Kjeltabs cu 3

Manufactured by Foss

Sourced in Denmark, Sweden, Italy

Kjeltabs Cu-3.5 is a product designed for use in Kjeldahl analysis. It is a tablet that contains a specific formulation for the determination of nitrogen in various sample types.

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Lab products found in correlation

Gallic acid, by Merck Group (2 mentions) Tecator digestor, by Foss (1 mentions) 2 2 diphenyl 1 picrylhydrazyl (dpph), by Merck Group (1 mentions) Trolox, by Merck Group (1 mentions) Acetonitrile, by Merck Group (1 mentions) Water pro water system, by Labconco (1 mentions) Potassium persulphate, by Merck Group (1 mentions) Boric acid, by Carlo Erba (1 mentions) Hydrogen peroxide solution, by Carlo Erba (1 mentions) Supelco 37 component fame mix, by Merck Group (1 mentions) Sodium carbonate, by Merck Group (1 mentions) 2 2 azino bis, by Merck Group (1 mentions) Sulfuric acid, by Carlo Erba (1 mentions)

3 protocols using kjeltabs cu 3

Kjeldahl Nitrogen Determination Protocol

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The protein determination procedure required the measurement of sample nitrogen content. A Kjeldahl measurement was performed according to method 984.13 of the AOAC International [24 (link)], using a Tecator digestor and Foss Tecator Kjeltec 8200 Auto Distillation Unit, considering a nitrogen-protein conversion factor of 6.25 [15 (link)]. Approximately 0.5 g of each sample was hydrolyzed with 12.5 mL of concentrated sulfuric acid containing two copper catalyst tablets (Kjeltabs Cu-3.5, Foss Analytics, Hillerød, Denmark) in the heat block at 420 °C for 1 h. After cooling, 80 mL of water was added to the hydrolysates before neutralization with 50 mL NaOH 50% and titration with HCl 0.1 N.

Doménech P., Duque A., Higueras I., Fernández J.L, & Manzanares P. (2021). Analytical Characterization of Water-Soluble Constituents in Olive-Derived By-Products. Foods, 10(6), 1299.

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Quantification of Antioxidant Compounds

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Standards of gallic acid and TROLOX (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) were provided from Sigma-Aldrich (Germany). As a source of free radical, DPPH (2,2-diphenyl-1-picrylhydrazyl, 95 %) was purchased from Sigma-Aldrich, while Folin-Ciocalteu's phenol reagent was obtained from Fluka (Switzerland). Ethanol, methanol and acetonitrile (98-100 %) HPLC grade were delivered by Merck (Germany), while hydrochloric, sulphuric, and boric acids were obtained from Kemika (Croatia). Kjeltabs Cu/3.5 (3.5 g potassium sulfate and 0.4 g cupric sulfate pentahydrate), which was used as a catalyst, was provided by Foss Tecator (Sweden). Ammonium sulphate, anhydrous sodium carbonate, sodium hydroxide, indicators bromocresol green and methyl red, acetone and petroleum ether (40-70 °C) were supplied by Kemika. Other reagents used in this work were of analytical reagent grade or higher. Ultra-pure water from a WaterPro water system Labconco (USA) with a resistivity of 18.2 MΩ cm (25 °C) was used in all experiments.

Klarić D.A., Mornar A., Kovačić J., Jeličić M.L., Brusač E., Brletić I, & Klarić I. (2022). Polyphenol content and antioxidant activity of phytoestrogen containing food and dietary supplements: DPPH free radical scavenging activity by HPLC. Acta pharmaceutica (Zagreb, Croatia), 72(3).

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Detailed Analytical Reagents Sourcing

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Sulfuric acid (H₂SO₄), 72% and 95–98%; hydrogen peroxide solution (H₂O₂), 30%; boric acid (H₃BO₃) 1% with indicator; sodium hydroxide (NaOH), 40%; anhydrous NaOH in pellets and hydrochloric acid (HCl), 0.1 N were all purchased from Carlo Erba (Carlo Erba Reagents S.r.l., Milano, Italy); catalysts Kjeltabs Cu/3,5 were obtained from the FOSS (FOSS, Padua, Italy). HCl 37%, petroleum ether (bp: boiling point 40–60 °C), methanol, and n-hexane were provided by Honeywell Fluka (Fisher Scientific Italia, Milan, Italy) and N-free filter paper (Cytiva Carta B-2 Parchment, Parchment Paper, B-2 grade) from Fisher Scientific Italia (Milan, Italy). Supelco 37 Component FAME Mix, Folin–Ciocalteu phenol reagent (FCR), gallic acid, 2,2-diphenyl-1-picrylhydrazyl (DPPH^•), 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS), potassium persulphate, 6-hydroxy-2,5,7,8-tetramethy-chromam-2-carboxylic acid (Trolox), and sodium carbonate were obtained from Sigma-Aldrich (Merck KGaA, Darmstadt, Germany). Solvents and chemicals were all of analytical grade.

Oteri M., Gresta F., Costale A., Lo Presti V., Meineri G, & Chiofalo B. (2021). Amaranthus hypochondriacus L. as a Sustainable Source of Nutrients and Bioactive Compounds for Animal Feeding. Antioxidants, 10(6), 876.

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