Zooplankton samples were collected from 18 stations in both summer and winter (2017), and their polycyclic aromatic hydrocarbon contents were measured by gas chromatography-mass spectrometry after ultrasound-assisted extraction. 
gas chromatography-mass spectrometry
Zooplankton samples were collected from 18 stations in both summer and winter (2017), and their polycyclic aromatic hydrocarbon contents were measured by gas chromatography-mass spectrometry after ultrasound-assisted extraction. 
ultrasound-assisted extraction