In‐line extraction employing functionalized magnetic particles for capillary and microchip electrophoresis

Abstract

An approach to performing in-line extraction employing functionalized magnetic particles for CE and microchip electrophoresis is presented. Silica-coated iron oxide particles were synthesized and used as the solid support. The particles were functionalized with octadecylsilane and used as reverse-phase sorbents for in-line SPE followed by electrophoresis. Magnets were used to locally immobilize these sorbents inside the capillary or microchip. Extraction, elution, and detection of the analytes were performed sequentially without interruption or need for sample handling. Mixtures of hydrophobic analytes were successfully extracted from solution using the synthesized magnetic sorbents. CE was able to extract and separate mixture of parabens within 10 min. In-line extraction was also carried out on a disposable PMMA microfluidic device with LIF detection. Electrophoretic separation of fluorescent dyes, Rhodamine 110 and SulfoRhodamine B, was completed in under a minute. The results demonstrated the feasibility of performing the in-line extraction/separation technique in a microchip platform enabling rapid analysis, low sorbent consumption, and increased analyte recovery (relative to the capillary format).

Microchip Emitter for Solid-Phase Extraction–Gradient Elution–Mass Spectrometry

“…The obtained elution order for peptides of the model mixture 1 was confirmed by classical HPLC-MS analysis of this sample (data not shown) using similar water−methanol gradient (from 5% to 40% of methanol in eluent solution). The HPLC separation was performed on 5C 18 -MS II COSMOSIL column (5 μm particle diameter, 2.0 mm i.d. × 150 mm length, Nacalai Tesque, Kyoto, Japan) with Accela HPLC apparatus (Thermo Scientific, San Jose, U.S.A.) and Thermo LTQ Velos instrument (Thermo Scientific, San Jose, U.S.A.).…”

“…4 Different bead surface modifications have been used for the binding of small organic molecules, 5 vitamins, 6 peptides and proteins of blood serum, 1−3 glycopeptides, 7 phosphopeptides, 8 or allergens. 9 Peptide isolation, desalting and proteome profiling are mainly performed using Mbs with hydrophobic coatings (C 4 , C 8 , C 18 , etc.). 10,11 These are commercially available as ready-to-use kits based on wellestablished off-line protocols for protein or peptide purification, desalting and fractionation prior to MALDI-MS analysis 12,13 with potential process automation.…”

“…16,17 For further miniaturization, such couplings have been realized in a microfluidic format. 18 Mbs have been used to create SPE concentrator for SPE-HPLC or SPE-CE to replace polymer based monolithic columns 19 or frits and septa for the retention of nonmagnetic particles inside the microchips 20,21 and separation capillaries 22 to form packed-bed columns. Other advantages of Mbs as a sorbent stem from their easy manipulation by application/removal of external magnetic field and hence the possibility of fast sorbent plug renewal simply by system flushing.…”

On-Channel Micro-Solid Phase Extraction Bed Based on 1-Dodecanethiol Self-Assembly on Gold-Deposited Colloidal Silica Packing on a Capillary Electrochromatographic Microchip

“…10 Various efforts have been reported to increase the analytical sensitivity by means of detection signal enhancement, sample stacking or preconcentration by employing SPE beds. [11][12][13][14][15][16][17][18][19][20][21] Among those preconcentration of the analytes utilizing the SPE technique would be a good choice for sensitivity enhancement. Desirable analytes can be extracted to the proper extraction bed from complex sample matrix, and then released for the separation by eluting with a solvent with different polarity.…”

“…Recently, many works on the microchips with on-chip SPE capability have been reported. [14][15][16][17][18][19][20][21] Commercial C 18 -silica beads were slurry-packed in a SPE chamber for the extraction of Rhodamine B with 70-220 fold concentration enhancements. 18 Relatively large SPE chamber about ~7 mm long and four times wider than the microchannel was formed for the packing of large C 18 -silica beads (3 m) to get proper extraction capacity.…”