Uv 2401pc

Decolorization was calculated from the initial dye concentration and dye concentration at time t (C₀ and C_t, respectively) by measuring the absorbance at the visible maximum absorption wavelength (583 nm for RB5 and 617 nm for Rb7). Decolorization (D) was reported in %:

Absorbance measurements were carried out with a UV–vis spectrophotometer (Shimadzu UV-2401 PC, Kyoto, Japan). In the working range, the dye absorbance (Abs) has a linear behavior versus the dye concentration (conc), according to the Equations (2) and (3):


The total organic carbon (TOC) was determined with a Shimadzu TOC5050A analyzer (Kyoto, Japan). The % degradation was calculated according to Equation (4).

where TOC₀ corresponds to the initial value and TOC_t is the value at time t.
In accordance with our previous studies [28 (link)], the dye degradation follows a first-order reaction with an electrochemical treatment. The discoloration rate constants (k_D) were calculated from the slope of the semilogarithmic plot of absorbance versus treatment time (t) following the kinetic Equation (5).

The mineralization rate constants (k_M) were calculated from the slope of the semilogarithmic plot of TOC versus treatment time (t), in accordance with Equation (6).

The specific UV absorbance (SUVA254) corresponds to the ratio of UV absorbance at wavelength of 254 nm, measured in a 1 cm quartz cuvette using a UV–vis spectrophotometer (UV-2401PC, Shimadzu, Kyoto, Japan) and TOC value [15 (link)]. TOC analysis was performed using a TOC-VCSN Shimadzu analyzer (Shimadzu Japan).

Thermal denaturation melting experiments were performed in a UV-Vis spectrophotometer (Shimadzu UV-2401PC). 900 μL of RNA-DNA hybrid nanoshape sample solution at 0.5 μM concentration was prepared with degassed buffer solution, transferred in a 1 cm quartz cuvette and covered with an oil layer to prevent evaporation. The temperature was raised from 15 to 80 °C at a rate of 0.5 °C per minute using a controlled temperature recirculating water system (Lauda RE 206), measuring the absorption every 1 °C at 260 nm.

A double-beam UV–Vis spectrometer (UV-2401 PC, Shimadzu Co., Japan) was used for collecting absorptions in the UV–Vis range. Spectra were recorded quadruply and averaged for noise reduction. Samples were placed in quartz cells with 20 mm path length and recorded digitally in the wavelength range 345–570 nm in 0.1 nm steps with a slit width of 1 nm.
Determination of pH was made by a glass combination electrode (ELMETRON pH-meter Cp-315 Co., Zabrze, Poland) following the 5-point calibration scheme described by IUPAC [41 (link), 42 (link)]. The calibration pH standard solution was traceable material (Merck Co., Darmstadt, Germany).

The total phenolic content was determined using the Folin–Ciocalteu method previously described by Gao et al. [41 (link)]. A sample extract of 0.1 mL was mixed with 0.2 mL of Folin–Ciocalteu reagent and 2 mL of water. This mixture was incubated at room temperature for 3 min, subsequently added with 1 mL of 20% sodium carbonate and was incubated at room temperature for 1 h. The absorbance was measured using an ultraviolet–visible light spectrophotometer (Shimadzu, UV-2401 PC, Kyoto, Japan) at a wavelength of 765 nm. Quantification was performed on the basis of the gallic acid standard curve constructed, and results were expressed as gallic acid equivalence in milligrams per 100 g of dw. All determinations were performed in triplicate.