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Thermal diesel-like analysis

Quality control by thermal and chemometric analysis

Journal of Thermal Analysis and Calorimetry
Authors: Alexandre G. S. Prado, Rômulo D. A. Andrade, Jez W. B. Braga, and Paulo A. Z. Suarez

pretreatments of the fuel samples. The results for accuracy, uncertainty, and CC β were promising, indicating that the developed model by thermogravimetric analysis is one alternative to be used in the quality control of biofuels. The

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A simple and sensitive high-performance thin-layer chromatographic (HPTLC) method was developed for the evaluation of biomarker lupeol in the leaves of five different species of genus Ficus (Ficus carica, Ficus nitida, Ficus ingens, Ficus palmata, and Ficus vest) belonging to family Moraceae. Chromatography was performed on glass-backed silica gel 60 F254 precoated HPTLC plates with solvents toluene-methanol (9:1, v/v) as the mobile phase. After development, the HPTLC plate was derivatized with p-anisaldehyde reagent, scanned, and quantified at 540 nm. The system was found to give compact spot for lupeol at R F = 0.32 ± 0.01. The precisions and accuracy (n = 6) for lupeol were found to be 1.47–1.64% and 1.63–1.86%, and 99–100% and 99.4–99.7%, respectively, for inter-day and intra-day. Lupeol was found to be present in four species, i.e., F. carica (0.4%, w/w), F. nitida (1.4%, w/w), F. palmata (0.33%, w/w), and F. vest (0.59%, w/w), while it was absent in F. ingens. The statistical analysis proved that the developed method is reproducible and selective. The developed method can be used as an important tool to assure the therapeutic dose of active ingredients in herbal formulations as well as for standardization and quality control of bulk drugs and in-process formulations. This method can also be employed for the further study of degradation kinetics and determination of lupeol in plasma and other biological fluids.

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Abstract  

The use of serpentine as a potential nuclear shielding material necessitates a chemical quality control of the samples before its use in reactors. With this in view, characterization of these mineral samples was carried out using inductively coupled plasma atomic emission spectrometry (ICP-AES) and Instrumental neutron activation analysis (INAA) methods. The analytical results obtained by both ICP-AES and NAA techniques were found to be comparable. Na, Cr, Co, Zn, and Cu were found to be present in all samples of Indian origin while Ga, Ag, Ni, and Cd were found to below the limits of detection. A comparison on the detection limits of elements of interest was also carried out by both the analytical techniques and found to be in good agreement. An infrared spectroscopic investigation was also carried out on all the mineral samples. Bands at 3,689 and 3,648 cm−1 were attributed to inner and outer hydroxyl stretching of Mg–OH, respectively. The weak and broad band centered around 3,416 cm−1 was assigned due to the stretching vibrations of the adsorbed water molecules while three bands at 1076, 1022 and 968 cm−1 were prescribed to the vibrations of the SiO4 tetrahedra.

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Abstract  

The effectiveness of the neutralization process on heavy metals precipitated in sludge has been evaluated using instrumental neutron activation analysis (INAA) facilities at the South African Nuclear Energy Corporation (Necsa). The elemental concentrations of Th, Fe, Ag, Co, Cr, As, Au and K were reduced after the neutralization process with the exception of Mn and Sn which appeared to be enhanced by the neutralization process. Even though the neutralization process was targeted at the basic ferric arsenate compound, it was found to be effective in reducing other elemental concentrations. The variations in the geochemical compositions of the sulphidic ores during treatment at various stages also showed that physical processing stages do not significantly alter the elemental concentrations in the feed materials, however, the chemically active processing stages do. Also, the enhancement of the elements at the chemical stages depends on total quality control, where the application was not very repeatable the pattern of variation of elements at some stages was found to be irregular irrespective of the ore grade. The elements; Sn, Fe, Th, K, Au, Ag, As, Cr, and Co were enhanced in almost all the chemically active stages. Au was much more enhanced during flotation and bio-oxidation processes. Correlation analysis performed to determine the distribution patterns show that Fe, As, Ag and Co are geochemically associated and might be enriched simultaneously.

