Search

Department of Chemistry, Sri Krishnadevaraya University. Anantapur-515 003. Andhra Pradesh, India Manuscript received 15 February 2007, accepted 17 May 2007 A simple and sensitive spectrophotometric method is developed for the determination of cobalt in aqueous medium. The metal ion forms a brown coloured partially soluble complex with 2,4-dihydroxybenzaldehyde isonicotinoyl hydrazone (2,4-DHBINH) in the pH range 2-10. However, the complex is found to be soluble in 25% aqueous DMF. The complex shows an absorbance maximum at 405 nm in the pH range 5-6. Beer's law is obeyed in the range 0.062- 1.5 µg.glml at pH 5.5. The molar absorptivity and the Sandell's sensitivity of the method are 3.20 ± 0.03 x 104 L moI-1 cm-1 and 0.0074 µg/cm2 respectively. The composition of the complex is 1 : 1. A method for the determination of cobalt by first order derivative spectrophotometry is also proposed. The method is applied for the determination of cobalt in alloy steel samples.

The most important nitrogen containing heterocycles of pyridine containing substituted phenyl azetidine-2-ones have found pharmacological application such as antibiotics and these compounds also have practical importance. The structure of the new derivatives was confirmed by the spectral data and elemental analyses. Out of five new derivatives, three were revealed mild to moderate activity compared with Streptomycin & Fluconazole as a reference standard. Among this new series, 3-chloro-1-(4-fluoro phenyl)/(4-chloro phe-nyl)-4-(pyridine-3-yl) azetidine-2-one (4a & b) were found most activity.

A highly sensitive spectrophotometric method has been developed for the determination of copper (II) using 3-methylthiophene-2-carbaxaldehyde-3-thilosemicarbazone (3-MTAT) as an analytical reagent. The 3-MTAT forms reddish brown species of copper (II) at a pH range of 5.0-7.0. The Cu (II)-3-MTAT complex shows maximum absorbance at 430 nm, with molar absorptivity and Sandell’s sensitivity being 1.6 x 104 L Mol-1 Cm-1 and 3.6 x 10-3 μg cm-2 respectively. The system obeys Beer’s law in the range of 0.35-3.53mg/L. The regression coefficient of the Beer’s law straight line is 0.338, and the correlation coefficient is 0.999. The detection limit of the method is 0.021 μg mL-1. Most of the common metal ions generally found associated with copper do not interfere. The repeatability of the method was checked by finding the relative standard deviation. The developed method has been successfully employed for the determination of copper (II) in leafy vegetable and pharmaceutical samples and this method was inter comparison of experimental values using AAS.

A new class of pyrimido pyrimidine derivatives that exhibits in vitro antimicrobial activity was synthesized. The protection of amino group in the compound 1 with acetic anhydride, followed by the reaction with POCl3, gave 3. The reaction of 3 with different substituted phenyl methanediamine in dry TEA under inert atmosphere led to the formation of 4. Deprotection of 4 followed by refluxion with different acid chlorides yielded title compounds 6a, 6b, 6c, 6d, 6e, 6f, 6g, 6h, 6i, 6j, 6k, 6l, 6m in good yields. The identities of these compounds were confirmed following elemental analysis, IR, 1H, 13C NMR, and mass spectral studies. All the title compounds exhibited pronounced in vitro antibacterial and antifungal activities.

A novel, selective and sensitive reverse phase-high performance liquid chromatography (RP-HPLC) method has been developed for the validated estimation of imidazol-1-yl-acetic acid in zoledronic acid formulations. The separation was achieved on a 5 μ C18 column (250 × 4.6 mm) using a mobile phase that consists of the buffer (4.5 g of di-potassium hydrogen phosphate anhydrous and 2.0 g of tetra butyl ammonium hydrogen sulphate (TBAHS) in 1000 mL of water) and methanol in the ratio of 900:100 v/v. The flow rate was maintained at 1.0 mL min −1 . The detection of the constituents was done at 215 nm using a UV detector. The retention times of imidazol-1-yl-acetic acid and zoledronic acid were 7.2 and 10.2 min respectively. Recovery studies were satisfactory and the correlation coefficient, 0.999 indicates linearity of the method within the limits. The developed method can be applicable for regular qualitative analysis.

