Did you add the color reagent phenolphthalein? Also you can dilute the sample with distilled water, the amount if dilution doesnt matter after you have measured your sample out because you are measuring the amount of acid in the sample. We use a white ceramic tile, put a dot in the middle, then after adding 0.5ml sample add another dot to the plate, add more NAOH, another drop, makes it easier to see the color change than just looking in the beaker. WVMJ