A Simple, Rapid, and Reliable Titrimetric Method for the Determination of Glycerol at Low Concentration

Glycerol can be determined in several products by various analytical techniques. Titrimetric ones have stood out for their low cost, being recommended as standards. However, reliable, simple, fast, and green methods with low quantification limits are still needed. Titration of glycerol is based on its oxidation by periodate (Malaprade reaction) producing formic acid, formic aldehyde, and iodate. Iodate and periodate are iodometrically titrated, but mutual interference between these ions has produced methods with some drawbacks. Here is proposed to mask periodate with molybdate, to eliminate interference, determining the glycerol content through iodate, employing iodometric titration. Solutions containing from 10 to 1000 μg of glycerol were analyzed (error < 3.4%). The method was successfully applied for the determination of glycerol in biodiesels from different raw materials. Recoveries were from 92.9 ± 0.4 to 111 ± 3%. Semi-micro extraction was done, providing a fast procedure for determining free glycerol in biodiesel (< 10 min).

Production of bioethanol from amla (Emblica officinalis Gaertn.)

On account of the increasing demand for valuable herbal products, an attempt was made to produce a functional fermented Ethanol from Amla. This study investigates the potential of ethanol production from Amla (Emblica officinalis Gaertn). In the present study, Amla juice was extracted, filtered, fermented and it shows a suitable medium for the growth of Saccharomyces cerevisiae on yeast peptone dextrose medium for the production of ethanol. Ethanol was separated by fractional distillation and then estimated at 4, 6, 8 and 10 days of the fermentation process by iodometric method for 30oC. The ethanol percentage estimated by the iodometric titration method was high on the 10th day, and it was found to be 1.63 gm% compared to all days. So, the outcome of this study reveals that amla fruit can be used as a crucial constituent for the yield of ethanol with a higher commercial value.

Production of bioethanol from amla (Emblica officinalis Gaertn.)

On account of the increasing demand for valuable herbal products, an attempt was made to produce a functional fermented Ethanol from Amla. This study investigates the potential of ethanol production from Amla (Emblica officinalis Gaertn). In the present study, Amla juice was extracted, filtered, fermented and it shows a suitable medium for the growth of Saccharomyces cerevisiae on yeast peptone dextrose medium for the production of ethanol. Ethanol was separated by fractional distillation and then estimated at 4, 6, 8 and 10 days of the fermentation process by iodometric method for 30oC. The ethanol percentage estimated by the iodometric titration method was high on the 10th day, and it was found to be 1.63 gm% compared to all days. So, the outcome of this study reveals that amla fruit can be used as a crucial constituent for the yield of ethanol with a higher commercial value.

Optimizing Sour Qualification Testing – Determination and Verification of H₂S Solubility from H₂S/N₂ Gas Mixtures up to 20,000 psig at 70 °F

Traditionally, the H&lt;sub&gt;2&lt;/sub&gt;S partial pressure (P&lt;sub&gt;H2S&lt;/sub&gt;) of the gas/hydrocarbon phase has been used as the primary sour severity metric for material qualification and selection under ANSI/NACE MR0175/ISO 15156 guidelines. While the P&lt;sub&gt;H2S&lt;/sub&gt; is appropriate for characterizing low total pressure systems, the strict, or ideal, Henry’s Law approach leads to over estimation of the dissolved H&lt;sub&gt;2&lt;/sub&gt;S concentration (C&lt;sub&gt;H2S&lt;/sub&gt;) for high-pressure, high-temperature (HPHT) wells by up to ~20 times at 70 °F (21 °C). Alternatively, the Ensemble Henry’s Law equation corrects for the non-ideal phase behavior of H&lt;sub&gt;2&lt;/sub&gt;S at HPHT conditions and avoids over-estimation of C&lt;sub&gt;H2S&lt;/sub&gt;. Given the industry’s reliance on using thermodynamic models to evaluate sour HPHT systems, an investigation was initiated to determine the accuracy of these model calculations. An empirical program was undertaken to verify C&lt;sub&gt;H2S &lt;/sub&gt;predictions for the H&lt;sub&gt;2&lt;/sub&gt;S-N&lt;sub&gt;2&lt;/sub&gt;-H&lt;sub&gt;2&lt;/sub&gt;O system. Multiple 2.7-L C-276 lined autoclaves were charged with a fixed inventory of H&lt;sub&gt;2&lt;/sub&gt;S in N&lt;sub&gt;2&lt;/sub&gt; at multiple total pressure steps, with increasing N&lt;sub&gt;2&lt;/sub&gt; pressure, between 30 and 20,000 psig (3 and 1,380 bar) at 70 ± 5 °F (21 ± 3 °C). Per total pressure step, H&lt;sub&gt;2&lt;/sub&gt;S levels in both the liquid and gas phases were measured using common H&lt;sub&gt;2&lt;/sub&gt;S sampling techniques (H&lt;sub&gt;2&lt;/sub&gt;S-specific colorimetric tubes and iodometric titration, respectively), following ANSI/NACE TM0177-2016 guidelines. The results were used to calculate total pressure corrected (apparent) H&lt;sub&gt;2&lt;/sub&gt;S solubility coefficients (&lt;sup&gt;A&lt;/sup&gt;k&lt;sub&gt;H2S&lt;/sub&gt;). Very good agreement was observed between empirically and computationally derived &lt;sup&gt;A&lt;/sup&gt;k&lt;sub&gt;H2S&lt;/sub&gt; values. Key words: ANSI/NACE TM0177-2016, ANSI/NACE TM0284-2016, Sour testing, Ensemble Henry’s Law, Ionic-equation of state (EOS) frameworks, H2S solubility, Iodometric titration.

