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Lambda 20 uv vis spectrophotometer

Manufactured by PerkinElmer
Sourced in United States

The Lambda 20 UV VIS Spectrophotometer is a dual-beam instrument designed for ultraviolet and visible spectroscopy. It measures the absorption or transmission of light through a sample across a specified wavelength range. The instrument features a monochromator, photodetectors, and a data processing system to analyze the spectral data.

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25 protocols using lambda 20 uv vis spectrophotometer

1

Magnolol Quantification in MAG-SMOF

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Magnolol concentration in MAG-SMOF samples was determined using the UV-Vis spectrophotometry method at room temperature on a Lambda 20 UV/Vis Spectrophotometer (PerkinElmer, Shelton, CT, USA). To collect the UV–Vis absorption spectra, 100 µL of MAG-SMOF was dissolved in 1 mL of dichloromethane, and the sample was filled up to 10 mL with methanol. Each sample was transferred to 1.0 cm quartz cells, and the measurements were conducted with respect to the intensity of light passing through a blank sample consisting of 100 µL of SMOFlipid (without the addition of magnolol), 1 mL of dichloromethane and filled up to 10 mL with methanol. The concentration of magnolol was calculated based on calibration curve performer in the range of 0.004 to 0.044 mg/mL with absorption determined at 291.2 nm. The calibration curve was performed by the dilution of the appropriate volume of standard stock solutions of magnolol in methanol (1 mg/mL) in a 10 mL of standard diluent obtained by the binary mixture of dichloromethane and methanol (1:9) and the addition of 100 µL of SMOFlipid.
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2

Antioxidant Activity of Propolis Extract

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The raw propolis samples were macerated and continuously homogenized for 24 h in 70% ethanol solution (1:100 w/v), and then evaporated to dryness. A reaction mixture containing 2,2-diphenyl-1-picrylhydrazyl (DPPH) 0.1 mM ethanoic solution and 0.6 mg/mL propolis solution was prepared. The absorbance was measured in a quartz cuvette (1 cm3) at λ = 515 nm with a Lambda 20 UV VIS Spectrophotometer (Perkin Elmer UV/VIS, Washington, DC, USA). Absorbance (A) was measured at the initiation of the reaction, then after 10 and 20 min. The antioxidant activity was calculated using the formula [65 ,66 (link)]: %RSA = (ADPPH − Asample)/ADPPH × 100.
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3

Optical and Electrochemical Characterization of Polymers

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Example 2

Film UV-Vis absorption spectra of polymers from Example 2 were acquired on a Perkin Elmer Lambda 20 UV/VIS Spectrophotometer. All film samples were spin-cast on ITO/ZnO substrates. Solution UV-Vis absorption spectra at elevated temperatures were collected on a Perkin Elmer Lambda 950 UV/VIS/NIR Spectrophotometer. The temperature of the cuvette was controlled with a Perkin Elmer PTP 6+6 Peltier System, which is supplied by a Perkin Elmer PCB 1500 Water Peltier System. Before each measurement, the system was held for at least 10 min at the target temperature to reach thermal equilibrium. A cuvette with a stopper (Sigma Z600628) was used to avoid volatilization during the measurement. The onset of the absorption is used to estimate the polymer bandgap.

Cyclic voltammetry was carried out on a CHI760E electrochemical workstation with three electrodes configuration, using Ag/AgCl as the reference electrode, a Pt plate as the counter electrode, and a glassy carbon as the working electrode. Polymers were drop-cast onto the electrode from DCB solutions to form thin films. 0.1 mol L−1 tetrabutylammonium hexafluorophosphate in anhydrous acetonitrile was used as the supporting electrolyte. Potentials were referenced to the ferrocenium/ferrocene couple by using ferrocene as external standards in acetonitrile solutions. The scan rate is 0.1 V s−1.

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4

Extraction of Total RNA from Rat Brain Tissue

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Total RNA was extracted from the brain tissue specimens of rats using a TriPure isolation reagent (Roche Diagnostics, Mannheim, Germany), according to the manufacturer’s instructions. Briefly, fresh or frozen tissues (~100 mg) were homogenized in 1 ml TriPure reagent and submitted to centrifugation at 21,578 × g for 10 min at 4°C. Following the addition of 0.2 ml chloroform to the supernatants, the mixture was incubated at room temperature for 20 min with occasional stirring. The samples were then submitted to centrifugation again, as aforementioned. The resulting supernatants were mixed with 0.5 ml isopropanol, incubated for 5–10 min and centrifuged as aforementioned. The pellet containing total RNA was washed with 1 ml ethanol (75%) and centrifuged at 8,429 × g for 5 min at 4°C. The RNA pellet was air dried, dissolved in 3 ml diethylpyrocarbonate-treated water and the optical density (OD) values were measured at 260 and 280 nm on a Lambda 20 UV/Vis spectrophotometer (Perkin-Elmer, Norwalk, CT, USA). The RNA concentration was calculated as follows: RNA concentration (μg/ml) = OD260 × dilution factor × 40/1,000. RNA purity was assessed by the OD260/OD280 ratio.
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5

