Thermo Scientific Dionex ICS-5000, Operator'S Manual

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Dionex ICS-5000 Operator’s Manual
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Doc. 065342-06 12/11
Before injection, pretreat samples that may contain high concentrations of
interfering substances by putting them through Thermo Scientific Dionex
OnGuard
™
cartridges. Refer to the installation and troubleshooting guide for
the Dionex OnGuard cartridge for instructions. The guide is located on the
Thermo Scientific Reference Library DVD (P/N 053891).
4.3.3 Diluting Samples
Because the concentrations of ionic species in different samples can vary
widely from sample to sample, no single dilution factor can be recommended
for all samples of one type. In some cases (for example, many water samples),
concentrations are so low that dilution is not necessary.
To dilute the sample, use eluent or ASTM Type I (18 megohm-cm) filtered
and deionized water that meets the specifications listed in
Section 1.5 . When
using carbonate eluents, diluting with eluent minimizes the effect of the water
dip at the beginning of the chromatogram. If you dilute the sample with
eluent, also use eluent from the same lot to prepare the calibration standards.
This is most important for fluoride and chloride, which elute near the water
dip.
To improve the accuracy of early eluting peak determinations, such as
fluoride, at concentrations below 50 ppb, dilute samples in eluent or spike the
samples with concentrated eluent to minimize the water dip. For example,
spike a 100 mL sample with 1.0 mL of a 100 X eluent concentrate.