Optimization of the separation of chlorophenols with stepwise gradient elution in reversed phase liquid chromatography

A novel mixed-mode adsorbent was prepared by functionalizing silica with tris(2-aminoethyl)amine and 3-phenoxybenzaldehyde as the main mixed-mode scaffold due to the presence of the plentiful amino groups and benzene rings in their molecules. The adsorption mechanism was probed with acidic, natural and basic compounds, and the mixed hydrophobic and ion-exchange interactions were found to be responsible for the adsorption of analytes. The suitability of dispersive solid-phase extraction was demonstrated in the determination of chlorophenols in environmental water. Several parameters, including sample pH, desorption solvent, ionic strength, adsorbent dose, and extraction time were optimized. Under the optimal extraction conditions, the proposed dispersive solid-phase extraction coupled with high-performance liquid chromatography showed good linearity range and acceptable limits of detection (0.22∽0.54 ng/mL) for five chlorophenols. Notably, the higher extraction recoveries (88.7∽109.7%) for five chlorophenols were obtained with smaller adsorbent dose (10 mg) and shorter extraction time (15 min) compared with the reported methods. The proposed method might be potentially applied in the determination of trace chlorophenols in real water samples.

Section: Introductionmentioning

confidence: 99%

Fabrication of a novel hydrophobic/ion‐exchange mixed‐mode adsorbent for the dispersive solid‐phase extraction of chlorophenols from environmental water samples

Gao

Wei

2016

“…A variety of methods including GC , electrophoresis , spectrophotometry , micellar LC and HPLC were used for analysis of chlorophenols in convoluted matrices. However, these instrumental techniques have limited sensitivity to detect trace amounts of analytes in complicated matrices.…”

Section: Introductionmentioning

confidence: 99%

Ultrasound‐assisted supramolecular‐solvent‐based microextraction combined with high‐performance liquid chromatography for the analysis of chlorophenols in environmental water samples

Karimiyan

Hadjmohammadi

2016

Ultrasound-assisted supramolecular-solvent-based microextraction combined with high-performance liquid chromatography for the analysis of chlorophenols in environmental water samplesAn efficient, inexpensive and environmentally benign ultrasound-assisted supramolecularsolvent-based microextraction technique combined with high-performance liquid chromatography was used for the determination of chlorophenols in environmental water samples. Different factors such as amount of decanoic acid, volume of tetrahydrofuran, pH of the sample, ultrasound time and ionic strength were investigated and optimized. The optimized extraction conditions were 60 mg decanoic acid, 1.5 mL tetrahydrofuran, 3 min ultrasound time, without salt addition. Under this condition, the extraction recoveries were 83.0-89.3 with preconcentration factors of 94-102. The calibration curves were linear from 5.0-400.0 ng/mL with square of the correlation coefficient higher than 0.9998 and the limits of detection were between 1.5-2.0 ng/mL. The values of intra-and inter-day relative standard deviations were 3.2-6.0 and 7.3-8.0%, respectively. Analysis of different samples showed that the concentration of 2,5-dichlorophenol in Babolrood river water was 80.6 ng/mL.

“…(1) is carried out when the retention is described by the quadratic model (Eq. (10)) or by other nonintegrable equations, where the gradient time is calculated by splitting the integral into multiple small isocratic steps [12,13]. On the other hand, different approaches have been used to derive Eq.…”

Section: Introductionmentioning

confidence: 99%

Some insights on the description of gradient elution in reversed‐phase liquid chromatography

Baeza-Baeza

García-Álvarez-Coque

2014

The so-called "fundamental equation for gradient elution" has been used for modeling the retention in gradient elution. In this approach, the instantaneous retention factor (k) is expressed as a function of the change in the modifier content (φ(ts )), ts being the time the solute has spent in the stationary phase. This approach can only be applied at constant flow rate and with gradients where the elution strength depends on the column length following a f(t-l/u) function, u being the linear mobile phase flow rate, and l the distance from the column inlet to the location where the solute is at time t measured from the beginning of the gradient. These limitations can be solved by using the here called "general equation for gradient elution", where k is expressed as a function of φ(t,l). However, this approach is more complex. In this work, a method that facilitates the integration of the "general equation" is described, which allows an approximate analytical solution with the quadratic retention model, improving the predictions offered by the "linear solvent strength model." It also offers direct information about the changes in the instantaneous modifier content and retention factor, and gives a meaning to the gradient retention factor.