Development of analysis procedures
for the determination of pesticides by use of multi-methods
The pesticide analysis methods that have
been used until now, can be generically described by:
1) solid phase extraction (SPE) of the (filtered) water
samples for the isolation and enrichment of the relevant analytes
2) performing of the necessary washing steps for the separation, respectively
depletion of the matrix
3) elution of the analytes in a small amount of adequate solvent
4) chromatographic analysis.
This generic process represents the best
available technology at the moment. It is however, because of the large number
of worksteps that have to be done manually, very expensive. Moreover, it
presents a whole series of difficulties, based particularly on the very
different chemical structures and features of the substances to be analysed:
not all the analytes can be equally well accumulated on the common (silica-based
C18-) SPE-materials, respectively eluted again from the strongly adsorbent
materials with small amounts of solvents (as it would be necessary for on-line
processes). The chromatographic separation of the analytes that are sufficiently
volatile can be done using the gas chromatography (GC), but requires liquid
chromatographic methods (HPLC) for polar and temperature sensitive substances.
Also for HPLC different chromatographic conditions, and therefore separate
runs, may be required. The commonly used UV-detection has so far the disadvantage
that it is not sensitive to certain analytes and therefore not selective enough.
Starting from the best available technology,
the following modifications and improvements of the above mentioned generic
methods have been researched
a) the enrichment of the analytes and elution
in the HPLC to be done on-line,
b) the detection of the analyte to be done with mass spectroscopy (MS).
The on-line enrichment and on-line elution have
the advantage that, in comparison with off-line processes, either considerably
lower detection limits can be achieved for the enrichment of the same amount of
sample, or the volume of the sample can be significantly decreased, maintaining
the same detection limits. The resulting advantage is mainly the acceleration of
the sample preparation, but also the smaller volume of sample required.
Moreover, the on-line enrichment has the advantage
that it can be automated. Under adequate boundary conditions, in order to ensure
the stability of the analyte until the analysis is done, it is possible to analyse,
in a special configuration, up to 50 samples in one sequence, so that the enrichment
and analysis interlace and are therefore more time effective.
The detection of the analyte by means of
mass spectrometry presents the advantage of a higher sensitivity, together with
a better selectivity of the determination.
The development work is professionally
Associate Univ. Prof. E.-E. Rosenberg, MSc. PhD. - Vienna University of Technology,
Institute for Chemical Technologies and Analysis, Department for Analytical Chemistry,
Univ. Prof. G. Allmaier, PhD.- Vienna University of Technology, Institute for Chemical
Technologies and Analysis, Assistent Prof. Hann, PhD. MSc. - University of Natural
Resources and Applied Life Sciences, Vienna, Institute for Chemistry, Department for
This research project has been financially supported by the Austrian Research Promotion
Agency Ltd. (FFG).