Dissertation committee:
Καθηγητής Μ. Κούππαρης (επιβλέπων), Αναπλ. Καθηγήτρια Τζ. Άττα-Πολίτου, Επίκ. Καθηγήτρια Ε. Αρχοντάκη
Summary:
The subject of the Thesis is to investigate the use of the quasi-universal
Evaporative Light Scattering Detector (ELSD) in the determination of some
common metals found in pharmaceuticals, biological and environmental samples.
In an attempt to study the effect of relative atomic mass (Ar) on the detector’
s response A (equation A=α·mb), in relation to the composition of the mobile
phase, the cations of IA and IIA groups of the Periodic Table are chosen. The
study uses a FIA–ELSD setup without separation column and four different
carrier solvents. The obtained observations are used for the determination of
the metals in the following chapters.Lithium is the first of the cations to be
studied. There have been developed and validated two LC-ELSD methods for the
determination of lithium salts in two pharmaceutical formulations, blood plasma
and urine. The first method uses a C18 separation column with an ion-pair
reversed phase mechanism, while the second one uses a cation-exchange column
CS14. Both methods show good linearity and sensitivity. Aluminum, in the form
of Al(OH)3, is determined by using an ion-pair mechanism. The method is applied
in three formulations, two chewable tablets and an oral suspension. There have
been developed two methods, by applying several dissolution protocols, due to
the differences in the pharmaceuticals’ composition. The results show
remarkable fluctuations, due to the heterogeneity of the sample and the
sampling procedure. In the following chapter, there have been developed two
methods, one by using a cation-exchange and the other by using a C18 separation
column, for the determination of zinc ions in an injectable insulin suspension.
The amount of total and free zinc, are determined, and the results comply with
European Pharmacopoeia specifications. Comparison of the proposed method with
the reference method, AAS, shows that although the HPLC-ELSD method lacks
sensitivity, can give reliable results for the injectable insulin formulation.
In the last chapter there have been developed methods for the determination of
ions in drinking water. Na+, K+, Mg2+ and Ca2+ ions are determined with the use
of a cation-exchange column. The method is applied in HPLC laboratory-water, in
commercial brands of mineral water, in samples from the main water supply and
in an injectable formulation of saline physiological serum. There has also been
developed a method for the determination of Cr(III) - Cr(VI), two pollutants
found in drinking water, with the use of a cation-exchange column and a
gradient elution program. Method is applied in water samples from the water
supply of two different urban centers. Comparison of the HPLC-ELSD method with
the official AAS method shows that the proposed one is much less sensitive but
determines simultaneously Cr(VI) and Cr(III) in one single run without tedious
pretreatment of the samples. Thus could be satisfactorily used in heavily
polluted water or in samples after preconcentration.
Keywords:
HPLC – ELSD, Metals, Pharmaceutical analysis, Environmental analysis, Clinical analysis
