This document describes the successful analysis of carbamates (a class of highly effective insecticides) and phenyl ureas (a class of herbicides) using liquid chromatography/mass spectrometry with electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photo ionization (APPI) sources. APPI and APCI exhibited lower background signals and fewer background peaks than ESI. Phenyl ureas, in general, exhibited better signal-to-noise ratios (S/N) from APCI or APPI than from ESI. However, it was just the opposite for carbamates. The S/N was better from ESI than from APCI or APPI. A small amount of post-column acetone was needed in the APPI source as a photoionizable dopant for charge transfer to the analyte.
This document details the analysis of carbamates and phenyl ureas using liquid chromatography/mass spectrometry (LC/MS) with three different atmospheric pressure ionization sources: electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photo ionization (APPI). The study utilizes the Agilent G1946D LC/MSD system to evaluate signal-to-noise ratios and background interference for these agricultural chemicals in environmental and food samples.
The text provides specific experimental conditions, including column types, solvent gradients, and instrument parameters for each ionization mode. It concludes that while ESI offers better response for carbamates, APCI and APPI provide superior signal-to-noise ratios for phenyl ureas. Additionally, the document highlights the necessity of using a post-column acetone dopant in APPI mode to enhance analyte signals.
| Column temperature | 30°C |
|---|---|
| Column flow rate | 1 mL/min |
| Drying gas flow (ESI) | 12 L/min |
| Veap voltage | 3500 V (ESI), 4500 V (APCI/APPI) |
| Vaporizer temperature (APCI/APPI) | 225 °C |
APCI or APPI exhibited better signal-to-noise ratios (S/N) for phenyl ureas than ESI.
ESI provided better signal-to-noise ratios for carbamates compared to APCI or APPI.
Yes, a small amount of post-column acetone is needed as a photoionizable dopant for charge transfer to the analyte.