Determination of Naphthlene in Soil Samples by Room Temperature Phosphorescence with Selective Enrichment on α-Cyclodextrin Modified Monolithic Material

Abstract

The α-cyclodextrin(CD) modified organic monolithic materials were synthesized and applied for the enrichment of polyaromatic compounds from environmental samples.Application of the modified materials in the solid extraction-room temperature phosphores(SPE-RTP) were studied and compared.The room temperature phosphorescence behaviors of 14 organic compounds on the α-CD modified substrate were examined.Compared with the β-CD modified material,the α-CD modified monolithic materials have less RTP background and therefore better sensitivity as well as enrichment capabilities for the double ring aromatic substances.The partition constants of naphthlene and 7,8-benzoquinolin on α-CD modified monolith were found to be 5.03×103 and 2.94×102,respectively,indicating that α-CD modified monolith has higher selectivity for naphthlene.Naphthol can form inclusion complex also with α-CD modified monolith.However,because of the large polarity and solubility in water,the extraction efficiency at higher concentration is relatively low.The largest enrichment volume for the concentration of 5×10-11 mol/mL naphthlene is 300 mL.With SPE-RTP,the detection limits for naphthlene and 7,8-benzoquinolin are 9.80×10-12 mol/mL and 4.60×10-11 mol/mL,respectively.The linear ranges are 5.00×10-11~8.00×10-9 mol/mL and 6.00×10-11 ~5.00×10-10 mol/mL,respectively,with RSD less than 3.7%.α-CD modified membrane was applied to the determination of naphthalene in polluted soil samples and results were further verified by GC-MS.With one step extraction by cyclohexane and then followed by SPE-RTP,naphthlene can be selectively concentrated from soil samples.With 0.012 8 mg naphthlene spiked in the soil samples,the recovery is(104.9±6.5)%.The concentration of naphthlene in the soil samples was determined as(5.61±0.12) mg/kg,which was in accord with the results of GC-MS.