Automated cleanliness diagnostic for mass spectrometer

A mass spectrometer or ion mobility spectrometer comprising:

• an ion source;
• a first vacuum chamber;
• a first vacuum pump for maintaining the pressure within the vacuum chamber lower than the pressure outside of the chamber;
• an inlet orifice arranged between the ion source and the vacuum chamber for allowing ions to pass from the ion source into the vacuum chamber;
• detecting means for determining when the vacuum pump causes the pressure within the vacuum chamber to fall below a predetermined threshold;
• wherein the detecting means comprises means for monitoring the value of at least a parameter that varies with the variation of pressure within the first vacuum chamber, and means for determining when said parameter reaches a threshold value that is indicative of the pressure in the first vacuum chamber being at said predetermined threshold, wherein said parameter is the gas flow rate pumped out of the first vacuum chamber by the first vacuum pump;
• and
• signal means for indicating that said inlet orifice is at least partially blocked when said detecting means determines that the pressure within the vacuum chamber has fallen below the predetermined threshold by determining that said gas flow rate has decreased to reach said threshold value.

A method of detecting a blockage in a mass spectrometer or ion mobility spectrometer comprising:

• providing a mass spectrometer or ion mobility spectrometer having an ion source, a first vacuum chamber, a first vacuum pump, an inlet orifice arranged between the ion source and the vacuum chamber for allowing ions to pass from the ion source into the vacuum chamber, a second vacuum chamber and a second vacuum pump;
• operating the first vacuum pump so as to reduce the pressure in the first vacuum chamber relative to the ambient pressure;
• operating the second vacuum pump to pump gas from the second vacuum chamber to an outlet region of the second vacuum pump, wherein the first vacuum pump pumps gas from the outlet region of the second vacuum pump to an outlet of the first vacuum pump so as to reduce the pressure of the outlet region of the second vacuum pump;
• determining when the first vacuum pump causes the pressure within the first vacuum chamber to fall below a predetermined threshold, comprising monitoring the value of at least one parameter that varies with the variation of pressure within the first vacuum chamber, and determining when said parameter reaches a threshold value that is indicative of the pressure in the first vacuum chamber being at said predetermined threshold;
• and
• signalling that said inlet orifice is at least partially blocked when it is determined that the pressure within the first vacuum chamber has fallen below the predetermined threshold by determining that the parameter has reached said threshold value;
• wherein one of said at least one parameters is the amount of power that the second vacuum pump is using or the amount of current that the second vacuum pump is drawing, and wherein the spectrometer signals that the inlet orifice is at least partially blocked when said power or current decreases to reach said threshold value;
• or
• wherein the spectrometer further comprises a temperature sensor that monitors the temperature of part of the second vacuum pump or a region in proximity to the second vacuum pump, wherein one of said at least one parameters is said temperature and the spectrometer signals that the inlet orifice is at least partially blocked when the temperature measured by the temperature sensor decreases to reach said threshold value.