Browsing by Author "B.B. Prasad"

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A new chelating polyelectrolyte for preconcentration and separation of trace metals employing resin-impregnated paper chromatography and determination by differential pulse anodic stripping voltammetry
(Springer-Verlag, 1995) B.B. Prasad; S. Sundd
A new chelate-forming polyelectrolytic resin bearing 5-sulfosalicylate counterions was prepared by an ion-exchange method. The resin was amorphous powder and therefore, batch method of separation endangered leaching of the ligand to the some extent. Nevertheless, the selective preconcentration and quantitative separation of Fe3+, Co2+, Cu2+ and Ni2+ were found to be feasible by employing chelating resin-impregnated paper chromatographic method, where separations involved a pH-independent differential migration procedure, based on solubility product equilibria, with aqueous mobile phases. The selectivity of resin for heavy metals, as monitored by differential pulse anodic stripping voltammetry, was found in the order Fe3+>Co2+>Ni2+≈Cu2+. © 1995 Friedr. Vieweg & Sohn Verlagsgesellschaft mbH.
Chelating resin immobilized sawdust packed chromatographic column: Application to separation and preconcentration of lead ion
(2005) B.B. Prasad; S. Banerjee; Dhana Lakshmi
Naturally abundant rubber sawdust has been utilized as a stationary support, which after immobilization with a chelating polyelectrolyte (xylenol orange as counterion) gets converted into a suitable column packing material for isolation and enrichment of trace level target analyte, accurately detectable by the technique of differential pulse anodic stripping voltammetry. The sorbent is robust and re-usable in column-chromatography without showing any leaching and interference complications. Its unique lead ion selectivity from multielemental complex matrices (synthetic water sample, blood serum) at optimized column conditions (pH 2.5 and flow rate 0.5 mL min-1) mitigates the usual problems of intermetallic and readsorption effects. Effects of flow rate, pH, equilibration time, and other variables are reported. The system has advantageous feature to be used in a single-column ion chromatography with satisfactory performance. A modest attempt has been made to determine lead fractions in human blood serum samples on the bases of selective retention of ionic and labile fractions on complexing resin. © 2005 Taylor & Francis Group Ltd.
Determination of diquat herbicide by selective enrichment by column chromatography on imprinted polymer immobilised on silica gel
(Friedr. Vieweg und Sohn Verlags GmbH, 2002) B.B. Prasad; S. Banerjee
A silica gel-bound, imprinted polymer for selective recognition of the diquat herbicide: 5,6-dihydropyrazino [1,2,3,4-lmn]-1,10-phenanthrolinium dichloride, is reported. It was used in the solid-phase extraction procedure, following liquid chromatography-differential pulse, adsorptive-stripping voltammetric (LC-DPAdSV) technique. The operational conditions for 100% retention of the diquat herbicide on a chromatographic column (13.0 × 1.4 cm, adsorbent bed 1.0 g) were realized at pH 6.9 and a flow rate of 5.0 mL min-1. The adsorbent used could be regenerated during elution with 5.0 mL M HCl within 20 min. The limit of detection was 0.65 nM (0.18 ppb) with an enrichment factor as high as 99-fold.
Electrochemical sensor for uric acid based on a molecularly imprinted polymer brush grafted to tetraethoxysilane derived sol-gel thin film graphite electrode
(2009) A.K. Patel; P.S. Sharma; B.B. Prasad
Determination of uric acid in human serum and urine is useful to provide treatment guidelines to hyperuricemic patients. An electrochemical sensor was developed for selective and quantitative recognition of uric acid by using a preanodised sol-gel coated graphite electrode with a molecularly imprinted polymer brush of poly(melamine-co-chloranil) grafted to its exterior surface. During a preconcentration step at (+ 2.0 V versus saturated calomel electrode), the encapsulated analyte recapture involved hydrophobically induced hydrogen-bondings in outwardly exposed MIP cavities in aqueous environment (pH 7.0), instantly oxidised as dications, and then cathodically stripped off as corresponding lactam responding differential pulse, cathodic stripping voltammetric signal. The uric acid was selectively detected without any cross reactivity in the windows of 14.56-177.42 μg mL- 1 (aqueous medium), 4.78-106.96 μg mL- 1 (blood serum), and 7.81-148.42 μg mL- 1 (urine) indicating detection limits in the range of 3.71-4.10 μg mL- 1 (3σ, RSD = 1.9%). © 2008 Elsevier B.V. All rights reserved.
