I hope this is the right place to put this. I made up a 63 % glucose solution by dissolving 630 g (dry weight) dextrose powder in a final volume of 1L. My supervisor wanted me to confirm the solution strength by measuring it on a glucose refractometer. When I did so the refractometer gave me a reading of 43 %. I also checked on a YSI glucose analyser which gave me a reading of 70 %. Can anyone explain why I'm seeing such differences?