What precautions should be taken when using a polarimeter?

What precautions should be taken when using a polarimeter? Polarimeter is a relatively common optical analysis instrument at present, which is an instrument for measuring the optical rotation of optically active substances
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By measuring the optical rotation of the sample, the concentration, content and purity of the substance can be determined by analysis
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So, what should be paid attention to when using it? Let’s find out with me below
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1.
Before the measurement, the polarimeter and the sample should be placed in a constant temperature chamber with a temperature of 20℃±0.
5℃ or a constant temperature chamber with a specified temperature.
A constant temperature water bath can also be used to keep the sample chamber or sample test tube at a constant temperature for more than 1 hour, especially some have great influence on temperature.
The optically active substances are particularly important
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2.
Before turning on the power, check whether there are foreign objects in the sample room, whether the sodium light source switch is in the specified position, whether the indicator switch is in the off position, and whether the instrument is placed in a suitable position.
move
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3.
After the sodium lamp is turned on, the normal glow time is at least 20min, and the light can be stable.
During the measurement, the sodium lamp should use DC power supply as much as possible to make the light stable
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If there is a polarity switch, the polarity should be changed frequently after shutdown to prolong the service life of the sodium lamp
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 　　4.
Before the measurement, when the polarimeter is set to zero, repeatedly press the re-measure switch to make the analyzer deviate from the optical zero position to the left or right respectively
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The repeatability and stability of the instrument can be checked by observing the stopping points of the left and right retests
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If the error exceeds the specification, the instrument should be repaired before use
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 　　5.
Put the measuring tube filled with distilled water or blank solvent into the sample chamber.
If there are bubbles in the measuring tube, make the bubbles float on the convex neck first, and dry the glass at both ends of the clear surface with a soft cloth
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During the measurement, the position and direction of the measuring tube should be fixed as much as possible, and the marking should be made to reduce the error of the stress of the measuring tube and the cover glass
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 　　6.
When the same optically active substance is measured with different solvents or at different pH values, due to the different conditions of association, solvation and dissociation, the specific rotation changes and even the optical rotation direction, so the specified solvent is used
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 　　7.
The solution that is cloudy or contains small particles cannot be measured.
Centrifuge or filter the solution first, and discard the initial filtrate for measurement
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Some material solutions whose optical rotation changes greatly after exposure to light should be protected from light
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Some placing time has a great influence on the optical rotation, and the reading is measured within the specified time
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 　　8.
When measuring the blank zero point or the stop point of the test solution, the readings should be read three times, and the average value should be taken
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For strict determination, the zero point should be calibrated with a blank solvent before each determination.
After the determination, the reagent should be used to check whether the zero point has changed.
If the zero point changes greatly, the determination should be re-measured
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 　　9.
When the measurement is over, the measurement tube should be washed and dried and put back in its original place
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The instrument should be placed in a dry place to avoid dust, and a little desiccant can be placed in the sample room to prevent moisture
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 　　The above is the relevant introduction about the key points of polarimeter use.
I believe that everyone has a corresponding understanding of this after reading, and everyone can use it as a reference.
I hope it will be helpful to you
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