Detection of small amounts of pesticides in GCMS

[HatMarRuz]

Hello dear colleges,
I have a problem with detection low concentrations. We could not detect concentrations of chlororganic pesticides below 100mg/mL. Could you help us to solve the following questions:
1. How to create SIM method in MSD ChemStation program?
2. How to ask selected ions in SIM method of MSD ChemStation?
3. How can we calculate concentrations using selected ions?
Thanks in advance.

[Rndirk]

Hi,

Sounds like you need training for the instrument since these questions are really basic.

If there is no one in your institute that knows how to work with the instrument, ask Agilent for training, or use the manual.

By the way 100 mg/mL is a really high concentration for GC-MS in SIM mode. Much too high.

[ThoSt]

100 mg/ml is crazy for capillary columns, but then again i have no idea about your gc setup. And often in my experience the problem is not the ms its a wrong or faulty gc-setup (GC is more challenging than LC...). So lets start with some basics:

- Do you use a Split/Splitless Injector? If so i somehow hope you have a split ratio with that standards? I hope this is around 1:1000? Lower concentration goes with lower split or even splitless injection.

- Do you have an appropriate liner in your system?

- Do you use a capillary column? If so which internal diameter?

- Do you use a standard MS-technique? (70 eV, Single Quad etc.) What temperature is your transferline?

[ThoSt]

Hello dear colleges,
3. How can we calculate concentrations using selected ions?
Thanks in advance.

If you have a standard, you use a calibration curve for example