In‐capillary preconcentration of pirimicarb and carbendazim with a monolithic polymeric sorbent prior to separation by CZE

Abstract

CZE was assayed for the separation of carbamate pesticides susceptible to protonation (Pirimicarb, Carbendazim). Different electrophoretic media with high organic contents were explored, adequate separation and resolution being achieved when a BGE based on ACN with acetic acid in the presence of SDS as an ionic additive was used. With a view to increasing the sensitivity of the method, an in-capillary SPE step prior to the electrophoretic separation was developed. We employed a monolithic polymer formed in situ within the capillary as a medium for analyte retention. The synthesized monolithic bed exhibited high porosity and allowed samples to be loaded at flow rates of about 65 microL/min by applying a pressure of 12 bar. A 5-cm length of monolithic sorbent was used to preconcentrate the target analytes from aqueous samples. The analytes retained were eluted from the polymeric phase directly in the separation capillary with the same electrophoretic medium used for their further separation by CZE. For a 15-min preconcentration time, the in-line SPE-CZE approach proposed here permitted the determination of these pesticides in drinking water at a concentration level of 0.1 microg/L, as demanded by current EU legislation.

Salting-out assisted liquid–liquid extraction with the aid of experimental design for determination of benzimidazole fungicides in high salinity samples by high-performance liquid chromatography

“…As can be seen from Table 6, some of the reported methods provide higher sensitivity for benzimidazole fungicides than the present method [3][4][5][6]. Nevertheless, in a sense, they are also involved in complex enrichment procedures, long time-consuming, rigorous detection media, or high cost.…”

“…Nevertheless, in a sense, they are also involved in complex enrichment procedures, long time-consuming, rigorous detection media, or high cost. For example, although there is an in-tube SPE method [5] for the extraction of the benzimidazole fungicides, the procedure for the whole process is complicated and needs a long time for the preparation of the SPE procedure. And most of all, no high salinity water samples were analyzed [3][4][5][6][7][8][9], which is very likely because the salinity will disrupt seriously the extraction process and decrease efficiency.…”

“…The low vapor pressure and the thermal instabililty of benzimidazole fungicides do not permit their direct analysis by gas chromatography unless they are derived into thermally stable derivatives. So the commonly used analytical techniques for benzimidazole fungicides are high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) coupled with utraviolet (UV), fluorescence detection or mass spectrometry [4][5][6][7][8][9].…”

“…In all the above work, many extraction methods such as molecularly imprinted solid phase extraction (MISPE) [4][5][6], dispersive liquid-liquid microextraction (DLLME) [7] and hollow fibrebased liquid phase microextraction (HF-LPME) [8] Abbreviations: ACN, acetonitrile; CBZ, carbendazim; CE, capillary electrophoresis; DLLME, dispersive liquid-liquid microextraction; DMSO, dimethylsulfoxide; FBZ, fuberidazole; HF-LPME, hollow fiber-based liquid phase microextraction; HPLC, high-performance liquid chromatography; LOD, limit of detection; MCL, maximum concentration level; MISPE, molecularly imprinted solid phase extraction; RSD, relative standard deviation; SALLE, salting-out assisted liquid-liquid extraction; TP, thiophanate; TPM, thiophanate-methyl; UV, ultraviolet.…”

In‐capillary microextraction using monolithic polymers: Application to preconcentration of carbamate pesticides prior to their separation by MEKC

“…Even though in recent years several authors [7][8][9][10][11][12] have addressed in-line SPE-CE, to our knowledge none of them have employed MEKC as the separation mode owing to the destruction of the micellar media in the organic solvents commonly employed to elute the analytes.…”