Titrable acidity, moisture content and total nitrogen (TN) were determined according to the Association of Official Analytical Chemistry [34 (link)] methods. In addition, pH was measured using a penetration electrode (Metrohm, Herisau, Switzerland) and fat content through the Van Gulik method [35 ]. Water-soluble nitrogen (WSN) was quantified by performing an aqueous extraction of the N-components, followed by nitrogen determination by the micro-Kjeldahl method using a Kjeltec System 1030 distilling coupled to a titration unit system (Tecator, Höganä, Sweden). Non-protein nitrogen (NPN) was determined by the N-component precipitation with a trichloroacetic acid (12%) solution and N determination on the filtrate (filter paper Whatman No. 42), using the micro-Kjeldahl method [36 (link)]. All chemical analyses were performed in triplicate.
Whatman no 42
Manufactured by Cytiva
Sourced in United Kingdom, United States
Whatman No. 42 is a high-quality cellulose filter paper designed for general laboratory filtration applications. It is a medium-speed, ashless filter paper with a nominal pore size of 2.5 microns. The Whatman No. 42 filter paper is suitable for a variety of filtration tasks, including the separation of fine precipitates and the clarification of aqueous solutions.
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Lab products found in correlation
37 protocols using whatman no 42
1
Comprehensive Chemical Characterization of Food
2
Extraction of Eucalyptus and Mint Leaves
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Eucalyptus (Eucalyptus globulus L.) leaves were collected from University of Agricultural Sciences, Dharwad, Karnataka whereas mint (Mentha piperita) leaves were collected from Jammu and Kashmir. The leaves were cleaned, dried under shade to remove moisture, powdered and stored for further use. 10 g of each powdered material was taken separately in a beaker containing 100 ml of de-ionized water and allowed to boil at 80 °C for 25–30 min under reflux condition and then cooled down to room temperature. Each solution was filtered through filter paper (Whatman No. 42) followed by centrifugation at 3000 rpm for 10 min for removal of heavy biomaterials. The clear solutions of plant extracts thus obtained were stored at 4 °C for further studies.
3
Quantifying Leaf Phosphorus Concentration
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To quantify the concentration of leaf phosphorus (P), approximately 1 g of dried leaf samples were separately ground and incinerated for 5 h at 550 °C in a muffle furnace. The digestion procedure was performed in a water bath at 28 °C for 25 min by adding 10 mL of hydrochloric acid (2N) into a 100 mL volumetric flask. The mixtures were filtered using filtration paper (Whatman No. 42, Whatman Corp. Little Chalfont, UK) and then diluted to 100 mL with the addition of distilled water. The amount of leaf phosphorus was measured spectrophotometrically at 880 nm, according to the vanadate-molybdate phosphoric acid method [29 ]. The standard curve was prepared by taking 0 to 1 mg/L of P concentrations. The samples were diluted based on the standard curve. The relative water content (RWC) was assayed in leaf samples according to the method outlined by He et al. [30 (link)]. Sampling was carried out an hour after solar noon. Six top fully expanded leaves from different plants per replication were sampled with a sharp knife and immediately used. The leaves were weighted (FW) and then were hydrated in distilled water for 24 h at room temperature. Turgid samples were quickly weighted (TW) after drying surface water with paper towels. Dry weights (DW) were measured after drying at 75 °C for 48 h. RWC was calculated according to the following equation:
4
Collecting Nasal Secretions for CRS Study
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The Internal Review Board of Seoul National University Hospital (No. C-1308-099-515) approved this study. All subjects were informed of the purpose of the study, and they all signed written informed consent forms. A diagnosis of CRS was based on patient history, physical examination, nasal endoscopy, and sinus computed tomography in accordance with the 2012 European position paper on rhinosinusitis and nasal polyps guidelines.28 (link) Patients possessing deviated nasal septa but lacking any sinonasal disease were considered as the control. Subjects that were less than 14 years of age and who were diagnosed with unilateral rhinosinusitis, antrochoanal polyps, allergic fungal sinusitis, cystic fibrosis, or immotile ciliary disease were excluded from the study. The demographic characteristics of the subjects are summarized in Table 1 . Nasal secretions were obtained from both sides of the nose as previously described.29 (link) Sterilized strips of filter paper (7 × 30 mm; Whatman No. 42, Whatman, Clifton, NJ, USA) were placed on the middle meatus for 10 minutes. Two filter papers from each subject were transferred into a tube. Then, 1 mL of nuclease-free water was added to each tube, and the tubes were rotated for 1 hour at room temperature. The nasal secretions were stored in aliquots at −70°C. The workflow is shown in Supplementary Fig. S1A .
