The effect of extraction methodology on the recovery and distribution of naphthenic acids of oilfield produced water

Saer Samanipour; Maryam Hooshyari; Jose A Baz-Lomba; Malcolm J Reid; Monica Casale; Kevin V Thomas

doi:10.1016/j.scitotenv.2018.10.264

The effect of extraction methodology on the recovery and distribution of naphthenic acids of oilfield produced water

Sci Total Environ. 2019 Feb 20:652:1416-1423. doi: 10.1016/j.scitotenv.2018.10.264. Epub 2018 Oct 26.

Authors

Saer Samanipour¹, Maryam Hooshyari², Jose A Baz-Lomba³, Malcolm J Reid³, Monica Casale², Kevin V Thomas⁴

Affiliations

¹ Norwegian Institute for Water Research (NIVA), Oslo 0349, Norway. Electronic address: saer.samanipour@niva.no.
² Department of Pharmacy, Genova University, Viale Cembrano 4, Genova 16147, Italy.
³ Norwegian Institute for Water Research (NIVA), Oslo 0349, Norway.
⁴ Norwegian Institute for Water Research (NIVA), Oslo 0349, Norway; Queensland Alliance for Environmental Health Science (QAEHS), University of Queensland, 20 Cornwall Street, Woolloongabba, QLD 4102, Australia.

PMID: 30586826
DOI: 10.1016/j.scitotenv.2018.10.264

Abstract

Comprehensive chemical characterization of naphthenic acids (NAs) in oilfield produced water is a challenging task due to sample complexity. The recovery of NAs from produced water, and the corresponding distribution of detectable NAs are strongly influenced by sample extraction methodologies. In this study, we evaluated the effect of the extraction method on chemical space (i.e. the total number of chemicals present in a sample), relative recovery, and the distribution of NAs in a produced water sample. Three generic and pre-established extraction methods (i.e. liquid-liquid extraction (Lq), and solid phase extraction using HLB cartridges (HLB), and the combination of ENV+ and C8 (ENV) cartridges) were employed for our evaluation. The ENV method produced the largest number of detected NAs (134 out of 181) whereas the HLB and Lq methods produced 108 and 91 positive detections, respectively, in the tested produced water sample. For the relative recoveries, the ENV performed better than the other two methods. The uni-variate and multi-variate statistical analysis of our results indicated that the ENV and Lq methods explained most of the variance observed in our data. When looking at the distribution of NAs in our sample the ENV method appeared to provide a more complete picture of the chemical diversity of NAs in that sample. Finally, the results are further discussed.

Keywords: Chemical space; Chemometrics; Extraction recovery; LC-HRMS; Naphthenic acids; Produced water.