Faculty of Applied Sciences
Permanent URI for this communityhttp://ir-dev.dut.ac.za/handle/10321/5
Browse
9 results
Search Results
Item Theoretical principles and applications of high performance capillary electrophoresis(Nova Science Publishers, 2015) Bathinapatla, Ayyappa; Kanchi, Suvardhan; Sabela, Myalowenkosi I.; Bisetty, KrishnaThis book chapter is aimed at addressing the theoretical principles and applications of capillary electrophoresis (CE) for the separation of high intensity artificial sweeteners. Electrophoresis is a technique in which solutes are separated by their movement with different rates of migration in the presence of an electric field. Capillary electrophoresis emerged as a combination of the separation mechanism of electrophoresis and instrumental automation concepts in chromatography. Its separation mainly depends on the difference in the solutes migration in an electric field caused by the application of relatively high voltages, thus generating an electro-osmotic flow (EOF) within the narrow-bore capillaries filled with the background electrolyte. Currently capillary electrophoresis is a very powerful analytical technique with a major and outstanding importance in separations of compounds such as amino acids, chiral drugs, vitamins, pesticides etc., because of simpler method development, minimal sample volume requirements and lack of organic waste. The main advantage of capillary electrophoresis over conventional techniques is the availability of the number of modes with different operating and separation characteristics include free zone electrophoresis and molecular weight based separations (capillary zone electrophoresis), micellar based separations (micellar electrokinetic chromatography), chiral separations (electrokinetic chromatography), isotachophoresis and isoelectrofocusing makes it a more versatile technique being able to analyse a wide range of analytes. The ultimate goal of the analytical separations is to achieve low detection limits and CE is compatible with different external and internal detectors such as UV or photodiode array detector (DAD) similar to HPLC. CE also provides an indirect UV detection for analytes that do not absorb in the UV region. Besides the UV detection, CE provides five types of detection modes with special instrumental fittings such as Fluorescence, Laserinduced Fluorescence, Amperometry, Conductivity and Mass spectrometry. Infact, the lowest detection limits attained in the whole field of separations are for CE with laser induced fluorescence detection. Regarding the applications of CE, the separation and determination of high intensity sweeteners were discussed in this chapter. The materials which show sweetness are divided into two types (i) nutritive sweeteners and (ii) non-nutritive sweeteners. The main nutritive sweeteners include glucose, crystalline fructose, dextrose, corn sweeteners, honey, lactose, maltose, invert sugars, concentrated fruit juice, refined sugars, high fructose corn syrup and various syrups. Non-nutritive sweeteners are sub-divided into two groups of artificial sweeteners and reduced polyols. On the other hand, based on their generation; artificial sweeteners can further be divided into three types as (a) first generation artificial sweeteners which includes saccharin, cyclamate and glycyrrhizin (b) second generation artificial sweeteners are aspartame, acesulfame K, thaumatin and neohesperidinedihydrochalcone (c) neotame, sucralose, alitame and steviol glycosides falls under third generation artificial sweeteners. Artificial sweeteners are also classified into three types based on their synthesis and extraction: (i) synthetic (saccharin, cyclamate, aspartame, acesulfame K, neotame, sucralose, alitame) (ii) semi-synthetic (neohesperidinedihydrochalcone) and (iii) natural sweeteners (steviol glycosides, mogrosides and brazzein protein). Polyols are other groups of reduced-calorie sweeteners which provide bulk of the sweetness, but with fewer calories than sugars. The commonly used polyols are: erythritol, mannitol, isomalt, lactitol, maltitol, xylitol, sorbitol and hydrogenated starch hydrolysates (HSH). The studies revealed that capillary electrophoresis was successfully used for the separation of high intensity artificial sweeteners such as neotame, sucralose and steviol glycosides. Additionally, the available methods for the other artificial sweeteners using capillary electrophoresis were reviewed besides the above indicated sweeteners.Item Biosynthesis of ZnO nanoparticles using Jacaranda mimosifolia flowers extract: Synergistic antibacterial activity and molecular simulated facet specific adsorption studies(Elsevier, 2016) Sharma, Deepali; Sabela, Myalowenkosi Innocent; Kanchi, Suvardhan; Mdluli, Phumlani Selby; Singh, Gulshan; Stenström, Thor-Axel; Bisetty, KrishnaThe naturally occurring biomolecules present in the plant extracts have been identified to play an