A new PANI biosensor based on catalase for cyanide determination

Figures & data

Figure 1. Cyclic voltograms of electropolymerization of aniline.

Figure 2. Impedance spectra of the immobilization steps [a) -▲-▲-(blue): PANI electrode, b) -•-•-(green): PANI–GLT electrode, -■-■-(red): PANI–GLT–CAT electrode].

Figure 3. The effect of aniline concentration on the biosensor response.

Figure 4. The effect of GLT concentration on the biosensor response.

Figure 5. The effect of GLT incubation period on the biosensor response.

Figure 6. The effect of enzyme amount on the biosensor response.

Figure 7. The effect of the number of scans on the biosensor response.

Figure 8. Effect of temperature on the biosensor response.

Figure 9. Effect of pH on the biosensor response.

Figure 10. Calibration curve of the biosensor.

Table I. Comparison of the methods developed and some of the reported methods for the cyanide determination.

Technique	Sample	Linear range (mg/L)	Detection limit (μg/L)	References
HF-HS-CE-UV	Urine	0.0056–0.52	2.08	Jermak et al. (2006)
FI fluorimetry	Water	0.001–0.2	0.26	Infante et al. (2008)
Spectrophotomery	Water	0.05–2	0.5	Hamza et al. (2010)
FI spectrophotometry	Water	0.01–0.04	1.5	Santelli et al. (2006)
GD-SI spectrophotometry	Water	0.0075–0.2	2.5	Themelis et al. (2009)
PANI bıosensor	Water	0.0136–0.65	2	This work

HS-SDME, headspace-single-drop microextraction; CE-UV, capillary electrophoresis with UV detection; FI, flow injection; GD-SI, gas diffusion-sequential injection; PANI, polyaniline

Figure 11. Storage stability of the biosensor.

Figure 12. Effect of interference materials on biosensor response.

Table II. Results of analysis of artificial waste water samples (*Average values of 5 measurements).

Added cyanide (mg/L)	*Found by biosensor (mg/L)	Recovery (%)	Relative differences (%)	*Found by spectrophotometric method (mg/L)
0.065	0.06350 ± 0.0012	97.70	2.30	0.06420 ± 0.0054
0.13	0.13136 ± 0.0021	101.05	1.05	0.1308 ± 0.0015
0.195	0.18817 ± 0.0071	96.50	3.50	0.1910 ± 0.0025
0.26	0.25875 ± 0.0064	99.52	0.48	0.2592 ± 0.0051
0.325	0.33306 ± 0.0017	102.48	2.48	0.3284 ± 0.0045

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