Electrolytic conductivity of crystal violet based quaternary ammonium polyelectrolytes in N,N′-dimethylformamide and dimethyl sulfoxide
(National Research Council of Canada, 1997) Meenakshi Singh; Anil Kumar; Shirley Easo; B.B. Prasad
Electrolytic conductivities of crystal violet based quaternary ammonium polyelectrolytes in very dilute solutions of dimethylformamide and dimethyl sulfoxide at 25°C have been investigated. The electrolytic conductivity (κ) as a function of concentration for systems having a reduced charge density (ξ) greater than unity revealed a very narrow range of linearity in the dilute region. A modest correlation has been made with the counterion condensation and the polycation conformations in order to explain the relative magnitude of limiting equivalent conductivities.
Extraction-Spectrophotometric Determination of Certain-β-Lactam Antibiotics with Methylene Blue
(2000) B.B. Prasad; S. Gupta
An extraction-spectrophotometric method was established for the determination of certain β-lactams, cefaclor, ampicillin and amoxycillin in pure and dosage forms using methylene blue (MB) as an analytical reagent. The method is based on the formation of a chloroform-extractable blue colored ion-association complex (MB cation-antibiotic anion) through the reaction of a β-lactam antibiotic with an excess of methylene blue at pH 9.5. Good agreement with Beer's law was found in the range of antibiotic concentration of 3.5-90.0 μg/ml with a detection limit of 3.0 μg/ml. The method is simple, precise and accurate for pure analyte with excellent recovery (97-102%); and also, this does not require any separation of soluble excipients in pharmaceutical preparations.
Highly sensitive and selective detection of creatinine by combined use of MISPE and a complementary MIP-sensor
(2007) P.S. Sharma; D. Lakshmi; B.B. Prasad
Guanidinoacetate methyltransferase deficiency is a recently discovered inborn defect of creatine biosynthesis which reduces serum creatinine concentrations to as low as 0.58 μg mL-1 (or 0.00058 μg mL -1 after 1,000-fold dilution). To measure ultra trace levels of creatinine in diluted samples, molecularly imprinted solid-phase extraction (MISPE) and molecularly imprinted polymer (MIP) sensor techniques have been found to be inadequate. A combination of these techniques (i.e. MISPE hyphenated with use of an MIP-sensor), reported in this paper, has been found to be highly suitable for direct assay of creatinine in highly diluted human blood serum without complicated pretreatment of the sample. The proposed technique has the potential to enhance the sensitivity of creatinine measurement from μg mL-1 to ng mL-1 in highly dilute aqueous samples in which the concentrations of interfering constituents are reduced to negligible levels. In this work the sensitivity to creatinine was found to be improved compared with that of the MIP-sensor method alone (limit of detection, LOD, 0.00149 μg mL-1). After preconcentration by MISPE and use of the sensor the detection limit for creatinine was as low as 0.00003 μg mL-1 (RSD = 0.94%, S/N = 3; 50-fold preconcentration factor) in aqueous samples. © 2007 Friedr. Vieweg & Sohn Verlag/GWV Fachverlage GmbH.
Histamine in relation to epidemic dropsy glaucoma
(1974) K.S. Mehra; B.B. Prasad; S.S. Gambhir; J.N. Char; R. Singh; P.K. Dass
In 23 cases of epidemic dropsy glaucoma and 17 normal control subjects, histamine levels of both plasma and blood cells and histamine skin sensitivity were measured. It was observed that there was no significant difference in the skin sensitivity to histamine between patients with epidemic dropsy glaucoma and normal subjects, whereas the histamine levels of both plasma and blood cells were significantly higher in patients with epidemic dropsy glaucoma. It is quite probable that the causative factor of glaucoma in these cases is the increased quantity of aqueous formation due to higher concentration of histamine in the blood.