A rapid and simple Spectrophotmetric method has been developed for the determination of microgram amount of Chromium (VI) in aqueous dimethyl formamide (DMF). Chromium (VI) forms a yellowish green coloured M:L complex with 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone in the acidic buffer medium (pH=6.0) at room temperature. The complex shows maximum absorption at 385nm. Beer's law is obeyed in the range 0.260 to 2.60 

A chromophoric reagent, 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC), was employed for the sensitive spectrophotometric determination of gold(III). The gold(III) ion forms a blue-coloured complex with HMBATSC in an aqueous dimethyl formamide at pH 6.0. The gold complex shows the absorption maximum at 385 nm, and Beer's law was obeyed in the range 0.49–8.37 μg mL−1. The molar absorptivity and Sandell's sensitivity were found to be L mol−1 cm−1 and 0.015 μg cm−2, respectively. The complex shows 1 : 1 [Au(III) : HMBATSC] stoichiometry with a stability constant of . The interference effect of various diverse ions has been studied. In addition to zero-order, first- and second-order derivative spectrophotometric methods were also developed for the determination of gold(III) in microgram amounts which were more sensitive than the zero-order method. The developed method has been used for the determination of gold(III) in environmental water samples and certified reference materials. The results were in excellent agreement with the certified values.

The synthesis, as well as spectroscopic and biological studies of a novel class of (3-(4-substitutedphenylamino)-8- azabicyclo (3.2.1) oct-8yl)-phenyl-methanone derivatives are described. All the synthesized compounds were characterized by elemental analysis FTIR, 1 H-NMR, 13 C NMR, and Mass spectral data. All the synthesized compounds were exhibit in vitro

A simple, sensitive, and selective second-order-derivative spectrophotometric method has been developed for the simultaneous determination of palladium(II) and ruthenium(III) using 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) as a chromophoric reagent. The reagent (HMBATSC) reacts with Pd(II) and Ru(III) at pH 3.0, forming soluble yellowish green and dark brown species, respectively. Palladium and ruthenium present in the mixture were simultaneously determined without solving the simultaneous equations by measuring the second derivative amplitudes at 445 nm and 385 nm, respectively. Further, the Beer's law was obeyed in the range 0.21–12.78 µg mL−1 and 0.25–13.42 µg mL−1 for Pd(II) and Ru(III), respectively. A large number of foreign ions did not interfere in the present method. The proposed method was successfully applied for the determination of palladium in hydrogenation catalysts and ruthenium in water samples.

A rapid and sensitive spectrophotometric method is developed for the determination of Copper (II) in aqueous DMF medium. The metal ion forms a light greenish yellow coloured complex with 5-bromo salicylaldehyde thiosemicar- bazone (5-BSAT) in acidic medium. The complex shows absorption maximum at 390nm. Beer's law is obeyed in the range 0.31 - 6.35 � gml -1 of Copper (II). The molar absorptivity (� ) and Sandell's sensitivity are found to be 1.08 X 10 4 l mole -1 cm -1 and 0.062 � gcm -2 respectively. A method for the determination of copper by third derivative spectrophotome- try is also proposed. The methods have been employed successfully for the determination of copper in grape leaves and aluminum based alloy samples.

