Arsenic speciation based on amine-functionalized bimodal mesoporous silica nanoparticles by ultrasound assisted-dispersive solid-liquid multiple phase microextraction

A new method based on ultrasound assisted-dispersive solid-liquid multiple phase microextraction (USA-DSL-MPME) was used for preconcentration and speciation of trace amounts of inorganic arsenic (III and V) and total organic arsenic (TOA) in waters and human urine samples. In this procedure bulky amine-functionalized bimodal mesoporous silica nanoparticles (NH2-UVM7) were immersed in ionic liquid (IL) as an extraction phase. Then, the mixture of NH2-UVM7 and IL/acetone [HMIM][PF6]/AC) was rapidly injected by a syringe into 10 mL of sample containing of As(V, III) and TOA at pH of 3.5. After ultrasonic and centrifugation, ILs settled down with nano particles of NH2-UVM7, which was extracted As(V) anion in centrifuge tube by binding to amine group ([Asv]− → + NH2-UVM7). Total amount of inorganic arsenic (TIA) was determined after oxidization of As(III) to As(V) by the addition of KMnO4 solution in acidic medium and then, As(III) was calculated by the subtracting TIA and As(V) content. The concentration of As(V) was determined by electro-thermal atomic absorption spectrometry (ET-AAS) after back extraction in separated phase by KOH solutions. Under the optimum conditions, the linear range (LR), limit of quantification (3σ), precision (%RSD) and enrichment factor for As(V) were obtained 0.02-1.65 μg L− 1, 11 ng L− 1, 4.3% and 100.5. The proposed method was applied successfully for determination of As(III) and As(VI) in natural water and human urine with corresponding recoveries in the range of 95-103%, also the accuracy of the USA-DSL-MPME method was obtained with acceptable recoveries in the range of 95-102% by using of certified reference material in urine (NIST-SRM). The amount of TOA was simply calculated with oxidation process of total arsenic (TA) to As(V) and subtracting the TA and TIA content by following the same procedure as described for As(V).