Advanced 600E Pump Testing 105
If you determine there is a problem with a check valve, remove and clean it (see
Section 4.2.6, Cleaning and Replacing Pump Check Valves). If a pump problem persists
(such as lack of eluent flow, or erratic flow rate), replace the check valve.
5.4.2 Gradient Proportioning Valve Pair Test
The gradient proportioning valve pair test allows you to evaluate the gradient
proportioning valve when you suspect a defective valve is causing erratic
chromatographic results.
The test can be performed in less than one hour using:
• Pure methanol
• UV-absorbing substance
Preparing Eluent
To prepare the eluent for the gradient proportioning valve pair test:
1. Fill reservoirs A and B with Eluent 1 (100% methanol).
2. Fill reservoirs C and D with Eluent 2 (100% methanol with 5.6 mg/L
propylparaben).
3. Eluent sparging is not required.
The concentration of propylparaben in methanol for Eluent 2 should produce
approximately 0.45 AU at 254 nm in this test. If you substitute another UV-absorbing
substance, determine the concentration that results in about 0.45 AU.
Note: Do not use acetone as the UV-absorbing substance since the lack of linearity (due
to rapid evaporation) will cause problems in interpreting the results.
Flushing the Eluent Lines
Be sure to flush any previous eluents from the system and change over thoroughly to the
test eluents (see Waters 600E Multisolvent Delivery System User’s Guide, Chapter 3,
Preparing Your 600E Multisolvent Delivery System for Operation).
Adjusting the Recorder
1. Before you begin, remove the column to prevent damage due to high flow rates.
2. Set the detector to 0.5 AUFS.
3. Pump eluent 1 (reservoir A or B) isocratically at 5 mL/min and adjust the recorder
to zero.
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