ONDREJ HEGEDUS, KATARINA SZARKA, ALZBETA HEGEDUSOVA, ZSUZSANNA GODANY, MIROSLAV SLOSAR, AURELIA CRISTINA NECHIFOR, SZENDE TONK VALIDATION AND QUALITY ASSURANCE OF ASCORBIC ACID DETERMINATION IN AGRICULTURAL PRODUCTS The study describes a method for the determination of ascorbic acid (AA) with the technique of high performance liquid chromatography with UV detection (UV-HPLC) modified for routine analysis of agricultural products. For successful use of the method in the test laboratory practice, the reliability of using this method has been confirmed by validation. The repeatability of method has been observed, which is 2.80 - 5.55% for the various crops. Relative combined standard uncertainty has a value of 6.2%. The accuracy of the method is 103.2% and calculated as recovery of the standard addition. The value of the LOQ computed from the upper limit of reliability is 26.7 mg kg-1, which ensures safe determination of AA in every major agricultural crop.