A highly sensitive and selective kinetic spectrophotometric method is proposed for the determination of silver in nanogram quantities. The method is based on catalytic activity of silver(I) in enhancing the green colour formation between potassium ferrocyanide and 2,4,6-tripyridyl-1,3,5-triazine (TPTZ) which is otherwise a very slow reaction at pH 2.0. The absorbance spectrum of the green coloured solution in presence of silver showed two peaks of almost equal intensity one at 405 nm and another at 600 nm. At both the wavelengths the absorbance of the experimental solution increased proportionally with the amount of silver(I) in the range 5 – 410 ng mL-1 and 10 – 610 ng mL-1 respectively. Other experimental conditions like pH, reagent concentration, ferrocyanide concentration and effect of time for obtaining maximum reaction rate were optimized. The molar absorptivity, Sandell's sensitivity, detection limit, determination limit and relative standard deviation (n = 8) were determined as 1.57 × 106 L mol-1 cm-1, 0.065 ng cm-2, 1.6 ng mL-1, 4.8 ng mL-1 and 0.81 % respectively. The effect of various diverse ions on the determination of silver was studied. The method was applied for the determination of silver in alloys, biological samples, effluents, real water and in ayurvedic medicines.

2-Hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) has been synthesized and its analytical applications are investigated. A rapid, simple, sensitive and selective spectrophotometric method is developed for the determination of palladium (II) in aqueous dimethyl formamide (DMF). Palladium (II) forms a yellowish green coloured M 2 L 3 complex with 2-hydroxy-3-methoxy-benzaldehyde thiosemicarbazone in the pH range 1.0-7.0 at room temperature. The complex shows absorption maximum at 380nm with molar absorptivity and Sandell's sensitivity of 2.198 x 10 4 l mol -1 cm -1 and 0.049μg cm -2 respectively. Beer's law is obeyed in the range of 0.426 to 4.257 μg ml -1 of Pd (II). A second order derivative spectrophotometric method for the determination of palladium (II) has also been proposed. Interference of various diverse ions has been studied. The proposed method is successfully applied for the determination of palladium in alloy steels and in hydrogenation catalysts.

A simple, sensitive, and selective second order derivative spectrophotometric method is proposed for the determination of microgram quantities of gallium(III) especially in presence of large excess of indium(III). Ga(III) reacts with 2‐hydroxy‐3‐methoxy benzaldehyde isonicotinoylhydrazone (HMBAINH) chromogene forming an intense greenish yellow coloured soluble complex in acidic buffers and in presence of 0.2% of triton X‐100. The complex showed maximum absorption at 405 nm and at pH 5.0, where the reagent has negligible absorbance. A second order derivative spectrum of the complex solution showed maximum derivative amplitude at 415 nm and again at 460 nm with a zero cross at 442 nm. Beer's law was obeyed in the concentration range 0.036–1.533 µg/ml and 0.070–1.533 µg/ml of Ga(III) at 415 nm and 460 nm, respectively. However, at 404 nm In(III)‐HMBAINH complex showed zero amplitude in the second order derivative spectrum where Ga(III)‐HMBAINH obeyed Beer's law in the range of 0.070–1.394 µg/ml. Thi...

A rapid, simple and sensitive spectrophotometric method was developed for the determination of cobalt(II) using 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) as a analytical reagent. The metal ion in aqueous medium forms a brown coloured complex with HMBATSC at pH 6.0. The complex has two absorption maxima at 375 nm and 390 nm. At 375 nm, the reagent shows considerable absorbance, while at 390 nm the reagent does not shows appreciable absorbance. Hence, analytical studies were carried out at 390 nm. Beer's law is obeyed in the range of 0.059-2.357 μg ml -1 of Co(II). The molar absorptivity and Sandall's sensitivity of the method are 2.74×10 4 mol -1 cm -1 and 0.0024 μg cm -2 respectively. The interference of various diverse ions has been studied. The complex has 1:2 [Co(II)-HMBATSC] stoichiometry. A method for the determination of cobalt(II) by second order derivative spectrophotometry has also been proposed. The proposed methods were applied for the determination of cobalt(II) in alloy steels, vitamin B 12 and in some biological samples.

