Whatman 4 filter paper

Manufactured by Cytiva

Sourced in United Kingdom

Whatman #4 filter paper is a general-purpose qualitative filter paper designed for filtration applications. It is made of high-quality cellulose and has a medium-slow filtration speed with a nominal particle retention of 20-25 microns. The filter paper is available in a range of standard sizes and can be used for a variety of laboratory filtration tasks.

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Lab products found in correlation

Ultrasonic cleaner, by Avantor (2 mentions) Glow discharge cleaned copper grid, by Electron Microscopy Sciences (2 mentions) Tecnai g2 spirit electron microscope, by Thermo Fisher Scientific (2 mentions) Whatman 1 filter paper, by Cytiva (2 mentions) Vacufuge plus, by Eppendorf (1 mentions) Leo 912ab tem, by Zeiss (1 mentions) Sodium carbonate, by Scharlab (1 mentions) Varian cary 50 bio, by Agilent Technologies (1 mentions) Folin ciocalteu reagent, by Merck Group (1 mentions) Methanol, by Carlo Erba (1 mentions) Ethyl acetate, by Merck Group (1 mentions) Whatman no 4 filter paper, by Cytiva (1 mentions) R 215, by Büchi (1 mentions) Silica gel 60 tlc plate, by Merck Group (1 mentions) R 300, by Büchi (1 mentions) Ultraturrax device, by IKA Group (1 mentions) V 550 uv vis spectrophotometer, by Jasco (1 mentions) 3800 cpxh water bath, by Emerson (1 mentions)

42 protocols using whatman 4 filter paper

Recrystallization of 1,4-DFDK in Sulfolane

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Example 2

To a 500 ml, flask fitted with a heating mantle, thermocouple, temperature controller, agitator and condenser, was added 1,4-DFDK (20.3 g) and sulfolane (112 g=100 mL). The mixture was heated, with agitation, to 150° C. The heat was turned off to allow the solution to cool just slightly, the solution was filtered through Whatman GF/F glass fiber filter pad in a pre-heated (125° C.) ceramic Büchner funnel into a clean 500 mL 3-neck flask. The initial flask was rinsed with hot sulfolane (38 g=30 mL) through the filter. The resulting filtered solution was reheated to redissolve the solids. The heating was discontinued and the solution allowed to cool at approximately 0.3° C./min to room temperature. The recrystallized solids were isolated by filtration in a Buchner funnel with a Whatman #4 filter paper. Air was pulled through the cake until no more solvent was seen dripping from the funnel. The solids were then transferred back to the 500 mL flask, Water and ethanol was added (250 mL of 90:10) and the slurry was agitated for 5 minutes and isolated by filtration in a Buchner funnel with a fresh Whatman #4 filter paper. The solids were transferred to an aluminum pan and vacuum oven dried at 130° C. and 27″ Hg for 24 h. The solids were allowed to cool to room temperature and transferred to a tared jar to afford 18.0 g (90%).

Analysis of the product is shown in Table 1

US11420920B2. Method for decreasing the concentration of a metal in a monomer composition comprising bis(benzoyl)benzene (2022-08-23). SOLVAY SPECIALTY POLYMERS USA, LLC [US]. Inventors: Chantal Louis [US], Scott A. Harding [US].

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Lipid Extraction from Bischofia polycarpa Seeds

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Solvent extraction was carried out according to the method of Gao et al. (2019) . Briefly, 40 g of Bischofia polycarpa seed power was supplemented with 200 mL of solvents (petroleum ether, n-hexane, ethyl acetate, Folch (chloroform/methanol, 2:1 v/v), Hx: Iso (n-hexane/isopropanol, 3:2 v/v), acetone and isopropanol, respectively). After homogenizing the mixture (7000 revolutions per minute) at room temperature (25–30 °C) for 8 min, the filtrate was collected using Whatman #4 filter paper. The rotary-evaporator (RE-201, Kexing, China) removed the solvent under vacuum control and a constant temperature water bath (30 °C). The residual solvent was then removed with nitrogen. After obtaining all oil samples, we transferred them into brown bottles and kept at −20 °C until analysis.

Wang Y., Su Y., Shehzad Q., Yu L., Tian A., Wang S., Ma L., Zheng L, & Xu L. (2023). Comparative study on quality characteristics of Bischofia polycarpa seed oil by different solvents: Lipid composition, phytochemicals, and antioxidant activity. Food Chemistry: X, 17, 100588.

