# Determination of Monoethylene Glycol in Gas Condensate Samples by Microchip Micellar Electrokinetic Chromatography Integrated With Capacitively Coupled Contactless Conductivity Detection

## TL;DR

The study introduces a new method using microchip-based MEKC with C4D detection to accurately measure monoethylene glycol in gas condensate samples.

## Contribution

A novel integration of MEKC and C4D for MEG analysis in gas condensates is developed and validated.

## Key findings

- The method showed linear behavior (r² ≥ 0.99) for MEG concentrations between 150–450 µmol L⁻¹.
- MEG concentrations in gas condensate samples ranged from 173 to 213 µmol L⁻¹ with recovery rates of 89–102%.
- The MEKC-C4D system is proposed as an ecological and promising tool for in-field MEG analysis.

## Abstract

This study describes the use of microchip micellar electrokinetic chromatography (MEKC) integrated with capacitively coupled contactless conductivity detection (C4D) for the determination of monoethylene glycol (MEG) in gas condensate samples. The samples were subjected to a liquid–liquid extraction step and then analyzed by chip‐based MEKC‐C4D. For this purpose, sodium dodecyl sulfate (SDS) was used as a surfactant at a concentration of 30 mmol L−1 added in 50 mmol L−1 phosphate (pH = 9.0). Samples were introduced into microchannels through floating injection mode by applying a voltage of 600 V during 10 s. Separations were performed under an electric field of 82 V cm−1 and monitored by C4D measurements recorded applying a 1200‐kHz frequency sinusoidal wave with 20‐Vpp excitation voltage. The proposed methodology employing MEKC‐C4D revealed a linear behavior (r2 ≥ 0.99) in the MEG concentration range between 150–450 µmol L−1 and LOD equal to 33 µmol L−1. Three gas condensate samples were then analyzed, and the achieved MEG concentration values ranged from 173 to 213 µmol L−1. Recovery experiments provided values between 89 and 102%. Based on the results reported in this study, MEKC‐C4D devices have demonstrated to be a promising and ecological analytical tool for MEG analysis with huge potential for in‐field applications.