Investigation on parabens occurrence in Romanian WWTP sludge by LC-MS/MS method

A sensitive and precise method for detection of five parabens in sewage sludge was developed based on
ultrasonic assistedextraction, SPE clean-up and LC-MS/MS. Most of the parameters that affect the extraction
step such as type of solvent and volume, extraction time were optimized. For ultrasonic extraction it was
used a mixture of methanol: acetone, then the extract was centrifuged in order to obtain clean supernatant
and the extract was purified on polymericSPE cartridges. The parabens were separated on C18 column in
13 min at 18ºC using a gradient of mobile phase of 0.01% acetic acid and acetonitrile. Using the method,
limit of quantitation (LOQ) were obtained ranging from 0.4 to 2ng/g. All recoveries ranged from 71% to 109%
for all compounds. The repeatability and reproducibility between days expressed as RSD (%) were less than
7.4% and 14.5%, respectively. The sum concentrations of all parabens for each sludge sample ranged
between 19 ng/g dry weight and 32.7 ng/g dry weight. The study of the profile sample composition shows
that the average contribution of each compound of the total parabens concentration was as follow: methyl
paraben 62.9%, ethyl paraben 18.6%, iso-propyl paraben 10.9%, propyl paraben 10.8%. This result indicate
that methyl paraben is the most used paraben followed by ethyl paraben.