V 730 uv vis spectrophotometer

There are many physicochemical parameters that affect the adsorption process. To determine the optimum adsorption conditions, the effects of different factors such as adsorbent dose, contact time, pH, presence of different ions, and Cr(VI) solution initial concentration on the adsorption system were investigated. In adsorption studies performed as a batch process, the volume of the 25 ppm Cr(VI) solution was kept constant at 10 mL, prepared from K₂Cr₂O₇. Adsorption experiments were carried out with 100 mL Erlenmeyer flasks in an orbital shaker with agitation of 120 rpm. After the experiments, the magnetic nanocomposites were easily separated from the Cr(VI) solution with the help of magnets. Concentrations of the remaining Cr(VI) solution were measured at 351 nm with a V-730 UV-Vis spectrophotometer (Jasco, Tokyo, Japan).
Adsorption capacity is a significant parameter for adsorption processes and is calculated with the formula shown in Eq. (1), where Co (mg/L) is the initial concentration of Cr(VI), Ce (mg/L) is the equilibrium concentration, m (g) is the amount of adsorbent, and V (L) is the solution volume.

FTIR-8400S SHIMADZU spectrometer (Shimadzu, Kyoto, Japan) was employed to record IR spectrum of the DAPH⁺Cl⁻ product ranging from 400 to 3600 cm^–1. ¹H and ¹³C NMR spectra of the DAPH⁺Cl⁻ were obtained on a Bruker Advance 400 MHz spectrometer (Bruker, Massachusetts, USA) in CDCl₃at 298 K. Steady-state absorption and other spectral data were obtained on a JASCO V-730 UV–Vis spectrophotometer (Jasco, Tokyo, Japan). A Perkin Elmer 2400 CHN microanalyzer (Perkin Elmer, Waltham, USA) was used to perform the elemental analysis.

The UV-visible spectra were recorded using a JASCO V-730 UV/vis spectrophotometer (JASCO, Japan).

This test was carried out as described by Gunathilake et al. (2018), with some modifications as described in Truong et al. (2019). Briefly, 1 ml of blood cell suspension was mixed with 1 ml of test extract of S. buxifolia bark; instead of the test sample, only saline was added to the control test tube. All centrifuge tubes containing reaction mixture (2 ml) were incubated in a shaking water bath at 56°C for 30 min. After incubation, the mixture was cooled down rapidly to room temperature and centrifuged at 700 g for 5 min to obtain the supernatant. The absorbance of the supernatant was measured at 560 nm using a spectrophotometer (V‐730 UV‐Vis Spectrophotometer, Jasco, USA). The level of hemolysis was calculated using the following equation: $\%\text{inhibition of hemolysis}=\left[\left(A1‐A2\right)/A1\right]\times 100,$ where A1 = absorption of the control and A2 = absorption of the test sample mixture.

As a negative control of the pOBP-based biosensor, the electrode surface was functionalized with the recombinant glutamine-binding protein (GlnBP). The expression and purification steps were performed following D’Auria et al. (2005) [42 (link)]. In brief, E. coli cells HB101 expressing GlnBP were grown overnight at 37 °C in LB in the presence of 100 μg/mL ampicillin and then were disrupted by osmotic shock. Next, the crude periplasmic preparations were equilibrated with Na phosphate buffer (pH 7.5) and applied to a DEAE–Sepharose column. Due to the high basicity of GlnBP, there was no adsorption at this pH value, and the protein was collected in the flowthrough fractions. Finally, the protein concentration of GlnBP fractions was estimated by measuring UV absorbance at 280 nm using Jasco V-730 UV/Vis spectrophotometer (molar extinction coefficient 22,920 M⁻¹ cm⁻¹).

¹H NMR spectra were obtained using a Bruker (Billerica, MA, USA) DRX-500 spectrometer. GPC measurements were performed using a Tosoh (Tokyo, Japan) RI-8020 reflective index detector, Tosoh DP-8020 pump, and Shodex (Tokyo, Japan) GF-7M column. A phosphate buffer (50 mM) at pH 9 and acetonitrile mixed solvent (9/1, v/v) was used as the eluent at 40 °C. The M_n(GPC) and M_w/M_n values for the polymers were calibrated using standard sodium poly(styrene sulfonate) samples. pH titration was performed using a Hiranuma Sangyo (Osaka, Japan) COM-1600 auto-titrator equipped with a glass electrode in 4.0 M KCl. PAAc was dissolved in 0.1 M NaOH at C_p = 5.0 g/L, which was titrated using 0.1 M HCl_aq. Ultraviolet–visible spectra were obtained using a Jasco (Tokyo, Japan) V-730 UV–vis spectrophotometer at 700 nm. To determine the UCST, the temperature was controlled using a Jasco ETC-717 temperature controller at a cooling rate of 1.0 °C/min. The T_p was defined as the temperature at which the %T at 700 nm starts to decrease.