A new method which is to use polyamide 6 nanofibers as solid phase will be developed to be coupled with column switching method in order to determine bisphenol A in environmental water samples. The parameters that will affect the extraction efficiency include column packing process and the amount of nanofiber polymer. This research will purpose a multiple reuse nanofibrous polymer in high pressure system. BPA level for water samples will be detected. The results will have high recovery, good precision and low limit of detection.
Several extraction parameters will be thoroughly investigated to enhance the extraction efficiency of the proposed extraction technique, an on-line SPE-UHPLC nanofibrous extraction. The parameters include composition and the flow rate of the washing mobile phase, the time taken of the extraction step, stability of nanofibers and column packing. This method is then assessed for linearity, relative recovery and reproducibility, limit of detection (LOD), limit of quantification (LOQ) and precision values (% RSD).
Pre-column with nanofibers will be used for extraction of samples. Supelco Ascentis® Express C18 (10 cm x 4.6 mm) column with 5µm of particle size will be used for separation. Water and methanol 95:05 (v/v) will be used as washing mobile phase. Water (solvent A) and acetonitrile (solvent B) will be used as gradient elution mobile phase.
50µL sample solution will be injected into the pre-column. The washing mobile phase will be used as a clean-up for the column. Pre-column will be washed for 1 minute at a flow rate of 1 mL min-1. The analytical column will be equilibrated to the initial conditions. BPA will be preconcentrated on the pre-column. Then, BPA will be eluted onto analytical column from the pre-column. The analysis will begin at 50% B. The concentration will be changed to 60% when 2 minutes is reached. Thereafter, concentration will be changed at 0.5 minute to 100% B. At 3.0rd minutes, the equilibration of the analytical column will be switched back to its initial conditions. The analytical and extraction column’s temperature will be set at 350C. The fluorescence detector will set for an excitation wavelength at 225 nm and an emission wavelength at 320 nm to detect BPA. 4.30 minutes will be used to run all the steps include extraction.
About 40g of PA6 nanofibers will be packed into a column cartridge (5 x 4.6 mm) and then will be fixed to the guard pre-column holder. UHPLC fittings will be used to connect the extraction pre-column to the system. 100% acetonitrile will be used to activate the sorbent for 15 minutes with an increasing flow rate. Then, wash with water for 5 minutes at flow rate of 1 mL min-1.
Polyamide 6 (PA6) will be dissolved in a mixture solution of formic acid and acetic acid (1:2 v/v) at 12 wt% concentration of PA6. Electrospinning is caused by a nanospider. The temperature and humidity level during electrospinning are 32% and 22.10C respectively. Nanofibers will be collected on nonwowen which caused a motion at the collecting electrode.
Water samples will be stored in the glass bottles at 40C. Samples will be filtered by 0.45µm PTFE syringe filters before analysis.
A standard solution will be prepared by dissolving bisphenol A in acetonitrile which have concentration of 1000mg/L. The standard solution will be stored at 40C in the dark.
A Nexera X2 UHPLC system (Shimadzu Corporation, Kyoto, Japan) will be provided with LC-30AD solvent delivery system, a DGU-20 A5R degassing tube, a SIL-30AS autosampler, a CBM-20A module and will be attached to an SPD-M30A DAD and RF-10AXL detector. In addition, a CTO-20AC column oven and a FCV-12AH high-pressure six-port switching valve. The evaluation of data will be accomplished by Shimadzu LC Lab Solution software version 5.57 (Shimadzu Corporation, Kyoto, Japan). A Nanospider NS1WS500U (Elmarco, Czech Republic) laboratory machine and patented technology will be used to developed the nanofibers.
Standard bisphenol A (;99% purity) will be purchased from Sigma-Aldrich, Chromasolv methanol and Chromasolv acetonitrile. Ultra-pure water will be purified by Mili-Q (Millipaore, Bedford, MA, USA). Nylon 6 will be purchased from BASF (Prague, Czech Republic).