BIA with Voltammetric Detection

A less flexible but simpler technique in comparison to the FIA system is BIA, which presents several advantages such as high reproducibility, elevated sampling rate, fast analysis time, and rapid response. BIA presents comparable sensitivity to FIA and does not require pumps, tubes, and commutators to introduce the samples. Moreover, motorized micropipettes provide very precise injections of small sample volumes at the constant rate due to the reproducible movement of the internal piston [40,102,103]. 

Voltammetric and amperometric measurements in BIA can be performed with the same electrochemical cells and detectors utilized in FIA, including wall-jet arrangement with injection of sample volume of a minimum 10 pi and the use of microelectrode arrays [104, 105]. Special attention has been attributed to the monitoring in agriculture due to the possibility of exploring portable instruments for in situ analysis. It occurs mainly through association between BIA and stripping voltammetric techniques. 

SimSes et al. [106] have presented a simple method based on BIA associated with square-wave voltammetry for detection of herbicide paraquat with good sensitivity. It was possible to quantify this herbicide at microgram per liter levels with the detection limit of 20 pg 1 and using a glassy carbon electrode without modification in its surface. Paraquat analysis was carried out without any preconcentration step and with fast responses ( 2 s). 

BIA in association with anodic stripping voltammetry has been applied in the determination of trace metals in water samples [107]. In this study, the authors used a solid sorbent fixed in the micropipette tip for on-line preconcentration of the metals. After the optimization of experimental parameters, it was possible to obtain peak currents about 10-15% higher than without preconcentration step and linear concentration ranges at low levels such as 10-100 nmol 1 for Cd analysis. 

Economou and Voulgaropoulos [108] have successfully exploited the combination between stripping voltammetry and BIA system for quantification of Cd , Pb +, Zn +, and In + (by anodic stripping voltammetry) and Ni +, Co +, U +, and Al (by adsorptive stripping voltammetry). A bismuth-film electrode was coated with Nation to increase the sensitivity and improve the mechanical stability to the film during the determination of Cd, Pb, and Zn. Adequate selectivity, quickness, simplicity, and low consumption of 

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