The mass spectrometer is an lab testing instrument that is used to analyse the molecular structure and molecular weight of a substance. It obtains information about the molecular structure and composition of a particular substance by breaking the substance into ion beams of protons and electrons and using the ion beams to detect and record the characteristics of the different molecules in the substance.

Due to the high sensitivity and resolution of the mass spectrometer, it has advantages in both qualitative and quantitative aspects, so more and more laboratories are now equipped with mass spectrometers. This is a summary of what needs to be done to repair the mass spectrometer, which applies to most liquid phase mass spectrometers.

Special attention should be paid to the control of room temperature and humidity during use. In general without external tube flight time, the mass spectrometer has more stringent environmental requirements and the external environment directly affects the accuracy of the mass axis. The mass spectrometer uses a two-stage pumping structure, with a mechanical front stage and a molecular turbine pump at the rear stage working by first reducing the pressure in the vacuum chamber to several orders of magnitude, and then by the rear stage pump reducing the pressure required for operation to the required pressure.

When used in combination with a liquid chromatograph, it is first necessary to filter with a membrane with a flowability <0.45 μm. A distinction needs to be made between organic and aqueous membranes, and samples also need to be filtered or centrifuged at <10,000 rpm to remove solid impurities.

When using liquid TFA, it is not advisable to use acids or salts that are difficult to volatilise, such as borates and phosphates; it is not advisable to use liquid TFA to inhibit ionisation, surfactants react quickly in mass spectrometers, especially with ESI sources, so detergents should not be used for all tube and apparatus cleaning, and ion-pairing reagents used to improve separation and peak shape should be used with caution. Acetic acid, formic acid, ammonium acetate, ammonium formate and ammonia are recommended for use in conjunction with the mass spectrometer.

The liquid phase is adjusted according to the selected ion source. The ESI source is generally 0.3~0.6 mL/min and the conventional HPLC column size is 5 μm, 4.6×250 mm with a typical flow rate of 1 mL/min. The flow rate into the mass spectrometer can be adjusted by using a post-column split. The temperature and flow rate of the atomisation gas are adjusted according to the flow rate into the mass spectrometer and the nature of the sample.

At the end of the sample test, the inlet tube needs to be cleaned, the pump operation is stopped after cleaning and standby is selected when the ion source temperature is reduced.