Thorough Multianalytical Characterization and Quantification of Micro- and Nanoplastics from Bracciano Lake’s Sediments

Abstract

Lake basins can behave as accumulators of microplastics released in wastewaters as such or resulting from degradation of larger items before and/or during their journey toward the marine environment as a final sink. A novel multianalytical approach was adopted for the detection and quantification of microplastics with size < 2 mm in the sediments of the volcanic lake of Bracciano, Italy. Simple analytical techniques such as solvent extraction/fractionation (for polyolefins and polystyrene) or depolymerization (for polyethylene terephthalate, PET), along with chromatographic detection (SEC and HPLC), allowed quantitative and qualitative determination of the main synthetic polymer contaminants. In particular, PET microplastic concentrations of 0.8–36 ppm were found, with variability related to the sampling site (exposure to incoming winds and wave action). Proton Nuclear Magnetic Resonance (1H-NMR) and Attenuated Total Reflectance Fourier Transformed InfraRed (ATR-FTIR spectroscopic investigations supported the identification and chemical characterization of plastic fragments and polymer extracts. The average molecular weight of solvent extractable polymers was evaluated from 2D 1H-NMR diffusion ordered spectroscopy (DOSY) experiments. The proposed, easily accessible multianalytical approach can be considered as a useful tool for improving our knowledge on the nature and the concentration of microplastics in sediments, giving insights on the impact of human activities on the health status of aquatic ecosystems.

Microplastics Pollution as an Invisible Potential Threat to Food Safety and Security, Policy Challenges and the Way Forward

“…The samples undergo further treatment by drying them in a ventilated oven and further sieving to separate 2 mm and 5 mm microplastics. An optical stereo microscope is used for the counting of larger retained particles that are to undergo identification by attenuated total reflectance (ATR) FTIR spectroscopy [ 56 ]. There are shortcomings related to these sampling and separation methods.…”

“…The chromatograms enable the identification of the most common microplastics: polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), polyamide (PA), polymethylmethacrylate (PMMA) and styrene-butadiene-rubber (SBR) as tire component [ 61 ]. Plastic fragments and polymer extracts can also be identified using proton nuclear magnetic resonance (1H-NMR) and attenuated total reflectance Fourier transformed Infrared (ATR-FTIR) [ 56 ].…”

Polymer Identification and Specific Analysis (PISA) of Microplastic Total Mass in Sediments of the Protected Marine Area of the Meloria Shoals

“…For the HPLC analyses of the dansylated amines the FLD detector response was calibrated against the concentration of dansylated AHA by recording a 4-point calibration using solutions in the 17.25-172.5 µg/L range plus a blank sample, all in triplicate; the same procedure was followed for dansylated HMDA, in the 13.25-132.5 µg/L range plus the blank sample. From the linear regression (Figure 4a For the HPLC quantification of TPA a linear calibration of the UV detector response was obtained by recording a 6-point calibration based on standard TPA solutions in 2N NaOH in the 0.21-1.68 mg/L range plus a blank, all in triplicate [23]. From the linear regression ( Figure 4c, A=2.32•10 5 •CTPA-7237; r 2 >0.995) the following values were calculated: LOD=0.117 mg/L; LOQ: 0.391 mg/L.…”

“…Here we report the results of the first investigation in which our recently developed analytical protocol for the quantitative determination of the total mass content of a well-defined set of microplastics [23], hereafter Polymer Identification and Specific Analysis (PISA), was employed for benthic marine sediments. The protocol allows the accurate quantification of the total mass of individual microplastic types, regardless of their size and morphology, of the following polymers: polyolefins (high density polyethylene, HDPE, low density polyethylene, LDPE, and polypropylene, PP), polystyrene (PS), polyethylene terephthalate (PET), and the two polyamides nylon 6 (polycaprolactame, the homopolymer of 6-aminohexanoic acid, AHA) and nylon 6,6 (copolymer of 1,6-hexanediamine, HMDA, with adipic acid) [24].…”

Polymer Identification and Specific Analysis (PISA) of Microplastic Total Mass in Sediments of the Protected Marine Area of the Meloria Shoals

“…Here we report the results of the application of our recently developed analytical protocol to the quantitative determination of the total mass content of a well-defined set of microplastics [ 22 ], hereafter Polymer Identification and Specific Analysis (PISA), in benthic marine sediments. The PISA protocol provides accurate quantitative (total mass of the contaminating MPs in the sediment sample, with separate quantification for each polymer type, as specified below) and qualitative (type of polymer) information with sensitivities orders of magnitude higher than those attainable with the general methodology most commonly adopted so far by researchers worldwide.…”