Masatada Satake

Spectrophotometric determination of nitrate and nitrite in water and some fruit samples using column preconcentration

A sensitive analytical method for the simultaneous assay of nitrate and nitrite in water and some fruit samples is presented. The method is based on nitrite determination using the diazotization-coupling reaction by column preconcentration and on the reduction of nitrate to nitrite using the Cd-Cu reductor column. Nitrite is diazotized with sulfanilamide (SAM) in the pH range 2.0-5.0, sulfamethizole (SM) in pH 1.8-5.6 and sulfadimidine (SD) in pH 1.8-4.0 in a hydrochloric acid medium to form water-soluble colourless diazonium cations. These cations were coupled with sodium 1-naphthol-4-sulfonate (NS) in the pH range 9.0-12.0 for the SAM-NS system, pH 8.6-12.0 for the SM-NS system and pH 9.4-12.0 for the SD-NS system to be retained on naphthalene-tetradecyldimethylbenzylammonium (TDBA)-iodide (I) adsorbent packed in a column. The solid mass is dissolved out from the column with 5 ml of dimethylformamide (DMF) and the absorbance is measured by a spectrophotometer at 543 nm for SAM-NS, 537 nm for SM-NS and 530 nm for SD-NS. The calibration graph was linear over 30-600 ng NO(2)-N and 22-450 ng NO(3)-N in 15 ml of final aqueous solution (i.e. 2-40 ng NO(2)-N ml(-1) and 1.5-30 ng NO(3)-N ml(-1) in aqueous sample) for three systems. The detection limits were 1.4 ng NO(2)-N ml(-1) and 1.1 ng NO(3)-N ml(-1) for SAM-NS, 1.2 ng NO(2)-N ml(-1) and 0.89 ng NO(3)-N ml(-1) for SM-NS, 1.0 ng NO(2)-N ml(-1) and 0.75 ng NO(3)-N ml(-1) for SD-NS, respectively. The concentration factor is eight for SAM-NS and SM-NS, and 12 for SD-NS. Interferences from various foreign ions have been examined and the method was successfully applied to the determination of low levels of nitrate and nitrite in water and some fruit samples.

Spectrophotometric determination of nickel after separation by adsorption of its α-furildioxime complex on naphthalene

A new method is proposed for collecting traces of nickel from aqueous solution by precipitation as the alpha-furildioxime complex and adsorption of this onto microcrystalline naphthalene. The precipitate is collected, dried, and dissolved in chloroform, and the nickel is determined spectrophotometrically at 438 nm. The linear calibration range is 2-35 mug/10 ml. The molar absorptivity is 1.6 x 10(4) l. mole(-1). cm(-1). The main advantage is that the nickel is collected quantitatively after only a few secondsshaking. The effect of varying pH, amount of reagent, naphthalene or buffer, shaking and standing time, and interferences have been investigated.

Spectrophotometric determination of nitrate and nitrite in soil and water samples with a diazotizable aromatic amine and coupling agent using column preconcentration on naphthalene supported with ion-pair of tetradecyldimethylbenzylammonium and iodide

Abstract Composite diazotization-coupling reagents containing sulfanilamide (SAM), sulfapyridine (SP) or sulfathiazole (ST) as the diazotizable aromatic amines and sodium 1-naphthol-4-sulfonate (NS) as the coupling agent using column preconcentration on naphthalene-tetradecyldimethylbenzylammonium(TDBA)-iodide adsorbent have been used for the spectrometric determination of trace nitrate and nitrite in soil and water samples. Nitrite ion reacts with SAM in the pH range 2.0–5.0, SP in the pH range 2.0–2.5 and ST in the pH range 2.0–3.3 in HCl medium to form water-soluble colourless diazonium cations. These cations were coupled with NS in the pH range 9.0–12.0 for the SAM system, 9.6–12.0 for the SP system and 8.5–12.0 for the ST system to be retained on naphthalene-TDBA-I material packed in a column. The solid mass is dissolved from the column with 5 ml of dimethylformamide and the absorbance is measured spectrometerically at 543 nm for SAM-NS, 533 nm for SP-NS and 535 nm for ST-NS. Nitrate is reduced to nitrite by a copper-coated cadmium reductor column and the nitrite is then treated with the diazotization-coupling reagent by column preconcentration. The absorbance due to the sum of nitrate and nitrite is measured and nitrate is determined by difference. The calibration graph was linear over the range 2–40 ng NO2−-N ml−1 and 1.5–30 ng NO3−-N ml−1 in aqueous samples for the SAM and ST systems and 2–48 ng NO2−-N ml−1 and 1.5–36 ng NO3−-N ml−1 in aqueous samples for the SP system, respectively. The sensitivity, accuracy and precision of the systems decreased in the order ST⪢SAM⪢SP. The detection limits were 1.4 ng NO2−-N ml−1 and 1.1 ng NO3−-N ml−1 for SAM, 1.6 ng NO2−-N ml−1 and 1.2 ng NO3−-N ml−1 for SP, and 1.0 ng NO2−-N ml−1 and 0.75 ng NO3−-N ml−1 for ST, respectively. The preconcentration factors are 8, 5 and 6 for SAM-NS, SP-NS and ST-NS, respectively. Interferences from various foreign ions have been studied and the methods have been applied to the determination of ng ml−1 levels of nitrite and nitrate in soil and water samples. The mean recovery was 95–102% for all three systems.

