Solid‐Phase Extraction Coupled to High Performance Liquid Chromatography Using a Micro Device Packed with Triacontyl‐Bonded Silica

Abstract

A comparison study of the adsorption capacity of octadecyl‐ and triacontyl‐ bonded phases was conducted. The latter exhibited greater capacity for phthalates dissolved in water than the former. A new device containing triacontyl packing was developed to couple solid‐phase extraction (SPE) to narrow‐bore column high performance liquid chromatography (HPLC) with ultraviolet absorption detection. The device consisted of a syringe filter unit packed with triacontyl‐bonded silica, a gas‐tight syringe (no needle), and an HPLC injection syringe needle. After a sample solution filled in a 5 mL syringe was delivered to the device by use of a syringe pump, the syringe was replaced with a 250 µL syringe filled with an eluting solvent. By inserting the needle of the device into the needle port of an injection valve followed by forcing the solvent through the packed bed, the analyte was desorbed from the bed and introduced into the sample loop of the valve. On rotating the valve, the extract was introduced into an HPLC column and separation was started. The performance of the device was evaluated by using diheptyl phthalate (DHP) and di‐2‐ethylhexyl phthalate (DEHP), spiked in water as samples. Preconcentration factors of 58 and 51 were attained with the device for DEP and DEHP, respectively. The method was linear in the range 1.0–50 ng/mL. Limits of detection (LOD)s were found to be 0.8 and 0.9 ng/mL for DHP and DEHP, respectively.

Keywords:

• Solid‐phase extraction
• phthalates
• water analysis