1. The composition and status of sample. Is the sample gas state, liquid state, solid state or mixed state? Can the sample be analyzed directly by gas chromatography?

2. Is the sample composition thermal-unstable, easy decomposable or easy catalytic reaction? Do time, temperature, pressure etc. cause the change of sample composition?

3. Are there dust, suspended substance, high boiling point compound and corrosive ingredient in sample? To consider how to collect sample and pre-treat sample.

4. Do easy source sample? Permitted sample consumption quantity. To select sample introduction method.

5. Composition and approximate concentration range which do not need analyze.

6. Daily analyzing frequency. Interval time between two analysises.