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The shortage and contamination of sources of surface water, as well as the increasing demand for agricultural practices, groundwater is important for many domestic, commercial, and industrial purposes. Human health and agricultural yields were significantly affected either by quality and concentration levels of groundwater. 25 groundwater samples were used in this study, which has been conducted in five different mandals of the Palnadu region. The samples were obtained from a variety of bore wells using the random sampling method, and the physical and chemical characteristics of water quality parameters were evaluated. The study covered the maximum amount of groundwater in the five mandals of Nuzendla, Vinukonda, Savalyapuram, Romicharla and Ipur as well as the suitable treatment methods for trying to turn the water in to the potable form.

The present investigation aimed to design a best performing improved photocatalytic-active material of extensive implications and suitable to achieve the emerging needs of water pollution abatement. In view of the above, the present research work planned to synthesized nickel and phosphorus double-doped TiO2 (NPT’s) by the sol–gel process, characterized by advanced instrumental techniques and applied for the abatement of methylene blue (MB) under visible light. Characterization results demonstrated that nickel and phosphorus co-doped TiO2 samples showed anatase phase determined by XRD. Structural aspects such as smooth surface with spherical shape morphology, less band gap, less particle size, and high surface area when compared with bare TiO2 were determined by SEM, UV–Vis. DRS, TEM and BET, respectively. The elemental composition and oxidation states were identified by XPS analysis. The substitutional doping of Ti4+ ion by Ni2+, P5+ ion and P3− ion with oxygen in the TiO2 lattice was evaluated by FT-IR spectroscopy. Based on the characterization results, the catalyst NPT5 was applied for the abatement of MB at various optimum reaction conditions, with pH 10, catalyst weight 0.1 g/l and starting MB concentration 10 mg/l. At these reaction conditions, the degradation was completed within 75 min in the visible light. The photostability of the NPT5 was verified by recycling up to five cycles. Finally, this research work was concluded with a plausible mechanism, using reactive species generated during the degradation process and these species were simultaneously tested using scavenger reagents.

Validation of stability indicating RP-UPLC assay method for the determination of Lacosamide and Quetiapine fumarate in pharmaceutical products. This method has showed a high degree performance in separation and quantification of Lacosamide and Quetiapine even in the presence of its impurities. The separation was quite efficient on waters acquity BEH C18 column (50 mm×2.1 mm, 1.7 μm) having used the phosphate buffer pH 2.5 and acetonitrile in the ratio of 75:25 v/v with a flow rate of 0.2 mL/min. The detection was carried out at 210 nm and the elution run time was 5.0 min. The method was linear and found to be in the range between 0.0149 μg/mL-74.71μg/mL (r2=0.9999) and 0.0148 μg/mL-74.67 μg/mL (r2=0.9999) for Lacosamide and Quetiapine respectively. The limit of detection 0.0149μg/mL, 0.0148μg/mL and quantification 0.031 μg/mL, 0.030 μg/mL for Lacosamide and Quetiapine were determined respectively. The precision result of the method ‘% RSD’ is less than 0.70 % and the recovery % of Lacosamide, Quetiapine is between 99.1 and 99.9. When the drug is subjected to different stress conditions, the consequential degradation products obtained could not interfere with Lacosamide and Quetiapine during the determination.

Undoped and Ni–S co-doped mesoporous TiO2 nano materials were synthesized by using sol–gel method. The characteristic features of as prepared catalyst samples were investigated using various advanced spectroscopic and analytical techniques. The characterization results of the samples revealed that all the samples exhibited anatase phase (XRD), decreasing band gap (2.68 eV) (UV–Vis-DRS), small particle size (9.2 nm) (TEM), high surface area (142.156 m2·g−1) (BET), particles with spherical shape and smooth morphology (SEM); there is a frequency shift observed for co-doped sample (FT-IR) and the elemental composition electronic states and position of the doped elements (Ni and S) in the TiO2 lattice analyzed by XPS and EDX. These results supported the photocatalytic degradation of Bismarck Brown Red (BBR) achieved with in 110 min and also exhibited the antibacterial activity on Staphylococcus aureus (MTCC-3160), Pseudomonas fluorescence (MTCC-1688) under visible light irradiation.

