title: Bacterial sensors based on Acidithiobacillus ferrooxidans Part II. Cr(VI) determination.
abstract: The aerobic acidophilic bacterium Acidithiobacillus ferrooxidans oxidizes Fe(2+) and S(2)O(3)(2-) ions by consuming oxygen. An amperometric biosensor was designed including an oxygen probe as transducer and a recognition element immobilized by a suitable home-made membrane. This biosensor was used for the indirect amperometric determination of Cr(2)O(7)(2-) ions owing to methods based on a mediator (Fe(2+)) or titration. Using the mediator, the biosensor response versus Cr(2)O(7)(2-) was linear up to 0.4 mmol L(-1), with a response time of, respectively, 51 s (2 x 10(-5) mol L(-1) Cr(2)O(7)(2-)) and 61 s (6 x 10(-5) mol L(-1) Cr(2)O(7)(2-)). The method sensitivity was 816 microA L mol(-1). Response time and measurement sensitivity depended on membrane material and technique for biomass immobilization. For example, their values were 90 s-200 microA L mol(-1) when using a glass-felt membrane and 540 s-4.95 microA L mol(-1) with a carbon felt one to determine a concentration of 2 x 10(-5) mol L(-1) Cr(2)O(7)(2-). For the titration method, the biosensor is used to determine the equivalence point. The relative error of quantitative analysis was lower than 5%.
authors.affiliation: Autonomous University of Baja California, Institute of Engineering, Blvd. Benito Juares S/N 21280 Mexicali, Mexico.
authors.forename: Roumen
authors.initials: R
authors.lastname: Zlatev
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Magnin
authors.forename: Patrick
authors.initials: P
authors.lastname: Ozil
authors.forename: Margarita
authors.initials: M
authors.lastname: Stoytcheva
mesh_terms: D042763:Acidithiobacillus / Q000187:drug effects* / Q000302:isolation & purification* / Q000378:metabolism; D001681:Biological Assay / Q000295:instrumentation* / Q000379:methods; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D002857:Chromium / Q000032:analysis* / Q000494:pharmacology*; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods; D004566:Electrodes; D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D019216:Metals, Heavy / Q000032:analysis / Q000494:pharmacology; D010100:Oxygen / Q000032:analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D019216:Metals, Heavy; D002857:Chromium; D010100:Oxygen