Thousand fold concentration of an alkaloid in capillary zone electrophoresis by micelle to solvent stacking

Selective extraction of alkaloids in human urine by on-line single drop microextraction coupled with sweeping micellar electrokinetic chromatography

“…The LOD varied from 0.2 to 1.5 ng mL −1 at a signal-to-noise (S/N) of 3 and the LOQ varied from 0.7 to 4.8 ng mL −1 at a signal-to-noise (S/N) of 10. These values showed better in sensitivity as compared with those of former literatures [50][51][52][53], which indicated that the proposed method was sufficiently sensitive to detect the analytes in human urine. Good recoveries were obtained at three concentration levels ( Table 2).…”

On-line sample concentration and determination of cationic alkaloids in human plasma by micelle to solvent stacking in capillary zone electrophoresis

“…As a result, the analytes then experienced an electrophoretic inversion or reversal, resulting in an analyte accumulation at the MSSB. MSS has been applied to the analysis of cationic [34][35][36][37] and anionic [38][39][40] analytes in CZE, and cationic analytes in both MEKC [41] and nonaqueous capillary electrophoresis (NACE) [42]. Among them, Zhu et al developed an MSS-CZE method for the determination of two different cationic alkaloids (ephedrine and berberine) in human urine samples [36] and an MSS method in nonaqueous capillary electrophoresis (NACE) for the determination of berberine and jatrorrhizine in urine samples [42].…”

“…To overcome this problem, some on-line preconcentration strategies have been developed to increase the sensitivity of CE, such as field amplification [20], dynamic pH junction [21], transient isotachophoresis (tITP) [22], isotachophoresis by acetonitrile stacking [23,24] and sweeping [25] or sweeping in couple with other techniques [26][27][28][29]. The more recent CE on-line preconcentration techniques include electrokinetic supercharging [30], analyte focusing by micelle collapse (AFMC) [31][32][33] and micelle to solvent stacking (MSS) [34][35][36][37][38][39][40][41][42]. The main advantage of the on-line preconcentration strategies is the ease of experimental manipulations without the need of modifications of the commercial CE instrumentation.…”

Determining ultraviolet absorbents in sunscreen products by combining direct injection with micelle collapse on-line preconcentration capillary electrophoresis

“…On-line preconcentration techniques in advance of MEKC can stack large sample ions in a narrow band by the manipulation of electrophoretic velocities, and several on-line preconcentration methods have been developed to increase sensitivity. Stacking strategies include micelle to solvent stacking [16][17][18][19], analyte focusing by micelle collapse-micellar electrokinetic chromatography (AFMC-MEKC) [20][21][22][23][24][25] and so on. Of these techniques, analyte focusing by micelle collapse-micellar electrokinetic chromatography (AFMC-MEKC) was introduced by Quirino et al [26] and enhanced the sensitivity by 160-to 200-fold compared to the MEKC mode.…”