Phytochemical, Proximate, and Vitamin C Content in Morinda citrifolia (Noni)

Morinda citrifolia, L commonly called noni, has a long history as a medicinal plant and is reported to have a broad range of therapeutic effects, including antibacterial, antiviral, antifungal, antitumor, antihelmin, analgesic, hypotensive, anti-inflammatory, and immune enhancing effects. Photochemical analyses of ethanol and hexane extracts of noni fruit revealed the presence of flavonoids, terpenoids, alkaloids and steroids. Proximate composition of the noni fruit revealed a moisture content of 54.21, crude protein 2.18, crude fat 3.25, crude fiber 4.49, ash 0.73 and carbohydrate 35.14%. The Vitamin C content was estimated using iodometric titration and found to be 134.10 mg/100g. This suggests that the noni fruit can if consumed can help promote good health.

Iodometric Quantitative Analysis Method of Ascorbic Acid in Tablets

Ascorbic acid is a water-soluble vitamin provided with strong antioxidant action, that fulfills an important immune protective role of the body against infections and prevents various cancers appearance. The main goal of this study was to exactly quantify pure ascorbic acid in tablets of two pharmaceuticals. Proposed objective consisted in improvement and application of a iodometric titration method in ascorbic acid quantitative analysis. Ascorbic acid content per tablet in both studied pharmaceuticals was 173.84 mg, very close to official stated amount of active substance (180 mg). Allowed percentage deviation from declared content of pure ascorbic acid was only 3.42 %, below maximum value of ± 5 % imposed by Romanian Pharmacopoeia 10-th Edition, according to European and International standards. Statistical analysis confirmed experimental obtained results and revealed low Standard Error value SE = 0.214476, which has fallen within normal limits. Confidence Level value (95.0 %) = 0.551328 and Standard Deviation SD = 0.525357. were within normal range of values. Relative Standard Deviation (Coefficient of variation or homogeneity) RSD = 26.268% was found below maximum range of accepted values (30-35%). P value = 7.44. 10-6 was located within normal limits, P < 0.001, so the experimental obtained results has shown highest statistical significance. Thus, studied titration method can be successfully used in quantitative analysis of ascorbic acid from different samples. Keywords: ascorbic acid, antioxidant action, quantitative analysis, iodometric titration, statistic study

Effect of A-/B-site Doping on Oxygen Non-Stoichiometry, Structure characteristics, and O2 Releasing Behavior of La1−xCaxCo1−yFeyO3−δ Perovskites

Oxy-fuel combustion is one of the proposed technologies with the potential to achieve zero CO2 emission. La1−xCaxCo1−yFeyO3−δ (LCCF) perovskites are promising materials with high selectively for oxygen. In this study, the oxygen non-stoichiometry of perovskites LCCF was investigated by means of iodometric titration. LCCF was prepared using the liquid citrate method, and the phase structures were identified by X-ray diffraction. Fixed-bed experiments were performed to study the oxygen desorption performance of LCCF. The oxygen deficiency of LCCF increased with increasing Ca molar content of A site, but the value of δ of LCCF with increasing Fe molar content in B site is nearly constant. Experimental observation demonstrated that the O2 release amount of LCCF does not depend on oxygen non-stoichiometry δ generated from A-site doping. At the same time, doping Fe in B site has an obvious impact on the oxygen desorption amount.

A Simple, Green and Fast Ultraviolet Spectrophotometric Method for the Carbamide Peroxide Determination in Dental Whitening Products

Background: The carbamide peroxide is the most commonly active ingredient used for home dental whitening products, its quantification in pharmaceutical products is of extreme importance due to the relation with the products potency and the previously related low carbamide peroxide stability. Once, there is only one official carbamide peroxide determination based on iodometric titration, this method is time-consuming and generates a lot of residues. The aim of this study was to carry out development and validation of a simple and fast ultraviolet spectrophotometer assay to quantify an innovative dental whitening gel. Methods: The proposed method was validated according international conference on harmonization guideline. Procedure is based on the iodide/iodine redox chemistry; iodine released through the action of hydrogen peroxide of carbamide peroxide with ultraviolet detection at 350 nm. Results: The procedure was linear in the concentration range of 1.0-4.0 µg/mL, specific to the excipients, robust for the evaluated parameters (variation of wavelength (± 5 nm); reagent addition (± 10%)), showing the results of RSD 1.88 and 0.39% respectively. Repeatability precision was RSD = 1.42%, with accurate RSD = 2.15% by adding reference solution. The assay used only water as solvent for sample preparation. In comparison to the pharmacopeial method, the latter is more time-consuming, as it generates a lot of residues, and it could not quantify small CP dosages. Conclusion: Thus, the proposed method was proved to be suitable to determine carbamide peroxide during the development and characterization of nanoparticle formulations in the present study.

Environmental friendly method of the epoxidation of limonene with hydrogen peroxide over the Ti-SBA-15 catalyst

This work presents the studies on the epoxidation of limonene to 1,2-epoxylimonene with hydrogen peroxide and over the titanium-silicate Ti-SBA-15 catalyst. The main object of the research was a solvent effect on the epoxidation process. The influence of solvents, such as: methanol, toluene, propan-2-ol (isopropyl alcohol), acetonitrile and ethanol has been studied. Furthermore, the influence of temperature in the range of 0-120°C and the reaction time in the range of 0.25-48 h have been investigated. Gas chromatography and iodometric titration methods were used to establish the products of this process and amount of the unreacted hydrogen peroxide. 1,2-Epoxylimonene, 1,2-epoxylimonene diol, perillyl alcohol, carvone and carveol have been determined as the main products of this process. All these compounds are very valuable raw materials for organic syntheses, medicine or cosmetic and food industry.