Chromatography Forum

Planning to develop new method for pesticides residue analysis for Black tea pesticides List ( around 650 pesticides). Need to clarify few points.

1. Which instrument brand is most prefer for above requirement. ( Thermo quantis and Thermo 9k GCMS/MS is good or ant other better options)

2. Pesticides standards individual or mixes?

3. Do we need to use internal standards, then how to identify internal standards if we use more than 300 pesticides in one run.

4. If the matrix is black tea there are some recovery issues for most pesticides, how to overcome this.

5. According to SANTE guideline recovery lower than 70% is acceptable any proof we can show to auditors regarding low recovery for black tea?

How "new" of a method are you developing, e.g. taking one in use and applying to newer equipment, or starting from scratch? I would expect there to be some methods developed from the EPA or other regulatory agencies as a good place to start.

For equipment I would recommend to look into APCI and nitrogen as the carrier gas for GC analysis. Since you're developing a new method that major shift shouldn't cause too many eyebrows to raise.

Good luck.