Platinum‐Graphite Biamperometric Determination of Thallium I
(1972) B.B. Prasad; G.D. Khandelwal
[No abstract available]
Platinum‐Graphite Biamperometric Indication for the Low Concentration Determination of Antimony, Arsenic and Tin
(1971) B.B. Prasad; G.D. Khandelwal
The application of a bi‐electrode system for the determination of Sb (III), As (III) and Sn (II) in dilute solutions is described. The electrode system consists of a platinum microelectrode and a wax‐impregnated graphite electrode. Iodine is used as oxidant. The determinations are quite accurate even in 10−3–10−4M concentration range. Copyright © 1971 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
Platinum-graphite electrode system for the biamperometric determination in non-aqueous and partially non-aqueous media - Application to Tin, Antimony and Arsenic
(Springer-Verlag, 1979) B.B. Prasad; T.B. Singh
[No abstract available]
Platinum-graphite electrode system for the biamperometric determination of iodine; [Biamperometrische Jodbestimmung mit dem Elektrodensystem Platin/Graphit]
(Springer-Verlag, 1971) B.B. Prasad; G.D. Khandelwal
[No abstract available]
POLAROGRAPHIC BEHAVIOUR OF THE BOLAFORM ELECTROLYTE alpha , alpha prime -BIS(4,4-BIPYRIDINIUM)-P-XYLENE DIBROMIDE IN WATER.
(1986) B.B. Prasad
Cathodic reduction of a bolaform electrolyte was carried out at dme in aqueous solutions of different pH ranging between 1. 90-7. 90, at constant ionic strength ( mu equals 0. 1 M). Two well-defined diffusion-controlled polarographic waves were observed in all solutions studied. Concepts based on the specific characteristics of the divalent bipyridinium bolaform salt regarding its 'intramolecular coulombic interactions' and a typical 'monoprotonation equilibrium' in aqueous solutions of varying pH have been invoked to explain the outstanding effect of pH variation on the relative wave heights including the mode of reduction as well as electron-transfer mechanism involved.
Polarographic Studies on Aqueous Solutions of Poly-o-xylylviologen Dibromide
(1985) B.B. Prasad
Dropping mercury electrode polarography of the redox polymer poly-o-xylylviologen dibromide in water gave two well-defined irreversible diffusion controlled reduction waves over the pH range 1.70 to 6.40. The half-wave potentials for both waves (Wave I) = -0.404 V, E 1 /2 (Wave II)= -0.981 V vs SCE) are independent of pH and the total concentration of the solutions. However, the gross effect of pH on the relative wave heights suggests that an equilibrium of the type BH =+ H' + B (where B represents the compound studied) exists in solution where the reduction of the protonated as well as of unprotonated form of the polymer results in Waves I and 11, respectively. A tentative mechanism for the reduction processes is proposed. The dissociation constant of the protonated species was found to be 1.0 X 0.1 M) on calculation from a pH-dependence study of the limiting currents for both waves at a particular concentration. © 1985, Taylor & Francis Group, LLC. All rights reserved.
Polarographic Study of the Redox Polymer Poly-p-xylylvioiogen Dibromide in Water
(1981) L.M. Mukherjee; B.B. Prasad
The polarographic behavior of the redox polymer poly-p-xylylviologen dibromide has been examined over the pH range 2.00-8.00. Two irreversible waves with half-wave potentials of -0.496 and -0.936 V vs SCE were observed. The pH dependence of the relative wave heights appears to suggest that the system conforms to a protonation equilibrium where the protonated form reduces, at the DME, at the lower negative potential and the second wave is due to the unprotonated species. Analysis of the limiting current-pH relationship for a given concentration of the compound yielded a value of 7.94 x 10″ (u = 0.1 M) for the dissociation constant of the protonated form. © 1981, Taylor & Francis Group, LLC. All rights reserved.
Production of Joshi-effect under Uni-, and Bi-electrode excitation
(1946) B.B. Prasad
Production of Joshi-effect δi, viz., an instantenous and reversible photo-diminution of current i in excited chlorine has been studied in an aerial current under uni-, and bi-electrode excitation. The current in dark, the net and relative Joshi-effect δi and % δi, in the latter, were comparatively low. Based on interference of anti-phase wave trains, together with a recently suggested phase-shift due to Prof. Josbi in the production of this effect, an explanation is developed for the reduced i (in dark), δi and % δi under bi-electrode excitation. © 1946 Indian Academy of Sciences.
