Identification of Unknown Pesticides in Food Using LC/MSD TOF and Ion Trap MS(n)

About this manual

The document outlines an identification scheme for unknown pesticides that combines liquid chromatography/mass selective detection (LC/MSD) with time-of-flight (TOF) and ion trap options. The approach involves accurate mass determination using LC/MSD TOF followed by MS/MS confirmation using the ion trap, and database analysis against Merck Index or ChemINDEX.

The procedure details a six-step process including initial detection of unknowns in vegetable extracts, checking for isotope patterns (A+2), searching databases for empirical formulas, performing ion trap MS/MS fragmentation analysis, combining data for tentative identification, and final confirmation with authentic standards. Two examples are provided where malathion and buprofezin were identified in cucumber and tomato extracts.

What's inside

• Abstract
• Introduction
• Experimental Methods
• Standard Vegetable Extraction
• Rapid Vegetable Extraction
• LC/MSD TOF Methods
• LC/MSD Ion Trap Methods
• Results and Discussion

Specifications

Frequently asked questions

How are sulfur-containing pesticides identified?

They are identified by checking for an A+2 ion pattern (approximately 8% intensity) and confirming with MS/MS fragmentation.

What is the maximum residue limit for banned compounds in vegetables?

The maximum residue limit for banned compounds is set at 0.01 mg/kg.

What are the dimensions of the ZORBAX Eclipse XDB-C8 column used?

The column dimensions are 4.6 mm x 150 mm with a particle size of 5 um.

What is the flow rate for the LC/MSD TOF and Ion Trap methods?

The flow rate used in both methods is 0.6 mL/min.