Extraction and quantification of polystyrene nanoplastics from biological samples

Accurate quantification of nanoplastics (NPs) in complex matrices remains a challenge, especially for biological samples containing high content of organic matters. Herein, a new method extracting and quantifying polystyrene (PS) NPs from biological samples was developed. The extraction included alkaline digestion, centrifugation, and cloud point extraction (CPE), and the quantification included gold nanoparticles formation and labeling on surfaces of the extracted NPs and thereafter measurement with single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). Results show that 25% tetramethylammonium hydroxide solution was an effective alkaline digestion solution for biological matrices, and CPE after centrifugation (3000 rpm, 10 min) was applicable to purify and enrich PS NPs with different sizes (100 and 500 nm) and surface functionalities (-COOH and -NH2 modifications) from the digestion solution. The efficiency of Au labeling on PS NPs surface was improved by about 70% in the presence of 100 mu M cetyltrimethylammonium bromide. The performance of the quantification method was examined by extraction and measurement of PS NPs spiked in four representative organism samples including bacteria, algae, nematode, and earthworm, and was further validated by analyzing the accumulated PS NPs in exposed nematodes. Good recovery rates (65 +/- 10%-122 +/- 22%) were achieved for spiking levels of 5-50 mu g g 1; the limit of detection was 3.7 x 107 particles g 1, corresponding to the mass concentration of about 0.02 and 2.5 mu g g 1 for the 100 nm and 500 nm PS NPs, respectively. The established extraction and quantification methods are efficient and sensitive, providing a useful approach for further exploring the environmental behavior and toxicity of NPs.

Automated summary

A new method for extracting and quantifying nanoplastics from biological samples was developed in this study. The method involved alkaline digestion, cloud point extraction, and gold nanoparticles formation for quantification using single particle inductively coupled plasma mass spectrometry. The method was proven to be efficient and sensitive, allowing for accurate quantification of different sizes and surface functionalities of polystyrene nanoparticles. The method was validated using representative organism samples and showed good recovery rates and low limits of detection, making it a useful approach for studying the environmental behavior and toxicity of nanoparticles.