deposition E of−1.2 Vwas applied for 300 s to concentrate the targeted
metals, as well as Bi, onto the surface of working electrode simultaneously.
After the preconcentration step, the ILGPE was transferred
quickly (in nomore than 2 s) to a testing cell containing 1.0 mL acetate
buffer solution (0.1 M, pH 4.5), followed by a stripping procedure at
0.3 V for 30 s. Subsequently, the place of the ILGPE was taken by a
polished GCE to perform a full DPASV procedure with a deposition
time of 240 s. Other parameters applied were the same as mentioned
above. Using this instrumentation we determined one kind of metal
ion at a scan. Notably, the calibration curves applied were established
by using clean mixed solution as supporting electrolyte. The clean
mixed solution was prepared as following: Real seawater and acetate
buffer solution (0.2 M, pH 4.5) were mixed in a ratio of 10:1(v/v);
the natural existing Pb2+ and Cd2+ in the mixed solution was removed
by electrodepositionmethod until the residualswere undetectablewith
either double stripping voltammetry or AAS.
YSI 556 Handheld Multiparameter Water Quality Meter (YSI Inc./
Xylem Inc., USA) was used to measure the pH and salinity of collected
seawater samples. All experiments in lab were conducted at room temperature
(22 ± 1 °C). The on-site determinations were conducted at
ambient temperature (about 19 ± 3 °C).