2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) has been synthesized, characterized and employed as a simple simultaneous second order derivative spectrophotometric method for the analysis of a three-component system containing cobalt(II) nickel(II) and vanadium(V) without separation. The reagent (HMBATSC) reacts with cobalt(II), nickel(II) and vanadium(V) at pH 6.0, forming soluble brown, yellow and green coloured species, respectively. Cobalt, nickel and vanadium present in the mixture are simultaneously determined without solving the simultaneous equations by measuring the second derivative amplitudes at 460 nm, 450 nm and 430 nm, respectively. Further, the derivative amplitudes obey Beer's law at 460 nm, 450 nm and 430 nm for Co(II), Ni(II) and V(V) in the range 0.059 – 3.535 μg ml−1, 0.058 – 3.425 μg ml−1 and 0.051 – 4.074 μg ml−1, respectively. A large number of additional ions did not interfere with the method. The simultaneous method can be applied for the determination of cobalt(II) ...

Two simple accurate, rapid and sensitive methods have been developed for the estimation of Atazanavir in the pharmaceutical dosage forms. The Method-A is based on reaction of Atazanavir with Mordant Black III to form an ion-association colored complex at pH-2.4. The method B is based on the reaction of Atazanavir with Solochrome black-T to form an ion-association colored complex in the presence of Potassium Phthalate buffer system. These Methods exhibits maximum absorption at 537nm and 491nm respectively and obeys the Beer's law in the concentration range of 10–90μg/mL, 1–12 μg/mL respectively. The Methods have been statistically evaluated and were found to be precise and accurate. The proposed Methods are economical and sensitive for the estimation of Atazanavir in the bulk drug and in its formulations.

A series of novel pyrrolidine sulfonamide derivatives were designed, synthesized and screened in silico for their β-gluscosidase inhibitory activity. The results showed that the pyrrolidine derivatives exhibited moderate inhibitory activity against human β-gluscosidases inhibitors. The structure-activity relationships were also briefly discussed. The studies indicated that compounds of Series B with imidazole sulfonyl group were the most potent inhibitors compared to the other compounds under investigation.

The members of the new class of pyrimido pyrimidine derivatives (I) display pronounced in vitro antibacterial and antifungal activities.

Department of Chemistry, Sri Krishnadevaraya University, Anantapur-515 003, Andhra Pradesh, India E-mail : raveendrareddy sku@yahoo. com Manuscript received 30 August 2006, revised 22 January 2007, accepted 22 January 2007 2-Hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBA TSC) has been synthesized, characterized and utilized as a reagent for simultaneous second order derivative spectrophotometric determination of nickei(II) and vanadium(V) without separation. The reagent (HMBATSC) reacts with nickei(II) and vanadium(V) at pH ~ 6.0, forming soluble yellow and green coloured species respectively. Nickel and vanadium present in the mixture are simultaneously determined without solving the simultaneous equations by measuring the second derivative amplitudes at 409.5 and 432 nm respectively. Further, the derivative amplitudes obey Beer's law at 409.5 and 432 nm for NiIIand Vv in the range 0.058-2.186 μg ml-1 and 0.051-4.074 μg ml-1 respectively. A large number of foreign ions do not interfere in the present method. The present simultaneous method is applied for the determination of nickei(II) and vanadium(V) in alloy steel samples.

