Pharmaceuticals and personal care products (PPCPs) can enter agricultural fields through wastewater irrigation, biosolid amendments, or urine fertilization. Numerous studies have assessed the risk of PPCP contamination, however there are no standardized methodologies for sample treatment. This makes interpretation of reported results challenging. Various time periods between sampling and analysis have been reported (shipping, storage, drying, etc.), but literature is lacking in the evaluation of PPCP degradation amidst this process. This paper assessed the stability of 20 pharmaceuticals (200 mg/L) in soil and crops stored at -40°C for 7, 30, and 310 days. After 310 days, caffeine, meprobamate, trimethoprim, primidone, carbamazepine, anhydro-erythromycin and dilantin were stable (≥75% recovered) in all matrices. Acetaminophen, amitriptyline, bupropion, lamotrigine, sulfamethoxazole, naproxen, ibuprofen, paroxetine, were unstable after 30 days in at least one matrix. Due to variations in analyte stability, fortification with isotopically-labelled surrogates at the point of sample collection was evaluated in comparison to fortification prior to extraction, but after shipment and storage. Chromatographic peak areas of stable analytes were found to be reproducible (±15%) in field-fortified samples, indicating that no additional errors are committed under field conditions despite having a less controlled environment. Unstable analytes revealed notable differences in peak areas between fortification times, suggesting that field-fortification is crucial to account for analyte losses during shipping and storage in order to obtain accurate quantification of PPCPs.

Field fortification to improve analytical accuracy in fate and transport studies of pharmaceuticals in the environment

ACS Fall 2021

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