164 / 302
8
Table 4. Validation results of the analytical method
Application to Environmental Samples
The method was used on the samples collected from the
water purification facilities. The raw water and river
water samples were treated in an ultrasonic extraction
apparatus for 30 min before being filtered through a
0.45 μm glass fiber filter. Also, one sample of cyanobacteria
from lake water that was separately stored was analyzed.
The four target algal toxins detected in the raw and
treated water from the water purification facilities and the
river water were well below the quantitation limit and
were considered to be not detected. On the other hand,
molecular ions of microcystin-LR were detected in
cyanobacteria lake water sample and were identified
through a comparison of the mass spectrum ratio of the
carbon isotope of the standard toxin (Figure 2). It took
approximately 16 hours to complete the calibration curve
and analysis of the blank sample and all the samples. It
was determined that the method could be used to rapidly
analyze a large number of samples, to reduce the amount
of labor and solvent necessary, and to contribute to
making quick responses in the field.
Conclusion
It is difficult to forecast algal blooms; therefore, rapid
diagnosis of cyanotoxins produced by cyanobacteria is an
important element in making quick responses at water
intake and purification facilities. In this study, a combination
of the online pre-concentration and injection method and
the high-resolution, full-scan mass spectrometry method
was used to assess algal toxins including microcystin-LR
and applied to environmental samples. Based on the
results, the following conclusions were reached:
• Microanalysis can be performed without a complex
pretreatment procedure. The online preconcentration
method produces 200 times the concentration effect
compared to the solid-phase extraction method, even
with a small sample of 1 mL. When combined with the
high-resolution, full-scan mass spectrometry method,
the method produced a linearity that was equivalent to
that of the SPE and LC-MS/MS method. The recovery
rate was over 70% and the degree of precision was
within 10%. At the same time, the method detection
limit (MDL) and the practical quantitation limit (PQL)
were determined to be 0.009-0.035 ng/mL and 0.03-
0.11 ng/mL, respectively. Based on these results, it was
deemed to have the same performance as the
conventional method.
• The application of the online preconcentration method
decreased the analysis time by 80% compared to the
conventional method and also reduced the amount of
labor, solvent, and solid-phase cartridge cost required.
Productivity was further enhanced with more samples
and, thus, it is expected to substantially improve
economic efficiency.
• Combining the instrumental analysis with the use of
high-resolution, full-scan mass spectrometry makes it
possible to detect non-target compounds. Thus, this
method could be utilized for retrospective search and
simultaneous quantitation of algal toxins with similar
physicochemical properties such as anatoxin
(mol. wt.: 165) and aplysiatoxin (mol. wt.: 672).
Compund
Fortified
Amount
(µg/L)
MDL
(µg/L)
PQL
(µg/L)
Recovery
(%)
RSD
(%)
Microcystin-LR
0.1
0.009
0.03
113.7
2.5
Microcystin-RR
0.1
0.013
0.04
70.3
5.3
Microcystin-YR
0.1
0.035
0.11
103.7
10.9
Nodularin
0.1
0.009
0.03
83.9
3.7
MDL: SD x t = SD x 3.14, (n=7, 1-a=0.99), PQL: SD x 10
(Ref: Standard Methods 20th Edition, 1030C Method Detection Level)