active role in the single step formation of nanoparticles with varied morphologies and sizes which is greener and environmen-tally benign. In the present work, spherical zinc oxide nanoparticles (ZnO NPs) of 2–4 nm size were synthesized using aqueous extract of fallen Jacaranda mimosifolia flowers (JMFs), treated as waste. The microwave assisted synthesis was completed successfully within 5 min. Thereafter, phase identification, morphology and optical band gap of the synthesized ZnO NPs were done using X-ray diffraction (XRD), high resolution transmission elec-tron microscopy (HRTEM) and UV–Visible spectroscopy techniques. The composition of JMFs extract was ana-lyzed by gas chromatography–mass spectrometry (GC–MS) and the ZnO NPs confirmation was further explored with fourier transform infrared spectroscopy (FTIR). The GC–MS results confirmed the presence of oleic acid which has high propensity of acting as a reducing and capping agent. The UV–Visible data suggested an optical band gap of 4.03 eV for ZnO NPs indicating their small size due to quantum confinement. Further, facet specific adsorption of oleic acid on the surface of ZnO NPs was studied computationally to find out the im-pact of biomolecules in defining the shape and size of NPs. The viability of gram negative Escherichia coli and gram positive Enterococcus faecium bacteria was found to be 48% and 43%, respectively at high concentration of NPs.Item Seasonal variation and distribution of Anionic Surfactants in and around Tirupati : a famous pilgrim centre in South India(Asian Publication Corporation, 2015) Ramanjulu, C.; Naidu, N. Venkatasubba; Kanchi, Suvardhan; Bisetty, KrishnaThis report presents the anionic surfactants concentration in water system collected in and around Tirupati, South India. The concentration of anionic surfactants such as sodium lauryl sulfate, sodium dodecyl sulfate, sodium hexadecyl sulfonate and sodium dodecyl benzene sulfonate were showed a rather homogeneous distribution (except sodium dodecyl benzene sulfonate) within the Tirupati, with high values of 80.0, 90.75, 46.90, 15.10 μg L–1 in Tirupati and slightly less concentration values of 75.0, 60.55, 35.40, 10.0 μg L –1 were found in samples collected from Renigunta Industrial Estate during pre-monsoon and monsoon seasons respectively. High concentration of these surfactants in open wells and open municipal wastewaters in Tirupati may be due to the huge discharge of domestic wastes into the drain system. The concentration of surfactants found in Renigunta Industrial Estate may be due to the direct discharge of industrial wastewater into the environment.Item Novel Dithiocarbamates for electrochemical detection of Nickel (II) in environmental samples(Asian Publication Corporation, 2015-06-22) Niranjan, T.; Kanchi, Suvardhan; Bisetty, Krishna; Naidu, N. VenkatasubbaAmmonium 4-phenylpiperazine-1-dithiocarbamate (Amm 4-PP-DTC) and ammonium 4-benzylpiperidine-1-dithiocarbamate (Amm 4-BP-DTC) were synthesized for the determination of nickel(II) using catalytic hydrogen currents (CHC’s) technique with DC Polarography. The method was based on the chelation of nickel(II) with Amm 4-PP-DTC/ Amm 4-BP-DTC in presence of NH 4 OH at pH 6.8 to produce catalytic hydrogen current at -1.50V and -1.41 V vs. SCE respectively. Optimized polarographic conditions were established by studying effect of pH, supporting electrolyte (NH4Cl), ligands and metal ion concentration and effect of adverse ions on peak height to improve the sensitivity, selectivity and detection limits of the present method. This technique is successfully applied for the analysis of nickel(II) in different matrices with recoveries ranging from 96.0-99.0 % and the results obtained were comparable with the atomic absorption spectroscopy.Item Analytical evaluation of steviol glycosides by capillary electrophoresis supported with molecular docking studies(Iranian Chemical Society, 2014-05-05) Ayyappa, Bathinapatla; Kanchi, Suvardhan; Singh, Parvesh; Dovey, Martin; Sabela, Myalowenkosi Innocent; Bisetty, KrishnaThis paper reports on a newly developed elec-trokinetic chromatographic method for the simultaneous separation and determination of steviol glycosides in real stevia samples by capillary electrophoresis and supported by molecular docking studies. Our results obtained using 30-mM heptakis-(2,3,6-tri-o-methyl betacyclodextrin) as a separating agent, suggest that at optimum experimental conditions the detection limits of 2.017 9 10-5 and 7.386 9 10-5 M and relative standard deviations (n = 5) of 1.10 and 1.17 were obtained for rebaudioside-A and stevioside, respectively. In addition, the molecular docking studies explained to a certain extent why the separation was successful. The calculated binding free energy results for the rebaudioside-A and stevioside complexes formed with the separating agent showed that although both ligands penetrated deeply into the hydrophobic