Advanced Microextraction Technique Enhances Barbiturate Detection in Serum Samples

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In this study, an efficient technique is described for extracting and quantifying barbiturates in serum samples, combining ultrasound and surfactant-assisted dispersive liquid–liquid microextraction (dLLME) with poly(ethylene oxide)-mediated stacking in capillary electrophoresis.

In a recent study published in the Journal of Separation Science, researchers Li Hsin Tseng, Pei-Chi Liang, and Ming-Mu Hsieh, from National Kaohsiung Normal University in Kaohsiung, Taiwan, and Tai-Chia Chiu of National Taitung University in Taitung, Taiwan, detailed a novel approach to achieve highly sensitive detection of barbiturates in human fluids (1). The method integrates ultrasound and surfactant-assisted dispersive liquid–liquid microextraction (dLLME) with poly(ethylene oxide)-mediated stacking in capillary electrophoresis (CE).

The researchers explored various parameters influencing the extraction and stacking performance, including the type and volume of extraction solvents, surfactant type and concentration, extraction time, salt additives, sample matrix, solution pH, and composition of the background electrolyte. Through careful optimization, they achieved the optimal detection sensitivity.

Under the optimized conditions (injecting 140 μL C2H4Cl2 [1,2-dichloroethane, or ethylene dichloride, EDC] into 1 mL of sample with pH 4 and sonication for 1 min, and separation conditions of 150 mM tris(hydroxymethyl)aminomethane-borate with pH 8.5 containing 0.5% [m/v] poly(ethylene oxide)), the method demonstrated remarkable limits of detection (signal-to-noise ratio = 3) for five barbiturates, ranging from 0.20 to 0.33 ng/mL. The calculated sensitivity improvement ranged from 868- to 1700-fold.

The results of the study indicated excellent linearity (R2 > 0.99), with relative standard deviations of 2.1%–3.4% for migration time and 4.3%–5.7% for peak area. The recoveries of spiked serum samples were within the range of 97.1%–110.3%. This proposed approach not only provides a rapid and practical method for quantifying barbiturates in biological fluids but also enhances the sensitivity of detection.

The key innovation lies in the combination of ultrasound and surfactant-assisted dLLME with poly(ethylene oxide)-mediated stacking. The extraction solvent, surfactant concentration, and electrophoresis conditions were carefully tailored to achieve optimal sensitivity, resulting in significant improvements in detection limits compared to conventional methods.


This advanced microextraction technique holds promise for applications in forensic analysis, clinical diagnostics, and pharmacokinetic studies, where accurate and sensitive detection of barbiturates is crucial. The method's efficiency, coupled with its simplicity and practicality, positions it as a valuable tool for researchers and practitioners in the field.

In conclusion, the collaborative efforts of the research team have yielded a sophisticated yet accessible method for the extraction and quantification of barbiturates in serum samples. By integrating ultrasound, surfactant-assisted dispersive liquid–liquid microextraction, and poly(ethylene oxide)-mediated stacking, this technique represents a notable advancement in analytical methods for detecting substances in biological fluids.

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(1) Tseng, L. H.; Liang, P.- C.; Chiu, T.- C.; Hsieh, M.- M. Ultrasound and surfactant-assisted dispersive liquid–liquid microextraction prior to poly(ethylene oxide)-mediated stacking in CE for highly sensitive determination of barbiturates in human fluids. J. Sep. Sci. 2023, e2300557. DOI: 10.1002/jssc.202300557