Table 6.
Recovery test of pretreatment methods in freshwater sediment and soil studies.
| No. | Matrix | Recovery test method | Type and size of MPs | Recovery rate | Ref. |
|---|---|---|---|---|---|
| 1 | Sediments | Spike 10 of each size range for all types of MPs Repeat in duplicate |
PE, PS, PP, PVC (<1 mm, 1–2 mm, 2–5 mm) | 80, 90, 100% (PE, PP; each size group), 70, 90, 100% (PS; each size group), 60, 80, 90% (PVC; each size group) | (Di and Wang, 2018) |
| 2 | Spike 300 MPs into 200 g of the muffled sand Filter using 10 mm stainless steel filter Count MPs using a stereomicroscope Repeat in triplicate |
Red PS (beads) (100 μm) | 66 ± 5.6% | (Liu et al., 2019a) | |
| 3 | Spike 10 beads or 15 secondary MPs into 20 g of dried sediment Repeat in triplicate for each MPs type | Beads: PE (0.71–0.85 mm), PP (2.45 mm), PS (4.4 mm) Secondary MPs: Nylon toothbrush bristles, PP cleaning brush bristles, rope fragments and PE mesh fruit packaging fragments |
100% (microbead) 49 ± 10.2–58 ± 7.7% (secondary MPs) |
(Blair et al., 2019) | |
| 4 | Assess adapted ZnCl2 protocol in a pilot spike-recovery test Spike 40 (62–250 μm) and 20 (250–700 μm) MPs into 60 g of sediment Repeat in triplicate |
PMMA fragments (1.18 g/cm3) (62–125 μm, 125–250 μm, 250–500 μm, 500–700 μm) | ± 8.7% (62–125 μm), 80.8 ± 6.3% (125–250 μm), ± 5.0% (250–500 μm), ± 0.0% (500–700 μm) | (Mani et al., 2019) | |
| 5 | Spike 40–80 MPs into 12.3 g of dried sediment Filter using 0.7 μm GF/F and dry at 40 °C overnight |
Acrylic, nylon, polyester, PE fibers | 70% | (Simon-Sánchez et al., 2019) | |
| 6 | Spike 125 MPs into 1500 g of quartz sand | PE, PP, PS, PMMA, PVC (25 particles each, sized 125–1000 μm) | 87.2 ± 4.5% | (Scherer et al., 2020) | |
| 7 | Spike 10 MPs into 200 g of elutriated soil and sediment Repeat five times |
PE, PP, PVC, PET, PS, expandable polystyrene (EPS) (<1 mm) | >90% | (Han et al., 2019b) | |
| 8 | Soils | Stain MPs with Nile Red in acetone (500 μg/mL) for 10 min Spike 20 MPs into 50 g of clean soil Repeat in triplicate |
PP, PE, PA, PET, PVC, PC, acrylonitrile butadiene styrene (ABS), PMMA, PS (1–5 mm) | 90.0 ± 10.0% (PP, PA), ± 0.0% (PE, PC, PMMA), 95.0 ± 5.0% (ABS), 96.7 ± 2.9% (PS), 0.0 ± 0.0% (PET, PVC due to the high density) | (Liu et al., 2018) |
| 9 | Use 27% NaCl (1.2 g/cm3) for small MPs Spike 10 MPs into 50 g of pure plastic free sand Test four different ways of density separation: 1. Sedimentation cylinder method, settle for 48 h 2. Self-constructed MP separator with additional air bubbling 3. Stir for 10 min and centrifuge for 30 min at 3450 G 4. Identical with third but with rubber disc inserted after centrifugation Removal of organic matter in a short time using HNO3 |