cavity of the sep-arating agent, the presence of additional hydrogen bonding in the case of stevioside is probably responsible for its stronger binding affinity than that of rebaudioside-A.Item A Box-Behnken Design and Response Surface Approach for the Simultaneous Determination of Chromium (III) and (VI) Using Catalytic Differential Pulse Polarography(ESG, 2004-09-29) Sabela, Myalowenkosi Innocent; Kanchi, Suvardhan; Ayyappa, Bathinapatla; Bisetty, KrishnaThe present paper describes an optimized Box-Behnken design using a catalytic-differential pulse polarograhic technique for the simultaneous determination of chromium (III) and (VI) in wastewater samples using ammonium piperidine dithiocarbamate as a complexing agent. The optimization strategy was carried out using a two level full factorial design. The results of the experimental design were based on an analysis of variance and demonstrated that only the pH, concentrations of the buffer and the complexing agent were statistically significant throughout the experiment. The optimal values for the three variables were 8.0, 0.2 mM and 5.0 mM for pH, concentrations of the buffer and the complexing agent respectively. Under optimum experimental conditions the detection limit of the proposed method was found to be 0.0841 µg L-1 while the linear range was 1.0-10.0 and 0.5-25.0 µg L- for chromium (III) and (VI) respectively. The present method was also applied for the simultaneous determination of chromium in the presence of some foreign ions with satisfactory analytical responses.Item The polarographic study of Cobalt(II)-dithiocarbamate complexes at DME(IJCAS, 2014) Giridhar, C.; Kanchi, Suvardhan; Niranjan, T.; Naidu, N. VenkatasubbaCobalt is a naturally occurring element in the earth’s crust. It is a very small part of our environment and very small amounts are needed for many animals and humans to stay healthy. Cobalt poisoning can occur when exposed to large amounts of cobalt. The aim of this study was to develop a facile, rapid, robust, sensitive and selective methodology for the determination of cobalt(II). Two new ligands, ammonium 2,6-dimethyl morpholine dithiocarbamate (ADMM-DTC) and ammonium 3-methyl piperdine dithiocarbamate (AMP-DTC) were synthesized in the laboratory. The method was based on chelation of cobalt(II) with ADMM-DTC/AMP-DTC in presence of NH4OH at pH 7.2 and 8.2 to produce catalytic hydrogen currents at -1.28 V and -1.38 V vs SCE respectively and prior detected by D.C polarography. Optimized polarogaphic conditions were established by studying effect of pH, supporting electrolyte (NH4Cl), ligand & metal ion concentrations and effect of adverse ions on peak height to improve the sensitivity, selectivity and detection limits of the present method. This technique is successfully applied for the analysis of cobalt(II) in different matrices with recoveries ranging from 93- 98 % and the results obtained were comparable with the differential pulse polarography (DPP).Item Dithiocarbamates as hazardous remediation agent : a critical review on progress in environmental chemistry for inorganic species studies of 20th century(Saudi Chemical Society, 2014-01) Kanchi, Suvardhan; Singh, Parvesh; Bisetty, KrishnaThis article provides a critical review and a wide range of applications of dithiocarbamates (DTCs) in environmental samples. The characteristics of DTCs are reviewed with particular emphasis on inorganic speciation studies using state-of-the-art analytical instrumentation coupled with computational methods of analysis.Item Polarographic catalytic hydrogen wave technique for the determination of copper(II) in leafy vegetables and biological samples†(ESG, 2013-03-01) Kanchi, Suvardhan; Singh, Parvesh; Sabela, Myalowenkosi Innocent; Naidu, N. Venkatasubba; Bisetty, KrishnaAn economical, novel, eco-friendly and robust method for the quantification of copper(II) in various leafy vegetables, milk and blood samples has been developed using direct current catalytic hydrogen wave (DC-CHW) technique involving the formation of ammonium salts of piperidine/morpholine dithiocarbamates metal complex. Ammonium piperidine/morpholine dithiocarbamates complexed with copper(II) in the presence of NH4Cl-NH4OH medium at pH 6.5±1 produces CHW’s at -0.35±1 V vs SCE. Consequently, various optimal parameters such as preparation medium, effect of pH, ligand concentration, metal ion concentration and indifferent ions effect on peak height were optimized to enhance the sensitivity and selectivity. The novel aspect in the work address the interaction of ammonium piperidine/morpholine dithiocarbamates with copper(II) were confirmed with cyclic voltammetry (CV) and supported by computational calculations using Density Functional Theory (DFT) methods. Furthermore, the student “t”-test and variance ratio “f”-tests indicated no significant difference between the present method and the differential pulse polarographic (DPP) method.