Solid-liquid separation after liquid-liquid extraction: spectrophotometric determination of iron(II) by extraction of its ternary complex with 2,2′-dipyridyl and tetraphenylborate into molten naphthalene

A method for the spectrophotometric determination of iron(II) after extraction of its ternary complex with 2,2′-dipyridyl and tetraphenylborate into molten naphthalene has been developed. Iron(II) reacts with 2,2′-dipyridyl to form a water-soluble coloured complex. This complex cation forms a water-insoluble stable ternary complex in the presence of sodium tetraphenylborate, which is easily extracted into molten naphthalene in the pH range 2.8–7.6 by vigorous shaking for a few seconds. The solid naphthalene containing the iron 2,2′-dipyridyl tetraphenylborate complex is separated by filtration and dissolved in acetonitrile. The absorbance is measured at 521 nm against a reagent blank. Beers law is obeyed in the concentration range 2.2–65.5 µg of iron in 10 ml of acetonitrile solution. The molar absorptivity and Sandells sensitivity are 8.89 × 103 l mol–1 cm–1 and 0.006 3 µg cm–2 at 521 nm, respectively. The interference of various ions has been studied in detail. The method has been applied to the determination of iron in standard metallic samples and the results are compared with those obtained by the 1,10-phenanthroline method.

Analysis of metals by solid-liquid separation after liquid-liquid extraction spectrophotometric determination of palladium(II) by extraction of palladium dimethylglyoximate with melted naphthalene

A method of liquid-liquid extraction of palladium di-methylglyoximate with molten naphthalene followed by solid-liquid separation is successfully applied to palladium. The complex between palladium and dimethylglyoxime is easily extracted into molten naphthalene. After extraction, the very fine solidified naphthalene crystals are dissolved in chloroform, and the absorbance of the resultant solution is measured at 370 nm against a reagent blank. Beers law is obeyed for 30-370 mug of palladium in 10 ml of chloroform, and the molar absorptivity is calculated to be 1.72 x 10(4) l.mole.(-1)mm(-1). Various alkali metal salts and metal ions do not interfere. The interference of nickel(II) is overcome by the extraction at pH 2, and that of iron(III) by masking with EDTA or by reduction to iron(II). The method is rapid and accurate.

Atomic-absorption spectrometric determination of copper(I) after adsorption of its 2,4,6-tri(2-pyridyl)-1,3,5-triazine complex with tetraphenylborate anion on microcrystalline naphthalene

An atomic-absorption spectrometric method for the determination of trace amounts of copper(I) after adsorption of tis 2,4,6-tri(2-pyridyl)-1,3,5-triazine tetraphenylborate ion-associated complex on microcrystalline naphthalene has been developed. This ion-associated complex is adsorbed on microcrystalline naphthalene in the pH range 2.2–8.0 by shaking for a few seconds. The solid mass so formed is separated by filtration, dissolved in dimethylformamide and the absorbance is measured at 324.7 nm. Beers law is obeyed in the concentration range 5.0–95.0 µg of copper in 10 ml of the dimethylformamide solution. Ten replicate determinations on a sample containing 40 µg of copper gave a mean absorbance of 0.225 with a standard deviation of 0.0018 and a relative standard deviation of 0.82%. The sensitivity for 1% absorption and the detection limit are 0.075 µg ml–1 and 0.018 µg ml–1, respectively. The method has been successfully applied to the determination of copper in some standard reference materials and biological samples.

