7.2 Methods

Instrument control, data acquisition and analysis parameters are stored in special 'program' files called methods. Methods are the heart of the GC/MS operational software.

• Methods store data acquisition parameters regarding: MS scan parameters, tuning parameters, temperature and gas flow parameters. Essentially, everything that is needed to collect and store the data.
• Data analysis parameters are also stored in methods; these instructions are used for automated data analysis when data is collected in sequence mode; manual acquisitions (that use only the data acquisition parameters in a method) require may require manual data analysis.
• We use different methods for different types of analysis. For example, we have a set of methods called GENx (where x=1-3); these are general purpose and screening methods. We also have methods for specialized tests, such as the GC/MS analysis of LSD samples and the volatile analysis method used for fire debris samples.
• By using keeping different methods at hand, we don't need to hand program the GC/MS parameters for each analysis.