Speciation Analysis of Mn(II)/Mn(VII) in Tea Samples Using Flame Atomic Absorption Spectrometry After Room Temperature Ionic Liquid-Based Dispersive Liquid–Liquid Microextraction

A simple and rapid method based on dispersive liquid–liquid microextraction with room temperature ionic liquid 1,3-dibutylimidazolium hexafluorophosophate ([BBIM][PF 6 ]) coupled to flame atomic absorption spectrometry was developed for the speciation of Mn(II)/Mn(VII) in tea samples. The main factors affecting dispersive liquid–liquid microextraction were investigated in detail. Mn(II) and total manganese [Mn(II)+Mn(VII)] were quantitatively extracted after adjusting aqueous sample solution to pH 10.0 and 7.0, respectively. Mn(VII) was calculated by subtraction of Mn(II) from total manganese. Under the optimized conditions, the limits of detection (3 σ ) for Mn(II) and Mn(VII) were 0.26 and 1.86 ng/mL, and their relative standard deviations were 2.6 and 4.8 % ( n  = 7, c  = 25.00 ng/mL). The proposed method was validated by the determination of Mn(II) and Mn(VII) in the certified reference material [GBW(E)08513] of tea sample and different local tea samples with satisfactory results.