Dr6000 uv vis spectrophotometer

Salmonella was cultured statically in Tryptic Soy Broth (TSB) medium at 37 °C until OD_600nm = 0.3 then equally divided into five Erlenmeyer flasks. Cinnamaldehyde was added to each flask to obtain final concentrations of 0, 16, 32 and 64 μg/mL. Subsequently, the flasks were cultured at 37 °C. Other conditions were unchanged, and DMSO was used as a control group. The absorbance of the culture at different growth times was measured by using a HACH DR6000 UV VIS Spectrophotometer.

High-resolution transmission electron microscopy image of TPSe NPs was acquired by a Talos F200X transmission electron microscope. Particle size was obtained by a Malvern Zetasizer Nano ZS 90. UV-VIS absorption spectra was obtained by employing a HACH DR6000 UV-vis spectrophotometer. Infrared thermal image was collected using a Fluke Ti480 Infrared Camera.

Total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD) of all samples were measured using Hach test kits (Hach, CO, USA). A Hach 36 chamber digestion block was used to digest water samples for the determination of COD. A DR 6000 UV Vis spectrophotometer (Hach, CO, USA) was used for all the analyses. Detection limits for TN and TP were 0.1 mg/L and 0.06 mg/L, respectively.

Nutrient analyses were performed at D0 in the lagoon water used to fill the mesocosms and at D3 and D7 in all the mesocosms, following the instructions of the LCK cuvette test systems provided by the manufacturer (Hach® Company). The preparation of samples for the dissolved nutrient analyses was performed using cuvette test systems LCK 304, 341, 339, and 349 for ammonium (NH₄⁺), nitrites (NO₂⁻), nitrates (NO₃⁻), and SRP, respectively, after the water samples were filtered through nylon membranes (Whatman^TM, porosity 0.45 µm, diameter 47 mm). The preparation of the samples for the TN and TP analyses was performed using unfiltered water samples, with LCK cuvette test systems LCK 138 and 349, respectively. The protocols for the TN and TP measurements included a digestion step at a high temperature, performed with a HACH HT 2500 thermostat. Finally, colorimetric determinations of the concentrations were obtained for all the nutrients using a HACH DR6000 UV‐VIS spectrophotometer.

Raw and pretreated ORW was analyzed for DOC, pH, zeta potential (ZP), turbidity, UV₂₅₄, and true color. Samples used for DOC and UV₂₅₄ measurement were pre-filtered using a 0.45 µm PES membrane filter (Supor 47 mm, 60043, Pall, Mississauga, ON, Canada). The filter material was selected to minimize the adsorption of organics, as recommended by Karanfil et al. [83 (link)]. A total organic carbon (TOC) analyzer (Pheonix 8000, Tekmar–Dohrmann, Cincinnati, OH, USA) was used for analysis of DOC according to Standard Method 5310/5310C, the UV–persulfate oxidation method [84 ]. Ultraviolet absorbance was measured at a wavelength of 254 nm according to Standard Methods 5910/5910A [84 ] using a Hach DR6000 UV–Vis spectrophotometer (LPV441.99.00002, Loveland, CO, USA). The feed water SUVA values were determined by dividing the UV₂₅₄ absorbance by the DOC. ZP was measured with a zetasizer nano particle analyzer (Nano ZS Series, Malvern Instruments Ltd., Worcestershire, UK). Turbidity was measured according to Standard Methods 2130/2130B [84 ] using a Hach 2100AN nephelometric laboratory turbidimeter (4700100, Hach, Loveland, CO, USA). The pH of all samples was measured using a benchtop meter (Symphony B10P, VWR, Mississauga, ON, Canada) and electrode (Red Rod, 89–321–580, VWR, Mississauga, ON, Canada).

The analysis by UV/VIS was conducted with a HACH^® DR6000 UV/VIS Spectrophotometer (Loveland, CO, USA) by applying a wavelength of 350–700 nm for the direct measure of absorbance.
The samples were scanned in a quartz cell with a 1 cm optical path by triplicate. The calibration curve obtained a coefficient of correlation (r²) of 0.999. The decolorization of the azo dye Carmoisine solutions was monitored from the absorbance (A) decay at its maximum absorption wavelength, 526 nm, determined from the spectra. The color removal efficiency or percentage of color removal was then calculated as follows (Equation (5)):
where A₀ and At denote the absorbance at initial time and after an electrolysis time t, respectively.

The biomass dry weight of the antifolate-treated algal cell cultures was measured on a daily basis. 10 mL of the cell culture were collected and filtered through the Whatman GF-C glass microfiber filters. The filters were then washed with 0.5 M ammonium bicarbonate to remove salts and dried in a 105 °C oven for 24 h. Four replications were conducted for each measurement. To extract pigments from the samples, 1-mL aliquots of the inoculated cell culture were pelleted through centrifugation and re-suspended in dimethyl sulfoxide (DMSO). A quarter volume of 0.4–0.6 mm glass beads were added to the cell suspension. The suspensions were treated with a cell disrupter (Mini-BeadBeater-24, USA) for several times under dim light (less than 0.02 μmol m⁻² s⁻¹) until the cell pellet turned colorless. The DMSO extracted pigments were collected by centrifuging at 3000g for 1 min. The concentrations of chlorophylls and carotenoids were quantified by using a DR6000 UV–vis spectrophotometer (HACH company, USA) [67 (link)], and the quantitative data were presented as mean ± S.D.