Azide-selective sensor based on tripodal iron complex for direct azide determination in aqueous samples.
Ashok Kumar Singh1, Udai P Singh, Vaibhave Aggarwal
1Department of Chemistry, Indian Institute of Technology-Roorkee, Roorkee, 247 667, India. akscyfcy@iitr.ernet.in
Analytical and Bioanalytical Chemistry
|May 7, 2008
Summary
A new potentiometric sensor using a novel iron complex provides highly selective and sensitive detection of azide ions. This azide sensor demonstrates excellent stability and can determine azide levels in various real-world samples like juice and urine.
Area of Science:
- Electrochemistry
- Analytical Chemistry
- Materials Science
Background:
- Potentiometric sensors are crucial for ion detection.
- Developing selective and sensitive azide sensors remains a challenge.
- Iron complexes offer potential as ionophores in electrochemical sensors.
Purpose of the Study:
- To develop a novel potentiometric azide-selective sensor.
- To investigate the performance of an iron(III) hydrotris(3,5-dimethylpyrazolyl)borate acetylacetonate chloride [Tp(Me2)Fe(acac)Cl] complex as a neutral carrier.
- To optimize membrane composition for enhanced azide selectivity and sensitivity.
Main Methods:
- Fabrication of a potentiometric sensor using a poly(vinyl chloride) (PVC) membrane incorporating [Tp(Me2)Fe(acac)Cl] as the ionophore.
- Systematic study of plasticizers (o-NPOE, DOP, DBP, BA) and an anion excluder (HTAB) to optimize membrane composition.
- Evaluation of sensor performance including selectivity, detection limit, Nernstian slope, response time, pH range, and long-term stability.
- Testing the sensor's ability to discriminate azide from interfering anions.
- Application of the sensor for direct azide determination in real samples (orange juice, tea extracts, human urine).
Main Results:
- The optimal membrane composition was determined to be [Tp(Me2)Fe(acac)Cl]/HTAB/DOP/PVC in a 5:2:190:100 (w/w) ratio.
- The sensor exhibited high selectivity for azide ions over a wide concentration range (6.3 x 10(-7) to 1.0 x 10(-2) M).
- A low detection limit of 3.8 x 10(-7) M and a Nernstian slope of 59.4 +/- 1.1 mV decade(-1) were achieved.
- The sensor demonstrated fast response (14 s), good reproducibility, long-term stability (over 45 days), and a wide working pH range (3.5-9.0).
- Successful direct determination of azide in orange juice, tea extracts, and human urine samples was achieved, showing good discrimination from other anions.
Conclusions:
- The developed potentiometric sensor based on [Tp(Me2)Fe(acac)Cl] offers excellent selectivity and sensitivity for azide detection.
- The sensor's robust performance characteristics make it suitable for practical applications.
- This sensor provides a reliable method for the direct determination of azide in complex matrices.
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