The accuracy was assessed through recovery tests. Sample solutions were prepared as described above and spiked in tree concentration levels (1.0, 3.0 and 5.0 mg L1) with adequate volumes from stock solution of HMF (1000 mg L1).
Analyses were performed in triplicate. Recovery percentages (%) were calculated as the amount of HMF recovered/amount of HMF added 100 and used as accuracy estimates.