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A method is presented for the spectrophotometric microdetermination of cobalt (II) in fresh waters, aquatic weeds, and animal tissues employing 7-nitroso-8-hydroxyquinoline-5-sulfonic acid. the method enables direct determination of cobalt (II) in presence of a large number of anions and cations commonly associated with cobalt, and is adequate for determining the metal in the concentration range of 0.001–10 ppm, which is commonly encountered in environmental samples.

Fifteen new hydroxamic acids were explored in conjunction with trioctyimethylammonium cation for the extractive separation of manganese into MIBK from the anions and cations commonly associated with the metal in environmental samples. The most rapid extraction with the maximum selectivity and sensitivity for the atomic absorption spectrometric determination of the metal in the MIBK extract was achieved with N-p-aminophenyl-2-furylacrylohydroxamic acid. The method enabled the determination of manganese at sub-ppb levels and was applied in the analysis of coal, manganese ore, plant tissue, animal tissue and natural waters.

Iron (III) was rapidly extracted as its ternary complex with tributyl phosphate and N-phenly1-2-furylacrylohydroxamic acid (PFHA) from weakly acidic (pH 1.0-1.5) solutions into isobutyl methyl ketone and was determined atomic absorption spectrometrically. The method tolerated the presences of a large number of anions and cations commonly associated with iron, and was successfully tested with certified samples of coal fly ash, alloys, and plant tissues. It was also applied to the analysis of animal tissues, natural waters, and wastewaters; validating it by standard addition technique. PFHA was selected from nine new hydroxamic acids.

Antimony (III) was separated from antimony (V) by extractive separation from 2–10−6 M HC1 media with N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) in chloroform and determined by graphite furnace atomic absorption spectroscopy at 2600°C using copper as matrix modifier. Antimony (V) was subsequently reduced to the trivalent form with acidic (-1M HC1) potassium iodide solution and determined as above. the mutual tolerance between antimony (III) and antimony (V) in the present mothod was very high-either of the species could be determined in presence of 15 times higher concentration of the other species. the sepatation-AAS determination system enabled accurate differential analysis of the metalloid in natural/ polluted waters down to 10−2 ppb (ug 1−1) levels. the method was also applied to the analysis of antimony in vehicle exhaust particulates, plant tissues, and animal tissues. the method was validated by analysing several certified reference materials with and without standard addition o...

A new series of reagents, N-phenyl-2-furylacrylohydroxamic acid and its eight analogues, together with eight pyridylazo reagents, were explored for the selective extraction and sensitive spectrophotometric determination of bismuth (III) in standard alloys and environmental matrices. Bismuth was first extracted with a hydroxamic acid into chloroform and a pyridylazo reagent was added to the extract to form an intensely coloured ternary complex for spectrophotometric analysis. The combination of N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) and 5-iodo-5-(dimethylamino)-2-(2-pyridylazo) phenol (IDEPAP) provided the maximum selectivity and sensitivity (e=6.5 × 104 1 mol−1 cm−1 at 590 nm). The enrichment attained through solvent extraction together with the intense colour of the ternary complex enabled analysis of bismuth at levels of 1ppb (0.001 ppm) and lower.

A highly sensitive, selective and rapid method for the spectrophotometric determination of trace amounts of vanadium(V) is described. Vanadium(V) is extracted from 3–6 molar hydrochloric acid solutions as a violet complex with N-o-methoxyphenyl-2-theno-hydroxamic acid (oMPTHA) in chloroform. The extract shows maximum absorbance at 545 nm (∊ = 7.2 × 103) and obeys Beer's Law over the range 0–15 μg/ml of vanadium; the Sandell sensitivity being 0. 007 μg/cm2. The method is suitable for simple and rapid determination of vanadium in presence of high concentrations (1:2000 to 1:600) of several cations and complexing anions including titanium(IV), zirconium(IV), iron(III), lanthanum(III), uranium(VI), molybdenum(VI), fluoride and phosphate. Vanadium can be determined in minerals, natural products, high purity niobium and tantalum metals, alloy steels, non-ferrous alloys and raffinates. The overall method of extraction and determination takes no more than 15 minutes. Variations in the volume of mother li...

Indium (III) was selectively extracted at pH 5.2–5.9 with N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) into chloroform. BPAR [5-bromo-4(2-pyridylazo) resorcinal] was added to the extract to form an intensely red coloured ternary complex measurable spectrophotometrically at 515 nm (e = 5.81 × 104 1 mol−1 cm−1). The extraction system enabled enrichment of indium and determination of the metal down to 10−4 ppm (0.1 ppb) levels. For atomic absorption spectrometric determination, indium was extracted with MFHA into methyl isobuyl ketone and measured at 303.9 nm resonance line in the air-acetylene flame. Both the methods were

A method is presented for the trace analysis of molybdenum (VI) in standard steel sample, plant tissues, animal tissues, and natural waters. The method is based on the extractive separation of molybdenum from complex matrices by chelating it with a new reagent N-p-methoxypheny1-2-furylacrylohydroxamic acid (MFHA) into isoamyl alcohol followed by spectrophotometric determination, Eight other new hydroxamic acids were studied for the same purpose and MFHA was chosen as it was the most sensitive of these as well as the other hydroxamic acids reported previously, The method enables rapid and reliable analysis of molybdenum at ppb lelvels in environmental matrices.

Thorium (IV) was separated from several anions and cations commonly associated with it in environmental samples by liquid-liquid extraction with N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) into chloroform at pH 3.6–5.5. The metal was then back-extracted into aqueous media containing 1.8–2.2 M HCl and determined spectrophotometricall) at 500 nm (e = 3.9 × 104 1 mol−1 cm−1) with 4-(2-pyridylazo) resorcinol [PAR]. The method was successfully applied to the analysis of thorium in coal fly ash, monazite, uranium-thorium ore, animal tissue, plant tissue, and natural waters. MFHA and PAR were chosen from thirteen hydroxamic acids and nine pyridylazo reagents, as the reagent combination that provided the maximum selectivity and sensitivity.

Hafnium (IV) was selectively extracted from 0.45-0.55 M HCl media as its chelate with N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) into chloroform. Xylenol orange was added to the extract to form an intensely colored ternary complex measurable spectrophotometrically at 545 nm (epsilon = 8.3 x 10/sup 4/l mol/sup -1/ cm/sup -1/) with a sensitivity better than 0.002 ppm. For atomic absorption spectrometric determination, hafnium was extracted with MFHA into methyl isobutyl ketone and measured with 286.6 nm resonance line in the nitrous oxide-acetylene flame. The methods were applied to the analysis of hafnium in alloys, plant tissues, animal tissues and natural waters. The MFHA-xylenol orange reagent combination was chosen after studying ten hydroxamic acids and five chromogenic reagents.

The paper briefly reviews the status of titanium as an environmental pollutant and presents a new method suitable for the microdetermination of the metals in plants, animal tissues and waters. The method is based on extractive separation of titanium as its chelate with N-p-methoxyphenyl -2-furylacrylohydroxamic acid (MFHA) in chloroform or isoamyl alcohol and subsequent spectrophotometric or atomic absorption spectrometric determination. MFHA was chosen from nine new hydroxamic acids as detailed in the paper. The overall sensitivity of the spectrophotometric method with chloroform as extracting solvent i s better than 1 ppb (0.001 ppm). For atomic absorption spectrometric determination isoamyl alcohol is used as extracting solvent and a sensitivity of 0.2 ppm, which is ten times better than attained earlier, is achieved. There was excellent agreement between the results obtained by the two different instrumental methods.