The Method of Use of Refractometer II

The Method of Use of Refractometer II

1. Place the refractometer in a bright place, but avoid direct sunlight. Pass the constant temperature water into the prism jacket with a super constant temperature bath. The temperature is based on the thermometer reading on the digital refractometer.

2. Twist the closing knobs of the measuring prism and the auxiliary prism, and turn the lens barrel so that the auxiliary prism faces upward. If the surfaces of the measuring prism and auxiliary prism are not clean, you can drop a few drops of propylene to clean the mirror surface (note that the tip of the dropper tube does not touch the mirror surface). If necessary, use mirror paper to dry the mirror surface or use the mirror paper to gently wipe the mirror surface in a single direction (the mirror surface cannot be wiped back and forth, and do not use filter paper).

3. After the mirror surface is dried, use a dropper to add 2 ~ 3 drops of sample to the mirror surface of the auxiliary prism. Close the prism and tighten the closing knob. If the liquid sample is volatile, the action should be rapid, or when the two prisms are close to close, inject the sample from the liquid addition tank, then close the two calibration mirrors, and lock the closing knob.

4. Turn the lens barrel to make it straight, and adjust the reflector to make the incident light enter the prism. Observe from the measuring telescope at the same time to make the field of view the brightest. Adjust the focal length of the eyepiece to make the crosshairs in the eyepiece clear and bright.

5. Turn the "prism rotating handwheel" located under the "dial cover" to gradually increase the indication on the dial scale until a color band or black-and-white critical line appears in the center of the field of view.

6. Turn the "Achromatic Sanshou Handwheel" to make a clear black-and-white light and dark critical line appear in the field of view.

7. Turn the "prism turn handwheel" so that the critical line is exactly at the center of the cross. If there is slight dispersion again at this time, the "achromatic dispersion handwheel" must be readjusted to make the critical line bright and dark.

8. When the critical line of light and dark is just at the center of the cross line, you can read it. When reading, first open the small window above the cover to let light enter, and then read the corresponding indication on the scale from the reading telescope. In order to reduce the reading error, the "prism rotating handwheel" should be turned. Repeat the measurement 3 times. The difference between the three readings cannot be greater than 0.0002, and then take the average. This average value is the refractive index of the sample to be tested.

The influence of the composition of the sample on the refractive index is very sensitive. Due to contamination or evaporation of volatile components in the sample, the reading will be inaccurate. Therefore, it is best to measure the refractive index of a sample three times, measure the data of three samples, and then take the average value.

9. When measuring the refractive index of a solid, draw a polished surface perpendicular to each other on the solid. The reflector and auxiliary prism are not used in the measurement, but one polishing surface of the solid is adhered to the polishing surface of the measuring prism with bromide naphthalene, and the other polishing surface is upward, and the subsequent operations are performed according to the fourth to seventh steps above. If the refractive index of the measured solid is greater than 1.66, diiodomethane should be used instead of bromonaphthalene for the sticky solid.

10. When measuring semi-permeable solids, a polished surface is required on the solids. The plane was glued to the measuring prism with bromoxo, the protective cover was removed as the light entrance surface, and the reflected light was used for measurement. Follow the above steps for the rest of the operations, and complete steps (4) ~ (7).

11. When measuring the mass fraction of sugar in the sugar solution, the operation process is the same as measuring the refractive index of the liquid. At this time, the indication value on the left side of the dial should be read as the mass fraction of sugar in the sugar solution.

Related News