“…A persistent yellowish-green colour was produced and was stable for seven days. This col-410 our is completely different from the salmon-pink produced after condensation reaction between reduced nitroimidazoles and DMAB (16). This is the first paper to report the use of DMAB as a coupling reagent in acidic solution.…”
Section: Chemistrymentioning
confidence: 79%
“…These spectrophotometric methods have their relative merits but the majority of them are carried out at elevated temperatures, time consuming, use relatively expensive reagents, involve extraction, use of buffer systems, not all determine MZ and TZ and many are multi-step procedures. The ability of p-dimethylaminobenzaldehyde (DMAB) to form Schiff's bases with aromatic amines has been utilized for the spectrophotometric determination of compounds such as metronidazole (16) and hydralazine (17). In the varied applications of DMAB, none involved its use as a coupling component to diazonium ion.…”
Nitro derivatives of five-membered heterocyles are of considerable interest. Some are biologically active with anti-inflammatory or vasodilatory activity (1). The 5-nitroimidazoles are used as antiamoebic, antiprotozoal and antibacterial agents. Two important members of this chemical class are metronidazole and tinidazole. Discovery of the anti-trichomonal properties of metronidazole revolutionized the treatment of disease. A new approach to the spectrophotometric determination of metronidazole (MZ) and tinidazole (TZ) has been developed. The procedure involves coupling of diazotized nitroimidazoles with p-dimethylaminobenzaldehyde (DMAB) to form a greenish-yellow solution. Optimal temperature and time were 0°C (iced) and 3 minutes for diazotization and 30°C and 2 minutes for coupling for both MZ and TZ. Coloured adducts of MZ and TZ showed shoulders at 406 nm and 404 nm, respectively, which were selected as analytical wavelengths. The reaction with p-DMAB occurred in a 1:1 mole ratio. Beer's law was obeyed within the 4.8-76.8 mg mL -1 concentration range with low limits of detection. The azo adducts were stable for over a week. Molar absorptivities were 1.101 0 3 (MZ) and 1.30´10 3 L mol -1 cm -1 (TZ). Overall recoveries of MZ and TZ from quality control samples were 103.2 ± 1.3 and 101.9 ± 1.3 % over three days. There was no interference from commonly utilized tablet excipients. No significant difference was obtained between the results of the new method and the BP titrimetric procedures. The azo approach using the p-dimethylaminobenzaldehyde procedure described in this paper is simple, fast, accurate and precise. It is the first application of DMAB as a coupling component in the diazo coupling reaction.
“…A persistent yellowish-green colour was produced and was stable for seven days. This col-410 our is completely different from the salmon-pink produced after condensation reaction between reduced nitroimidazoles and DMAB (16). This is the first paper to report the use of DMAB as a coupling reagent in acidic solution.…”
Section: Chemistrymentioning
confidence: 79%
“…These spectrophotometric methods have their relative merits but the majority of them are carried out at elevated temperatures, time consuming, use relatively expensive reagents, involve extraction, use of buffer systems, not all determine MZ and TZ and many are multi-step procedures. The ability of p-dimethylaminobenzaldehyde (DMAB) to form Schiff's bases with aromatic amines has been utilized for the spectrophotometric determination of compounds such as metronidazole (16) and hydralazine (17). In the varied applications of DMAB, none involved its use as a coupling component to diazonium ion.…”
Nitro derivatives of five-membered heterocyles are of considerable interest. Some are biologically active with anti-inflammatory or vasodilatory activity (1). The 5-nitroimidazoles are used as antiamoebic, antiprotozoal and antibacterial agents. Two important members of this chemical class are metronidazole and tinidazole. Discovery of the anti-trichomonal properties of metronidazole revolutionized the treatment of disease. A new approach to the spectrophotometric determination of metronidazole (MZ) and tinidazole (TZ) has been developed. The procedure involves coupling of diazotized nitroimidazoles with p-dimethylaminobenzaldehyde (DMAB) to form a greenish-yellow solution. Optimal temperature and time were 0°C (iced) and 3 minutes for diazotization and 30°C and 2 minutes for coupling for both MZ and TZ. Coloured adducts of MZ and TZ showed shoulders at 406 nm and 404 nm, respectively, which were selected as analytical wavelengths. The reaction with p-DMAB occurred in a 1:1 mole ratio. Beer's law was obeyed within the 4.8-76.8 mg mL -1 concentration range with low limits of detection. The azo adducts were stable for over a week. Molar absorptivities were 1.101 0 3 (MZ) and 1.30´10 3 L mol -1 cm -1 (TZ). Overall recoveries of MZ and TZ from quality control samples were 103.2 ± 1.3 and 101.9 ± 1.3 % over three days. There was no interference from commonly utilized tablet excipients. No significant difference was obtained between the results of the new method and the BP titrimetric procedures. The azo approach using the p-dimethylaminobenzaldehyde procedure described in this paper is simple, fast, accurate and precise. It is the first application of DMAB as a coupling component in the diazo coupling reaction.
