Heart-cut two-dimensional separation method via hyphenation of micellar electrokinetic capillary chromatography and capillary zone electrophoresis using analyte focusing by micelle collapse.

A novel two-dimensional (2D) separation method, which hyphenated micellar electrokinetic capillary chromatography (MEKC) and capillary zone electrophoresis (CZE), was developed for analysis of flavonoids in Leonurus cardiaca. The Leonurus cardiaca sample was separated and purified in first dimension by MEKC. Then only a selected portion of the first dimension separation was transferred into the second dimension by pressure. Finally, the zone of flavonoids was separated by CZE. As the key to successful hyphenation of MEKC and CZE, an analyte focusing by micelle collapse (AFMC) concentration method was employed between the two dimensions to release analytes from the micelle interior to a liquid zone and to overcome the sample zone diffusion caused by mobilization pressure. The whole heart-cut 2D separation process can be performed in a conventional CE analyzer. The relative standard deviation of peak height, peak area and migration time were in the range of 2.3-4.2%, 1.5-3.8% and 3.6-5.5%, respectively, and detection limits (S/N=3) were 15-55 ng/mL. The new methodology was applied with success for the flavonoids separation of Leonurus cardiaca.

The long-term effect of carbon source on the competition between polyphosphorus accumulating organisms and glycogen accumulating organism in a continuous plug-flow anaerobic/aerobic (A/O) process.

Laboratory experiments were conducted in a continuous plug-flow anaerobic/aerobic (A/O) process to kinetically investigate the long-term effect of the different carbon sources (i.e., acetate, acetate/propionate, propionate and glucose) on the competition between polyphosphorus accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs). It was found that propionate was more benefit than acetate for PAOs even in the A/O process, and PAOs enriched with acetate were readily able to metabolize propionate without the requirement of adaptation. Glucose gave GAOs metabolic advantage in the PAOs-GAOs competition, which thereby worsened the EBPR performance. Nevertheless, the EBPR capacity could recover by returning carbon to acetate, with the acclimation time of approximately 2-SRTs. This suggests that the varying of carbon can be an effective approach to provide PAOs a competitive advantage over GAOs. Additionally, MLVSS/MLSS could indicate the shift of the microorganism between GAOs and PAOs, but it was not as precise as the biomass-P content.

Determination of aflatoxins in high-pigment content samples by matrix solid-phase dispersion and high-performance liquid chromatography.

A fast, efficient, and cost-effective method was developed for the analysis of aflatoxins in farm commodities with high-pigment content, such as chili powder, green bean, and black sesame. The proposed method involved matrix solid-phase dispersion (MSPD) and high-performance liquid chromatography (HPLC)-fluorescence detection (FLD) with postcolumn electrochemical derivatization in a Kobra cell. The MSPD procedure combined the extraction with neutral alumina and pigment cleanup with graphitic carbon black (GCB) in a single step. The recoveries of aflatoxins ranged from 88% to 95% with the relative standard deviations (RSD) less than 6% (n = 6). The limits of detection (LODs) were 0.25 ng/g aflatoxin B1, G1, and 0.10 ng/g aflatoxin B2, G2, respectively. The analytical results obtained by MSPD were compared to those of the immunoaffinity column (IAC) cleanup method. No significant differences were found between the two methods by t-test at the 95% confidence level.