1. Preface Calcium tablets are taken orally and digested and absorbed through the gastrointestinal tract to supplement calcium ions in the human body. Foods with moisture have different storage stability periods due to their varying water content. Therefore, testing the water content of calcium tablets has become an important reference indicator for measuring the product's shelf life. In this paper, the moisture content of a certain brand of calcium tablets was determined by the JH-C3 fully automatic coulometric moisture meter. The operation was easy, the process was simple, and the repeatability of the experimental data was good. 2 Instruments and equipment 2.1 Instruments JH-C3 Fully automatic Karl Fischer Moisture Analyzer (Coulometric method), dual platinum electrodes, 5mL burette unit. 2.2 Reagents Karl Fischer titrant, anhydrous methanol. 3 Experimental Methods 3.1 Experimental Procedures Through the liquid discharge device of the moisture titrator, the residual liquid is removed. Then, 40mL of solvent methanol is added to the titration cup, with the solvent covering the electrode. After setting the parameters, the instrument starts the pre-titration. When the instrument is in standby mode, click on the system injection, open the rubber stopper of the feeding port, select the injection volume according to the volume of titration solution consumed by the sample, and quickly add the sample Immediately cover the rubber stopper, click "Start Measurement", titrate with Karl Fischer titrant to the endpoint, input the sample weighing amount, and calculate the moisture content of the sample. 3.2 Parameter Settings stirring rate 35% Mixing time?： 80s destination?： 150mv Termination type： Termination of relative drift Control area?： 350mv Maximum refilling rate： 5mL/min Drift value?： 50ug/min Minimum liquid addition rate： 80uL/min 3.3 Calculation Formula: X =? ? In the formula: X - represents the moisture content of the sample (%); V1 - The volume (mL) of titration liquid consumed when titrating the sample; m - The weighing amount of the sample (g); T - represents the concentration of the titrant (mg/mL). 4 Results and Discussion 4.1 Experimental Results ? Sample number ? ?titrant concentration (mol/L) ? Sampling volume (g)? ? Titration volume (mL) ? ?Moisture content (%)? ? Average moisture content (%) RSD???（?%?） 1 ? ? 2.0792 0.1944 4.065 5.772 ? ? 5.778 ? ? 0.7931 2 0.1756 3.673 5.736 3 0.1452 3.078 5.827 4.3 Experimental Conclusion The moisture content of calcium tablets was measured using the JH-C3 fully automatic Karl Fischer moisture meter (Coulometric method). The result was that the moisture content of the calcium tablets was less than the stipulated 6%, and they were determined as qualified products, which was not much different from the specialized calcium tablet detector. The greatest advantage of JH-C3 is that it can detect a wide variety of products and has extensive application fields. References [1] GB 5009.3-2016 Determination of Moisture in Food [S]