Improvement And Application Of A Time-series Sampler For Monitoring Polycyclic Aromatic Hydrocarbons In Water

Sample collection,which has a great effect on the accuracy and reliability of the monitoring data,is a key step in the environmental monitoring.Passive sampling is widely applied in the collecting of polycyclic aromatic hydrocarbons(PAHs)in waters,but it is unable to get time-series data.Based on osmotic pump(OP)and liquid phase microextraction(LPME),a time-series sampler(OP-LPME sampler)has been developed in our research group.It could be used to collect PAHs in water and time-series data could be obtained.However,this sampler is still in its early stage,more work is needed.In this study,the OP-LPME sampler was modified and the performance reference compound(PRC)calibration method was investigated.Finally,the modified sampler was tested in Jiulong River to monitor time-series concentrations of PAHs.The main work and results of this study are summarized as follows:(1)The extraction solvents were optimized.Due to its low loss during extraction and high extraction efficiency for PAHs in water,n-heptane was selected as the extraction solvent of the sampler.The use of n-heptane makes it feasible to use PRC to calibrate the sampler.CuCl2 solution with bright color was used as the segment solution to separate extraction solution because its segment would not be broken when moving inside extraction tube.This make the time-stamp of the sampler more reliable.The layout and materials of the sampler parts were modified.Based on above modifications,a new OP-LPME sampler was developed.(2)The kinetic parameters of the PAHs extraction and PRCs release on the sampler were investigated in laboratory.The PRC calibration method for the samplers was established with these data.Performance test of the sampler were carried out in laboratory and the results showed that the sampler is capable of extracting 9 PAHs in water and the PAHs concentrations in the extraction solution were in approximate agreement with that of the water sample.Semi-quantitative analysis could be achieved with this sampler.(3)The sampler was deployed in Jiulong River to monitor the variation of PAHs concentration in the riverine water.The sampler ran smoothly for 15 days and 7 PAHs were collected.With the established PRC method,the PAHs concentrations in the riverine water were calculated.The obtained PAHs concentrations of the sampler were in approximate agreement with that of spot sampling.These results indicated,to some extent,the long-term variation of PAHs concentration in the sampling site.The sampler is a potential tool to monitor time-series concentration of PAHs in waters.