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Summary

Background: The fruits of Benincasa hispida (Thunb.) Cogniaux, a ‘rasayana’ in ‘Ayurveda’, are enriched with several secondary metabolites, and rutin is one of them. Fruits are used for their anabolic, brain tonic, carminative, diuretic, memory enhancer, refrigerant, and vitalizer properties. Objective: In view of the fact that herbal medicines and/or products are facing challenges towards global acceptance due to the lack of universally accepted standardization method (s), the aim of the current investigation was to develop and validate a high-performance thin-layer chromatography (HPTLC)-densitometry method for the quantification of rutin in the hydroalcoholic extracts of the fruit pulp of B. hispida (HABH). Materials and methods: The separation was achieved in a solvent system consisting of ethyl acetate-formic acid-acetic acid-water at a ratio of 7.2:0.7:0.7:1.4 by volume on a TLC aluminum plate pre-coated with silica gel 60 F254. Quantifications were performed by densitometric scanning under a deuterium lamp at a wavelength of 268 nm in the absorbance mode. The precision, accuracy, and reproducibility of the HPTLC method were validated by the International Conference on Harmonization (ICH) guidelines. Results: The mobile phase employed for HPTLC/TLC resulted in good separation for rutin (R F = 0.357). The limit of detection and limit of quantification of the analysis were found to be 0.1 and 0.3 µg per band, respectively. The rutin concentration in the HABH was found to be 178.28 ± 3.62 µg in 10 mg of the extract. Conclusion: The method developed here is simple, fast, reliable, and sensitive and can be implemented in the analysis and routine quality control of B. hispida formulations containing rutin.

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Arapid and simple method for simultaneous quantitative analysis of the natural carbohydrates fructose, glucose, and sucrose in different types of wine (white and red; dry, semi-dry, semi-sweet, and sweet) by OPLC in overrunning mode is presented. The compounds were separated on precoated silica gel F254 OPLC plates with acetonitrile-water 26:4 (v/v) as mobile phase. Visualization was by spraying with a mixed solution of aniline and diphenylamine, then densitometry in absorbance mode was performed at 420 nm. Linear regression analysis of the calibration data was indicative of a good linear relationship between the peak area and the concentration in the range 0.5–5.0 μg per band (r glucose 0.99051, r fructose 0.98547, r sucrose 0.99506). In this paper we give the results obtained from analysis of 49 samples of white and red wines. In the most of the samples we did not find sucrose, only fructose and glucose in different ratios depending on the type of the wine. We found few white and red wine samples for which the content of reducing sugars was not in agreement with the label description. The results obtained for the wines show this OPLC method can be useful for routine monitoring of the quality of commercial wine. Amajor advantage of the method is that it enables simultaneous analysis of approximately 20 samples in less than 2 h.

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An HPTLC method has been established for analysis of α-solanine and α-chaconine in potatoes during industrial processing. Chromatography is performed on silica gel plates in a horizontal developing chamber. Post-chromatographic derivatization by dipping the plates into antimony(III) chloride solution and subsequent heating results in red chromatographic bands. The reaction products are detected and quantified densitometrically by reflectance scanning at 560 nm. The limit of quantification is approximately 30 ng per zone. Depending on the matrix of the sample, the detection limit for both compounds is between 5 and 20 ng per zone. The calibration plots for α-solanine and α-chaconine are linear in the range 30 to 700 ng. Polynomial regression with low relative standard deviation is possible from 30 to 1500 ng. Easy sample preparation, ruggedness, and high selectivity are outstanding advantages of this method. The method is applicable to samples at all stages of processing — raw, peeled, blanched, cooked, and dried potatoes, and byproducts such as peel, waste mash, and processing waters. After steam-peeling, the total glycoalkaloid (TGA) concentration in the analyzed cultivar Karlena was reduced to approximately 25% of its original content in the whole potato, which can increase to more than 1000 mg TGA kg −1 fresh weight. Because of further leaching during processing, the commercial potato flakes tested contained less than 6 mg TGA kg −1 reconstituted mashed potatoes. Food with TGA concentrations of up to 100 mg kg −1 is regarded as completely safe. The ratio of α-chaconine to α-solanine was between 4:1 to 2:1 for all the samples analyzed.

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JPC - Journal of Planar Chromatography - Modern TLC
Authors: Agnė Kučinskaitė, Loretta Pobłocka-Olech, Mirosława Krauze-Baranowska, Vitalis Briedis, Aruñas Savickas, and Małgorzata Sznitowska

SPE and TLC have been used for qualitative and quantitative analysis of salidroside, rosavin, rosarin, and rosin in commercially available dry extracts from Rhodiola rosea roots. The best separation of all the compounds was achieved on silica gel TLC plates with ethyl acetate-methanol-water, 77 + 13 + 10 ( v / v ), as mobile phase. UV detection was performed at λ = 215 nm for salidroside and at λ = 245 nm for the rosavins (rosavin, rosarin, and rosin). Detection limits for salidroside and the rosavins were 90 ng and 60 ng per spot, respectively. Results from quantitative analysis confirmed the manufacturer’s declaration of the amounts of salidroside and the rosavins in the extracts.

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