A rapid, simple, sensitive and selective spectrophotometric method is developed for the determination of molybdenum (VI) in aqueous dimethyl formamide (DMF). Molybdenum (VI) forms a yellow coloured complex with 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone in the pH range 1.0-6.0. The complex shows maximum absorbance at 375nm and in the pH range 1.0-2.0. However, at this wave length, the reagent shows considerable absorbance. At 385nm, the complex shows large absorbance while the reagent blank shows negligible absorbance. Hence, analytical studies are carried out at 385nm and at pH 1.5 against reagent blank. Beer's law is obeyed in the range 0.24-4.32 µg ml-1. The molar absorptivity and Sandell's sensitivity forthe coloured solution are found to be 2.3 x 10-4 1 mol-1 cm-1 and 0.0042 µg cm-2 respectively. The interference effect of various diverse ions has been studied. The complex shows 1:1 [Mo (VI): HMBATSC] stoichiometry with a stability constant 2.35 x 10(6). The standard deviation of the method in the determination of 2.396 µg ml-1 of Mo(VI) is calculated as ± 0.0012. A second order derivative spectroscopic method is developed for the determination of molybdenum(VI), which is more sensitive than the zero order method.. The developed method has been employed for the determination of molybdenum (VI) in food stuffs and in alloy steels. The results are in excellent agreement with the certified values

A simple and new simultaneous fourth derivative spectrophotometric method is proposed for the analysis of a two-component system containing cobalt(II) and nickel(II) without separation using 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) as a chromophoric reagent. The reagent reacts with cobalt(II) and nickel(II) at pH 6.0, forming soluble brown and yellow colored species, respectively. Cobalt(II) and nickel(II) present in the mixture are simultaneously determined without solving the simultaneous equations by measuring the fourth derivative amplitudes at 468.5 nm and 474.5 nm, respectively. The derivative amplitudes obey Beer's law at 468.5 nm and 474.5 nm for Co(II) and Ni(II) in the range 0.059–3.299μgmL-1and 0.058–3.285μgmL-1, respectively. A large number of foreign ions do not interfere in the present method. The present simultaneous method is used for the determination of micro amounts of cobalt in biological samples, nickel in plant samples, and in some alloy steels and soil sample.

Department of Chemistry, Sri Krishnadevaraya University, Anantapur-515 003, Andhra Pradesh, India Manuscript received 20 June 2005, revised 2 August 2006, accepted 2 August 2006 2-Aminoacetophenone isonicotinoyl hydrazone (2-AAINH) has been proposed as a sensitive and selective reagent for the spectrophotometric determination of palladium(u) in alloy samples. The palladium ion forms an intense orange red coloured soluble complex with l-aminoacetophenone isonicotinoyl hydrazone (2-AAINH) in the acidic pH medium. The orange red color of PdII-2-AAINH solution exhibits maximum absorbance at 500 nm in the pH range 3-5. Beer's law is obeyed in the range 0.30-3.00 μg/ml of PdII at pH 4.0. The molar absorptivity and Sandell's sensitivity of the colored solution are found to be 3.00 x 104 L mol-1 cm-1 and 0.0035 μg cm-2 respectively. The absorbance is found to increase linearly with increase in concentration of PdII, which is corroborated by the calculated correlation coefficient value (0.9998). The effect of foreign ions absorbance of the colored solution has been studied. The composition of the complex is calculated as 1 : 2 {PdII-2-AAINH}. The first derivative spectrum shows a peak at 540 nm with a zero cross at 494 nm. The second derivative spectrum shows a maximum at 560 nm and a minimum at 500 nm with a zero cross at 537 nm. Thus, sensitive first and second derivative spectrophotometric methods for the determination of PdII are also proposed.

Department of Chemistry, Sri Krishnadevaraya University, Anantapur-515 003, Andhra Pradesh, India Manuscript received 1 April 2004, revised 27 October 2005, accepted 28 November 2005 A simple and sensitive spectrophotometric method has been developed for the determination of nickel(ll) in aqueous medium.The metal ion forms an yellow coloured soluble complex with 2,4-dihydroxy benzaldehyde isonicotinoyl hydrazone (2,4-DHBINH) at pH 6.0 with λmax at 400 nm. Beer's law is obeyed in the range of 0.059-1.17 μg ml-1 of NiII.The molar absorptivity and the Sandell's sensitivity of the method are 4.00 x 104 L mol-1 cm-1 and 0.0015 μg cm-2 respectively. The interference of various diverse ions has been studied.The complex has a 1 : 1 [NiII : 2,4-DHBINH] stoichiometry. A method for the determination of nickel(II) by first order derivative spectrophotometry has also been proposed. &nbsp

