Thermo Scientific Dionex ICS-2000, Руководство оператора

Страница: 78 / 390

ICS-2000 Ion Chromatography System
3-14
Doc. 031857-03 4/06
Filter groundwater and wastewater samples through 0.45
µ
m filters
before injection, unless samples were filtered after collection.
Before injection, pretreat samples that may contain high concentrations of
interfering substances by putting them through Dionex OnGuard
®
cartridges. Refer to the Installation and Troubleshooting Guide for
OnGuard Cartridges (Document No. 032943) for instructions.
3.9.3 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.
Use eluent or ASTM filtered, Type I (18-megohm) 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.
3.10 Loading and Injecting Samples
The two techniques for loading samples into the sample loop are: (1) with an
autosampler or (2) with a syringe or vacuum syringe through the injection port on
the ICS-2000 front door.
For autosampler injections, the injection port tubing is disconnected from the ICS-
2000 injection valve and replaced by the autosampler outlet tubing. Other setup
requirements depend upon the model of autosampler.