Derivatization of Acidic Herbicides with Selected Tetraalkyl Ammonium and Trimethyl Sulfonium Hydroxides for Their GC Analysis

Abstract

This work presents studies on phenoxy acid [MCPP—2‐(4‐chloro‐2‐methylphenoxy)propanoic acid; MCPA—(4‐chloro‐2‐methylphenoxy)acetic acid; 2,4‐D‐2,4‐dichlorophenoxyaceticacid; 2,4,5‐T‐(2,4,5‐trichlorophenoxy)acetic acid] and phenolic [PCP—pentachlorophenol, dinoterb‐2‐(1,1‐dimethylethyl)‐4,6‐dinitrophenol, dinoseb‐2‐(1‐methylpropyl)‐4,6‐dinitrophenol] herbicides with derivatization aimed at their gas chromatographic determination. The derivatization was performed in an injection port of a gas chromatograph with trimethylphenylammonium hydroxide (TMPH), trimethylsulfonium hydroxide (TMSH), and tetramethylammonium hydroxide (TMAH). The effects of temperature of the injection port, reaction medium (solvent), and reagent excess on derivatization yield were investigated. TMPH in 20‐fold excess in methanol was selected for analysis. Dichloromethane was also found to be an appropriate solvent. Repeatability of the results was poor when tert‐butyl methyl ether (MTBE) was used as reaction medium.

Keywords:

• Phenoxy acid herbicides
• Derivatization
• Gas chromatography