In the present work, thiazole functionalized receptors, S1 and S2, containing aminophenol as a signaling unit have been prepared and evaluated by UV–vis and fluorescence methods. These receptors consisting of conjugated benzothiazol-aminophenol system, which exhibited rapid and selective response towards cyanide anion. These two probes showed dramatic color change from wine red/purple to colorless, and optical quenching was also observed upon addition of CN− ions based on intramolecular charge transfer (ICT) transition in aqueous media. The detection limit of the probe S1 and S2 for CN− was calculated as 3.6 and 4.2 μM by spectrophotometric, 0.5 and 0.6 μM by spectrofluorophotometric methods, respectively. The binding stoichiometry between probes and cyanide was found to be 1:1, and the binding mechanism was also proposed.

A new rhodamine 6G based fluorescent and colorimetric chemosensor, containing N-methyl imidazole nucleus, for the selective detection of Hg2+ ion was designed and synthesized. The results of UV-Vis and fluorescence spectral study indicated that the receptor is selective and sensitive towards Hg2+ with no noticeable interference with other competitive metal ions. The addition of Hg2+ to the receptor induced a rapid color change to pink from colorless and the turn-on fluorescence response toward Hg2+ among different cations was studied. The stoichiometric ratio of 1:1 between the receptor and Hg2+ was supported by Job's plot. The color change and turn-on fluorescence response upon addition of Hg2+ ion was ascribed by the spirolactam ring-opening mechanism. The probable mode of binding between the receptor and Hg2+ was confirmed by 1H NMR and Mass spectral study. For the practical application, its electrospun nanofiber test strips successfully applied to recognize Hg2+ ion in aqueous media. Graphical Abstract Schematic representation of Hg2+ detection by rhodamine based sensor.

In the present research work a potentially improved Copper (Cu) and Boron (B) codoped TiO2 nano materials were synthesized by varying the different dopant concentrations (Copper 0.25, 0.50, 0.75, 1 wt% and Boron 0.25, 0.50, 0.75, 1 wt%) using solgel method for the photocatalytic degradation of Lissamine Green B. In order to investigate the physical, chemical and optical properties of a catalyst, which play a key role in its photocatalytic activity, as prepared samples were characterized by various instrumental techniques. The crystalline phase study performed for all the samples using X-ray powder diffraction (XRD) confirmed the formation of anatase TiO2. Chemical composition of the prepared catalyst investigated by X-ray photo electron spectroscopy (XPS) affirmed the presence of constituent elements (Ti, O, Cu & B) on the catalyst surface. The surface microstructure studied by field emission scanning electron microscopy (FE-SEM) revealed that the TiO2 particles having spherical shape with rough surface morphology. The average particle size and surface area of the catalyst determined by high-resolution transmission electron microscopy (HRTEM) and Brunauer-Emmett-Teller (BET) surface area analyser, revealed that the codoped catalyst shows a high percentage of small particles of size 6.8 nm and a high surface area of 135.6 m2/g, respectively. The band edge absorption shift of the samples was determined by diffuse reflectance spectroscopy analysis (DRS) and the results exhibited that among all the codoped samples Copper 0.25 wt% and Boron 1 wt% (CBT1) catalyst shows a reduced band gap energy of 2.73 eV. The characterization results supported the photocatalytic activity of the catalyst for the degradation of Lissamine Green B within 90 min at the optimum reaction parameters such as dopant concentration of Cu at 0.25 wt% & B at 1 wt%, pH = 3, catalyst dosage 0.075 g/L and dye concentration 10 mg/L under visible light irradiation. The mechanism of enhanced photocatalytic performance of the catalyst was proposed by the results obtained from the PL spectra and main reactive species trapping measurements.

Nickel and sulfur co-doped TiO2 photocatalyst were prepared by using sol-gel method with dopants precursors of nickel nitrate and thiourea. Prepared samples were characterized by XRD, UV-Vis-DRS, TEM, BET, FT-IR and SEM-EDX. These characterization and experimental results revealed that there is a formation of anatase phase, decreased band gap 2.62 eV for NIST-2, small particle size 7.3 nm and high surface area 142.62 m2/g. The FT-IR frequency shift for Ti-O-Ti was observed from 569 cm-1 to 460-560 cm-1 for co-doped TiO2. The efficiency of photocatalytic and antibacterial was evaluated by degradation of Orange-II dye and Escherichia coli (MTCC-443) respectively. The complete degradation of Orange-II was achieved in 120 min at optimum reaction parameters for NIST-2 at pH-3, catalyst dosage-100 mg/L and initial dye concentration at 10 mg/L.