Department of Chemistry, Sri Krishnadevaraya University, Anantapur-515 003, India Manuscript received 23 April 2003, accepted 24 November 2004 A simple, sensitive and selective spectrophotometric method has heen developed for the determination of iron(lll) in aqueous solution. The metal ion forms yellowish-brown coloured, soluble complex with 2,4-dihydroxy benzaldehyde isonicotinoyl hydrazone (2,4-DHBINH) at pH 3.0 with λmax at 400 nm. Beer's law is obeyed in the range 0.07-2.20 µg/ml-1 of FeIII. The molar absorptivity and the Sandell's sensitivity of the method are 1.75 ± 0.025 x 104 L mol-1 cm-1 and 0.0034 µg cm2 at 400 nm respectively. The interference of various ions has been studied. The complex has a 1 : 1 [FeIII : 2,4-DHBINH] stoichiometry. A method for the determination of FeIII by first order derivative spectrophotometry has also been proposed.

Department of Chemistry, Sri Krishnadevaraya University, Anantapur-515 003, India Manuscript received 25 March 2003. revised 6 February 2004. accepted 18 March 2004 A first order derivative spectrophotometric method is employed for the determination of molybdenum(VI) and simultaneous determination of molybdenum(VI) and titanium(IV). Molybdenum(VI) gives a golden yellow colour with 2,4-dihydroxy benzaldehyde isonicotinoyl hydrazone (DHBINH)' in the pH range 1-3. The first derivative spectrum shows maximum amplitude at 490 nm. Beer's law is obeyed the range 0.19 to 6.0 µg-ml-1 of MoVI at 495.5 nmwhere there is no interference from TiIV. Molybdenum(Vl) and titanium( IV) are determined simultaneously by measuring the derivative amplitudes at 495.5 nm and 580 nm in the concentration ranges 0.2 to 6.0 µg ml-1 and 0.05 to 2.40 µg ml-1 respectively, without using simultaneous equations. The method is applied for the analysis of alloy and steel samples for the molybdenum and titanium content with good accuracy.

Department of Chemistry, Sri Krishnadevaraya University, Anantapur-515 003, India Manuscript received 16 June 1999, revised 11 February 2003, accepted 12 March 2003 A simple and sensitive spectrophotometric method is developed for the determination of cobalt in aqueous DMF medium. The metal ion forms a brown coloured complex with 5-bromosalicylaldehydethiosemicarbazone (5-BSAT) in acidic medium. The complex shows absorption maximum at 410 nm. Beer's law is obeyed in the range 0.29-5.89µg ml-1 of cobalt(ll). A method for the determination of cobalt by third derivative spectrophotometry is also proposed. The methods have been employed successfully for the determination of cobalt in steel samples.

Department of Chemistry, Sri Krishnadevaraya University, Anantapur-515 003, India E-mail : sku1@hyd.ap.nic.in Fax: 91-08554-55808 Manuscript received 20 February 2002, revised 8 July 2002, accepted 16 July 2002 Electrochemical behavior of 5-bromosalicylaldehyde isonicotinoylhydrazone has been studied at dropping mercury and glassy carbon electrodes by employing DC polarography and cyclic voltammetry in Britton-Robinson buffers (pH 2-10). The compound exhibits two polarographic waves in solutions of pH 2-10. In cyclic voltammetric studies, the hydrazone exhibits two cathodic peaks in acid solutions (pH 4.0) and one cathodic peak in alkaline solutions (pH 8.0). The electrode reactions are attributed to the reductive cleavage of =N-N- linkage and the reduction of amide formed in the cleavage.

