Tips for using the legal amount of vitamin B2 in fluorescent phosphorescence

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vitamin
B12 in a certain wavelength of light exposure, will emit green fluorescence, the production of multi-dimensional glucose powder sample standard curve, according to the fluorescence intensity can be calculated in multi-dimensional glucose powder vitamin B12 content.objective ofstudy the analytical principle of vitamin B2 in multi-dimensional glucose powder by studying fluorescent phosphorescence.Master the operation technique
of fluorescent phosphorescometer
techniques and methods of determining vitamin B2 in multi-dimensional glucose powder.Fluorescence analysis experimental principle at room temperature, the
molecules
in the base state absorb a certain amount of ultraviolet visible light radiation can become excitation molecules, excitation molecules through radiation-free jump to the first excitation state of the lowest vibration energy level, and then in the form of radiation jump back to the base state, emits a longer light than absorbing light waves and produce fluorescence.In a sparse solution, fluorescence intensity IF has the following relationship with substance concentration c:When experimental conditions are certain, fluorescence intensity is linearly related to the concentration of fluorescent substances:this is the theoretical basis for the analysis of fluorescence
spectral
quorum.of fluorescence analysis a. Fluorescence analysis has a higher sensitivity than ultraviolet-visible phosphorescence.b. Selectivity is good. Fluorescence can identify matter according to both emission spectrum and absorption spectrum.970CRT fluorescence photophoometer (Shanghai Analysis Instrument Factory) 5 mL straw 1, 2 mL straw 1, 50 mL
bottle
7 10.0-mL-1VB2 standard solution (stored in the dark), ice acetic acid (AR),multidimensional glucose powder sample c. Less samples required and simple operation methods.fluorescence spectrumexcitation spectrumexcitation spectrum: fixed measurement wavelength (select maximum emission wavelength),
compound
emission fluorescence intensity and irradiated wavelength relationship curve. At the highest point of the excitation spectral curve, the most molecules are in the excitation state and the fluorescence intensity is the largest.emission spectrum emission spectrum: fixed excitation wavelength (select maximum excitation wavelength), fluorescence intensity of compound emission and emission light wavelength relationship curve. the fixed wavelength of the emitted light is used to scan the excitation wavelength to find out the maximum excitation wavelength, and then to fix the excitation wavelength to scan the fluorescent emission wavelength to find the maximum fluorescent emission wavelength. The choice of excitation wavelength and emission fluorescent wavelength is the key to this experiment. multidimensional glucose powder vitamin B2 content determination vitamin B2 (also known as nucleoflutin, VB2) is orange odorless needle crystallization, its structure is: vitamin B2 is soluble in water but not ether and other
organic
solvents, stable in neutral or acidic solution, light easy to break down, stable to heat. B2 solution emits green fluorescence at a peak wavelength of 525 nm under 430 to 440 nm of blue light. The fluorescence of VB2 is strongest at pH of 6 to 7 and disappears at pH of 11. Vitamin B2 in alkaline solution by light exposure will be broken down and converted to photofluin, lutein fluorescence than the fluorescence of nucleoflutin, so the fluorescence of VB2 fluorescence solution should be controlled in the acidic range, and in light-avoiding conditions. multidimensional glucose contains vitamins B1, B2, C, D2 and glucose, wherein vitamin C and glucose do not fluorescent in aqueous solutions, vitamin B1 itself is not fluorescent, in alkaline solutions with potassium iron cyanide oxidation after the production of fluorescence, vitamin D2 with chloroacetic acid treatment after fluorescence, they do not interfere with the determination of vitamin B2. the analysis principle vitamin B2 in multi-dimensional glucose powder by using the fluorescent phosphorescence method in the experimental preview of the experiment. v to understand the procedure of fluorescence photometrics and the method of determining vitamin B2 in multi-dimensional glucose powder. instruments and
reagents 970CRT fluorescence photonometer (Shanghai Analytical Instrument Factory) 5 mL straw 1, 2 mL suction tube 1, 50 mL capacity bottle 7 10.0-mL-1VB2 standard solution (saved in the dark), ice acetic acid (AR), multidimensional glucose powder sample basic operation 1. Turn on the
Xenon
, then turn on the host, then turn on the computer to start the workstation and initialize the instrument. 2. After the initialization of the instrument, select the measuring item on the working interface and set the appropriate instrument parameters: excitation wavelength: 440 nm, emission wavelength, 540 nm. 3. Sample determination. 4. Exit the main program, turn off the computer, turn off the host first, and finally turn off the xenon light. experimental step1. Preparation of standard series solutions and determination of fluorescence intensity of standard solutions: in six clean 50 mL capacity bottles, respectively, absorb 0.50, 1.00, 1.50, 2.00, 2.50 and 3.00 mL VB2 standard solutions, each added 2.00 mL of ice acetic acid, dilution to tick, shake. Measure the fluorescence intensity of a range of standard solutions from thin to thick. 2. Determination of unknown samples: called take 0.15-0.20 g multi-dimensional glucose powder sample, dissolved with a small amount of water and transferred to a 50 mL capacity bottle, plus 2.00 mL of ice acetic acid, diluted to the scale, shake well. The fluorescence intensity is measured using the same conditions as in the standard series. data processing 1. The standard working curve is drawn with the fluorescence intensity of the standard series solution. 2. According to the fluorescence intensity of the liquid to be tested, the concentration of VB2 in the sample is calculated from the standard working curve. Precautions and Problems Vitamin B12 emits the strongest fluorescence intensity under pH of 6.0 to 7.0, but vitamin B12 breaks down under alkaline conditions and the emission fluorescent group is destroyed, so this experiment needs to be maintained under acidic conditions.