The present study explored the Photocatalytic & antibacterial activity of Mesoporous Mn and S co-doped TiO2 nano material synthesized by sol-gel method. As prepared samples were characterized by X-ray diffraction (XRD), X-ray photo electron spectroscopy (XPS), Scanning electron microscopy (SEM), Energy dispersive X-ray Spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), UV–vis Diffused Reflectance Spectroscopy (UV–vis-DRS), Transmission electron Microscopy (TEM), Brunauer-Emmett-Teller (BET) and Photoluminescence (PL). The Characterization results revealed that all the co-doped and undoped samples shows anatase phase. The Frequency shift of Ti-O-Ti in the catalyst samples was observed in FT-IR due to substitutional doping of Mn and S by replacing Ti and O, Further the catalyst shows smooth spherically shaped small particle size (7.6 nm) with high surface area (155.87 m2/g) and having less band gap energy (2.58 eV). The most reactive •OH are produced during the progress of reaction was determined by using Photo luminescence (PL) technique. The photocatalytic efficiency and antibacterial activity was evaluated by degradation of Indigo carmine(IC), Bacillus coagulans and klebsiella pneumonia respectively. The complete degradation of IC was achieved at optimum reaction parameters such as 0.150 g of the catalyst dosage, solution pH = 4 and initial dye concentration 20 ppm with the catalyst of 1.0 Wt% of Mn-0.25 Wt% of S co-doped Titania with in 90 min. The zone of inhibition bacterial growth was observed (24 mm and 23 mm) compared to control value (Chloramphenicol) 25 mm and 24 mm.

In this research article, the mesoporous hetero-structured TiO2-SrTiO3 nanocomposite was synthesized using sol-gel method at different weight percentages (wt %) of Gemini surfactant (GS) by varying the Ti/Sr ratios ranging from (1 to 0.6/0.0 to 0.4). The prepared samples were characterized by XRD, UV-Vis DRS, FT-IR, SEM-EDX, XPS, TEM and BET surface area analyzer. The characterization results attributed that XRD patterns of catalyst exhibits the formation of both [001] facets of anatase TiO2 and SrTiO3 with a band gap of 2.75 eV; The frequency shift (FT-IR) was observed for GS which was encapsulated the composite; SEM, EDX and XPS results showed that a prominent change in surface morphology, presence of elements and their oxidation states, respectively. TEM and BET results indicated the decrease in particle size and increase in surface area of the catalyst which lead to the enhancement in photocatalytic degradation of Acid orange dye. The optimum conditions for efficient degradation of Acid Orange in visible light was achieved by changing the reaction parameters such as, effect of Ti/Sr ratio at different weight percentages of Gemini surfactant with respect to composite, effect of pH, effect of catalyst dosage and effect of initial concentration of dye.

Phosphorus and cobalt codoped TiO2 nanomaterial was successfully prepared by single step sol-gel method by doping different weight percentages of dopants concentrations into TiO2 lattice. The co-doped TiO2 samples were characterized to confirm the structural and morphological changes in TiO2 crystal lattice by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (UV-vis. DRS), X-ray photo electron spectroscopy (XPS), Brunauer-Emmmett-Teller surface area analyzer (BET) and Fourier transform infrared spectroscopy (FT-IR). The characterization results revealed that all the codoped samples show anatase phase, nanoparticle (5.8 nm) and narrow band gap (2.54 eV). These results enhance the photocatylytic activity of codoped TiO2 in visible light for the degradation of Fast Green dye within 60 min.

A simple and sensitive normal phase liquid chromatographic method was developed and validated for quantification of Colchicine (COL) enantiomers on rat dried blood spots (DBS). The COL was extracte...

The polythiophene supported tin doped titanium nanocomposites (PTh/Sn-TiO 2 ) were synthesized by modified sol-gel process through oxidative polymerization of thiophene. The fourier transform infrared spectroscopy (FT-IR) and UV–Vis diffuse reflectance spectroscopy (UV-DRS) analysis confirms the existence of synergetic interaction between metal oxide and polymer along with extension of absorption edge to visible region. The composites are found to be in spherical form with core-shell structure, which is confirmed by scanning electron spectroscopy (SEM) and transmission electron microscopy (TEM) images, the presence of all respective elements of composite are proven by energy-dispersive X-ray spectroscopy (EDX) analysis. The importance of polythiophene on surface of metal oxide has been were studied as a function of photocatalytic activity for degradation of organic pollutant congo red and gas sensor behavior towards liquid petroleum gas (LPG). All the composites are photocatalytically active and the composite with 1.5 wt% thiophene degrades the pollutant congo red within 120 min when compared to remaining catalysts under visible light irradiation. On the other hand, same composite have shown potential gas sensor properties towards LPG at 300 °C. Considering all the results, it can be noted that polythiophene acts as good sensitizer towards LPG and supporter for the tin doped titania that improve the photocatalytic activity under visible light.

