Abstract: Determination of vitamin C(V/C)in guava fruits by HPLC with 0.1% orthophosphoric acid as the mobile phase was studied.Three different solutions were used to extract the VC.The method with 3% metaphosphoric acid-8% acetic acid showed high mean recoveries(98.5 %),while the LC-extraction method with 0.1% oxalic acid was proved to be unacceptable in some cases with mean recoveries as low as 72.5%.The good precision(RSD=1.6%)is achieved with the metaphosphoric acid-acetic acid LC--extraction method for determining VC in guava fruits with recovery as high as 98.5%,as a perfect routine analysis method.The content of VC in the fruit varied with different parts.The pulp close with the pericarp contained the higest content as 220.4mg/100g,while the middle part the lowest with only 85.78mg/100g.

Key words: guava fruits, vitamin C, HPLC(high performance liquid chromatography)