This article is excerpted from Zhong Hongmei and Hou Deshun's "WXG-4 Polarimeter Measuring Optical Rotation Operation Method", which mainly introduces the zero point calibration and use method of WXG-4 polarimeter, as follows:
Zero point calibration
Connect the polarimeter to 220V AC power supply. Turn on the power switch of the instrument, and after about 5 minutes, the sodium lamp glows normally, and the zero point calibration starts. Take an optical rotation tube with a length of 1 dm, wash it and fill it with distilled water at about 20 °C, install a rubber ring, and tighten the nut until it does not leak (drain the air bubbles in the optical rotation tube to the protruding part of the optical rotation tube ). Put the light rotating tube into the lens barrel, adjust the eyepiece to make the object bright and clear, then turn the scale gently and slowly turn the handwheel, so that the dial is turned clockwise or counterclockwise near the zero point until the brightness of the three parts of the field of view is consistent , write down the reading on the dial, accurate to 0.05 (°). When the dial rotates clockwise, the reading is recorded as a positive number; when the dial is rotated counterclockwise, the reading is recorded as a negative number, and the value is equal to 180 minus the dial reading value. Then turn the dial of the polarimeter to make the boundary between light and dark in the field of view, and then turn it until the brightness of the three parts of the field of view is consistent; repeat this operation and record 3 times, and take the average value as the zero point correction value α0.
Method of use
Pour out the water in the optical rotation tube, rinse the optical rotation tube twice with the sample solution, then fill it with the test solution at about 20 ℃, install the rubber ring, tighten the nut , and wipe off the sample overflowing the tube with a flannel cloth Put the optical rotation tube into the lens barrel , turn the dial and turn the handwheel, so that the scale slowly rotates clockwise until the brightness of the three parts of the field of view is the same, record the reading on the dial, and it is accurate to 0.05 (°); then rotate Turn the handwheel on the dial to divide the light and dark field of view , and then turn it until the brightness of the field of view is consistent; repeat this operation and record 3 times, and take the average value as the reading value of optical rotation.
Sample optical rotation α = α measured - α0.
