Abstract
•Develop and validate ASE (accelerated solvent extraction) for Methyl xanthine (MX).•To quantify MX using ultra high performance liquid chromatography (UHPLC-DAD).•To apply the ASE-UHPLC/DAD method for quantification of MX in different tea classes.•To establish the method as quality evaluation tool in market available tea samples.
Methyl xanthines (MX), known for its psychostimulant effect, occurs mostly in tea and coffee samples. However most of the market available products does not mention the proper amount and quality of MX present where, its consumption in high amount may pose health risks.
To develop and validate a fast, efficient and reliable method of MX extraction along with a sensitive, rapid and precise method for simultaneous analysis of MX i.e. Theobromine (TB), Theophylline (TH) and Caffeine (C), with application in commercial tea and coffee samples.
Accelerated Solvent Extraction (ASE) was utilized for the first time to extract MX, whereas UHPLC-DAD was applied in order to quantify MX.
ASE resulted a high extract yield (940.22 ± 192.28 mg/g) with optimized conditions of temperature (100 °C) and solvent (MeOH). UHPLC-DAD showed retention time (min) of 1.51 (TB), 1.81 (TH), 2.30 (C) with r2 values (0.980–0.988). Average MX (μg/mL) was as; TB (14.73 ± 20.9), TH (32.05 ± 55.5), C (121.87 ± 32.3). The method application in commercial samples showed a high extract yield with MX concentration (mg/g) as; TB (0.13–0.38), TH (0–0.55), C (7.14–11.20). Temperature and solvent variation showed important correlation with samples in terms of extraction yield.
ASE-UHPLC/DAD revealed a fast and sensitive method of MX extraction, quantification and quality determination in market available tea and coffee samples.