7. Key Problem Areas and Preventive Maintenance

The chart below lists the most common problems that occur with each LC module. In the right-hand column are listed preventive maintenance practices that can reduce the failure rate. The numbers in parentheses are suggested intervals between maintenance. The LC's operator and service manuals may have additional suggestions for preventive maintenance.

A. Reservoir

Possible Cause	Preventive Maintenance
1. Blocked inlet frit	1. a. Replace (3–6 months)
	b. Filter mobile phase, 0.5 µm filter
2. Gas bubbles	2. Degas mobile phase

B. Pump

Possible Cause	Preventive Maintenance
1. Air bubbles	1. Degas mobile phase
2. Pump seal failure	2. Replace (3 months)
3. Check valve failure	3. Filter mobile phase; use inlet-line frit;
	keep spare

C. Injector

Possible Cause	Preventive Maintenance
1. Rotor seal wear	1. a. Do not overtighten
	b. Filter samples

D. Column

Possible Cause	Preventive Maintenance
1. Blocked frit	1. a. Filter mobile phase
	b. Filter samples
	c. Use in-line filter and/or guard column
2. Void at head of column	2. a. Avoid mobile phase pH >8
	b. Use guard column
	c. Use precolumn (saturator column)

E. Detector

Possible Cause	Preventive Maintenance
1. Lamp failure; decreased detector	1. Replace (6 months) or keep spare lamp
	response; increased detector noise
2. Bubbles in cell	2. a. Keep cell clean
	b. Use restrictor after cell
	c. Degas mobile phase

F. General

Possible Cause	Preventive Maintenance
1. Corrosive/abrasive damage	1. Flush buffer from LC and clean when not
	in use

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