Determination of pharmaceuticals in freshwater sediments using ultrasonic-assisted extraction with SPE clean-up and HPLC-DAD or LC-ESI-MS/MS detection

Abstract

A robust and sensitive analytical method is presented for the extraction and determination of six pharmaceuticals in freshwater sediments. The pharmaceuticals were extracted from sediment using ultrasonic extraction with 2% NH 4 OH in methanol (MeOH), followed by extraction into 2% formic acid in MeOH and then MeOH only. The resulting extracts were then analysed, after clean-up on HLB solid phase extraction cartridges, using a single gradient run using a Zorbax Eclipse XDB-C18 (150 × 4.6 mm, 5 m) column and a mobile phase consisting of 10 mM ammonium acetate and MeOH (pH=4.8). Analytes were detected and quantified using either Diode Array Detector (DAD) or tandem mass spectrometry (MS/MS) with electrospray ionization in positive mode. Validation studies were carried out using ten sediments sampled from the UK and Iraq with a wide range of characteristics. The mean calculated recoveries for fortified samples in all studied sediments ranged from 74.5 to 114.6% for atenolol, 72.3 to 124.9% for amitriptyline, 76.5 to 105% for mefenamic acid and 70.1 to 102% for diltiazem. Cimetidine and ranitidine showed lower recoveries which ranged from 40.2 to 68.4% and 30.4 to 55.2% respectively. Relative standard deviations (RSD) of recoveries for all sediment-pharmaceutical combinations ranged from 1.6 to 15.8%. The detection limits in sediments for the six analytes ranged from 15 to 58.5 ng g -1 and 0.03 to 3.5 ng g

Multi-residue enantioselective analysis of chiral drugs in freshwater sediments

“…Such limits enable the determination of drugs at the enantiomeric level considering the concentrations previously reported in sediments (Vazquez-Roig et al 2010;Silva et al 2011). Furthermore, the method detection and quantitation limits are similar to previously published achiral methodologies for sediments (Vazquez-Roig et al 2010;Al-Khazrajy and Boxall 2017).…”

Factors affecting the dissipation of pharmaceuticals in freshwater sediments

“…The study pharmaceuticals were extracted from the test sediments using sonication‐assisted extraction, and extracts were then cleaned up using solid‐phase extraction (SPE) according to the procedures previously developed by our group (Al‐Khazrajy and Boxall ). In brief, frozen samples were thawed at room temperature, then 10 mL of 2% NH 4 OH in methanol was added.…”

“…The performance of the analytical method (precision, accuracy, limit of detection [LOD], and limit of quantification) are described in Al‐Khazrajy and Boxall (). Recoveries for the test chemicals ranged from 40.1% (ranitidine in Bishop Wilton sediment) to 120.6% (amitriptyline in Harborough sediment), and LODs ranged from 0.02 (diltiazem) to 2.5 ng/g (mefenamic acid).…”

Targeted multi-analyte UHPLC-MS/MS methodology for emerging contaminants in septic tank wastewater, sludge and receiving surface water

“…The USE method for the extraction of sediments described by Al-Khazrajy and Boxall 25 was modified to optimise extraction of the selected 68 ECs from sludge. To accommodate the higher concentrations of ECs in sludge compared to sediments, 60 a smaller mass of 0.1 g was used.…”

“…[9][10][11] It is a suitable approach to determine low concentrations of ECs in the presence of other organics at comparatively high concentrations in complex environmental matrices, such as wastewater. 9,11,19,25 Typically, solid phase extraction (SPE) is used to enrich, isolate and/or purify the target ECs, with reversed-phase hydrophilic-lipophilic balanced (HLB) polymeric sorbents being the most common. 3,26,27 Although a wide range of compounds can be analysed with HLB sorbents, recoveries are low for very polar compounds such as the antidiabetic drug metformin.…”