Disk-based solid phase extraction for the determination of diclofenac and steroidal estrogens E1, E2 and EE2 listed...

The aim of this study was to develop and validate an analytical method for determining estrone, 17β-estradiol, 17α-ethynyl estradiol and diclofenac in whole surface water samples at or below the limits of quantification as set out in Decision 2015/495/EU. The method is based on solid-phase extraction using Atlantic® HLB disks in a semi-automated system (SPE-DEX® 4790). The method involved extracting 10L of whole surface water samples followed by derivatization with N-methyl-N-(trimethylsilyl)trifluoroacetamide) and analysis by gas chromatography-mass spectrometry. Drying the disks overnight at 25°C followed by elution with ethyl acetate resulted in extraction recoveries between 75.9% and 120% and limits of quantification of 0.290ngL^-1 for estrone, 1.37ngL^-1 for 17β-estradiol, 0.724ngL^-1 for 17α-ethynyl estradiol and 0.119ngL^-1 for diclofenac. Despite extracting 10L of sample, obtained limits of quantification for 17β-estradiol and 17α-ethynyl estradiol were above those set in the Decision 2015/495/EU, while limits of quantification for estrone and diclofenac were lower. The method was applied to six Slovene surface waters, among which four contained detectable concentrations of only diclofenac (0.313ngL^-1-5.69ngL^-1). To our knowledge, this is the first study reporting a large volume solid-phase extraction using disks for the determination of estrone, 17β-estradiol, 17α-ethynyl estradiol and diclofenac in whole surface waters.