Method of improving signal-to-noise for quantitation by mass spectrometry

A method for determining an extracted ion current window to use for a mass spectrometer measurement, comprising:

• acquiring a plurality of mass spectra of a material over a period of time;
• selecting an initial extracted ion current window;
• setting the extracted ion current window equal to the initial extracted ion current window and calculating from the plurality of mass spectra an intensity as a function of time for an ion using the extracted ion current window;
• and
• repeating steps comprising:
• changing a parameter of the extracted ion current window by an increment,
• calculating from the plurality of mass spectra a next intensity as a function of time for the ion using the parameter, and
• calculating a next signal-to-noise ratio from the next intensity,
• until a stop condition is reached.

A mass spectrometry system, comprising:

• a mass spectrometer;
• and
• a computer system in communication with the mass spectrometer that:
• acquires a plurality of mass spectra of a material over a period of time;
• selects a first extracted ion current window and calculates from the plurality of mass spectra a first intensity as a function of time for an ion using the first extracted ion current window;
• selects a second extracted ion current window and calculates from the plurality of mass spectra a second intensity as a function of time for the ion using the second extracted ion current window;
• compares a first signal-to-noise ratio of the first intensity with a second signal-to-noise ratio of the second intensity;
• and
• if the second signal-to-noise ratio is greater than the first signal-to-noise ratio, uses the second intensity for the measurement.

A computer-readable medium whose contents cause a processor to perform a method for improving selectivity of a measurement from a mass spectrometer, the contents comprising:

• acquiring a plurality of mass spectra of a material over a period of time;
• selecting a first extracted ion current window and calculating from the plurality of mass spectra a first intensity as a function of time for an ion using the first extracted ion current window;
• selecting a second extracted ion current window and calculating from the plurality of mass spectra a second intensity as a function of time for the ion using the second extracted ion current window;
• comparing a first signal-to-noise ratio of the first intensity with a second signal-to-noise ratio of the second intensity;
• and
• if the second signal-to-noise ratio is greater than the first signal-to-noise ratio, using the second intensity for the measurement.