The color evolution of UEMn, PEMn, UPPEMn, and PPEMn solutions at different pH was assessed by spectrophotometry. Each sample was diluted (1 mg/mL) with phosphate buffers at 100 mM, in the pH range 1–10. Three reductants were tested (100 mM aqueous solutions extemporaneously): sodium dithionite, sodium sulfite, and ascorbic acid. Spectrophotometric measurements were realized in a 96-well microplate reader (Bioteck Instruments Inc., Winooski, VT, USA) and in a 2 mL quartz cuvette closed with a septum for oxygen-free experiments, using UV-visible spectrophotometers UV-3100PC (VWR, Leuven, Belgium) and a Varian UV-Visible spectrophotometer, model Cary 100. Freshly prepared, nitrogen-purged reagents were injected through the septum into the samples using a microliter glass syringe Hamilton 50 µL (Hamilton, Giarmata, Romania). The samples were titrated until fully reduced (yellow), then briefly exposed to air and shaken to induce reoxidation. In a second step, oxidization was forced using hydrogen peroxide 35 wt % (Aldrich, Merck KGaA, Darmstadt, Germany).
Uv 3100pc
Manufactured by Avantor
Sourced in United States, Germany
The UV-3100PC is a UV-Vis spectrophotometer designed for a wide range of applications in laboratories. It provides accurate and reliable measurements of absorbance, transmittance, and concentration of samples across the ultraviolet and visible light spectrum.
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Lab products found in correlation
Infinite f50, by Tecan (2 mentions)
Multiskan go, by Thermo Fisher Scientific (2 mentions)
Sigmaplot 13, by Grafiti LLC (1 mentions)
Bs 300, by Mindray (1 mentions)
Bs 300 chemical analyzer, by Mindray (1 mentions)
V 650 uv vis spectrophotometer, by Jasco (1 mentions)
Os 30p fluorometer, by Opti-Sciences (1 mentions)
19 protocols using uv 3100pc
1
Redox-Dependent Color Evolution of Polyoxometalates
2
DPPH Radical Scavenging Assay
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Antioxidant capacity was determined using the free radical scavenging activity with DPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) according to the method of Igual et al. [48 (link)] in triplicate. A UV-visible spectrophotometer (UV-3100PC, VWR, Radnor, PA, USA) was used to measure the absorbance at 515 nm. The results were indicated as µg Trolox equivalents (TE) per gram dry weight (µg TE/g d.w.).
3
Rhamnolipid Production and Cell Growth Monitoring
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Cell growth was monitored by measuring the optical density at λ = 600 nm (OD600) using a spectrophotometer (UV-3100 PC, VWR GmbH, Darmstadt, Germany). Consumption of glucose and acetate was determined from the supernatant samples using d -glucose, respectively acetate assay kits (Enztech yellow line, R-Biopharm AG, Darmstadt, Germany) following the manufacturers’ instructions. Rhamnolipid determination was performed as described previously (Horlamus et al. 2019 (link)). All graphical and regression analysis for production rates and yield coefficients was performed using scientific graphing and data analysis software (SigmaPlot 13.0, Systat Software Inc., San Jose, CA). If applicable, four parameter logistic fits for biomass and rhamnolipid concentration were used for calculation (Henkel et al. 2014 (link)).
4
Cellulose Porosity and Surface Area Analysis
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The accessible surface area of the cellulose and the relative porosity of the LB were determined by Simons’ staining as previously described [114 (link), 115 (link)]. Direct Blue 1 (DB1) was purchased from Pylam Products Company (USA). Direct Yellow 11 (DY11) was obtained from Sigma-Aldrich (USA). DY11 was purified with 100 kDa (molecular weight cutoff) polyethersulfone membranes, and only the supernatant with a MW > 100 kDa, was used. DB1 and DY11 were prepared to yield 10 mg/mL by adding deionised water. Substrate (10 mg) was added in 2-mL tubes and mixed with 0.1 mL of phosphate buffer (140 mM NaCl, 0.3 M phosphate, pH 6.0), an increasing volume of both dyes (0.025, 0.05, 0.75, 0.1, 0.15 and 0.2 mL) followed by the addition of deionized water to bring the final volume to 1 mL. The tubes were incubated at 70 °C for 6 h with agitation of 300 rpm. After incubation, the tubes were centrifuged at 12,000g for 5 min, and the absorbance of the supernatant was analysed after 100-fold dilution with a spectrophotometer (UV-3100 PC, VWR, USA) at 430 and 600 nm. The amount of dye adsorbed onto the biomass was determined as the difference between the concentration of the initially added dye and the concentration of the dye in the supernatant, as described by Alam et al. [81 (link)].
5
Quantitative Methylene Blue Analysis
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Methylene blue concentration of sampled tablets was measured by UV-Vis spectroscopy (UV-3100 PC, VWR International GmbH, Darmstadt, Germany) using a previously conducted linear calibration linking methylene blue concentration and absorption. Samples consisting of three tablets were ground with a pestle and mortar. Afterward, 100 mg of the ground powder was dispersed in 10 mL of a 1 M aqueous hydrochloric acid solution and stirred for 10 s using a vortex blender. 3 mL of the supernatant was filtered through a microporous filter (mean pore size of 0.45 µm) to remove residual particles. The filtered solution was photometrically examined at a wavelength of 660 nm as a three-fold determination and the average methylene blue concentration was calculated. Measured absorbance values below 0.005 were considered 0 as they were outside the calibration range. To correct the possible adsorption of solved tracer on particle surfaces, an additional calibration was performed. A linear relationship between methylene blue concentration of pure tracer and blends of tracer and bulk powder (applying a constant amount of tracer powder) was found and applied as a correction factor.
