Separation and on‐line preconcentration of nonsteroidal anti‐inflammatory drugs by microemulsion electrokinetic chromatography

Abstract

The MEEKC separation and on-line preconcentration of nonsteroidal anti-inflammatory drugs (NSAIDs) were investigated. In this work, two microemulsion (ME) systems were employed. Complete separation could be achieved at a pH of 5.5 with octane as the oil phase (ME I). The LODs for the determination of flurbiprofen, fenoprofen, naproxen, ketoprofen, suprofen, and indoprofen were 0.45, 0.32, 0.10, 0.48, 0.77, and 0.29 mg/L, respectively. To enhance the sensitivity, anion selective exhaustive injection-sweeping (ASEI-sweeping) and stacking with reverse migrating pseudostationary phase (SRMP) were compared. For having a simple process without polarity switching and shorter analysis time, a suppressed EOF and di-n-butyl-L-tartrate as the oil phase (ME II) were used for the simultaneous determination of NSAIDs. The sensitivity for ASEI-sweeping was enhanced approximately 280-fold. However, there was much background noise, and some of the analytes were co-eluted. When SRMP was used, all of the analytes could be detected simultaneously, and baseline separation could be achieved. The sensitivities of all of the analytes, except for indoprofen, were enhanced approximately 170-fold compared with the normal MEEKC, and the LODs were 2-45 μg/L. Herein, we propose a simple method for the direct determination of NSAIDs at therapeutic and toxic levels in urine throughout a wide concentration range.

Determination of the retention factor of ionizable compounds in microemulsion electrokinetic chromatography

“…The surfactant and the cosurfactant act as stabilizers, reducing the surface tension that exists between the oil droplets and water, and allowing the creation of the ME [4]. MEEKC has been used in different applications over recent years, as a separation technique for highly hydrophobic compounds [5][6][7], or as a method to predict biopartitioning properties, such as lipophilicity, which can be estimated from the retention factor of compounds in the ME media [8][9][10][11], among others.…”

Microemulsion-based anthocyanin systems: effect of surfactants, cosurfactants, and its stability

“…Short oil hydrocarbon chains result in deep organic phase insertions into the interface membrane. [4,6] Consequently, microemulsions are remarkably stable, but the long hydrocarbon chain oil phase is beneficial in increasing the dissolution. Therefore, microemulsion preparation should comprehensively consider drug dissolution.…”

“…These conditions cannot be satisfied by the single oil phase; thus, different oil phases should be used. [2,6] The dosage and type of surfactants used in microemulsions directly influence the microemulsion formation size and toxicity. The common percentage of surfactants is 20-30% w/w.…”