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Myrtle Powder Extraction Protocol

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Myrtle extracts were prepared using the by-products of the industrial preparation of myrtle liqueur as raw material. Seeds were removed from berries, freeze-dried, and powdered to obtain a homogeneous sample. Seven grams of powder were extracted twice with 60 mL of an ethanol/water solution (70% EtOH). In both extractions, the mixtures were sonicated in an ultrasonic cleaner (VWR International, Leuven, Belgium) for 1 h at 25 °C, then centrifuged at 3000× g for 10 min. The organic extracts were combined and filtered with Whatman 4 filter paper, evaporated to dryness under nitrogen flow to remove ethanol, then freeze-dried to remove water.

Bellu E., Cruciani S., Garroni G., Balzano F., Satta R., Montesu M.A., Fadda A., Mulas M., Sarais G., Bandiera P., Ventura C., Kralovič M., Sabo J., Amler E, & Maioli M. (2021). Natural Compounds and PCL Nanofibers: A Novel Tool to Counteract Stem Cell Senescence. Cells, 10(6), 1415.

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Extraction of Barley Phenolic Compounds

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Free phenolic molecules from the barley whole meal flour were extracted from adapted protocols of previously published studies using an ethanol 90% solution with modifications [27 (link),34 (link)]. One gram of powder was extracted with 15 mL of ethanol 90% and sonicated in a water bath at 70 °C for 1 h with periodical inverting of tubes. The supernatant was filtered, using Whatman#4 filter paper, into new tubes and concentrated under a vacuum at 60 °C for 2 h using Eppendorf Vacufuge Plus (Eppendorf, Germany). The residue was suspended in 500 μL HPLC-grade methanol, then sonicated for 5 min at 50 °C until complete solubility. This methanolic extract was centrifuged at 12,000× g rpm for 20 min, and 140 μL aliquot was transferred into vial inserts prior to HPLC analysis.

Wijekoon C., Netticadan T., Sabra A., Yu L., Kodikara C, & Badea A. (2022). Analyses of Fatty Acids, Proteins, Ascorbic Acid, Bioactive Phenolic Compounds and Antioxidant Activity of Canadian Barley Cultivars and Elite Germplasm. Molecules, 27(22), 7852.

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TEM Imaging of DNA Origami Structures

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For TEM imaging, structures were stained using a 1% Uranyl acetate solution and imaged on a FEI Tecnai G2 Spirit electron microscope. For each preparation, 6–8 μl of 1 nM DNA origami sample was wicked onto a glow-discharge-cleaned copper grid (Electron Microscopy Sciences, Hatfield, PA) and incubated for 5–10 min. The sample solution was then removed carefully with Whatman #4 filter paper and the grids were immediately stained with two 6 μl drops of 1% Uranyl acetate solution. Grids were dried for at least 10 min before imaging. TEM images were analyzed by ImageJ to try to quantify the length of the gap between the two barrels to determine if the L6 + L3 + L1 had a smaller gap at zero force than the other devices. However, the angular distribution prevented the quantification of the gap length (Supplementary Fig. S19).

Robbins A., Hildebolt H., Neuhoff M., Beshay P., Winter J.O., Castro C.E., Bundschuh R, & Poirier M.G. (2024). Cooperative control of a DNA origami force sensor. Scientific Reports, 14, 4132.

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Liposomal Morphology Analysis by TEM

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As a second method to examine the liposomal morphology, transmission electron microscopy (TEM) was used. The sample preparation was carried out on 400 mesh copper grids, coated with 1.2% Formvar and carbon (Plano GmbH, Wetzlar, Germany). Briefly, the liposomes were diluted to 1:10 ratio with HEPES (20 mM, pH 7.4) and 10 µL were placed on a grid. After 5 min of incubation, the liquid was withdrawn by suction with a Whatman 4 filter paper (Whatman plc, Maidstone, UK). Then the grids were placed for 5 min on 20 µL 2% uranyl acetate, which was used as contrast agent for the negative staining. The liquid was withdrawn by suction again and the grids were placed on 20 µL H₂O as a washing step. After the remaining liquid was carefully removed, the grids were left to dry. To obtain the images, samples were examined using a Leo 912 AB TEM (Carl Zeiss Microscopy GmbH, Jena, Germany) with different magnifications and an accelerating voltage of 100 kV.

Lehmann J., Agel M.R., Engelhardt K.H., Pinnapireddy S.R., Agel S., Duse L., Preis E., Wojcik M, & Bakowsky U. (2021). Improvement of Pulmonary Photodynamic Therapy: Nebulisation of Curcumin-Loaded Tetraether Liposomes. Pharmaceutics, 13(8), 1243.

