For the analysis of organic acids by HPLC, UV detection at around 210 nm has been conventionally used as a convenient and simple technique.The UV detection method, however, has poor sensitivity and/or selectivity when analyzing organic acids in food, environmental or biological samples which include many kinds of UV absorbing co-existing compounds.Conductivity detection is one of the most popular techniques to detect the ionic compounds with high selectivity, because sensitivity for unionized compounds is pretty low.On the other hand, this feature means that it is difficult to gain good sensitivity for acidic compounds in acidic mobile phase.