A new rhodamine 6G based fluorescent and colorimetric chemosensor, containing N-methyl imidazole nucleus, for the selective detection of Hg

A Sn-doped TiO2/polythiophene nanohybrid (SPNH) was synthesized by a modified sol–gel process at low temperature. The prepared catalyst was characterized by X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV−Vis) diffuse reflectance spectrophotometry (UV-DRS), and Brunauer-Emmett-Teller surface area analysis. The XRD results confirmed that polythiophene (PTh) had no effect on the crystal structure of TiO2. IR spectra and UV-DRS indicated that an interaction occurs between the interface of PTh and metal oxide in SPNH, and doped metal oxide nanoparticles were incorporated into PTh to form a core-shell structure. XPS analysis confirmed the presence of Sn4+ and respective elements of PTh and TiO2 in SPNH. SPNH displayed higher adsorption capacities for pollutants than Sn-doped TiO2 nanoparticles (STN). In addition, SPNH exhibited higher photocatalytic activity and stability than STN towards the degradation of organic pollutants nitrobenzene (NB) and malachite green (MG) under visible-light irradiation. Because of the presence of PTh on STN, there was an increase in the adsorption of NB (24%) and MG (21%) on the surface of SPNH, which led to a higher photocatalytic yield. The recyclability of the photocatalytic activity for the photocatalyst was examined by about five runs and not found any depletion or degradation of PTh under visible light irradiation. The high photocatalytic activity of SPNH makes it an attractive candidate as a photocatalyst for industrial water purification.

The influence of lightning over surface-level trace gases was examined for pre-monsoon and monsoon seasons in the year 2012. Lightning events were measured using ground-based electric field monitor (EFM) and space-based lightning imaging sensor (LIS). The results showed that lightning frequency was higher during pre-monsoon period compared to monsoon, which is in good agreement with the satellite retrievals. The increase in concentration of NOx on lightning event led to a subsequent decrease in surface O3 due to the titration reaction. Source apportionment study of SO2/NOx (S/N) and CO/NOx (C/N) ratios and poor correlation of NOx vs CO and NOx vs SO2 on the lightning day confirmed the emission of NOx from dissimilar sources.

The chemistry and variation in light molecular weight (C2–C5) volatile organic compounds (VOCs) and nitrogen oxides (NO x = NO + NO2) over the formation of tropospheric ozone (O3) was studied for a time period of 1 year (2013) at a tropical urban site located in Deccan plateau region of Hyderabad, India, with semi-arid climate. Diel pattern of hydrocarbons showed maxima in the morning and night and minima in the afternoon. Ethylene and propylene showed relatively larger diurnal amplitude than other hydrocarbons. Among the analyzed hydrocarbons, acetylene was the most abundant with an annual mean of 5.5 ± 1.3 ppbv. All the VOCs exhibited a seasonal variation with monsoon and summer minimum and winter maximum. Ozone formation potentials (OFP) and propylene-equivalents (propy-equiv.) were calculated to account the contribution of individual hydrocarbons towards formation of O3. Propylene had the highest contribution of propy-equiv. (34 %) and OFP (28.4 %) among the VOCs observed. The concentrations of VOCs and their reactivity with hydroxyl radicals played a significant role on the levels of propy-equiv. and OFP. Strong correlations 0.65 and 0.77 were observed between O3 vs. propy-equiv. and O3 vs. OFP, respectively. The crossover point relationship between NO x , VOCs, and O3 showed enhancement of O3 at lower levels and decreased at higher levels of NO x in the range of VOCs concentrations studied. Among hydrocarbons, propylene (10) and ethane (6.5) showed the highest and lowest crossover points, respectively.

