Page 203 - Materials Chemistry, Second Edition

184 Life Cycle Assessment of Wastewater Treatment

the type of solid sorbent, elution solvent, and amount of additives. Recently, a few
methods based on MSPD have been reported for the determination of pharmaceu-
ticals in sewage sludge. Triñanes et al. (2016) reported a method for the determina-
tion of non-steroidal anti-inflammatory drugs. They proposed soaking 0.2 g of dried
sludge sample with 100 μL of aqueous potassium hydroxide solution, mixing with
anhydrous sodium sulfate, and adding 1 g of Florisil. The mixture was introduced
into an empty column containing a 3 g layer of silica as clean-up sorbent. Elution was
carried out with 15 mL of hexane:acetone (1:2, v/v). Analytical determination was
carried out by liquid chromatography/quadrupole time-of-flight mass spectrometry
(LC-QTOF-MS). Recoveries in the range of 86%–105% and LOQs in the range of
−1
0.005–0.05 ng g were obtained. Li et al. (2016) reported a method for the deter-
mination of 45 pharmaceuticals. Their best results were obtained by mixing sludge
(0.1 g) with C18 and eluting with methanol and acetonitrile:oxalic acid 5% (8:2, v/v).
Analytical determination was carried out by LC-MS/MS. Recoveries were in the
range of 50%–107%, RSD% was lower than 15%, and LOQs were in the range of
−1
0.11–5.5 ng g .

9.2.2 exTracT clean-up
After sample extraction by UAE, MAE, and PLE, clean-up is usually applied to
eliminate interfering compounds that can affect analytical determination, especially
when LC-MS/MS with electrospray ionization source is employed (Table 9.1). The
most frequently used technique for extract clean-up is SPE using Oasis HLB car-
tridges (Okuda et al., 2009; Barron et al., 2008; Dobor et al., 2010; Martín et al., 2010).
Nevertheless, the use of other cartridges such as Oasis MAX (Seira et al., 2013) and
Oasis MCX (Petrie et al., 2016), among others, has also been reported (Table 9.1).
For instance, Ternes et al. (2005) reported the use of Oasis MCX cartridges for acidic
pharmaceuticals, RP-C18 for neutral pharmaceuticals, and ENV+solute® /RP-C18
for iodinated contrast media.

9.2.3 analyTical DeTerMinaTion
LC-MS/MS is widely used for the determination of pharmaceuticals in sewage sludge
(Zuloaga et al., 2012; Omar et al., 2016) (Table 9.1). Nevertheless, due to the high cost
of LC-MS/MS, this equipment is unaffordable for many laboratories, making routine
control of pharmaceuticals in sewage sludge difficult. In such cases, gas chroma-
tography-mass spectrometry (GC-MS) can be an excellent alternative that provides
comparable sensitivity and specificity to the LC-MS/MS system (Omar et al., 2016).
Nevertheless, because most pharmaceuticals are polar and relatively non-volatile
compounds, their analysis by GC-MS requires a previous derivatization step (Yu and
Wu, 2012; Kumirska et al., 2015; Zhang et al, 2016). GC-MS has been commonly
used for the determination of acidic pharmaceuticals (Dobor et al., 2010) and estro-
gens after derivatization. Kumirska et al. (2015) applied GC-MS to the determination
of eight non-steroidal anti-inflammatory drugs and five estrogens. Derivatization was
performed at 60 °C for 30 min by adding N,O-bis(trimethylsilyl)trifluoroacetamide
(BSTFA) containing 1% of trimethylchlorosilane (TMCS) and pyridine (dried with