“…3 However, PMMA cannot satisfy the mechanical requirements of dentures. 10,13 PMMA is susceptible to fracture due to its poor strength, 5 low impact, 5,12,13 and inferior flexural strength. 1,5,13 The present study evaluated the effects of different loading of Al 2 O 3 micro-and nano-particles on fracture toughness, flexural properties, and water absorption and solubility of PMMA denture base.…”
Section: Discussionmentioning
confidence: 99%
“…8 To date, the mechanical properties of pure PMMA denture base do not meet the required level for denture fabrication. 4,9,10 PMMA exhibits poor strength, 3,5,11 low resistance impact, 5,12 low flexural strength, 1,5,12 insufficient ductility, 13 crazing, 14 susceptibility to distortion, 10 tendency to aging, 15 insufficient surface hardness, and poor antibacterial property, which can lead to fracture. 1 Several attempts were made to improve the mechanical properties of PMMA dentures and solve denture fracture problem.…”
This research investigated the effects of alumina (Al 2 O 3 ) micro-and nano-particles on poly(methyl methacrylate) (PMMA) denture base. Al 2 O 3 was surface treated using (3-methacryloxypropyl)trimethoxysilane (γ-MPS), added to methyl methacrylate (MMA), and mixed with PMMA powder. The filler volume fractions in the micro-composites were 0.5, 1, 2, 5 and 7 wt. %, whereas those in the nano-composites were 0.13, 0.25, 0.5, 1, 2 and 5 wt. %. The treated fillers were examined using Fourier transform infrared spectroscopy (FTIR). The influence of filler size and loading on mechanical properties was studied using fracture toughness and flexural tests. The thermal stability of the PMMA/Al 2 O 3 composites was investigated using thermogravimetric analysis (TGA). In addition, the water absorption and solubility characteristic of the prepared composites was also investigated. The FTIR spectra showed new absorption bands, indicating the occurrence of surface modifications. Both micro-and nanoscale particles showed increased fracture toughness. The maximum value of 2.02 MPa·m 1/2 was achieved with the addition of 0.5 wt. % nano-Al 2 O 3 , which accounts for a 39 % increase. In contrast to the flexural strength, the flexural modulus improved with increasing filler content. The micro-composites showed higher thermal stability than nano-composites. The water absorption and solubility of the prepared composites were slightly higher than those of the control. The use of low concentrations of Al 2 O 3 nanoparticles may be of considerable interest in future studies to improve the mechanical properties of PMMA denture base.
“…Aromatic aldehydes like vanillin, cinnamaldehyde and p-dimethylaminobenzaldehyde have been applied to the colorimetric determination of drugs with aromatic amines in acidic medium. [33][34][35] Method C is based on the formation of chromogenic schiff's base between the primary amino group of MSL and aldehyde group of vanillin. The produced chromogen exhibits λ max at 395 nm ( Figure 2) and is stable for 2 h. The probable reaction mechanism is given in Scheme 2.…”
Recebido em 26/10/10; aceito em 30/1/11; publicado na web em 1/4/11 Three simple, sensitive, economical and reproducible spectrophotometric methods (A, B and C) are described for determination of mesalamine in pure drug as well as in tablet dosage forms. Method A is based on the reduction of tungstate and/or molybdate in Folin Ciocalteu's reagent; method B describes the reaction between the diazotized drug and α-naphthol and method C is based on the reaction of the drug with vanillin, in acidic medium. Under optimum conditions, mesalamine could be quantified in the concentration ranges, 1-30, 1-15 and 2-30 µg mL -1 by method A, B and C, respectively. All the methods have been applied to the determination of mesalamine in tablet dosage forms. Results of analysis are validated statistically.
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