6
Carotenoids, Phenols, and Antioxidant Capacity
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The method proposed by Olives Barba et al. [30 (link)] was used to determine total carotenoids (TC). The AOAC spectrophotometric method [31 ] was used to quantify TC and is expressed as the milligrams of β-carotene per 100 g of sample.
This property was determined (at 503 nm) using the TC extract and is expressed as milligrams per 100 g of the sample [32 ].
Igual et al. [33 (link)] described the method for measuring total phenols (TP). A UV-3100 PC (VWR, Radnor, Philadelphia, PA, USA) was used to measure the absorbance of the sample at 765 nm, and the TP is expressed as milligrams per gallic acid/100 g of dry solid sample.
The 2,2-diphenylpicrylhydrazyl (DPPH) method described by Igual et al. [33 (link)] was used to determine antioxidant capacity (AC). The absorbance was measured at a wavelength of 515 nm, and the results were expressed as milligram Trolox equivalents (TE) per 100 g of dry solid sample. An average of 3 measurements were made in each characteristic.
This property was determined (at 503 nm) using the TC extract and is expressed as milligrams per 100 g of the sample [32 ].
Igual et al. [33 (link)] described the method for measuring total phenols (TP). A UV-3100 PC (VWR, Radnor, Philadelphia, PA, USA) was used to measure the absorbance of the sample at 765 nm, and the TP is expressed as milligrams per gallic acid/100 g of dry solid sample.
The 2,2-diphenylpicrylhydrazyl (DPPH) method described by Igual et al. [33 (link)] was used to determine antioxidant capacity (AC). The absorbance was measured at a wavelength of 515 nm, and the results were expressed as milligram Trolox equivalents (TE) per 100 g of dry solid sample. An average of 3 measurements were made in each characteristic.
7
Automated Spectrophotometric Analysis Protocol
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Spectrophotometry: a UV-Vis UV-3100PC, VWR (Hamburg, Germany) single-beam spectrophotometer was used to record the UV-Vis spectra. The Vis spectrum was measured every 2 nm in the range of 350–700 nm in plastic cuvettes with an optical path of 1 cm. An Infinite F50 (Tecan, Mannedorf, Switzerland) was used for measurement on a polystyrene microtiter plate (Gama Group a.s., Ceske Budejovice, Czech Republic). Automated spectrometric measurements: BS-300 chemical analyser from Mindray (Shenzhen, China), cuvettes 5 × 6 × 30 mm, optical path 5 mm and a volume of the reaction mixture in the cuvette 180–500 µL. Photometric detector measuring at wavelengths: 340, 405, 450, 510, 546, 578, 630, and 670 nm. Reagents and samples were placed on the cooled sample holder (4 °C) and automatically pipetted directly into plastic cuvettes. Incubation proceeded at 37 °C. The mixture was consequently stirred. The washing steps by distilled water (18 mΩ) were done in the midst of the pipetting. Apparatus was operated using the software BS-300 (Mindray, Shenzhen, China) and LADYS (Prevention Medicals, Studenka, Czech Republic).
8
Measuring Film Opacity and Light Barrier
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The light barrier properties of films against visible light and ultraviolet (UV) were determined according to the method of Peng et al. [45 (link)]. Rectangular film strips (9 mm × 40 mm) were placed in the spectrophotometer cuvette and the absorbance was measured at 600 nm by a spectrophotometer UV-3100PC, VWR (Rosny-sous-Bois, France). The opacity of the films was calculated using Equation (1):
where O (A.mm−1) is the opacity of films, Abs 600 is the value of absorbance at 600 nm (A), and L is the film specimen thickness (mm).
where O (A.mm−1) is the opacity of films, Abs 600 is the value of absorbance at 600 nm (A), and L is the film specimen thickness (mm).
9
Fluorescent Tonic Water Analysis
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Four commercially available tonic waters – three non-coloured tonic waters and one coloured tonic water – were deliberately spilled (1 mL) in working fields for cytotoxic handling (Chemoprotect®), and the produced fluorescence was monitored under 300–400 nm UV light (BeamZ®) (Table 1 ).
An ultraviolet/visible (UV/Vis) spectrophotometer from VWR® (UV-3100PC) was used to perform the UV/Vis spectrophotometric analysis of the tonic water samples that exhibited fluorescence in quartz cuvettes (VWR®). All tonic water samples were previously submitted to a degassing procedure in an ultrasonic cleaner (Sonorex®) for 15 min, at room temperature.
The UV/Vis spectrophotometric analysis was also performed for two quinine solutions (concentrations of 0.05 mol/L and 0.1 mol/L). Quinine solutions were prepared by dilution of quinine hydrochloride solution (250 mg/mL) (Labesfal®, Portugal). Determinations were performed in triplicate, for 11 different wavelengths, at intervals of 20 nm, between 300 nm and 500 nm.
An ultraviolet/visible (UV/Vis) spectrophotometer from VWR® (UV-3100PC) was used to perform the UV/Vis spectrophotometric analysis of the tonic water samples that exhibited fluorescence in quartz cuvettes (VWR®). All tonic water samples were previously submitted to a degassing procedure in an ultrasonic cleaner (Sonorex®) for 15 min, at room temperature.
The UV/Vis spectrophotometric analysis was also performed for two quinine solutions (concentrations of 0.05 mol/L and 0.1 mol/L). Quinine solutions were prepared by dilution of quinine hydrochloride solution (250 mg/mL) (Labesfal®, Portugal). Determinations were performed in triplicate, for 11 different wavelengths, at intervals of 20 nm, between 300 nm and 500 nm.
10
Vanadium Ion Crossover Measurement Protocol
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