LC-MS Applications for Environmental Analysis

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Figure 3: Overlay of 20 repeated injections of Cr (VI) and Cr (III)
Quantification of Cr (III) and Cr (VI) in tap water
Potable water was collected locally and analyzed using the
proposed method. As can be seen from the chromatogram
in Figure 4, only trace amounts of Cr (VI), at a retention
time of ~40 s, could be detected in this sample. After
external calibration, the amount of Cr (VI) observed was
found to be 42.5 ± 1 pg/g. As an additional proof that the
detected peak corresponds to Cr and is not affected by
possibly co-eluting compounds causing spectral
interferences (e.g. chlorine or carbon based polyatomic
species), the isotope ratio 52Cr+/53Cr+ was calculated and
corresponds well to the theoretical value of 8.81).
Conclusions
Through the combination of the ICS-5000 ion
chromatography system with the iCAP Qc ICP-MS, a
sensitive, robust method for the speciation analysis of
trace levels of Cr (III) and Cr (VI) in natural waters has
been developed. The method developed enables fast and
reliable speciation analysis of both Cr (III) and Cr (VI)
species in water samples without prior incubation steps
and with high purity nitric acid as mobile phase. The
short, but highly efficient Dionex AG-7 column, provides
complete separation of both species in under 150 s,
enabling high sample throughput for the routine analysis
of water samples.
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AN43098_E 03/12C
Application Note 43098
The new flatapole cell technology introduced in the iCAP
Q ICP-MS provides interference-free detection of the 52Cr
and 53Cr ions. Sub-ppt detection limits are achievable due
to the completely metal free pathway of the ICS-5000 and
the high instrumental sensitivity offered by the iCAP Q’s
He KED mode.
References
1. Séby, F., Charles, S., Gagean, M., Garraud, H., Donard,
O. F. X., J. Anal. At. Spectrom. 18 (2003), 1386-1390
2. Xing, L., Beauchemin, D., J. Anal. At. Spectrom. 25
(2010), 1046-1055
3. Dionex homepage
products/columns/ic-rfic/specialty-packed/ionpac-as7/
lp-73274.html)
Chemicals Used in this Note
Chemical Fisher Scientific
Catalogue Number
IonPac AG-7 Guard Column (2 x 50 mm) 063099
Fisher Optima grade nitric acid A467-500
For more information please contact your local Fisher
Scientific organization and/or visit: or
Thermo Fisher Scientific (Bremen) GmbH
Management System Registered to ISO 9001:2008
Figure 4: 52Cr and 53Cr chromatograms of a locally source potable water.