A novel copper doped TiO2 (TiO2–Cu)/polythiophene (PTh) nanohybrid material with discrete polymer concentrations is devised by a modified sol–gel technique at low temperature. The XRD outcome revealed that the polythiophene and copper contents do not affect the crystal structure of TiO2. SEM and TEM images of the TiO2–Cu and nanohybrid denoted the presence of a nanoparticle sized core–shell structure. UV–visible absorption spectra of nanohybrid catalyst with diverse polymer concentrations broadcasted a broad and strong absorption in the visible region. A strong interaction between the interface of PTh and TiO2–Cu was confirmed by FT-IR. The presence of Cu2+ ion and positively charged sulfur (polarons) throughout the polymer carbon content was manifested by XPS spectra. The photocatalytic activity of nanohybrid catalyst has been evaluated by degradation of Rhodamine B (RhB) under visible light irradiation. The effect of solution pH, catalyst dosage and initial concentration of RhB on the photocatalytic activity of TiO2–Cu/PTh nanohybrid with different loadings is studied. It has been observed that the rate of degradation of RhB over TiO2–Cu/PTh nanohybrid is better than TiO2–Cu metal oxide under visible light irradiation.

Increasing concentration of tropospheric ozone (O3) is a serious air pollution problem faced commonly by the urban people. The present study emphasizes on variations of air pollutant concentrations viz., O3, nitrogen oxides (NOx), carbon monoxide (CO), sulfur dioxide (SO2) and black carbon (BC) at a tropical urban site located in the Deccan plateau region with semi-arid climate. The air monitoring site revealed typical diurnal/seasonal trends attributing to the complex chemistry of surface O3 formation from its precursors. Role of SO2 in the formation of free radical ( $$ {\text{HO}}_{2}^{ \cdot } $$ ) and its impact on O3 concentration is distinguished part of the study. The results showed the highest mean O3 in summer (57.5 ± 15.2 ppbv) followed by winter and monsoon. Observations of BC aerosols showed the highest mean value during winter (8.2 ± 2 μg m−3) and the lowest in monsoon (4.2 ± 1 μg m−3). Besides local influences, long-range transport of air masses were also studied by simulating back trajectories at different elevations during the study period. Furthermore, statistical analysis and modeling was performed with both linear (regression) and nonlinear (neural network) methods.

Chemical speciation of Pb (II), Cd (II) and Hg (II) complexes of L-methionine in 0.0-60.0 % v/v propylene glycol-water mixtures has been studied pH metrically maintaining an ionic strength of 0.16 M at 303 K. The active forms of ligand are LH3 + , LH2 and LH. The predominant species detected are MLH, ML and ML2. Models containing different numbers of species were refined by using the computer program MINIQUAD75. The bestfit chemical models were arrived at based on statistical parameters. The trend in variation of complex stability constants with change in the dielectric constant of the medium is explained on the basis of electrostatic and non-electrostatic forces.

Speciation of mixed ligand complexes of Pb(II), Cd(II) and Hg(II) with L-glutamic acid and L-methionine was studied in varying amounts (0.0-36.83%>w/v) of urea in aqueous solutions maintaining an i...

Using thallium(III) as an oxidant, we developed titrimetric and spectrophotometric methods for the estimation of glyoxal at mmole and µmole levels, respectively. In the titrimetric method, thallium(I) formed is determined oxidimetrically with potassium bromate. In the spectrophotometric method, the absorbance of thallium(III) at 260 nm in the presence of 0.1 mol/L sodium chloride and 1.0 mol/L perchloric acid is measured. A plausible mechanism for the oxidation of glyoxal is proposed. Based on the selective oxidation of the probable oxidation products of glyoxal (namely, glyoxylic acid, formic acid, and oxalic acid), a convenient titrimetric method is described for analyzing ternary mixtures of these products.

Chemical speciation of Pb(II), Cd(II), Hg(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of L - methionine in 0.0-60 % v/v 1,2-propanediol-water mixtures maintaining an ionic strength of 0.16 M at 303 K has been studied pH metrically. The active forms of ligand are LH 2 + , LH and L - . The predominant species detected are ML, MLH, ML 2 , ML 2 H, ML 2 H 2 and MLOH. Models containing different numbers of species were refined by using the computer program MINIQUAD 75. The best-fit chemical models were arrived at based on statistical parameters. The trend in variation of complex stability constants with change in the dielectric constant of the medium is explained on the basis of electrostatic and non-electrostatic forces. KEY WORDS : Complex equilibria, Chemical speciation, L-Methionine, 1,2-Propanediol, Metals Bull. Chem. Soc. Ethiop. 2007 , 21(3), 363-372.

