Quantitative and Qualitative Characterization of Liquid Materials - Broadband Reflectometry for Enhanced Diagnostics and Monitoring Applications - page 82

data analysis techniques (such as Principal Component Analysis, PCA) might be
employed to distinguish adulterated oils from pure olive oils on the basis of the
whole combined set of Cole-Cole parameters.

4.4.2.4 Considerations on Possible Practical Implementation

Results show that different oils exhibit different dielectric characteristics, particu-
larly in terms of relaxation frequency. The uncertainty value associated with the
evaluation of the relaxation frequency provides a self-consistent parameter for test-
ing the performance and the suitability of dielectric spectroscopy for quality control
of vegetable oils.
For this purpose, results may be collected in a database (together with the as-
sociated confidence intervals) and used as reference values for successive 'offline'
measurements on unknown oils.
Most importantly, results on mixture of oils demonstrate that dielectric spec-
troscopy is sensitive to the presence of adulterants in oils. In practical applications,
provided that some reference dielectric data are given for specific unadulterated oil,
the possible presence of adulterants may be inferred, for example, as a deviation
between reference and measured dielectric data. The major advantage of employing
this method would be that the personnel in charge of control may perform the check
directly in situ, without overwhelming the few available laboratories with unnec-
essary requests. In other words, if the dielectric spectroscopy-based analysis gives
a 'positive' result (i.e., adulterant might be present), then further specific analyses
may be required from dedicated laboratories; on the other hand, if the result is neg-
ative, then there is no need to carry out additional expensive and time-consuming
analyses.

References

[1] High precision time domain reflectometry. Agilent Application Note 1304-7, USA
(2003)
[2] Akhadov, Y.Y.: Dielectric properties of binary solutions. Pergamonj, Oxford (1980)
[3] Buckley, F., Maryott, A.A.: Tables of dielectric dispersion data for pure liquids and
dilute solutions. National Bureau of Standards Circular 589 (1958)
[4] Castiglione, P., Shouse, P.J.: The effect of ohmic losses on time-domain reflectometry
measurements of electrical conductivity. Soil Sci. Soc. Am. J. 67, 414-424 (2003)
[5] Cataldo, A., Catarinucci, L., Tarricone, L., Attivissimo, F., Trotta, A.: A frequency-
domain method for extending TDR performance in quality determination of fluids.
Meas. Sci. Technol. 18(3), 675-688 (2007)
[6] Cataldo, A., Tarricone, L., Attivissimo, F., Trotta, A.: A TDR method for real-time
monitoring of liquids. IEEE Trans. Instr. Meas. 56(8), 1616-1625 (2007)
[7] Cataldo, A., Vallone, M., Tarricone, L., Attivissimo, F.: An evaluation of performance
limits in continuous TDR monitoring of permittivity and levels of liquid materials. Mea-
surement 41(7), 719-730 (2008)