Rajesh Kumar Dubey

Differential Pulse Polarographic Determination of Gallium and Niobium in Samples After Preconcentration of Their Quinolin-8-Olate Complexes on Microcrystalline Naphthalene

Abstract Gallium and niobium react with quinolin-8-ol to form water insoluble complexes which are quantitatively adsorbed on microcrystalline naphthalene from the large volume of their aqueous solutions in the pH range of 3.5 - 8.2 and 6.2 - 9.4, respectively. After filtration, the metal complexes were desorbed with 10 ml of HCl (1M for Ga and 11 M for Nb) and determined by using a differential pulse polarograph (DPP). The dissolved oxygen is removed by adding a few milliliters of 4% NaBH4 solution in the case of gallium. The detection limits are 0.04 ppm for gallium and 0.05 ppm for niobium at the minimum instrumental settings (signal to noise ratio = 2). The linearities are maintained in the concentration range 0.1 - 5.0 ppm for gallium and 0.4 - 6.0 ppm for niobium with correlation factors of 0.9997 and 0.9996 and relative standard deviations of 0.81 and 0.95%, respectively. Characterization of the electroactive process included an examination of the degree of reversibility. Various parameters such as ...

Simultaneous determination of lead and cadmium in various environmental and biological samples by differential pulse polarography after adsorption of their morpholine-4-carbodithioates onto microcrystalline naphthalene or morpholine-4-dithiocarbamate-CTMAB-naphthalene adsorbent.

A highly selective, sensitive and rapid differential pulse polarographic method (DPP) has been developed for the simultaneous estimation of trace amounts of lead and cadmium in standard alloys, biological and environmental samples. The morpholine-4-carbodithioates of the samples were absorbed on microcrystalline naphthalene in the pH range of 5-10 for lead and 3.4-11 for cadmium. The metal complexes were desorbed with 10 ml of 1M HCl and determined simultaneously with a differential pulse polarograph. These metals can alternatively be quantitatively adsorbed on morpholine-4-dithiocarbamate-cetyltrimethylammonium bromide-naphthalene adsorbent packed in a column and determined similarly. The detection limits are 0.14 ppm for Pb and 0.014 ppm for Cd at minimum instrumental settings (signal-to-noise ratio = 2). The linearity is maintained in the concentration ranges of Pb, 0.7-15 ppm and Cd, 0.07-10 ppm with a correlation factor of 0.9997 and relative standard deviations of 0.95 and 0.81%, respectively. Various parameters such as the effect of pH, volume of aqueous phase, and interference of a number of metal ions on the estimation of lead and cadmium have been studied in detail to optimize the conditions for their simultaneous estimation in various biological and environmental samples.

Differential pulse polarographic determination of trace amounts of vanadium and molybdenum in various standard alloys and environmental samples after preconcentration of their morpholine-4-carbodithioates on microcrystalline naphthalene or morpholine-4-dithiocarbamate cetyltrimethyl-ammonium bromide-naphthalene adsorbent

A highly selective, sensitive, and fairly rapid and economical differential pulse polarographic (DPP) method has been reported for the determination of trace amounts of vanadium and molybdenum in standard alloys and various environmental samples. The morpholine-4-carbodithioates of these metals were retained (>99% recovery) quantitatively on microcrystalline naphthalene in the pH range 4.5-6.9 for vanadium and 1.5-4.5 for molybdenum. These metals were determined by DPP after desorption with 10 ml of 1 M HCl. Vanadium and molybdenum may also be preconcentrated by passing their aqueous solutions under similar conditions on morpholine-4-dithiocarbamate CTMAB-naphthalene adsorbent packed in a column at a flow rate of 1-5 ml min(-1) and determined similarly. The detection limits are 0.20 ppm for vanadium and 0.04 ppm for molybdenum at minimum instrumental settings (signal to noise ratio=2). The linearity is maintained in the following concentration ranges, vanadium 0.50-10.0 and molybdenum 0.10-9.0 ppm, with a correlation factor of 0.9996 (confidence interval of 95%, slopes 0.0196 and 0.01497 muA mug(-1), intercepts 3.65x10(-3) and -1.92x10(-3) respectively) and relative standard deviation of 1.1% in the microcrystalline method, while in the column method, the linearity is maintained in the concentration ranges, 0.50-6.5 for vanadium and 0.10-5.5 ppm for molybdenum with correlation factor of 0.9994 (with confidence interval of 95%, slopes 0.0194, 0.015 muA mug(-1), intercepts 3.60x10(-3) and -1.90x10(-3) respectively) and relative standard deviation of 1.4%. Various parameters such as the effect of pH, reagent, naphthalene and CTMAB concentrations, volume of aqueous phase and interference of a large number of metal ions on the estimation of vanadium and molybdenum have been studied in detail to optimize the conditions for their voltammetric determination at trace level in various standard alloys and environmental samples.

Preconcentration of Indium(III) from Complex Materials After Adsorption of Its Morpholine-4-dithiocarbamate on Naphthalene or Using Morpholine-4-dithiocarbamate-cetyltrimethylammonium Bromide-naphthalene Adsorbent

Abstract A highly selective, sensitive and rapid differential pulse polarographic method has been developed for the estimation of trace amounts of indium in standard alloy, ore, synthetic and environmental samples. The morpholine-4-dithiocarbamate of indium(III) is adsorbed on microcrystalline naphthalene in the pH range 3.5–6.4. The metal complex is desorbed with HCl and determined with a differential pulse polarograph (DPP). This metal may alternatively be quantitatively retained on morpholine-4-dithiocarbamate-cetyltrimethylammonium bromidenaphthalene adsorbent packed in a column at a flow rate of 0.5–5.0 ml/min and determined similarly. The detection limit is 0.10 ppm at the minimum instrumental setting (signal to noise ratio = 2). Indium has been determined in the concentration range 0.70–15.0 ppm with a correlation factor of 0.9996 and a relative standard deviation of 0.76% (n = 8). In the column method, the linearity is maintained in the concentration range 0.70–8.5 ppm with a correlation factor of...