School of Chemistry, Andhra University, Visakhapatnam-530 003, Andhra Pradesh, India E-mail: gollapalli@yahoo.com Manuscript received 6 June 2006, revised /0 January 2007, accepted 7 Februat)' 2007 An electrometric investigation of protonation equilibria of L-glutamic acid and L-methionine in aqua-urea media of varying composition (0-36.83% w/v) has been made at different concentrations of the amino acids at 303 K and an ionic strength of 0.16 mol dm-3. The best fit chemical models were arrived at based on firm statistical ground~ employing crystallographic R factor, א, skewness and kurtosis. The variation in the protonation constants with the dielectric constant of the medium is attributed to the electrostatic and non-electrostatic forces and to protonating ability of urea.

School of Chemistry, Andhra University, Visakhapatnam-530 003, Andhra Pradesh, India E-mail : gollapalli@yahoo.com Manuscript received 10 April 2006, revised 15 June 2006, accepted 22 June 2006 The speciation of PbII, CdII, HgII, CoII, NiII, CuII and ZnII complexes of L-glutamic acid has been investigated pH-metrically in urea-water mixtures (0-36.83%, w/v) at 303 K and an ionic strength of 0.16 mol dm-3.The predominant species detected for PbII is ML; for HgII ML and MLH; for CdII, CoII and ZnII ML, ML2 and ML2H2; for NiII ML, ML2, ML2H and for CuII ML, ML2, ML2H and ML2H2. The trend in the nriation of stability constants of the complexes with the dielectric constant of the medium is attributed to the electrostatic and non-electrostatic forces and complexing ability of urea. &nbsp

Department of Inorganic and Analytical Chemistry, Andhra University, Visakhapatnam-530 003, India E-mail : gollapalli@yahoo.com Fax: 91-891-2755547 Manuscript received 3 June 2002, revised 3 March 2003, accepted 2 April 2003 Speciation of L-arginine complexes of Call and MgII is investigated pH-metrically in 0-2.5% anionic, cationic and neutral micellar media. The stability constants are calculated using the computer program MINIQUAD75. The best-fit chemical models are arrived at based on statistical parameters. The effects of micelles, dielectric constant of the medium and the electrostatic interactions between the complex species on the stability of the complexes are discussed.

Department of Organic Chemistry, Foods, Drugs and Water, Andhra University, Visakhapatnam-530 003, India E-mail : csp_sastry@rediftinail.comFax : 91-0891-755547 Manuscript received 16 October 2001. revised 20 February 2002. accepted 18July 2002 Three simple, sensitive and reproducible visible spectrophotometric methods (A-C) are described for the determination of amiodarone (as hydrochloride, AD) or ondansetron (as hydrochloride, OST) in pure samples and pharmaceutical formulation. Methods A, B and C are based on the formation of charge-transfer complexes between AD or OST and chloranil, chloranilic acid or DDQ with \(\lambda \,\)max540, 540 or 455 nm, respectively. Regression analysis of Beer's law plots showed good concentration ranges (20-300, 25-300), (30-300. 15-150) and (15-150, 5-60) pg ml-1for (AD, OST) in methods A, B and C, respectively. The applicability of the methods has been examined by analyzing tablets of AD or OST.

Bioinorganic Chemistry Laboratories, Andhra University, Visakhapatnam-530 003, India E-mail: muvvala_2000@yahoo.com Fax: 9I-0891-555547 Manuscript received 30 May 2001, revised 27 September 2001, accepted 28 December 2001 The reduction of thallium(III) with glyoxal is catalyzed by light especially in the presence of bromide ions. The reaction is also catalyzed at higher temperature. Based on this reaction, a convenient method is described for the estimation of thallium(lll) alone and in mixtures with thallium(I).

Bio-Inorganic Chemistry Laboratories, Andhra University, Visakhapatnam-530 003 Manuscript received 3 November 1995, revised 26 June 1996, accepted 9 July 1996 Thallimetric Oxidations. X. Titrimetric Method for the Determination of Mandelic acid and Analysis of Binary Mixtures of Mandelic Acid and Hypophosphite and Ternary Mixtures of Mandelic Acid, Oxalic Acid and Hydrogen Peroxide.

Inorganic Chemistry Laboratories, Andhra University, Visakhapatnam-530 003 Manuscript received 29 September 1993, revised 13 July 1994, accepted 26 July 1994 Thallimetric Oxidations. Part-VIII. Titrimetric and Spectrophotometric Methods for the Estimation of Mesoxalic Acid.