Page 204 - Materials Chemistry, Second Edition

Determination of Pharmaceutical Compounds in Sewage Sludge 185

solid KOH). Zhang et al. (2016) applied derivatization with BSTFA for 2 h at 40 °C
to the determination of acidic pharmaceuticals and estrogenic hormones. Zuo et al.
(2007) applied microwave irradiation to reduce the derivatization time of five estro-
genic hormones. Derivatization was carried out with BSTFA and TMCS in pyridine
solution by irradiation at 800 W for 60 s. Azzouz and Ballesteros (2012) applied
derivatization with BSTFA + 1% TMCS for 20 min at 70 °C to the determination
of eight pharmaceuticals (analgesics, antibacterials, anti-epileptics, β-blockers, lipid
regulators, and non-steroidal anti-inflammatories) in sewage sludge. LC-MS/MS has
been applied to the determination of a wider group of pharmaceutical compounds
than GC-MS (Table 9.1). For instance, Gago-Ferrero et al. (2015) and Peysson and
Vulliet (2013) developed LC-MS/MS methods for the determination of 148 and 136
pharmaceuticals, respectively. LC-MS/MS has also been applied to the determination
of pharmaceutical enantiomers. The method reported by Evans et al. (2015) allows the
determination of the enantiomers of 11 pharmaceutical compounds using a Chirobiotic
V column (Sigma-Aldrich, UK) packed with Vancomycin. The main problem associ-
ated with LC-MS/MS determination of pharmaceuticals in sewage sludge is matrix
effect. Matrix effect is due to co-extracted substances that cause signal suppression
or enhancement, especially when electrospray source is used. Gago-Ferrero et al.
(2015) reported signal suppression in the range from −92% to −3% for 136 out of the
148 target compounds and signal enhancement in the range of 11%–90% for the oth-
ers. Matrix-matched calibration curves are commonly applied for quantification when
matrix effect cannot be reduced by clean-up (Dorival-García et al., 2015). High per-
formance liquid chromatography (HPLC) with diode-array (DAD) and fluorescence
(Fl) detectors online has also been reported for the determination of pharmaceuti-
cals in sewage sludge (Martín et al., 2010). The main advantage of HPLC-DAD-Fl
is the use of relatively inexpensive detectors with adequate selectivity and sensitivity
(Ribeiro et al., 2013), which makes HPLC-DAD(Fl) significantly more affordable for
routine laboratories than LC-MS/MS (Martín et al., 2010). Moreover, the derivatiza-
tion required for GC-MS determination is not needed. Martín et al. (2012a) employed
HPLC-DAD-Fl to obtain information about the occurrence and fate of pharmaceu-
ticals in wastewater and sludge from WWTPs, their removal, the ecotoxicological
impact of wastewater discharges and sludge disposal (Martín et al., 2012a,b), and
their distribution and temporal evolution alongside sewage treatment (Martín et al.,
2012b). Ribeiro et al. (2013) applied HPLC-Fl to evaluate the enantioselectivity of the
biodegradation of alpreonolol and propranolol using a Vancomycin-based chiral col-
umn. The results indicated slightly higher biodegradation rates for the S-enantiomeric
forms of both β-blockers.

9.3 APPLICABILITY OF ANALYTICAL DETERMINATION OF
PHARMACEUTICALS IN SEWAGE SLUDGE: CASE STUDIES
Pharmaceutical compounds can be degraded or accumulated onto sludge depend-
ing not only on their different physicochemical properties but also on the different
composition of each type of sludge, which can result in different retention mecha-
nisms. The sorption onto sludge is strongly affected by many factors, including the
characteristics of the compound (molecular structure, in particular the presence of