Liquid extraction surface analysis in-line coupled with capillary electrophoresis for direct analysis of a solid...

Area of Science:

• Analytical Chemistry
• Environmental Science

Background:

• Capillary Electrophoresis (CE) is typically limited to liquid samples.
• Analyzing solid surfaces for contaminants requires specialized techniques.

Purpose of the Study:

• To develop a direct surface analysis method for solid samples using CE.
• To determine organophosphorus pesticides on fruit surfaces.

Main Methods:

• Liquid Extraction Surface Analysis (LESA) was in-line coupled with CE.
• Direct extraction of analytes from an apple surface into a capillary.
• In-capillary derivatization with a fluorophore followed by CE-Laser Induced Fluorescence (LIF) detection.

Main Results:

• Successfully determined glufosinate-ammonium, aminomethylphosphonic acid, and glyphosate on an apple surface.
• Achieved limits of detection (LODs) of 2.5, 1, and 10 ppb, respectively.
• LODs were significantly lower (at least 20x) than US EPA tolerance limits.

Conclusions:

• LESA-CE is a sensitive and convenient method for direct solid surface analysis.
• The technique avoids sample pretreatment, preventing analyte dilution.
• Enables direct determination of pesticides on food surfaces.