Simultaneous Determination of Cobalt and Nickel in Standard Alloys, Environmental and Biological Samples by Differential Pulse Polarography After Preconcentration of Their Morpholine-4-carbodithioates on Microcrystalline Naphthalene or Morpholine-4-dithiocarbamate-CTMAB-naphthalene Adsorbent

Abstract A highly sensitive, selective, simple and economical differential pulse polarographic (DPP) method has been developed for the simultaneous determination of trace amounts of cobalt and nickel in standard alloys, biological and environmental samples. The morpholine-4-carbodithioates of cobalt and nickel are quantitatively adsorbed on microcrystalline naphthalene in the pH range 3.5–9.0 and 4.1–9.5 respectively and determined simultaneously with DPP after desorption with 10 ml of 1 M HCl. These metals can alternatively be adsorbed on morpholine-4-dithiocarbamate-cetyltrimethylammonium bromide-naphthalene (MCDT-CTMAB-naphthalene) adsorbent packed in a column and determined similarly. The detection limits are 0.15 ppm for cobalt and 0.20 ppm for nickel at minimum instrumental settings (signal-to-noise ratio=2). The linearity is maintained in the concentration ranges, cobalt 0.6–12.0/0.6–7.0 and nickel 1.0–20.0/1.0–12.0 ppm with a correlation factor of 0.9996 and relative standard deviations of 1.2 and...

Determination Of Arsenic In Various Environmental And Oil Samples By Differential Pulse Polarography After Adsorption Of Its Morpholine-4-Carbodithioate On To Microcrystalline Naphthalene Or Morpholine-4-Dithio-Carbamate-Ctmab-Naphthalene Adsorbent

ABSTRACT A highly selective, sensitive, rapid and economical differential pulse-polarographic (DPP) method has been developed for the quantitative determination of trace amounts of arsenic in various environmental and crude oil samples. The morpholine-4-carbodithioate of arsenic was quantitatively adsorbed on microcystalline naphthalene in the pH range of 6.0–9.5. The metal complex alongwith naphthalene was shaken with 10 ml of 1 M HCl and arsenic determined with a differential pulse polarograph using HCl-pyridine-NaCl as the supporting electrolyte. Arsenic may also be adsorbed quantitatively under similar conditions on morpholine-4-dithiocarbamate-cetyltrimethylammonium bromide-naphthalene adsorbent packed in a column at a flow rate of 0.5–5.0 ml/min and determined similarly. The detection limit is 0.016 ppm at the minimum instrumental setting (signal to noise ratio=2). Arsenic is being determined in the concentration range of 0.08–9.0 ppm with a correlation factor of 0.9996 and a relative standard devia...

Differential-pulse polarographic determination of zinc and manganese in various pharmaceutical and biological samples after adsorption of their morpholine-4-carbodithioates on microcrystalline naphthalene

A highly selective, sensitive, rapid and economical differential-pulse polarographic method was developed for the simultaneous determination of trace amounts of zinc and manganese in various standard alloys and pharmaceutical, biological and environmental samples after adsorption of their morpholine-4-carbodithioates on microcrystalline naphthalene in the pH range 4.1-9.0 for manganese and 6.5-10.2 for zinc. After filtration, the metal complexes are shaken with 10 ml of 1 mol l-1 HCl and determined simultaneously using a differential-pulse polarograph. There is no need to remove naphthalene from the solution. Dissolved oxygen is removed by adding a few millilitres of 4% NaBH4 solution. The detection limits are 0.06 ppm for Mn and 0.1 ppm for Zn (signal-to-noise ratio = 2). Linearity is maintained in the concentration ranges 0.06-10 ppm for Mn and 0.1-12 ppm for Zn with a correlation factor of 0.9997 and relative standard deviations of 0.95 and 0.81%, respectively. The characterization of the electroactive process included an examination of the degree of reversibility. Various parameters such as the effect of pH, volume of aqueous phase and interference of a number of metal ions on the determination of manganese and zinc were studied in detail to optimize the conditions for their simultaneous determination (based on the large difference in their Ep values) in various biological, pharmaceutical and environmental samples.

Differential-pulse polarographic determination of cadmium in various environmental samples after adsorption of its quinolin-8-olate complex on to microcrystalline naphthalene

A highly selective, rapid and economical differential-pulse polarographic method has been developed for the determination of trace amounts of cadmium in various standard alloys and environmental samples after adsorption of its quinolin-8-olate on to microcrystalline naphthalene. The cadmium complex is quantitatively adsorbed on to microcrystalline naphthalene in the pH range 6.1–10.0 and is determined by differential-pulse polarography after desorption in 10 ml of 1 mol l–1 hydrochloric acid. Dissolved oxygen is removed by adding a few millilitres of 4% NaBH4 solution. The detection limit is 0.7 ppm (signal-to-noise ratio = 2) and the linearity is maintained in the concentration range 0.7–17 ppm, with a correlation coefficient of 0.9997 and a relative standard deviation of ±0.74%. Characterization of the electroactive process included an examination of the degree of reversibility. Various parameters, such as the effect of pH, volume of aqueous phase and interference of a number of metal ions on the determination of cadmium, have been studied in detail to optimize the conditions for its determination in complex materials.