Chromatographic Symptoms 3
Agilent 7890 Series Troubleshooting 47
Larger Peaks Than Expected
• Check each configured column’s dimensions against the
actual column dimensions. (See “Configurable Items to
Always Keep Current”.) Refer to To configure a single column
or To configure multiple columns in the Advanced User
Guide for procedures on configuring columns.
• Check the autosampler injection volume. In the normal
injection mode, the sampler uses fast injection to deliver a
representative amount of the sample. Fast injection
minimizes needle fractionation. Chromatograms from
manual injection or slower auto injection devices show
higher levels of low molecular weight materials versus higher
molecular weight materials because the volatiles boil out of
the needle faster than the higher weight materials.
• Check the vial caps. Loose vial caps can cause selective loss
of lighter materials from a sample. The cap should not rotate
easily if installed properly.
• Check configured syringe size. Some syringe sizes are
specified at half-capacity. If the maximum syringe volume is
marked at half-height on the barrel, not at the top of the
barrel, enter twice the labeled volume when configuring the
syringe size.
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