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Lipid Oxidation Measurement by TBARS Assay

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Lipid oxidation (Lox) was measured by the thiobarbituric acid reactive substances (TBARS) method [34 (link)]. Meat samples (10 g) were homogenized with 20 mL of 10% trichloroacetic acid at 4500 rpm for 1 min, in an ice bath. After, the slurry was centrifuged (at 2300× g/4 °C/for 20 min) and filtered (Whatman 4 filter paper). In total, 2 mL of filtrate were mixed with 2 mL of TBA (0.02 M) in test tubes, placed in a water bath (97–98 °C) for 20 min, and subsequently cooled. The absorbance was measured at 531 nm. TBARS values were calculated from a 1, 1, 3, 3-tetramethoxypropane standard curve and expressed as mg malondialdehyde/kg of the meat sample (mg MDA/kg).

Vargas-Sánchez R.D., Torrescano-Urrutia G.R., Torres-Martínez B.D., Pateiro M., Lorenzo J.M, & Sánchez-Escalante A. (2019). Propolis Extract as Antioxidant to Improve Oxidative Stability of Fresh Patties during Refrigerated Storage. Foods, 8(12), 614.

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Protein Structural Analysis by Negative Stain EM

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To determine sample quality and success of complex formation, purified proteins were diluted to 0.05 mg/mL and applied onto plasma-cleaned (Gatan Solarus) copper grids with a continuous carbon layer (Electron Microscopy Sciences). The grids were washed twice with droplets of water, and then blotted with Whatman 4 filter paper to remove the excess solution. The grids were stained with two applications of 1% uranyl formate (EMS), and again blotted. After drying, the grids were imaged using a FEI Spirit 120 kV microscope equipped with a digital CCD camera with 2k × 2k resolution using a pixel size of 2.1 Å. In total, 30–50 images were collected for the native and refolded PhuR with and without sABs, using peak SEC fractions diluted into SEC buffer at the aforementioned concentration to prepare the ns-EM grids. Images were processed using Relion-3.0 to obtain two-dimensional class averages^{41 (link)}.

Knejski P.P., Erramilli S.K, & Kossiakoff A.A. (2023). Chaperone-assisted cryo-EM structure of P. aeruginosa PhuR reveals molecular basis for heme uptake. bioRxiv.

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Extraction and Oxidation of H. dulcis

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Malgeunsan Agricultural Union Corp. cultivated H. dulcis at Sanchung in the Gyeonnam province. The leaves and branches were harvested from October to November in 2021, and leaves were treated using our patented oxidation treatment protocol [18 ]. Raw leaves (RL) and oxidation-treated leaves (OL; 4 g) were added to water (100 mL) and heated at 95 °C for 3 h for water extracts. The air-dried branches (4 g) were also added to 100 mL water and heated at 95 °C for 3 h. After 4 h heating, hot water extracts were filtered with Whatman # 4 filter paper and freeze dried.

Je J., Song M., Baek J.H., Kang J.S., Chung H.J., Lee K., Park S.W, & Kim H.J. (2021). Combined Water Extracts from Oxidation-Treated Leaves and Branches of Hovenia dulcis Has Anti-Hangover and Liver Protective Effects in Binge Alcohol Intake of Male Mice. Nutrients, 13(12), 4404.

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Determination of Walnut Oil Peroxide Value

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The method developed by Buege and Aust (1978) [26 (link)], with slight modifications, was used to the determination of the peroxide value (mmol O₂/g of walnut oil). A total of 5 g of walnut oil and 30 mL of acetic acid solution (50% acetic acid (Normapur, NWR), 50% chloroform (Normapur, NWR)) were homogenized in a 250 mL test flask.
After vortexing, the samples were incubated in hot water (50 °C) for 30 min. Then, samples were filtered using Whatman # 4 filter paper. The filtrate was received in 0.5 mL of KI (Scharlau, Sentmenat, Spain) (50%), kept in darkness for 2 min, three drops of 1% starch (Panreac-Apllichem, Barcelona, Spain) were added (as an indicator), and the mixture was titrated with Na₂S₂O₃ · 5H₂O (Scharlau, Sentmenat, Spain) (0.01M) added dropwise until reaching the end point.
The peroxide value, expressed in milliequivalents of active oxygen per kg of oil, was calculated using the following formula: PV = volume of sodium thiosulphate × 0.1 N × 1000/mass of oil.

Gómez-López V.M., Noguera-Artiaga L., Figueroa-Morales F., Girón F., Carbonell-Barrachina Á.A., Gabaldón J.A, & Pérez-López A.J. (2022). Effect of Pulsed Light on Quality of Shelled Walnuts. Foods, 11(9), 1186.

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