5
Lipid Peroxidation Assessment in Nuggets
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Lipid peroxidation of nuggets was recorded by measuring thiobarbituric acid-reactive substances (TBARS) at an interval of 3 days during refrigerated storage. The TBARS number (mg malonaldehyde/kg) of nuggets was estimated using the extraction method outlined by Witte et al. [24 (link)] with slight modifications, as the slurry was centrifuged at 3000× g for 10 min (Biofuge Primo R, Heraeus, Hanau, Germany) instead of filtration through Whatman No. 42.
6
Extraction of Bioactive Compounds from Medicinal Plants
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The air-dried; powdered roots of P. stellatum, O. integrifolia and V. amygdalina were exhaustively extracted with chloroform using maceration technique. Maceration was carried out using one liter of the respective solvent for 72 h, with regular shaking. The mixture was filtered with whatman No. 42 filter paper (Whatman No.42, England) and the filtrate was kept at +4oc. The marc was macerated again in the same solvent two times and filtered. The filtrates were combined evaporated under reduced pressure on a rotary evaporator (Buchi Rota Vapor R-200) and dried in oven at 40oc (Gallenkamp, England).
In parallel, the air-dried and powdered roots of P. stellatum were soxhlet extracted with 80% methanol (4:1, methanol: water). The extracts were filtered and evaporated under reduced pressure on a rotary evaporator and lyophilized. The extracts were kept refrigerated and away from light.
In parallel, the air-dried and powdered roots of P. stellatum were soxhlet extracted with 80% methanol (4:1, methanol: water). The extracts were filtered and evaporated under reduced pressure on a rotary evaporator and lyophilized
7
Extraction and Analysis of Seed Compounds
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The seeds (1 Kg) were coarsely powdered and defatted with petroleum ether (60°C to 80°C) for 7 days by cold maceration. The fat-exhausted drug was further extracted with ethanol (95% v/v) by soxhlation for 72 h. The extract was concentrated in a rotary vacuum evaporator to yield 25.0% w/w of dark-brown-coloured extract. The ethanol extract of seeds was diluted with ethanol and filtered with Whatman No. 42 to obtain a particle-free extract for analysis by GC-MS.
8
Nitric-Perchloric Acid Digestion Protocol
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For the sample preparation, we utilized analytical grade nitric acid (65%, Sigma Aldrich) and perchloric acid (70%–72%, Sigma Aldrich) and the mixture was prepared in a 4:1 ratio of nitric acid and perchloric acid using a hot plate inside fuming hood. To ensure dryness, the temperature was slowly increasing for 2–3 h due to exothermic nature of the oily compounds that would burn with a flame. The procedure was repeated until the evolution of white fumes suggesting the end of the digestion process and dryness. After that, solutions were allowed to cool and filtered into a calibrated flask (100 mL) using Whatman no. 42 and diluted up to the mark.
9
Soil Nitrogen Dynamics Analysis
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Soils were destructively sampled for mineral nitrogen measurements and isotope measurements on days 0, 7, and 15 immediately after gas sampling. There were four replicates at each sampling day. Subsamples of 2 g soil were collected for soil DNA extraction, and 50 g of soil in the 500 ml vials was shaken with 250 ml 2M KCl (1:5 ratio soil:KCl solution) for 1 h at 200 rpm at room temperature, and the supernatant was filtered through a qualitative Whatman No. 42 filter paper. The extracts (30 ml) were stored at −20°C prior to analysis of -N and -N on a segmented-flow analyser (Skalar SAN++, Breda, Holland). The 15N enrichment of and was determined by a micro-diffusion method as reported by Saghir et al. (1993 (link)), with the modification that an acidified filter paper disc (Whatman No. 41) was used instead of the petri dish of acid to absorb NH3 and analysis by the Isotope Ratio Mass Spectrometer (Hydra 20–20, Sercon, Crewe, UK).
10
Determination of Mineral Composition
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The minerals potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), zinc (Zn), and copper (Cu) were determined [57 ]. The sample was ashed as described before. The obtained ash was dissolved using 1 mL HCl conc. at crucible walls. Dissolved samples were transferred to a 50 mL volumetric flask and de-ionized water was added to complete the total volume. The solution was filtered through ash-less filter paper Whatman No. 42 and stored in a refrigerator until a determination by Atomic Absorption Units (GBC 932 AA).
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