Maintenance methods of GC-MS

I. Daily maintenance

The daily maintenance shall focus on the followings: carrier gas, sample inlet, glass lining, sample inlet gasket, O-ring and chromatographic column, etc.

1. Carrier gas

1.1 Check the steel cylinder pressure. It is suggested to replace the gas when the carrier gas pressure is 3 mpa, and not use up the carrier gas. The continuous drop of gas pressure may worsen the map of standard solution for test because of interference by foreign gas.

1.2 Inspect the vacuum state, check the vacuum gauge, and by comparison to routine records, check if the vacuum is normal. 

1.3 Check the atlas, and check if the vacuum is abnormal.

2. Sample inlet

2.1 It is suggested to renew the inlet gasket after 150 automatic feeds or 50 manual feeds of samples.

2.2 It is suggested to renew the glass lining after 150 automatic feeds of samples. What shall be highlighted specially is that the glass wool must be filled evenly at the satisfying position.

2.3 Every day before test, the standard solution shall be checked to judge if the retaining time or area reproducibility of standard solution changes; in case of great change, the glass lining can be replaced; if the problem is not eliminated, the instrument shall be cleaned thoroughly (ion source cleaning, and instrument adjustment).

3. Chromatographic column

During test, check if the ghost peak appears, the peak is trailing, and the retaining time and integral area changes greatly; if yes, the following measures shall be taken: 1. Cut the column head when cleaning the ion source, to cut off the dirty part; 2. Age the tube column within 2 h at best.

4. Others

4.1 Clean the whole instrument, and ensure that the instrument has no residual organic reagent or dirt.

4.2 Check if the cleaning liquid bottle and waste liquid bottle are placed correctly, the cleaning liquid is sufficient and clean, and the waste liquid is drained.

4.3 Check if the automatic feeder and turntable operate normally.

4.4 Check if the instrument wiring falls off.

II. Weekly maintenance (including biweekly maintenance)

2.1 Check the air strainer, and clean or replace the air strainer that is dirty. The dirty air strainer can be cleaned with cleaning agent, rinsed with tap water and pure ware, then dried and next refitted.

2.2 Weekly check the He pressure. The steel cylinder whose pressure is below 3 Mpa must be replaced.

III. Monthly maintenance

3.1 Monthly check the liquid level in the vacuum oil pump: keep the oil level of vacuum oil pump within the marks (between the upper and lower limits). Change the oil of vacuum oil pump: turn off the instrument (GC-MS), unplug the pump pipe connected to the instrument, drain the used oil, fill the new oil, and turn on and operate the pump; repeat those steps for times.

3.2 Clean the ion source once a month; when necessary, cut off the column head at the sample inlet by 2~3 cm.

For operation of ion source, it is required to wear the clean and powder-less gloves, and wash the adopted tools with acetone (or methyl alcohol) to avoid pollution. Care shall be taken when dismantling the ion source, and the excessive force shall be avoided. It is required to handle every component gently, and not touch the filament. The damage of instrument shall be avoided; the dismantled components shall be placed at the suitable positions to avoid cross contamination.

Place the components in the clean beaker, fill the acetone or methyl alcohol (above the analytical purity), clean them ultrasonically, and finally dry them.

IV. Annual maintenance (including semiannual maintenance)

4.1 Change the vacuum pump oil once every half a year.

4.2 Replace the O-ring of quartz liner once a year or so.

4.3 Replace the gas purifying tube once a year or so.