Browsing by Author "Sandeep Gupta"

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Determination of cefaclor by selective sample enrichment/clean-up on silica gel bonded polyelectrolyte in ion-exchange column chromatography
(2000) Sandeep Gupta; Bhim Bali Prasad
A silica gel-bound cationic polyelectrolyte, poly[N-chloranil N, N, N', N'- tetramethylethylene diammonium dichloride], modified as ion-exchanger capable of molecular recognition of β-lactam antibiotic, was used in solid phase extraction through column chromatography for a sample clean-up and enrichment of analyte from a dilute solution. The optimum and selective sorption conditions for a model antibiotic, cefaclor, were established. The high selectivity of polymer at pH 9.5 and flow rate as high as 5 ml/min were observed for the quantitative sorption of cefaclor. The desorption by 0.1 N HCl at flow rate of 0.1 ml/min and subsequent heating at 80°C for 2 h allowed the antibiotic to be detected as corresponding oxazolone form in UV-spectrophotometric and differential pulse adsorptive stripping voltammetric measurements. The potential of the suggested approach was illustrated by estimating cefaclor in urine and blood plasma samples. © 2000 Elsevier Science B.V.
Genosensor based on a nanostructured, platinum-modified glassy carbon electrode for Listeria detection
(Royal Society of Chemistry, 2015) Kashish; Sandeep Gupta; Suresh Kumar Dubey; Rajiv Prakash
In this article, we describe the development of a simple and cost-effective genosensor probe based on a glassy carbon electrode modified with platinum nanomaterials dispersed in a chitosan matrix. Further, this probe was explored for the label-free detection of Listeria monocytogenes obtained from milk samples. DNA-based interfacial interaction between target DNA and platinum nanomaterials (PtNPs) immobilized with 24 mer ssDNA was investigated using impedance spectroscopy. As-prepared nanomaterials (for electrode fabrication) were characterized by UV-vis, FT-IR, TEM and cyclic voltammetry before fabricating the impedimetric sensor platform. The interfacial interaction between PtNPs and DNA results in the increase of charge transfer resistance (RCT) on hybridization with consecutive increasing concentrations of target DNA. This user-friendly and simple platform was used for the detection of target DNA and shows excellent response and specificity (even for 1-bp mismatch of target DNA). Also, this sensing platform was utilized for the detection of Listeria monocytogenes in real samples (milk beverage) and had a wide range of detection from 1 × 10-12 M to 1 × 10-4 M. In general, our simple and user-friendly sensor probe shows potential for detection of Listeria monocytogenes in food samples with high specificity. © The Royal Society of Chemistry 2015.
Indirect measurement of cephalosporins and penicillins by differential pulse adsorptive stripping voltammetry at mercury electrode
(Croatian Pharmaceutical Society, 2000) Bhim Bali Prasad; Sandeep Gupta
In order to determine certain β-lactam antibiotics at trace level, a differential pulse adsorptive stripping voltammetric (DPAdSV) method has been suggested. The model cephalosporin, viz., cefaclor, was transformed into the corresponding electroactive oxazolone derivative under drastic acid treatment. It was then subjected to the adsorptive accumulation onto a hanging mercury drop electrode [accumulation potential -0.1 V vs. Ag/AgCl, accumulation time 60 s, 40% ethanolic buffer (pH ≃ 8, I = 0.1 mol L-1)] for DPAdSV measurement. The detection limit for cefaclor was as low as ppb level (≥4 ng mL-1, S/N = 3, RSD = 2.9%, n = 5) at an accumulation time of 60 s. The method was found to be useful for the quantitative analysis of cefaclor, ampicillin and amoxycillin at trace levels, and extended to the analysis in their pharmaceutical preparations.
Primary squamous cell carcinoma of gallbladder presenting as acute cholecystitis
(2004) Sandeep Gupta; Sanjeev Kumar Gupta; N.C. Aryya
Primary squamous cell carcinoma of gall bladder accounts for only 0-12.7% of all cases of gall bladder cancer. We here report a case of primary squamous cell carcinoma of gall bladder presenting as acute cholecystitis. A 50 year old man was admitted with the complaints of pain in right hypochondrium and fever of 2 days duration. Abdominal examination revealed tenderness along with guarding and rigidity in right hypochondrium with positive Murphy's sign. The patient was conservatively treated as a case of acute cholecystitis. After 12 hrs of unrewarding treatment patient was operated upon and cholecystectomy done. The specimen revealed thick walled gall bladder with multiple calculi. Histopathology revealed squamous cell carcinoma grade II.
Voltammetric studies of an oxazolone derivative of cefaclor in aqueous buffers
(2002) Bhim Bali Prasad; Sandeep Gupta; Shouri Banerjee
Electrochemical properties of cefaclor at a mercury electrode in aqueous solution of varying pH have been studied through tast, pulse (normal and differential), and cyclic voltammetric techniques. For this, the electroinactive cefaclor is transformed into electroactive penicillenate analogue 'oxazolone derivative' under strong acidic hydrolysis condition. The derived oxazolone system underwent two-steps irreversible reductions involving proton-participations (2e-, H+; 4e-, 4H+) when voltammograms scanned cathodically. However, in cyclic voltammetry, a typical wave due to sulphhydryl group oxidation is noticed on scan reversal in anodic direction. The results have been discussed by taking into account the implications of reactant and product adsorptions onto electrode surface during the course of reductions.