Merck

A solid-phase extraction method for rapidly determining the adsorption coefficient of pharmaceuticals in sewage sludge.

Water research (2014-10-10)
Laurence Berthod, Gary Roberts, David C Whitley, Alan Sharpe, Graham A Mills
RESUMEN

The partitioning of pharmaceuticals in the environment can be assessed by measuring their adsorption coefficients (Kd) between aqueous and solid phases. Measuring this coefficient in sewage sludge gives an indication of their partitioning behaviour in a wastewater treatment plant and hence contributes to an understanding of their subsequent fate. The regulatory approved method for measuring Kd in sewage sludge is the US Environmental Protection Agency's Office of Prevention, Pesticides and Toxic Substances (OPPTS) guideline 835.1110, which is labour intensive and time consuming. We describe an alternative method for measuring the Kd of pharmaceuticals in sewage sludge using a modified solid-phase extraction (SPE) technique. SPE cartridges were packed at different sludge/PTFE ratios (0.4, 6.0, 24.0 and 40.0% w/w sludge) and eluted with phosphate buffer at pH 7.4. The approach was tested initially using three pharmaceuticals (clofibric acid, diclofenac and oxytetracycline) that covered a range of Kd values. Subsequently, the sorption behaviour of ten further pharmaceuticals with varying physico-chemical properties was evaluated. Results from the SPE method were comparable to those of the OPPTS test, with a correlation coefficient of 0.93 between the two approaches. SPE cartridges packed with sludge and PTFE were stable for up to one year; use within one month reduced variability in measurements (to a maximum of 0.6 log units). The SPE method is low-cost, easy to use and enables the rapid measurement of Kd values for a large number of chemicals. It can be used as an alternative to the more laborious full OPPTS test in environmental fate studies and risk assessments.

MATERIALES
Referencia del producto
Marca
Descripción del producto

USP
Methyl alcohol, United States Pharmacopeia (USP) Reference Standard
USP
Residual Solvent Class 2 - Acetonitrile, United States Pharmacopeia (USP) Reference Standard
Sigma-Aldrich
Potassium phosphate monobasic, meets analytical specification of Ph. Eur., NF, E340, anhydrous, 98-100.5% (calc. to the dried substance)
Sigma-Aldrich
Potassium phosphate dibasic, ACS reagent, ≥98%
Sigma-Aldrich
Acetonitrile, ReagentPlus®, 99%
Sigma-Aldrich
Potassium phosphate monobasic, ACS reagent, ≥99.0%
Sigma-Aldrich
Acetonitrile, biotech. grade, ≥99.93%
Sigma-Aldrich
Acetonitrile, suitable for DNA synthesis, ≥99.9% (GC)
Sigma-Aldrich
Acetonitrile, puriss. p.a., ACS reagent, reag. Ph. Eur., ≥99.5% (GC)
Sigma-Aldrich
Acetonitrile, ACS reagent, ≥99.5%
Sigma-Aldrich
Acetonitrile
Sigma-Aldrich
Potassium phosphate monobasic, buffer substance, anhydrous, puriss. p.a., ACS reagent, reag. ISO, reag. Ph. Eur., 99.5-100.5%
Sigma-Aldrich
Potassium phosphate dibasic, puriss. p.a., ACS reagent, anhydrous, ≥99.0% (T)
Sigma-Aldrich
Acetonitrile, suitable for HPLC, gradient grade, ≥99.9%
Sigma-Aldrich
Acetonitrile, suitable for HPLC-GC, ≥99.8% (GC)
Sigma-Aldrich
Acetonitrile, suitable for HPLC, gradient grade, ≥99.9%
Sigma-Aldrich
Acetonitrile, HPLC Plus, ≥99.9%
Supelco
Methanol solution, contains 0.10 % (v/v) formic acid, UHPLC, suitable for mass spectrometry (MS), ≥99.5%
Millipore
Oxytetra Selective Supplement, suitable for microbiology
USP
Monobasic potassium phosphate, United States Pharmacopeia (USP) Reference Standard
Sigma-Aldrich
Acetonitrile, electronic grade, 99.999% trace metals basis
Sigma-Aldrich
Potassium phosphate monobasic, powder, suitable for cell culture, suitable for insect cell culture, suitable for plant cell culture, ≥99.0%
Supelco
Acetonitrile, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Monobasic Potassium Phosphate, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Acetonitrile, HPLC Plus, ≥99.9%, poly-coated bottles
Sigma-Aldrich
Acetonitrile, anhydrous, 99.8%
Sigma-Aldrich
Acetonitrile, ≥99.5%, ACS reagent
Sigma-Aldrich
Sodium phosphate, 96%
Sigma-Aldrich
Potassium phosphate dibasic, 99.95% trace metals basis
Sigma-Aldrich
Potassium phosphate monobasic, 99.99% trace metals basis