NOPR Collection:

Spectrophotometric method for the simultaneous determination of piroxicam and 2-aminopyridine

Fri, 01 Apr 2005 00:00:00 GMT

Title: Spectrophotometric method for the simultaneous determination of piroxicam and 2-aminopyridine Authors: Suntornsuk, L; Bunavitayakij, P; Pitayatienanan, P Abstract: A rapid and simple spectrophotometric method is proposed for the simultaneous determination of piroxicam (Pi) and 2-aminopyridine (2-Ap). Piroxicam is stable under basic hydrolysis, but yields 2-Ap as one of the degradation products under acid hydrolysis. The method is based on the measurement of absorbances of 2-Ap and Pi at 300 and 360 nm, respectively, and the calculations are based on the binary method. The absorbances of both compounds obey Beer-Lambert 's law over the concentration range of 5-25 µg L^-1 with good linearity (r²>0.99). The recoveries are with in 100.8- 106.4% for Pi and are within 96.4-98.9% for 2- Ap. Precision is good with acceptable limits of detection (LOD) and quantitation (LOQ) for both compounds. The method has been applied for the determination of Pi and 2-Ap in piroxicam capsules. The average content of two different brands of piroxicam is 97.4 and 98.5% (n = 3), which complies with the USP 26 (92.5- 107.5%). Under the stress condition (refluxing with 0.1 N HCI), the percentages of piroxicam decrease from 100% (0 h) to 18.9% (21 h) and 2-Ap increase from 0% (0 h) to 63.6% (21 h). Page(s): 737-740

Determination of free and total zinc using 2-[(5-bromo-2-pyridylazo)]- 5-diethylaminophenol in mixed surfactant medium

Fri, 01 Apr 2005 00:00:00 GMT

Title: Determination of free and total zinc using 2-[(5-bromo-2-pyridylazo)]- 5-diethylaminophenol in mixed surfactant medium Authors: Banjare, Ravi Kumar; Thakur, Manisha; Deb, Manas Kanti Abstract: A simple and sensitive spectrophotometric method for chemical fractionation and determination of zinc in cosmetics and pharmaceuticals is described based on the formation or red coloured species of Zn(II) with 2-[(5-bromo-2-pyridylazo)]-5-diethylaminophenol (5-Br-PADAP) and mixed surfactants (TX-100 and Brij-35) in the pH range 8.2- 10.5. The red coloured Zn(II)-5-Br-PADAP-(TX-100+Brij-35) complex in aqueous medium shows maximum absorbance at 550 mm with molar absorptivity of 1.6010⁵ dm³ mol^-1 cm^-l. The detection limit or the method is 6 ng Zn(II)/cm² and obeys Beer's law up to 0.4 µg Zn(II)/cm² in aqueous phase. Relative standard deviation for ten determinations for solution containing 0.2 µg Zn(II)/cm² is 1.5%. The validity of the method has been satisfactorily examined for the determination of zinc (free and total) in cosmetics and pharmaceutical formulating samples manufactured in India, with RSD value from actual analyte content ranging between 2.1 and 2.7% for cosmetics and between 1.9 and 2.8 % for pharmaceutical formulations. Page(s): 733-736

Synthesis and characterisation of 5,6- bis(salicylideneimino )-1,10-phenanthroline and its trinuclear complexes

Fri, 01 Apr 2005 00:00:00 GMT

Title: Synthesis and characterisation of 5,6- bis(salicylideneimino )-1,10-phenanthroline and its trinuclear complexes Authors: Demirhan, Nebahat; Avclata, Ulvi; Gul, Ahmet Abstract: As a multidonor ligand with phenanthroline and salicylaldimine functionalities on the same molecule, 5,6-bis(salicylideneimino)-1,10-phenanthroline (LH₂) has been synthesized by the reaction of 5,6-diamino-1,10-phenanthroline with salicylaldehyde and its metal complexes with Ni(II) and Cu(II) have been prepared. Both of the isolated complexes are trinuclear with metal ligand ratio of 3:2. Protonation constants of LH₂ which have been determined by potentiometric titration in solution are log K₁=8.96, log K₂=15. 88, log K₃=8.73 and log K₄=2.78. The newly synthesized compounds have been verified by IR, ¹H NMR and mass spectra together with elemental analysis. Page(s): 729-732

