Styrene is used in a variety of chemical industries. Environmental and occupational exposures to styrene occur predominantly through inhalation. The major metabolite of styrene is present in two enantiomeric forms, chiral R- and S- hydroxy-1-phenyl-acetic acid (R-and S-mandelic acid, MA). Thus, the concentration of MA, particularly of its enantiomers, has been used in urine tests to determine whether workers have been exposed to styrene. This study describes a method of analyzing mandelic acid using molecular imprinting techniques and HPLC detection to perform the separation of diastereoisomers of mandelic acid. The molecularly imprinted polymer (MIP) was prepared by non-covalent molecular imprinting using (+) MA, (-) MA or (+) phenylalanine, (-) phenylalanine as templates. Methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) were copolymerized in the presence of the template molecules. The bulk polymerization was carried out at 4ºC under UV radiation. The resulting MIP was grounded into 25~44¼m particles, which were slurry packed into analytical columns. After the template molecules were removed, the MIP-packed columns were found to be effective for the chromatographic resolution of (±)-mandelic acid. This method is simpler and more convenient than other chromatographic methods.

Ibuprofen and ketoprofen are chemically similar non-steroidal anti-inflammatory drugs widely used in the treatment of arthritis. Using a molecular imprinting technique, a simple and rapid method was developed for the simultaneous separation and determination of ibuprofen and ketoprofen. Molecular imprinting introduces artificial binding sites into a synthetic polymer matrix, allowing it to exhibit selective rebinding of template molecules. Imprinted polymers can be regarded as an HPLC stationary phase, important for pharmaceutical analysis.Most molecularly imprinted polymers (MIPs) are synthesized by free radical polymerization of functional monomers, resulting in an excess of crosslinking monomers. In this study, MIPs have been prepared with a ibuprofen template, which can form intramolecular hydrogen bonds. Methacrylic acid (MAA) and ethyleneglycol dimethacrylate (EGDMA) were used as the functional monomer and cross-linker, respectively. Bulk polymerization was carried out at 4°C under UV radiation. The resulting MIP was ground into 25~44 mm particles, which were slurry-packed into analytical columns. Template molecules were removed by methanol-acetic acid (9:1, v/v). We evaluated the template binding performance of the MIP using HPLC, with ultraviolet (UV) detection at 234 nm. Chromatographic resolution of ibuprofen and ketoprofen on the MIPs were appraised using buffer/acetonitrile (45/55, v/v) as the mobile phase. Results show that the MIPs prepared using ibuprofen as the template had a significant molecular imprinting effect. The method was successfully applied to the separation and analysis of ibuprofen and ketoprofen in pharmaceuticals.

Two molecularly imprinted polymers (MIPs) were prepared using (S)-ibuprofen as the template molecule as well as methacrylic acid (MAA) or 4-vinylpyridine and ethylene glycol dimethacrylate (EGDMA) as the functional monomer and crosslinker, respectively. Free radical polymerization was carried out at 4 degrees C under ultraviolet (UV) radiation. The MIPs thus obtained were ground into 25-44 mu m, which were slurry packed into analytical columns. The template molecules were removed by acetic acid/methanol solution (1:9, v/v). high-performance liquid chromatography (HPLC), with UV detection, was used to evaluate the binding performance of the MIP for the template. The selectivity of (S)-ibuprofen and naproxen on the host-guest system were assessed using acetonitrile-based mobile phases. The limits of detection of ibuprofen and naproxen were found to be 0.1844 mmol/L and 0.3264 mmol/L, while the limits of quantitation were 0.6262 mmol/L and 1.0909 mmol/L, respectively. The stationary phase was applied successfully to the commercial tablet analysis. Ibuprofen and naproxen were extracted from tablets with acetonitrile; analysis results showed a good relative standard deviation (RSD) of 0.81-1.24% and accuracy from -4.01 to +2.98% for ibuprofen as well as an RSD of 0.59-0.86% and accuracy from -4.01 to -2.01% for naproxen. (c) 2006 Wiley Periodicals, Inc

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