimized multi-step gradient eluent program using NaOH as the eluent. Proposed method was applied for the simultaneous determination of cyanide and hexavalent chromium in electroplating bath solutions and in industrial wastewater. Cyanide and hexavalent chromium could be measured in the linear dynamic ranges of 0.6 -961.5 µmol L‾ 1 and of 0.9 -118.5 µmol L‾ 1 , respectively. The limit of detection and limit of quantification of cyanide were 0.18 and 0.61 µmol L‾ 1 , and these values for chromium(VI) were 0.26 and 0.86 µmol L‾ 1 , respectively. GRAPHICAL ABSTRACTDownloaded by [University of Cincinnati Libraries] at 06:50 31 May 2016 2 INTRODUCTİONCyanide ion (CNˉ) and hexavalent chromium (Cr(VI)), which are highly toxic compounds, are extensively used in electroplating industry. Since cyanide compounds can form stable complexes with metals in a wide spectrum, they are used in mining, metallurgy, manufacture, photography, etc. The complexes of zinc, nickel, copper and cadmium metals with cyanide can be ionized in acidic medium and they are known as weak acid dissociable (WAD) species. In addition to free cyanide, WAD species, metal cyanide and strongly complexed metal cyanides, thiocyanate, cyanogen chloride, and cyanate show very distinct differences in terms of toxicity, reactivity, and effect on the environment. The ionization constants of metallocyanides have significant differences with oxidation state, pH, temperature, and photodegredation playing as important factors. [1] The toxicity of metallocyanides exhibits diversity according to their stabilization constants. The concentration of cyanate gradually increases with time as the cyanide concentration decreases in environment due to oxidation of cyanide. [2] The most harmful cyanide species to the environment are shown to be free and WAD cyanides. [3] Inhalation of hydrocyanic acid (prussic acid (HCN)) or digestion of cyanide salts causes fast-appearing symptoms. HCN vapors are formed by mixing the salts with acids or in the stomach following oral ingestion. The lethal dose is probably 100 mg for hydrocyanic acid while it is 300 mg for potassium cyanide. [4] Furthermore, according to US EPA, the maximum contaminant level for cyanide in drinking water is 0.2 mg Lˉ1. [5] Downloaded by [University of Cincinnati Libraries] at 06:50 31 Ma...

No abstract

No abstract