Reactions of [(µ-H) Os₃(CO)₈- {Ph₂PCH₂P(Ph)C₆H₄}] and [Os₃(CO)₁₀ (µ-dppm)] with 2-mercaptoimidozole, 2-mercaptobenzimidazole and 2-mercaptobenzothiazole: X-ray structure of [(µ-H)Os₃(CO)₈(µ-dppm)(µ-η¹-SN₂C₃H₃)]

Fri, 01 Apr 2005 00:00:00 GMT

Title: Reactions of [(µ-H) Os₃(CO)₈- {Ph₂PCH₂P(Ph)C₆H₄}] and [Os₃(CO)₁₀ (µ-dppm)] with 2-mercaptoimidozole, 2-mercaptobenzimidazole and 2-mercaptobenzothiazole: X-ray structure of [(µ-H)Os₃(CO)₈(µ-dppm)(µ-η¹-SN₂C₃H₃)] Authors: Begum, Noorjahan; Hassan, Md Manjur; Hossain, G M Golzar; Kabir, Shariff E Abstract: The electron-deficient compound [(µ-H)Os₃(CO)₈-{Ph₂PCH₂P(Ph)C₆H₄}] 2 reacts with 2-mercaptoimidozole, 2- mercaptobenzimidazole and 2-mercaptobenzothiazole at 80°C to give [(µ-H)Os₃(CO)₈(µ-dppm)(µ-η¹-SN₂C₃H₃)] 3, [(µ-H)Os₃(CO)₈(µ-dppm)(µ-η¹-SN₂C₇H₅)] 4 and [(µ-H)Os₃(CO)₈(µ-dppm)(µ-η¹-SN₂C₇H₅)] 5 in 30, 50 and 59% yields, respectively. The compounds are formed by the oxidative addition of S-H bond followed by demetallation of the phenyl ring of the orthometallated dppm ligand. Compounds 3-5 have also been obtained from the reactions of [Os₃(CO)₁₀(µ-dppm)] 1 with 2- mercaptoimidozole, 2-mercaptobenzimidazole and 2- mercaptobenzothiazole, respectively at 110ºC but in some what lower yields. The compounds have been characterized by elemental analysis, IR, ^IH NMR and ³¹p{¹H} NMR spectroscopic data together with single crystal X-ray diffraction studies for 3. Compound 3 crystallizes in the triclinic space group PI with a=11.3453(12), b=13.651(2), c=15.069(2) Å, α=84.709(l1), b=72.7C6(9), γ=68.265(9)º, Z=2 and V=2069.5(4) Å³. The structure consists of an equilateral triangle of osmium atoms with a bridging dppm, a bridging hydride and a bridging 2- mercaptoimidazolato ligand. Page(s): 723-728

NOPR Collection:

Spectrophotometric method for the simultaneous determination of piroxicam and 2-aminopyridine

Determination of free and total zinc using 2-[(5-bromo-2-pyridylazo)]- 5-diethylaminophenol in mixed surfactant medium

Synthesis and characterisation of 5,6- bis(salicylideneimino )-1,10-phenanthroline and its trinuclear complexes

Reactions of [(µ-H) Os3(CO)8- {Ph2PCH2P(Ph)C6H4}] and [Os3(CO)10 (µ-dppm)] with 2-mercaptoimidozole, 2-mercaptobenzimidazole and 2-mercaptobenzothiazole: X-ray structure of [(µ-H)Os3(CO)8(µ-dppm)(µ-η1-SN2C3H3)]

Reactions of [(µ-H) Os₃(CO)₈- {Ph₂PCH₂P(Ph)C₆H₄}] and [Os₃(CO)₁₀ (µ-dppm)] with 2-mercaptoimidozole, 2-mercaptobenzimidazole and 2-mercaptobenzothiazole: X-ray structure of [(µ-H)Os₃(CO)₈(µ-dppm)(µ-η¹-SN₂C₃H₃)]