Nanodisc Formation from DMPC/DMTAP Lipids

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Ten mg total lipid, consisting of 100 % DMPC or 70 % DMPC / 30 % DMTAP (w/w), was dissolved in chloroform / methanol (3:1 v/v) and dried under a stream of N2 gas, forming a thin film on a glass vessel wall. Residual organic solvent was removed under vacuum. The prepared lipids were dispersed in phosphate buffered saline (PBS; 20 mM sodium phosphate, 150 mM sodium chloride, pH 7.0) by bath sonication. Subsequently, 4 mg apoA-I was added to the lipid dispersions. Sonication was continued until the turbid mixture clarified, indicating lipid/protein complexes (i.e. ND) had formed. Sample absorbance measurements at 325 nm were made on a Perkin Elmer Lambda 20 UV/VIS spectrophotometer.
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6

Quantifying Propolis Phenolics via Folin-Ciocalteu

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For this determination, the Folin–Ciocalteu method was used [61 (link),62 (link)]. Dried raw propolis was grounded in a mixer to a fine powder, dissolved and homogenized in ethanol and filtered. An equivalent quantity of Folin–Ciocalteu reagent was added. The absorbance was measured against a blank (distilled water) at 765 nm with a Lambda 20 UV VIS Spectrophotometer (Perkin Elmer UV/VIS, Washington D.C., USA). The total phenolic concentrations were compared to a standard curve of gallic acid.
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7

Determination of HMF in Honey

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For the determination of HMF in honey, 10 g of honey was dissolved in approximately 25 mL of distillate water and transferred to a 50 mL volumetric flask; 2 mL of honey solution and 5 mL of p-toluidine were placed in two test tubes. In one tube 1 mL of distilled water was added (reference solution) and in the other 1 mL of barbituric acid solution 0.5% (sample solution). The absorbance was read in 1 cm cuvettes at 550 nm with a Lambda 20 UV VIS Spectrophotometer (Perkin Elmer, Waltham, MA, USA). The HMF content was determined by the external standard method (p 99%, Sigma-Aldrich, Milan, Italy) and by using the proposed formula for the method [53 ].
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8

Dbp5 ATPase Kinetics and Stimulation

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Time courses of Dbp5 (0.6–1 μM) steady state ATPase assayed by absorbance change at 340 nm using the NADH-coupled assay were acquired on a Perkin-Elmer Lambda 20 UV-Vis spectrophotometer thermostatted at 25 °C.13 (link), 43 (link), 66 The [ATP]-dependence of the initial steady-state ATPase rate (v0) was fitted to the Michaelis-Menten equation:
v0=kcat[H]T[T][T]+KM,ATP where kcat is the maximal turnover rate of Dbp5 at saturating ATP in units of s−1, [H]T is the total Dbp5 concentration, KM,ATP is the Michaelis constant for ATP, and [T] is the total [ATP]. The [ADP] under our conditions of 2 mM ATP is ~7 μM.43 (link) Steady-state ATPase assays were also performed using ATPγS as a substrate.
RNA-stimulated steady-state ATPase experiments were performed as detailed above, using 100 nM Dbp5 and 20 mM ATP. Data was fitted to the quadratic form of the Briggs-Haldane equation 
vobs=(kcat-k0)[H]T+[R]T-KM,RNA-([H]T+[R]T-KM,RNA)2-4[H]T[R]T2[H]T+k0 where [R]T is the total RNA concentration in nucleotides.66
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9

Quantifying Brain Lipid Peroxidation

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The quantitative measurement of lipid peroxidation in the whole brain was measured according to the method of Wills (1966 (link)). The amount of malondialdehyde (MDA) concentration formed was measured by the reaction with thiobarbituric acid at 532 nm using Perkin Elmer lambda 20 UV-vis spectrophotometer (Norwalk, CT, USA). The results were expressed as nano moles of MDA per milligram protein using the molar extinction coefficient of chromophore (1.56 × 10 M/cm) and represented as percentage of naive.
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10

Characterization of Novel Compounds

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All the reagents were purchased from Sigma Aldrich and used without any further purification. Infrared spectra (FTIR) were obtained using KBr pellets or NaCl windows on a Perkin-Elmer Frontier FT-IR/FIR spectrometer. Electronic spectra were recorded in methanol on a Perkin Elmer Lambda 20 UV–Vis spectrophotometer. Thermogravimetric analysis (TGA) was carried out with a Perkin-Elmer Pyris 1 TGA apparatus under an N2 atmosphere at a flow rate of 10 mL/min over a temperature range of 25 to 800 °C at a heating rate of 5 °C/min and analyzed using the Pyris version 11.1.1.0492 software package. Electron paramagnetic resonance spectra (EPR) of polycrystalline samples at 298 K and solution at 77 K were recorded in quartz tubes with a Joel JES-TE300 spectrometer equipped with a cylindrical cavity (TE011 mode) operating at X band frequency (9.4 GHz) at 100 KHz field modulation. Gas chromatograms were recorded on an Agilent 7890B-GC System equipped with a mass selective detector, the Agilent 5977A.
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