An analytical method for the simultaneous trace determination of acidic pharmaceuticals and phenolic endocrine disrupting chemicals in wastewater and sewage sludge by gas chromatography-mass spectrometry

Abstract

This article presents an analytical method based on solid-phase extraction (SPE) and gas chromatography coupled with mass spectrometry for the simultaneous determination of the most frequently used acidic pharmaceutical residues, ibuprofen, diclofenac, naproxen and ketoprofen (KFN), and phenolic endocrine disruptors, bisphenol (BPA), triclosan (TCS), nonylphenol, nonylphenol monoethoxylate and nonylphenol diethoxylate, in wastewater and sewage sludge samples. In the first phase of the study, each compound has been characterized individually and afterwards in mixture as a trimethylsilyl derivative in order to identify the characteristic ions (m/z ratio) constituting the mass spectrum and to choose the ions for quantification and confirmation. Subsequently, derivatization was evaluated by testing different variables such as the volume of the derivatization solvent bis(trimethylsilyl)trifluoroacetamide and the effect of each catalyst, pyridine and 1% trimethyl chlorosilane, in the derivatized solution. For the analysis of wastewater samples, two commercial SPE cartridges, C18 and Oasis HLB, were compared for their extraction efficiency of the target compounds. The key parameter of extraction procedure included the effect of pH (2.5, 5.3 and 7) of the loading solution. For solid samples, parameters such as the extracted biomass, the volume of the extraction organic solvent and the effect of matrix interferences in chromatographic analysis were evaluated. By using C18 cartridges as purification procedure and ultrasound sonication, satisfactory mean relative recoveries with BPA-d16 and meclofenamic acid as surrogates were obtained ranging from 91% to 117% for wastewater and 84% to 107% for sewage sludge samples. Nine-point calibration of the standard mixture was performed by linear regression analysis with a correlation coefficient >0.99 for all the tested compounds. Limits of detection for the developed methods were established between 0.3 (KFN) and 14.8 (BPA) ng L(-1), and 15.0 (TCS) and 32.9 (BPA) ng g(-1) for wastewater and sewage sludge, respectively. Application to real samples of the wastewater treatment plant in Athens, the capital of Greece, demonstrated the presence of all tested compounds in most of the samples.

Determination of emerging contaminants in environmental matrices

“…As shown in Table 2.2, LODs ranged from 0.5 to 3.6 ng g -1 and LOQs from 1.8 to 12.1 ng g -1 , being amitriptyline the compound with the highest limit, since it is the one that presents the quantifier MRM with lowest abundance. The LODs obtained with the proposed method are in the same range or lower than those reported by other authors in the analysis of pharmaceutical compounds in biosolids (Dobor et al, 2010;Martín et al, 2010;Peysson and Vulliet, 2013;Radjenovic et al, 2009a;Samaras et al, 2011). …”

“…In our study, we did not find residues of ketoprofen in any of the samples analyzed and naproxen was only found in three samples at low concentrations, from 12 to 23 ng g -1 (Jelic et al, 2011) performed the monitoring of pharmaceuticals in three conventional WWTPs over a period of two years and no residues of both NSAIDs were detected in any of the samples analyzed concluding that these compounds do not accumulate in sludge. Ketoprofen was not detected or quantified in sewage sludge from WWTPs in Athens (Greece) (Samaras et al, 2011) and Seville (Spain) (Martín et al, 2010), The anti-epileptic drug carbamazepine was not found in any of the samples at levels above LOD. Carbamazepine has a very low removal regardless of the treatment applied and does not adsorb onto the sludge (Jelic et al, 2011;Radjenovic et al, 2009b) although it has been found in sludge from different locations (Nieto et al, 2007(Nieto et al, , 2010aRadjenovic et al, 2009a).…”

“…Pharmaceutical substances are a source of increasing environmental concern and together with endocrine disrupting chemicals have been classified as the most frequently detected organic contaminants in the environment (Samaras et al, 2011).…”

“…Several methodologies have been developed for determination of pharmaceuticals in sewage sludge using pressurized liquid extraction (Ding et al, 2011;Jelic et al, 2009;Nieto et al, 2007;Radjenovic et al, 2009a;Saleh et al, 2011), ultrasound assisted extraction (Chenxi et al, 2008;Martín et al, 2010;Samaras et al, 2011), microwave assisted extraction (Dobor et al, 2010) and QuEChERS (Peysson and Vulliet, 2013).…”

“…Moreover, there is a clear impact on electrospray ionization of these compounds when working with complex matrices such as biosolids producing either ion enhancement or suppression that hinders the quantification of target compounds (Samaras et al, 2011).…”