HPLC determination of 4-acetylaminophenylacetic acid

A fast and sensitive reverse phase ion-pair chromatographic method was repo rted for the separation and quantification of 4-aminophenylacetic acid (Act arit) and its related compounds. The compounds were separated using a Kroma sil C18 column (5 mum, 4.6 x 25cm) with a mobile phase containing 70% metha nol and 1% Tetrabutylammonium bromide in water flowing at 1.0 mL/min, and w ere detected using a UV detector operating at 245nm. Actarit was completely separated from its related compounds that included its synthetic starting materials and degradations. The retention times were 3.1, 4.0, 9.4, 21.4, a nd 25.8min for blank solvent, 4-aminophenylacetic acid Actarit, 4-nitrophen ylacetonitrile, and 4-nitrophenylacetic acid, respectively. Three known and one unknown compound (retention time 13.7minute) were detec ted after Actarit was boiled in acidic, neutral, and basic conditions, each for two hours. The linear response between peak area (A) and Actarit conce ntration (c) over the range of 0.5 - 2.5 mug/mL, was A = -2285.20 + 40760.97c, r = 0.99993, (n = 5). The detection limit at signal-to-noise ratio two was 5.08 ng/mL. The recove ry was 98.64 - 101.72% (n=5) (within day) and 99.60 - 101.86% (n=5) (day to day). The relative standard deviations were 0.87 - 1.77% (n=5) (within day ) and 0.51 - 1.92% (n=5) (day-to-day), respectively. Good correlation was f ound between this HPLC method and a spectrophotometric method when measurin g;the contents of Actarit in three batches of commercial tablets. The conte nts were 97.32, 99.20, and 97.58% when measured by this; HPLC method, and 9 7.76, 100.43, and 98.02% by a spectrophotometric method. Good separation, l inearity, recovery, and accuracy implied that the chromatographic method is suitable;for quantitative analysis of Actarit.