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Photocoupler
Determination of hydrogen peroxide content by ultraviolet spectrophotometry
Ultraviolet spectrophotometric determination of hydrogen peroxide content analysis instrument Keywords: spectrophotometry; hydrogen peroxide; analysis instrument ; UV-1500 [principle] H 2 O 2 and titanium sulfate (or titanium chloride) The yellow precipitate of the peroxide-titanium complex was formed, which was dissolved by H 2 SO 4 and then measured by colorimetry at a wavelength of 415 nm. Within a certain range, the color depth is linear with the H 2 O 2 concentration. [Instruments and utensils] mortar; pipette 0.2ml and tip, 5ml × 1; volumetric flask 10ml × 7, centrifuge tube 5ml × 8; centrifuge; UV-1500 UV-visible spectrophotometer. [Reagents] 100 μmol/L H 2 O 2 reagent; 2 mol/L sulfuric acid; 5% (W/V) titanium sulfate; acetone; concentrated ammonia water. 30% H 2 O 2 refers to the mass ratio of hydrogen peroxide solution, its density is 1.1g/cm3, and the molecular weight of hydrogen peroxide is 34.02. Through these parameters, we can calculate the mole of hydrogen peroxide by 30%. The concentration was 9.7 mol/L. [Method] 1. Prepare a standard curve: Take 7 tubes of 10 ml centrifuge tubes, number sequentially, and add reagents according to Table 40-1. Table 40-1 Determination of H 2 O 2 Concentration Standard Curve Configuration Table
Reagent (ml) Centrifuge tube number 1 2 3 4 5 6 7 100μmol/LH 2 O 2 0 0.1 0.2 0.4 0.6 0.8 1.0 Pre-cooled acetone at 4°C 1.0 0.9 0.8 0.6 0.4 0.2 0 5% Titanium sulfate 0.1 0.1 0.1 0.1 0.1 0.1 0.1 concentrated ammonia 0.2 0.2 0.2 0.2 0.2 0.2 0.2 3000r/min Centrifuge for 10min, discard the supernatant, leave 2mol of sulfuric acid 5.0 5.0 5.0 5.0 5.0 5.0 5.0
After the precipitate was completely dissolved, carefully transfer it into a 10 ml volumetric flask, and rinse the centrifuge tube several times with distilled water. The washing solution was combined and adjusted to a volume of 10 ml, and the color was measured at a wavelength of 415 nm. 2. Sample extraction and determination: (1) Weigh 2~5g of fresh plant tissue (depending on the content of H 2 O 2 ), add pre-cooled acetone at 4 ° C and a little according to the ratio of material to extractant 1:1. After the quartz sand is ground into a homogenate, it is centrifuged at 3000 r/min for 10 min, and the residue is discarded. The supernatant is the sample extract. (2) Pipette 1 ml of the sample extract, add 5% titanium sulfate and concentrated ammonia water according to Table 35-1, centrifuge at 3000 rpm/min for 10 min after the formation of the precipitate, and discard the supernatant. The precipitate was washed repeatedly with acetone 3 to 5 times until the plant pigment was removed. (3) To the precipitate after washing, 5 ml of 2 mol of sulfuric acid was added, and after completely dissolved, the volume was adjusted to the same color as the standard curve. 3. Calculation of results: H 2 O 2 content in plant tissues (μmol/g Fw)= In the formula, the H 2 O 2 concentration (μmol) in the sample is found on the C-standard curve; V t — the total volume of the sample extract (ml); V 1 — the volume of the sample extract used in the measurement (ml); FW—plant tissue Fresh weight (g). Customized Products
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