Column preconcentration of cobalt in alloys and pepperbush using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol and ammonium tetraphenylborate adsorbent supported on naphthalene with subsequent determination using atomic absorption spectrometry

A method has been established for column preconcentration and determination of cobalt using an ion-pair produced from an ammonium cation and a tetraphenylborate (TPB) anion supported on naphthalene in a simple funnel-tipped glass tube. Cobalt forms a water-soluble chelate cation with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP). The chelate cation is retained as a water-insoluble Co–5-Br-PADAP–TPB complex on the surface of the naphthalene, which is packed in a column. Cobalt is quantitatively retained on the ammonium tetraphenylborate adsorbent supported on the naphthalene in the pH range 3.0–8.0 at a flow rate of 1 ml min–1. The solid mass is stripped from the column with 5 ml of dimethylformamide (DMF) and the cobalt determined by flame atomic absorption spectrometry at 240.7 nm. The calibration graph is linear over the concentration range from 1 to 20 µg of cobalt in 5 ml of final DMF solution. Seven replicate determinations of 12 µg of cobalt gave a mean absorbance of 0.124 with a relative standard deviation of 1.0%. The sensitivity for a 1% absorption is 0.085 µg ml–1. The effect of foreign ions was studied and the proposed method applied to the determination of cobalt in certified reference material samples of alloy, steel and pepperbush.

Analysis of Metals by Solid-Liquid Separation. Spectrophotometric Determination of Cadmium by Extraction of Cadmium Salt of Oxine with Melted Naphthalene

A method is described for the spectrophotometric determination of a minute quantity of cadmium. A cadmium complex stable at 90°C is easily extracted with melted naphthalene. The resulting mixture of cadmium complex and naphthalene is dissolved in dimethylformamide and absorbance of the solution is measured at 400 nm. Effects of pH, amounts of oxine, naphthalene and diverse salts are given.

Column chromatographic pre-concentration of iron(III) in alloys and biological samples with 1-nitroso-2-naphthol-3,6-disulphonate and benzyldimethyltetradecylammonium-perchlorate adsorbent supported on naphthalene using atomic absorption spectrometry

The solid ion-pair material produced from the reaction between benzyldimethyltetradecylammonium chloride (BDTA) and sodium perchlorate on naphthalene provides the basis for a simple, rapid and selective technique for pre-concentrating iron from up to 500 ml of aqueous solution. Iron reacts with disodium 1-nitroso-2-naphthol-3,6-disulphonate (Nitroso-R salt) to form a water-soluble coloured chelate anion. The iron chelate anion forms a water-insoluble, stable iron-Nitroso-R-BDTA complex on naphthalene packed in a column. Trace amounts of iron are quantitatively retained on naphthalene in the pH range 3.5-7.5 and at a flow-rate of 1-2 ml min-1. The solid mass is dissolved out from the column with 5 ml of N,N-dimethylformamide and iron is determined by means of an atomic absorption spectrometer at 248 nm. The calibration graph is linear for concentrations of iron over the range of 0.5-20 micrograms in 5 ml of final solution. The standard deviation and relative standard deviation were calculated. The detection limit of the method was 0.0196 micrograms ml-1 of iron. The sensitivity for 1% absorption was 0.072 microgram ml-1 (0.165 microgram ml-1 by direct atomic absorption spectrometry of aqueous solution). The proposed method was applied to the determination of iron in standard alloys and biological samples.

Column chromatographic preconcentration of palladium with dimethyl glyoxime and acenaphthenequinone dioxime on naphthalene

Abstract A solid material consisting of dimethyl glyoxime (DMG), acenaphthenequinone dioxime (ANDO) or DMG-ANDO on naphthalene provides a very convenient, rapid and economical method for the preconcentration of palladium in synthetic samples. Pd-DMG, Pd-ANDO and Pd-DMG-ANDO are quantitatively retained on naphthalene in the column in the pH ranges 2.2–4.4, 1.8–5.6 and 1.7–6.8, respectively. The solid mixture consisting of the metal complex together with naphthalene is stripped from the column with 5 ml of dimethylformamide (DMF)-n-butylamine and the absorbance is measured at 247.6 nm with an atomic absorption spectrometer. Calibration graphs are linear over the palladium concentration range 5–25 μg per 5 ml of the final solution for all the three complexes. Ten replicate determinations of a sample solution containing 10 μg of palladium gave mean absorbances of 0.180, 0.225 and 0.230 with relative standard deviations of 1.8, 1.7 and 1.6% using the reagents DMg, ANDO and DMG-ANDO, respectively. The sensitivity of the method is better than the direct atomic absorption spectrometric determination of palladium. It is highest in case of the mixed ligands, i.e., DMG-ANDO (0.038 μg ml −1 for 1% absorption). The method can be applied to the trace determination of palladium in complex materials.