Abstract :
Quercetin an inhibitor of ?-amylase enzyme that functions in the breakdown of
carbohydrates, thus solving process and absorption of carbohydrates will interfere so that the
blood glucose level in hyperglycemia can be derived. This study aims to determine the levels
of quercetin in the juice of bulb onion (Allium cepa L). The analytical method used is the
reversed phase HPLC (High Performance Liquid Chromatography) with C18 column
(Oktadesilsilika) as stationary phase and methanol: 0.1% ortho phosphotic acid (65: 35) as
mobile phase, which flow rate of 1 ml / min. The detector is set at a wavelength of 371 nm
and the maximum injection volume is set at 20 ?L. Standard curve created in the
concentration range of 2 to 10 ppm obtained linearity with correlation coefficient 0.9986. The
results showed that in a sample of juice bulb onions (Allium cepa L) contain quercetin
positive with levels of 0.7087 mg% and the coefficient of variation of 1.4014%.