title: A combination of statistical and analytical evaluation methods as a new optimization strategy for the quantification of pharmaceutical residues in sewage effluent.
abstract: In this study, a new solid-phase microextraction (SPME) method for simultaneous extraction of pharmaceutical compounds with acidic and basic characteristics (ibuprofen, fenoprofen, diclofenac, diazepam and loratadine) from residual water samples is proposed. In this procedure, the extraction is processed using two distinct sample pH values. The extraction is begun at pH 2.5 to promote the sorption of acidic pharmaceuticals and after 35 min the sample pH is changed to 7.0 by adding 0.4 mol L(-1) disodium hydrogenphosphate, so that the basic compounds can be sorbed by the fiber (20 min). The pH change is performed without interruption of the extraction process. A comparison between the proposed method and the SPME method applied to each group of the target compounds was performed. Gas chromatography coupled to mass spectrometry was used for separation and detection of analytes. The extraction conditions for the three methods were optimized using full factorial experimental design, response surface through a Doehlert matrix and central composite design. Limits of detection (0.02-0.43 microg L(-1)) and correlation coefficients (0.9970-0.9998) were determined for the three methods. The proposed extraction procedure was applied to samples of sewage treatment plant effluent and untreated wastewater. Recovery and relative standard deviation values ranged from 67 to 116% and 4.6 to 14.5%, respectively, for all compounds studied. Modification of sample pH during the extraction procedure was shown to be an excellent option for all of the compounds and may be extended to the simultaneous extraction of other compounds with different acid-base characteristics.
authors.affiliation: Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, SC 88040-900, Brazil.
authors.forename: Eliane A
authors.initials: EA
authors.lastname: Suchara
authors.forename: Dilma
authors.initials: D
authors.lastname: Budziak
authors.forename: Edmar
authors.initials: E
authors.lastname: Martendal
authors.forename: Lea L F
authors.initials: LL
authors.lastname: Costa
authors.forename: Eduardo
authors.initials: E
authors.lastname: Carasek
mesh_terms: D008401:Gas Chromatography-Mass Spectrometry; D006863:Hydrogen-Ion Concentration; D015999:Multivariate Analysis; D004364:Pharmaceutical Preparations / Q000032:analysis*; D012680:Sensitivity and Specificity; D012722:Sewage / Q000737:chemistry*
chemical_list: D004364:Pharmaceutical Preparations; D012722:Sewage