A technique of diffusive gradients in thin films (DGT) for the measurement of Mo(VI) in water was developed using poly(quaternary ammonium salt) (PQAS) solution as the binding phase in the liquid-type DGT device (PQAS DGT). The Mo(VI) uptake by PQAS DGT increased linearly with time (r2 = 0.9989) with a recovery of 98.8% in synthetic solution. The DGT performance was independent of solution pH over the pH range of 4–10 and ionic strength range from 0.0001 to 0.1 mol L−1 NaNO3. The concentration of Mo(VI) in river water determined by PQAS DGT was 3.21 μg L−1, and the recoveries of the spiked Mo(VI) were 97.3–101.5%. The results show that PQAS can be used as a binding phase in the liquid-type DGT device for the measurement of Mo(VI) in water.

•The DGT technique can be used to determine lead in soybean sauce samples.•Sodium poly (aspartic acid) (PASP) was used as the binding agent of DGT device.•The DGT performance was independent of pH (3–6) and salinity (4–14 g L−1 NaCl).A diffusive gradients in thin films (DGT) device with sodium poly (aspartic acid) (PASP) as a novel binding agent (PASP DGT) combined with graphite furnace atomic absorption spectrometry (GFAAS) was developed for the sampling and measurement of lead in soybean sauce samples. The performance of PASP DGT was independent of pH in the range of 3–6 and salinity in the range from 4 to 14 g/L (as NaCl). There was no significant difference between PASP DGT technique and hydride generation atomic fluorescence spectrometry (HG-AFS) method for the measurement of lead in soybean sauce samples. The recoveries of lead in spiked soybean sauce samples determined by PASP DGT coupled with GFAAS were 94.3–97.2% with the relative standard deviations of 2.52–3.09%. The concentrations of Pb in twelve soybean sauce samples determined by PASP DGT coupled with GFAAS were in the range of 0.09–0.71 mg/L.

A technique of diffusive gradients in thin films (DGT) for the measurement of Mo(VI) in water was developed using poly(quaternary ammonium salt) (PQAS) solution as the binding phase in the liquid-type DGT device (PQAS DGT). The Mo(VI) uptake by PQAS DGT increased linearly with time (r2 = 0.9989) with a recovery of 98.8% in synthetic solution. The DGT performance was independent of solution pH over the pH range of 4–10 and ionic strength range from 0.0001 to 0.1 mol L−1 NaNO3. The concentration of Mo(VI) in river water determined by PQAS DGT was 3.21 μg L−1, and the recoveries of the spiked Mo(VI) were 97.3–101.5%. The results show that PQAS can be used as a binding phase in the liquid-type DGT device for the measurement of Mo(VI) in water.