ICS-900 Operator’s Manual
38
Doc. 065215-02 9/09
cartridges. For instructions, refer to
Installation and Troubleshooting
Guide for OnGuard Cartridges
(Document No. 032943). The manual is
included on the Dionex Reference Library CD-ROM (P/N 053891).
3.10.3 Diluting
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.
Use eluent or ASTM Type I (18 megohm-cm) filtered and deionized
water to dilute the sample. 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 standards 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.
