Microextraction by packed sorbent (MEPS) as a suitable selective method for l-ascorbic acid determination in beverages

In this study the modern microextraction by packed sorbent (MEPS) method followed by HPLC–UV analysis was optimised and evaluated for determination of l-ascorbic acid (AA) content in beverages. In this case 300 μL of sample was passed through silica BIN (barrel insert and needle assembly) and entrapped AA was eluted by 60 μL of methanol–water (10%, v/v) solution. Recovery of the proposed method for three concentration levels ranged between 97.46% and 106.88% with relative standard deviation 8.7% (low conc.), 2.49% (medium conc.) and 1.98% (high). Obtained results of AA contents in real samples were in the ranges 56.5–195.4 μg/mL and 130.4–1090.0 μg/mL for ice-tea and fruit juice samples, respectively. Proposed method was compared with iodometric titration and DPPH methods, but microextraction method was found to be more selective for AA determination in tested samples.