Production of the Joshi-effect in the aerial current under electrical discharge in chlorine
(1949) B.B. Prasad
Arising out of Joshi's observation of the dependance of the Joshi-effect -Δi on circuital parameters and especially the author's earlier work on Δi under uni- and bi-electrode excitation has been the finding that in an isolated sample of purified chlorine (300 mm.) excited by an ozoniser discharge due to 4-10 kV of 50 cycle frequency the negative Joshi-effect %Δi=100×Δi/iD, detected with an aerial increased from 5-90% current diminution in but ordinary light, as its capacity was decreased progressively. Introduction of a serial capacitance in the aerial circuit tends to increase (numerically) the net Joshi-effect -Δi; that of a by-pass capacity decreases it. These results are in accord with Joshi's view that H.F.'s constitute the seat of -Δi. A large (48%) and reproducible ad libitum positive Joshi-effect, i.e., an increase +Δi of the discharge current under light, occurs in the L.T. line, especially under H.F. rejection, it is suggested that the positive effect may be associated with the low frequencies of the discharge current. © 1949 Indian Academy of Sciences.
Quaternary Ammonium Polyelectrolytes: Solution Studies of Certain Systems
(1983) L.M. MUKHERJEEt; B.B. Prasad
The investigation relates to density, viscosity, and conductance studies of four linear quaternary ammonium bromides with molecular weights ranging from 680 to 11,000. Of these, the two DMF-soluble compounds had their backbone quaternary centers attached to bulky substituents outside the chain and the other two, which dissolved in water, involved heterocyclic ring nitrogens carrying the positive charges in the repeating unit of the chain. Attempts have been made to comprehend the behavior of individual systems in terms of the competing solvophobic and electrostrictional interactions with the media. Concepts based on spatial disposition of the substituents and their ability to provide “pockets” for possible solvent entrapment and migration of electrostricted solvent molecules as well as formation of a “cage” of hydrogen-bonded waters around the backbone of the chain have. © 1983, Taylor & Francis Group, LLC. All rights reserved.
Separation and preconcentration of copper and cadmium ions from multielemental solutions using Nostoc muscorum-based biosorbents
(2000) B.B. Prasad; U.C. Pandey
Nostoc-based biosorbents (AlgaSORBs) useful as chromatographic column-packing materials were prepared by immobilizing cyanobacteria onto solid support in three different fashions: (i) cyanobacterial biofilm (Nostoc-dimethylformamide slurry) over polymer-modified silica gel, (ii) cyanobacterial biofilm over bare silica gel, and (iii) cyanobacteria as such onto polymer-modified silica gel. The materials were characterized for their stabilities and metal sorption/elution conditions under static and dynamic equilibrations. Preconcentrated metals from a test sample were detected following 'standard addition' method using a differential pulse anodic stripping voltammetric technique. All sorbents showed 100% affinity for Cd2+ ion in a multielemental sample at pH 6.9 and a flow rate of 0.5 ml/min with a preconcentration factor varying between 28- and 75-fold. The first type of AlgaSORB was also found to be selective for Cu2+ ion in multielemental analysis at pH 5.2 and a flow rate of 1.0 ml/min with a preconcentration factor of 75. The low capacity and favourable kinetics of these sorbents for Cu2+, Cd2+, Zn2+ and Pb2+ ions reflect the suitability of AlgaSORB columns for satisfactory performance in single column ion-chromatography. The polymer spacer between cyanobacterial biofilm and silica gel plays a vital role in holding the immobilized biofilm resulting in better endurance and recyclability for the first type of biosorbent.
Separation and preconcentration of lead from aquatic environment using microcystis - based biosorbent
(2001) B.B. Prasad; U.C. Pandey
The naturally abundant Microcystis surrounded by a slime layer has been immobilized as biofilm on a polymer-modified silica gel to obtain a lead-selective robust column packing material which is recyclable for 70 times without any distinct deterioration. The biosorbent has shown quantitative sorption with a preconcentration factor of 83 for trace level lead ion (initial concentration 0.48 µg ml1) in multielemental/natural water samples at pH 5.0 and flow rate 1.0 ml min1. © 2001 Taylor & Francis Group, LLC.