This work mainly describes an electrochemical microsensor based on the reduction of molybdophosphate complex for total phosphorus (TP) determinations in water. The microelectrode was fabricated using microelectromechanical systems (MEMS) techniques and porous, branching gold nanoparticles (AuNPs) were electrodeposited on the microelectrode to improve its sensitivity. Calibration of the microsensor was performed with standard phosphate solutions prepared with KH₂PO₄ with pH adjusted to 1.0. The experimental results showed that both sensitivity and current response are improved effectively using this modified microelectrodes: The limit of detection of the microsensor is 1.2 × 10⁻⁷ mol/l and linear range is 3 × 10⁻⁷ to 3 × 10⁻⁴ mol/l. The sensitivity of unmodified electrode is −0.27 nA/μmol·l⁻¹ (R ² = 0.994), whereas the sensitivity of AuNPs modified electrode is −0.89 nA/μmol l⁻¹(R ² = 0.98). The current response of modified electrode is 6 times larger than that of unmodified electrode in average. Detection of TP was also carried out with digested TP standard solutions for both modified and unmodified electrodes, and results were consistent with the nominal value of phosphorus concentration. This microsensor provides the probability of combining TP detection device with micro-digesting device to form a TP detection system, which can realise the automotive and on-line monitoring of TP in surface water.

References

1. 1)
  - 14. Udnan, Y., McKelvie, I.D., Grace, M.R., Jakmunee, J., Grudpan, K.: ‘Evaluation of on-line preconcentration and flow-injection amperometry for phosphate determination in fresh and marine waters’, Talanta, 2005, 66, pp. 461–466 (doi: 10.1016/j.talanta.2004.12.064).
2. 2)
  - 6. Bulatov, A.V., Tsapko, A.A., Moskvin, L.N.: ‘Photometric cyclic-injection determination of phosphate and silicate ions simultaneously present in aqueous solutions’, J. Anal. Chem., 2009, 64, (6), pp. 580–584 (doi: 10.1134/S1061934809060082).
3. 3)
  - D. Xiao , H.Y. Yuan , J. Li , R.Q. Yu . Surface-modified cobalt-based sensor as a phosphate-sensitive electrode. J. Anal. Chem. , 288 - 291
4. 4)
  - 11. Jain, A.K., Gupta, V.K., Raisoni, J.R.: ‘A newly synthesized macrocyclic dithioxamide receptor for phosphate sensing’, Talanta, 2006, 69, pp. 1007–1012 (doi: 10.1016/j.talanta.2005.12.023).
5. 5)
  - 1. Ministry of Environmental protection of the People's Republic of China, ‘Environmental quality report of the first half of 2012 in key river water environments,’ Announcement No. 52, 2012.
6. 6)
  - 7. Ministry of Environmental protection of the People's Republic of China, Environmental quality standards for surface water, GB 3838-2002, 2002.
7. 7)
  - S.O. Engblom . The phosphate sensor. J. Biosens. Bioelectron. , 981 - 994
8. 8)
  - 9. Kwan, R.C.H., Leung, H.F., Hon, P.Y.T., Cheung, H.C.F., Hirota, K., Renneberg, R.: ‘Amperometric biosensor for determining human salivary phosphate’, Anal. Biochem., 2005, 343, pp. 263–267 (doi: 10.1016/j.ab.2005.05.021).
9. 9)
  - 15. Carpenter, N.G., Hodgson, A.W.E., Pletcher, D.: ‘Microelectrode procedures for the determination of silicate and phosphate in waters – fundamental studies’, Electroanalyais, 1997, 9, (17), pp. 1311–1317 (doi: 10.1002/elan.1140091703).
10. 10)
  - I. Kubo . Potentiometric phosphate-sensing system utilizing phosphate-binding protein. J. Anal. Bioanal. Chem. , 273 - 275
11. 11)
  - 5. Shyla, B., Mahadevaiah, , Nagendrappa, G.: ‘A simple spectrophotometric method for the determination of phosphate in soil,detergents, water, bone and food samples through the formation of phosphomolybdate complex followed by its reduction with thiourea’, Spectrochim. Acta A, Mol. Biomol. Spectrosc., 2011, 78, pp. 497–502 (doi: 10.1016/j.saa.2010.11.017).
12. 12)
  - 8. Patey, M.D., Rijkenberg, M.J.A., Statham, P.J., Stinchcombe, M.C., Achterberg, E.P., Mowlem, M.: ‘Determination of nitrate and phosphate in seawater at nanomolar concentrations’, Trends Anal. Chem., 2008, 27, (2), pp. 169–182 (doi: 10.1016/j.trac.2007.12.006).
13. 13)
  - 2. Xueju, A.: ‘Determining phosphate ions in precipitation with ion chromatography’, J. Heilongjiang Environ. J., 2009, 33, pp. 37–39.
14. 14)
  - Y. Yokoyama , T. Danno , M. Haginoya , Y. Yaso , H. Sato . Simultaneous determination of silicate and phosphate in environmental waters using pre-column derivatization ion-pair liquid chromatography. J. Talanta , 308 - 313
15. 15)
  - 13. Jońca, J., Fernández, V.L., Thouron, D., Paulmier, A., Graco, M., Garçon, V.: ‘Phosphate determination in seawater: toward an autonomous electrochemical method’, Talanta, 2011, 87, pp. 161–167 (doi: 10.1016/j.talanta.2011.09.056).

Electrochemical microsensor based on gold nanoparticles modified electrode for total phosphorus determinations in water

References

Related content