Department of Chemistry, Sri Krishnadevaraya University, Anantapur-515 003, India Fax : 91-08554-55244 Manuscript received 7 February 2000, revised 20 February 2001, accepted 19 May 2001 2-Hydroxy-1-naphthaldehydebenzoylhydrazone (OHNABH) reacts with Vv and CuII at pH 5.0 forming respectively yellow and green coloured soluble complexes in 30% DMF. The first derivative amplitude measurements show that Beer's law is obeyed in the range 0-7.5 µg ml-1 for V at 465 nm and 0-4.5 µg ml-1 for Cu at 443 nm. The sensitivity of the method is greater than the zero order method, and foreign ions like UVI, ThIV, CrVI' which interfere in zero order method, do not interfere even in large excess. Vanadium and copper present in a mixture are simultaneously determined without solving the simultaneous equations by measuring the first derivative amplitudes at 412.6 and 430.2 nm for V and Cu, respectively. The method is applied for the determination of Cu in food materials, V in alloy steels, and both V and Cu in chromium-vanadium steel.

Department of Chemistry, Sri Krishnadevaraya University, Anantapur-515 003, India Manuscript received 23 May 1997, revised 28 December 1998, accepted 4 February 1999 2,4-Dihydroxybenzophenone benzoic hydrazone (DHBPBH) is employed as an analytical reagent for the spectrophotometric determination of copper and iron. The reagent forms 1 : 1 greenish yellow coloured complex with copper(II) at pH 4.0 and λmax 380 nm (E 1.55 x 104 dm3 mol-1 cm-1); Sandell's sensitivity 0.004 µg cm-2, and Beer's law range 0.31-2.2 µg ml-1.It results a brown coloured 2: 3 complex with iron(lll) at pH 5.0 and λmax 380 nm (E 2.8 x 104 dm3 mol-1 cm-1); Sandell's sensitivity 0.002 µg em-1 and Beer's law range 0.14-1.0 µg ml-1.The method has been applied for the determination of copper in soil and alloy samples and iron( Ill) in cement sample.

A simple and sensitive spectrophotometric method is developed for the determination of throium in aqueous medium. The metal ion forms yellow coloured complex with 2,4-dihydroxybenzaldehyde isonicotinoyl hydrazone (2,4-DHBINH) in the pH range 2.0–8.0. The complex shows an absorption maximum at 390 nm. The absorbance of the complex is maximum at pH 5.5 Beer's law is obeyed in the range 0.30–7.00 μg/ml of thorium(IV). The molar absorptivity and the Sandell's sensitivity of the method are 2.20· 104 l·mol−1·cm−1 and 0.0106 μg/cm−2, respectively. The interference of various ions was studied. The composition of the complex is 1:1 {Th(IV) : 2,4-DHBINH}. The first derivative spectrum of the complex shows a zero cross at 391.2 nm and maximum amplitude at 415 nm. Thus a sensitive derivative spectrophotometric method for the determination of Th(IV) is proposed.

Department of Chemistry, Sri Krlshnadevaraya University,Anantapur-515 009 Manuscript received 27 October 1988, revised 19 April1989,accepted 22 July 1989 Polarographic and Cyclic Voltammetric Reduction of o-Nitrobenzaldehyde lsonicotinoylhydrazone &nbsp

Physiochemico Laboratories, Department of Chemistry, Sri Krishnadevaraya University, Anantapur-515 003 Manuscript received 26 October 1987, revised 11 April 1988, accepted 28 May 1988 o-Hydroxybenzaldehyde isonicotinoylhydrazone (o-OH-BAINH) exhibits two waves in solutions of pH 2 -8 while one wave has made its appearance in solution of pH 9. However, the cyclic voltammogram of the compound exhibits three cathodic peaks in acid solutions and two cathodic peaks in alkaline solutions. The electrode reactions are attributed to the reductive cleavage of =N -N - linkage and the reduc­tion of the amide formed in the cleavage