what is the meaning of goting those in every run?

[che313]

In GC-MS library search report, what is the meaning of goting the following in every run?

1- GC stationary phase
2- septum bleed
3- diisooctylphthalate
4- butyl-2-methylpropylphthalate

[sassman]

1 is from your column. 2 is from the septum. 3 and 4 are platicizers which are coming from some plastic that which has been in contact with your sample or the solvents used in processing your sample. They are in every run because they are contaminants present in your samples. You can probably just ignore these peaks unless they become very large or have the same retention time as your analyte.

[che313]

how can I avoid them?
is 1 - stationary phase will effect the column? its life? its performance?

[sassman]

Use a column with low bleed that is made for GC/MS. Use the best available septum for your GC injection port. Use the highest purity solvents that you can afford.