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Acta Chromatographica
Authors: N. Ravanić, S. Filipić, K. Nikolić, G. Popović, I. Vovk, B. Simonovska, and D. Agbaba

Summary

A simple and reliable TLC method for analysis of -lipoic acid (LA) with post-chromatographic derivatisation with palladium(II) chloride immersion reagent has been developed and evaluated. Separation of LA was performed on 20 cm × 10 cm RPTLC plates with 2-propanol-methanol-acetone-water-acetic acid 6:4:2:8:0.2 (v/v) as mobile phase. Yellow complexes formed in situ were scanned at 375 nm. The migration distance of LA was 43.0 mm. The relationship between peak area and amount of LA applied was evaluated by use of linear (1.0–3.0 µg per band) and second-degree polynomial (0.5–5.0 µg per band) regression functions. The correlation coefficient (r = 0.999), the limit of quantification (0.39 µg per band), recovery (98.5–105.2%), and precision (1.8–2.9%) obtained by use of the procedure were satisfactory. The method was used for analysis of LA in several drug formulations and selected dietary supplement preparations. The LA content was 99.5–101.0% in the drug formulations, 98.8–99.5% in three of five dietary supplements tested, and 48.0–185.0% in two other dietary supplements.

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The application of a simple, selective, precise, and accurate thinlayer chromatographic method for quantification of l-carnitine in dietary food supplements, including drinks, capsules, and tablets, was reported. The high-performance thin-layer chromatography (HPTLC)-cellulose plates as stationary phase, and mixture: methanol-water-glacial acetic acid (10:2:0.1 ν/ν) as mobile phase were chosen. The chromatograms were analyzed densitometrically in the maximum absorption at 420 nm, after ninhydrin-based derivatization reaction. The analytical procedure has been validated in terms of basic parameters, such as linearity, precision, and accuracy. The developed method is characterized by LOD sensitivity of 2.51 μg per spot, as well as LOQ for 7.61 μg per spot and high accuracy established by recovery studies between 99.50% and 103.60 % with good precision (RSD below 1.55%). Presented TLC method illustrated suitability for routine qualitative and quantitative analyses of l-carnitine in dietary supplements.

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The effect of omega–3 fatty acids in the human body is multidirectional. They are used in cancer and cardiovascular disease prevention, to stabilize blood pressure, to improve immune function, and in the treatment of concentration disorders. Omega-3 acids, especially eicosapentaenoic and docosahexaenoic acids, are needed for proper human growth. There are several groups of pharmaceutical products containing these compounds, available in pharmacies and markets. Due to a high accessibility of various consumable products such as dietary supplements or food, their quality monitoring is advisable. Therefore, analytical procedures are needed, which will allow the quality of these products to be fast and accurately defined. In our work, thin-layer chromatography (TLC) with densitometric detection was designed for the identification and quantification of the omega–3 fatty acids. The stationary phase constituted TLC silica gel plates activated by AgNO3 solution. As the mobile phase, a mixture of toluene–n-propanol–acetic acid (20:2:0.1, v/v) was used. Detection was performed at 520 nm, after staining with iodine vapor. The method was validated according to the International Conference on Harmonisation (ICH) guidelines. The correctness of the results guarantees good precision and satisfactory recovery (96.59–103.20%). The presented analytical method was used for the determination of omega-3 fatty acids in selected dietary supplements and cooking oils giving satisfactory results.

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Acta Chromatographica
Authors: Andreea Silvia Neamţu, Andrei Biţă, Ion Romulus Scorei, Gabriela Rău, Ludovic Everard Bejenaru, Cornelia Bejenaru, Otilia-Constantina Rogoveanu, Carmen Nicoleta Oancea, Antonia Radu, Cătălina Gabriela Pisoschi, Johny Neamţu, and George Dan Mogoşanu

, 10 ]. Since July 2013, NAR became accessible in dietary supplement form under the brand name NIAGEN® (Chromadex Incorporated, Irvine, California, USA). A lot of different other products that contain the compound have been commercially

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The paper discusses a possibility to grow seeds on solutions of microelements and application of sprouts enriched in such a way as an alternative to commercial dietary supplements. It contains a short review of the approaches reported till now and a systematic experimental study, carried on the most frequently used seeds (Lens culinaris, Helianthus annuus, Vigna radiata, Glycine max, and Lepidium sativum).Seven metals (Fe, Cu, Zn, Ni, Co, Cd, and Mn) were studied. Seeds were grown on cellulose in 20°C temperature using deionized water enriched with metals in concentrations: 100, 50, 25, 12.5, 6.25, and 3.125 mg/L in a period of 4 days. The reference samples were the seeds grown on pure deionized water. Sprouts were mineralized by microwave radiation, and the metal content was quantified by ion chromatography with on-line post-column derivatization and spectrophotometric detection.The conclusions can be treated as general recommendations, which seeds should be grown and what concentrations of metals in solutions should be applied to provide good enrichment and to avoid risk of microelement overdose.

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Thin-layer chromatography (TLC) is generally regarded as a common analytical technique. Everybody ‘knows’ it and it is used to some extent in almost every laboratory in the world. Unfortunately for most analysts TLC remains what it has been for many years — a rapid, simple, inexpensive, and not very precise tool. When one considers the latest technical and methodological developments, however, modern high-performance thin-layer chromatography (HPTLC), also known as planar chromatography, is a reliable and powerful analytical technique, which can be in full compliance with current good-manufacturing practice (cGMP). TLC is the method of choice when many samples must be compared, when flexibility is important, and when rapid quantitative and semi-quantitative data are needed at low cost per sample.

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References [1] US Food and Drug Administration , 21 CFR Part 111, Current good manufacturing practice in manufacturing, packaging, labeling, or holding operations for dietary supplements: final

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, (trade name Levitra), and tadalafil (trade name Cialis) [ 7 , 8 ]. Another class of substances frequently subjected to counterfeiting is herbal dietary supplements for weight loss. The use of herbal products for these two types of adjustments has

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Summary  

The thermal neutron prompt gamma-ray activation analysis (PGAA) facility, operated by the US Food and Drug Administration and National Institute of Standards and Technology Center for Neutron Research, has been redesigned to lower background radiation levels and improved analytical capabilities. Analysis of 22 element standards and food and botanical certified reference materials revealed significant sensitivity increases and lower limits of detection for H, B, C, N, Na, Al, P, S, Cl, K, Ca, Fe, and Cd. Mass fractions for these elements, as well as Mg, Al, Si, Ti, Mn, Fe, Cu, I, Zn, Sm, and Gd, were determined for 6 dietary supplements.

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A particularly rapid HPTLC method has been established for chromatographic separation and quantification of p -aminobenzoic acid (PABA) in complex dietary supplement tablets. After chromatography, PABA was determined by spectrodensitometry at 270 nm. PABA spots were then visualized by a novel staining procedure involving the Bratton-Marshall coupling reaction after spraying with 8-hydroxyquinoline in situ on the chromatographic plates. After visualization, spectrodensitometric analysis was repeated at 500 nm. Linearity, intermediate precision, sensitivity, accuracy, and precision were compared for both methods. Results from tablet analysis were verified with the modified Bratton-Marshall spectrophotometric procedure.

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