1. Joy Qiu ♦ Dr. Greg Swain ♦ HSHSP 2014
Electroanalytical Detection of Propranolol using Flow Injection Analysis
Joy Qiu ♦ Dr. Greg Swain ♦ HSHSP 2014

2. Overview
To evaluate the ability of the following electrodes to sensitively, reproducibly and stably detect propranolol:
Glassy carbon
Boron-doped diamond thin film
Nitrogen-incorporated tetrahedral amorphous carbon (ta- C:N) thin film
Using flow injection analysis with amperometric detection (FIA-EC)

3. Flow Injection Analysis (FIA)
Sample (analyte) is injected into a continuous flowing stream of carrier solution (electrolyte)
Analyte passes over the surface of the working electrode, resulting in an oxidation reaction
Movement of charge (electrons) generates a detectable current
Current  concentration R
O + 2H+ + 2e¯

4. Application Why use flow injection analysis?
Better methods: HPLC, polarography, etc.
FIA: cheap, simple, fast, versatile
Enables quick detection of multiple analytes with good sensitivity
Pharmaceutical applications
Drug quality or purity
Non-invasive detection of pharmaceutical compounds in human body/urine

5. FIA System Set Up
Cell volume = μL
Injection volume = μL

6. Propranolol Adrenergic non-selective beta-antagonist
Used to treat hypertension, anxiety, and panic
Effective plasma levels: mg/mL
Excreted as metabolites in urine
Oxidation of propranolol
C16H21NO2
MW = g/mol
B. C. Lourencao et al., Electrochim. Acta. 2014, accepted

7. Glassy Carbon (GC) Extensive body of research
Structure and characteristics
Combines glassy and ceramic properties of non-graphitizing carbon with graphite
sp2 hybridization structure
Graphitic nanoribbons
Anisotropic microstructurally
Polishing

8. Boron-Doped Diamond (BDD)
sp3 hybridized carbon bonding
High stability and chemical inertness
B2H6 incorporated (boron doping) into diamond films
Doping increase electrical conductivity
Grown on silicon substrates
Thin-film  does not require polishing
~1 cm

9. Nitrogen-Incorporated Tetrahedral Amorphous Carbon (TaC:N)
sp2 and sp3 bonded carbon
Nitrogen impurities added during growth
Shares many properties with diamond
More cost effective and versatile
Diamonds: °C
TaC: °C
~1 cm

10. Figures of Merit What are optimum conditions for detection?
Hydrodynamic Voltammetry
How reproducible is the method?
Short-Term Reproducibility
How well can the method detect propranolol?
Calibration Curve Determination

11. Hydrodynamic Voltammetry
500 μM PROP injected; 0.1 M PBS, pH = 7.2 used as carrier solution
PROP oxidation
What concentration of propranolol was used here?
(a) Glassy Carbon
(b) Diamond
(c) TaC
Large increase in the current arises from the oxidation of water that occurs at a higher rate at the more positive potentials.

12. Short Term Reproducibility
5 μM PROP injected; 0.1 M PBS, pH = 7.2 used as carrier solution
Glassy Carbon
Edet = 1.25 V
RSD: %
(b) Diamond
Edet = 1.35 V
RSD: 5.040%
What was injected here? Good to put the concentration of analyte injected and the carrier solution. What was the detection potential?
(c) ta-C:N
Edet = V
RSD: 3.245%

13. Calibration Curve
Slopes for diamond and ta-C:N curves greater than that for glassy carbon. This shows greater sensitivity!

14. Summary of Detection Figures of Merit
Figure of Merit
Glassy Carbon
Diamond
ta-C:N
Detection Potential (mV)
1250
1350
1325
Sensitivity (nA/μM)
73.4 ± 3.0
154.6 ± 6.7
172.7 ± 8.2
Limit of Quantification (nM)
371.8 ± 87.8
76.5 ± 19.5
111.6 ± 12.2
Upper Limit of Linearity (μM) 50
100
Detection Limit (nM)
111.5 ± 26.3
22.9 ± 5.8
33.5 ± 3.7
R2 Value
0.9986
0.9983
Reproducibility (%RSD for 25 injections of 5 μM PROP)
5.925%
4.866%
3.245%

15. Conclusions Diamond and TaC v. Glassy Carbon Diamond v. TaC
Lower detection limit and wider linear dynamic range
More reproducible (less fouling/surface absorption)
More sensitive (ability to distinguish between signal and noise)
Diamond v. TaC
Similar detection potentials
Diamond: lower detection limit and wider linear dynamic range
TaC: more reproducible and sensitive

16. Conclusions (cont.) FIA-EC: viable method for detection of propranolol
Electrodes
Diamond and ta-C:N outperform glassy carbon
Diamond and ta-C:N perform similarly
ta-C:N is preferred for cost effectiveness and versatility

17. Future Directions Further optimize the method for detection
Test other pharmaceutical/biological compounds
Hydrochlorothiazide
Norepinephrine
Replicate commercial conditions - collect and test real urine samples

18. Acknowledgements Dr. Swain D’Nisha Hamblin Romana Jarosova
Dr. Richmond
HSHSP’14