HPLC AMC Checklist: What Every Maintenance Visit Should Cover — Analytical Instrument Guide

An Annual Maintenance Contract is only as good as the visits it pays for. Two AMCs with the same price can deliver very different results: one engineer replaces the wear parts, tests every module and leaves a clear report; another wipes the instrument down and signs a form. This checklist helps you tell the difference, both when you choose a contract and when the engineer is standing in your lab.

It is written for HPLC systems, but most of it applies to GC and UV-Vis instruments too.

Before you sign: what the contract should say

Read the contract for these points. If any of them is missing or vague, ask for it in writing before you agree.

• Which instruments and modules are covered. List each one by model and serial number: pump, autosampler, column oven, detector and degasser. A contract that says only "one HPLC" leaves room for argument later.
• How many preventive maintenance visits per year, and roughly when. High-use systems running buffers every day need more attention than an instrument used once a week.
• What happens on a breakdown. How you raise a call, who you call, and whether breakdown visits are included or charged separately.
• Spare parts. In an AMC, parts used in repairs are usually billed separately. In a CMC, parts consumed in covered repairs are included, within agreed limits. Our AMC vs CMC guide explains the difference in detail.
• What is excluded. Consumables such as columns, lamps, filters and vials are usually outside both AMC and CMC. Damage from misuse, power problems or pests is usually excluded too. Know this before the first invoice.
• Whether calibration or qualification is part of the visit. Calibration and IQ, OQ and PQ are separate services in many contracts. If your auditors expect a calibration certificate after each preventive maintenance, say so.
• The documents you will receive after each visit.

The preventive maintenance checklist, module by module

Use this list during the visit. Not every item applies to every model, and the engineer will adjust it for your system and usage, but the main areas should all be covered.

Solvent delivery and degasser

• Solvent inlet filters checked and replaced if discoloured or blocked.
• Solvent lines checked for cracks, kinks and air.
• Degasser channels checked for proper function; a failing degasser causes pressure ripple and baseline noise.

Pump

• Piston seals replaced, based on usage. Seals are a wear part and should be changed on a schedule, not after a leak.
• Check valves cleaned or replaced if the pressure ripple is high.
• Pistons inspected for scratches and salt deposits.
• Seal wash system checked if you run buffers.
• Purge valve and its frit checked.
• Pressure test or leak test passed, and pressure ripple recorded.
• Flow rate verified against the set value.

Autosampler or injector

• Needle, needle seat and rotor seal inspected and replaced if worn. A worn rotor seal causes carryover and sheds particles that block the column.
• Syringe or metering unit checked for leaks and smooth movement.
• Wash solvent and wash settings checked.
• Injection precision checked with repeated injections where the contract includes it.
• Carryover checked by injecting a blank after a concentrated standard.

Column oven

• Temperature checked against the set value with a calibrated probe where calibration is in scope.
• Door seal and fan checked.

Detector

• Lamp hours and lamp energy or intensity recorded. A lamp near the end of its life gives noise and fails sensitivity tests; plan its replacement rather than waiting for failure.
• Flow cell cleaned and checked for air and contamination.
• Wavelength accuracy checked, usually with the detector's built-in test. Our UV-Vis wavelength check guide explains how this works.
• Baseline noise and drift checked against the specification for the method.

Leaks, fittings and general condition

• Every fitting from the pump to the detector checked for leaks and salt.
• Leak trays and leak sensors cleaned and dry.
• Waste lines checked for blockage and routed safely.
• Cooling fans and air vents clean. Dust-blocked fans cause overheating faults on older modules.

Computer and software

• Communication between the computer and every module checked.
• Instrument configuration matches the actual modules.
• Any software issue noted in the report for your IT or validation team. Do not let anyone change validated software settings without your change control.

What you should receive after each visit

A good service visit leaves a paper trail that your auditors can follow.

• A service report listing the instrument model and serial number, the date, the engineer, the work done, the parts replaced with part numbers and the test results.
• A list of parts recommended for the next visit, so you can plan the budget.
• Calibration certificates where calibration was in scope, with the details of the reference standards used and their traceability.
• An honest note of anything still wrong. A report that says "everything fine" while the pressure ripple is high helps nobody.

Keep these reports in the instrument's logbook. When an auditor asks how you know the system is fit for use, the history of reports is your answer.

Frequently asked questions

How many preventive maintenance visits does an HPLC need each year?

It depends on how much the system is used and what it runs. Systems running buffers for long hours every day wear their seals, valves and rotor seals faster and need more frequent visits than lightly used instruments. Many laboratories plan two visits a year; heavily used systems may need more. Agree the number in the contract based on your actual usage.

Is an AMC worth it for an old HPLC?

Often yes, because older instruments need parts and attention more often. For an older system that runs every day, a CMC can make the yearly cost more predictable because covered repair parts are included. The main question for an old system is parts availability, which is worth discussing before you sign.

What is the difference between preventive maintenance and calibration?

Preventive maintenance replaces wear parts and checks that each module works properly. Calibration measures the instrument's performance, such as flow rate accuracy, temperature and wavelength accuracy, against reference standards and records the results. Many laboratories need both, and they can be done on the same visit when both are agreed in the contract.

Which parts should be replaced at every preventive maintenance visit?

There is no fixed list for every lab, because it depends on usage. Pump piston seals, solvent inlet filters and other wear parts are commonly replaced on a schedule, while check valves, rotor seals, needle seats and lamps are replaced when their condition or test results show wear. The service report should say what was replaced and why.

Can one AMC cover instruments from different brands?

Yes, a contract can list instruments from different makers, as long as the service provider supports each model. Send the full model name of each instrument, because support is confirmed model by model, not assumed from the brand.

Planning an AMC with us

We provide AMC and CMC plans for HPLC, GC and UV-Vis instruments in Mumbai, Thane, Navi Mumbai, Pune and nearby areas. To get a proposal, send us the list of instruments with model names, how many hours a week each one runs, whether you run buffers, and what documents your auditors expect after each visit.