Development and validation of alternative methods by non-aqueous acid-base titration and derivative ultraviolet spectrophotometry for quantification of sildenafil in raw material and tablets

Henderson-Hasselbalch relation is generally the simplified theoretical framework used to introduce students to acid-base titration. However, it is not always valid and its limitations should be made clear to chemistry students. The appropriate parameter to evaluate its validity is K a /C 0 , in connection with Ostwald dilution law. For more advanced students, it is possible to deduce analytical expressions that always fit accurately acid-base titrations and allow an evaluation of Henderson Hasselbalch relation. Gran plot appears as a particularly sensitive technique to the breakdown of Henderson Hasselbalch relation.

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Cotton stalk-derived hydrothermal carbon for methylene blue dye removal: investigation of the raw material plant tissues

Bioresources and Bioprocessing ◽

10.1186/s40643-021-00364-8 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Libo Zhang ◽

Junyan Tan ◽

Gangying Xing ◽

Xintong Dou ◽

Xuqiang Guo

Keyword(s):

Methylene Blue ◽

Functional Materials ◽

Raw Material ◽

Plant Tissues ◽

Chemical Compositions ◽

Waste Biomass ◽

Cotton Stalk ◽

Acid Base ◽

X Ray ◽

Bet Analysis

AbstractConversion of the abundant agricultural residual cotton stalk (CS) into useful chemicals or functional materials could alleviate the fossil fuels caused energy shortages and environmental crises. Although some advances have been achieved, less attention has been paid to the plant tissues effect. In this study, the plant tissue of CS was changed by part degradation of some components (hemicelluloses and lignin, for example) with the aid of acid/base (or both). The pretreated CS was transformed into hydrochar by hydrothermal carbonization (HTC) method. Morphological and chemical compositions of CS hydrochar were analyzed by various techniques, including elemental analysis, Fourier transform infrared (FTIR), BET analysis, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Methylene blue (MB) removal of prepared CS hydrochar was used to evaluate CS hydrochar pollutions adsorption capacity. Results reveal acid/base (or both) pretreatment is beneficial for CS raw material to prepare high-quality CS hydrochar. The effects of some parameters, such as initial MB concentration, temperature, pH value and recyclability on the adsorption of MB onto both acid and base-pretreated CS hydrochar (CS-H2SO4 + NaOH-HTC) were studied. The present work exhibits the importance of agricultural waste biomass material plant tissues on its derived materials, which will have a positive effect on the direct utilization of waste biomass.

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Direct Synthesis of 3,5-Dinitropyrazole Catalyzed by Newly Sulfated Nanosolid Superacid TiO2/ SO

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.391-392.1296 ◽

2011 ◽

Vol 391-392 ◽

pp. 1296-1301

Author(s):

Li Min Xi ◽

Xin Xin Zhang

Keyword(s):

Direct Synthesis ◽

Sol Gel ◽

Acid Base ◽

Direct Transformation ◽

Acid Base Titration ◽

Optimal Reaction Condition ◽

Superacid Catalyst ◽

Average Size ◽

Optimal Reaction ◽

Xrd And Tem

The newly sulfated nanosolid superacid TiO2/SO4 prepared by sol-gel method was broadly characterized by acid base titration, XRD and TEM, which identified that the superfine solid TiO2/SO4 showing good dispersibility with average size of 27 nm belongs to kind of crystalline nanoparticles. With the help of the catalyst TiO2/SO4, the optimal reaction condition for direct transformation of pyrazole and nitrosonitric acid into 3, 5-Dinitropyrazole was n (pyrazol)=0.10 mol, m (TiO2/SO4 )＝1.5g, V(n-octannol)＝90mL, and V(nitrosonitric acid)＝50mL. Moreover, the optimal yield of the catalytic reaction reached up to 59.4% when the reaction time is 7 hours. The nanosolid superacid catalyst is still of high activity after regenerating eight times by calcination at 600。C.

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Development and Validation of a Green Analytical Method for the Determination of Norfloxacin in Raw Material by FTIR Spectrophotometry

Journal of AOAC International ◽

10.5740/jaoacint.16-0177 ◽

2016 ◽

Vol 99 (6) ◽

pp. 1533-1536 ◽

Cited By ~ 5

Author(s):

Jéssica Sayuri Hisano Natori ◽

Eliane Gandolpho Tótoli ◽

Hérida Regina Nunes Salgado

Keyword(s):

Urinary Tract ◽

Organic Solvents ◽

Analytical Method ◽

Environmentally Friendly ◽

Raw Material ◽

Waste Generation ◽

Ftir Spectrophotometry ◽

Tract Infections ◽

Development And Validation

Abstract Norfloxacin is a broad-spectrum antimicrobial agent, widely used in humans and animals for the treatment of urinary tract infections. It is a second-generation fluoroquinolone. Several analytical methods to analyze norfloxacin have been described in the literature. However, most of them are complex and require the use of large amounts of organic solvents. This paper describes the development and validation of a green analytical method for the determination of norfloxacin in raw material by FTIR spectrophotometry. This method does not require the use of organic solvents, minimizing waste generation in the process and its environmental impacts. The development of methods that promote the reduction, prevention, or elimination of waste generation has become highly attractive to the pharmaceutical industry because of the growing demand from civil society and government authorities for environmentally friendly products and services. The FTIR spectrophotometry method was validated according to International Conference on Harmonization guidelines, showing adequate linearity (r = 0.9936), precision, accuracy, and robustness. This validated method can be used as an environmentally friendly alternative for the quantification of norfloxacin in raw material in QC routine analysis.

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