PP (0.5–1 mm) | 93% (3), 97% (1,2), 98% (4) | (Scheurer and Bigalke, 2018) | |
| 10 | Spike MPs into cleaned sands | PP, PE (200 μm-5 mm) | 97% | (Zhou et al., 2018) | |
| 11 | Spike 10 MPs into 50 g of soil Pre-digestion (30% H2O2), density separation and filtration |
PE, PP, PS, PA, ABS, PET (<2 mm) | NaI: 97.78 ± 1.57% NaCl: 80.56 ± 2.08% (except PET) ZnCl2: 97.22 ± 2.08% |
(Li et al., 2019) | |
| 12 | Spike each type of MPs into 5 g of soil sample Repeat in triplicate |
Fiber: Acrylic (length: 2.7 ± 1.4 mm) (width: 0.04 ± 0.01 mm) (area: 0.12 ± 0.06 mm2) Polyester (length: 1.6 ± 1.1 mm) (width: 0.04 ± 0.01 mm) (area: 0.07 ± 0.06 mm2) Nylon (length: 2.3 ± 0.8 mm) (width: 0.05 ± 0.01 mm) (area: 0.98 ± 0.37 mm2) LDPE (0.16 ± 0.1 mm2) PVC (0.10 ± 0.08 mm2) |
98% (LDPE), 90% (Polyester), 88% (PVC), 77% (Nylon), 49% (Acrylic) | (Corradini et al., 2019) | |
| 13 | Stain MPs with Nile Red in acetone for 10 min except for PMMA, PS and ABS Calculate each recovery rate using three density solutions (NaCl, NaBr or CaCl2) |
Type: PE, PET, POM, PVC, PC, ABS, PMMA, PS (shredding/grinding 3 mm bead and passed through 7–160 mesh) Size: PE (100–500 μm, 500–1000 μm, 1000–3000 μm) Shape: PE (particle, fiber, film) (100–500 μm) |
>90% (All type of MPs) 75.0–96.7% (100–500 μm PE) 100% (>1 mm PE) 65–98.3% (Three shape-different PE; of them, NaBr: 85–98.3%) |
(Liu et al., 2019b) | |
| 14 | Spike 20 films or particles into 20 g of clean soil | LDPE film (1 × 1 mm) LDPE particle (250 μm) |
100% (film), 98% (particle) | (Huang et al., 2020) | |
| 15 | Spike 30 mg of MPs into 200 g of clean soil sample Stir for 20 min at 25 °C Weigh by electronic balance |
PE (>2 mm, 0.9–2 mm, 0.28–0.9 mm, 0.15–0.28 mm) | 96% (>2 mm) 85% (0.9–2 mm) 87% (0.28–0.9 mm) 84% (0.15–0.28 mm) |
(Li et al., 2020) | |
| 16 | Spike 30 MPs into 50 g of clean soil Count by stereomicroscope |
PVC, PE, PP, PS, Polyamide (500 μm-2 mm) | 75.9–112.4% | (Zhou et al., 2020) | |
| 17 | Spike each 10 of six type MPs with two size range | PE (sheet), PET, PP, PS (fragment), PVC, nylon (fiber) (300–500 μm, 700–1000 μm) | 97.8 ± 4.8% | (Kim et al., 2021) | |
| 18 | Spike MPs into clean soil | High density polyethylene (HDPE), PP, LDPE, PS, PP fibers (1.2–1.6 mm) | 85% (HDPE), 90% (PP), 85% (LDPE), 100% (PS) | (Ragoobur et al., 2021) | |
| 19 | Soil sample was heated at 500 °C to remove MPs and organic materials Spike 100 mg of MPs into 10 g of soil and centrifuge at a speed of 3700 min−1 for 10 min |
LDPE, PP, PS, flexible PVC (63–1000 μm) (recovery test) PET (63–150 μm, 150–212 μm, 212–500 μm, 500–1000 μm, 63–1000 μm) (Tests to identify how size affects MPs recovery) |
97–98% (LDPE, PP, PS, fPVC) 81% (PET; 63–150 μm), 94.0 ± 2.1% (PET; 500–1000 μm), 94.9 ± 2.4% (PET; 63–1000 μm) |
(Grause et al., 2022) |