Table 2.
Applications of LPME on sample extracts obtained by conventional solvent extraction.
| LPME | Analytical techn. | Sample | Analytes | Extraction procedure for solid sample | Optimized extraction conditions for s.s. | LPME procedure | Method performance | Ref. |
|---|---|---|---|---|---|---|---|---|
| DLLME | GC-ECD | soil | 5 PCBs | 1 g s.s. + 10 mL AC; mech. shaking 30 min; upper layer | extraction solvent | 1.0 mL AC extract (DS) + 30 µL Cl-benzene (ES) inj. into 5.0 mL w.; centrif.; sedim. phase evaporated, rediss. in 20 µL n-hexane | η 82.3%–113.6% (3 levels); RSD < 6.4%; LOD 0.20–0.50 ng/g |
[60] |
| US-DLLME | GC-MS (SIM) | soil | endosulfan & 5 metab. |
0.5 g s.s. + 1.25 mL AC; US (10 min); centrif. | not given | AC extract (DS) + 58 μL TCE (ES) inj. into 5.0 mL w. + 7% Na2SO4; US (2 min); centrif.; direct injection | experimental design for US-DLLME optimization; η 89.0%–99.7%; RSD < 6.3%; LOD 0.316–2.494 ng/g; no interference from sample matrix observed |
[61] |
| DLLME | HPLC-FLD | sediment | PAHs | 0.2 g s.s. + 2 mL ACN, VA (2 min), centrif. | extraction solvent, vortex time | 1.0 mL ACN extract (DS) + 80 μL CH2Cl2 (ES) inj. into 5.0 mL w.; centrif.; sedim. phase evaporated, rediss. in 40 μL ACN | η 72.9%–97.8% (3 levels); RSD < 8.0%; LOD 2.3–6.8 ng/g; no interference from sample matrix observed |
[62] |
| DLLME | LC-FLD | soil | carbaryl, triazophos | 1 g s.s. + 10 mL MeOH, mech. shaking (30 min); filtered | extraction solvent | 1.0 mL MeOH extract (DS) + 50 µL TtCE (ES) inj. into 5.0 mL w.; centrif.; sedim. phase evaporated, rediss. in 25 μL MeOH | η 80.8%–111.1% (3 levels); RSD < 4.3%; LOD 0.014–0.110 ng/g; some matrix interferences present in chromatograms |
[63] |
| US-IL-DLLME | HPLC-UV | soil | 3 pesticides | 10 g s.s. + 30 mL sol. (60% MeOH, 5 mg NaCl); US, centrif. + filtr.; repeat; evaporated to dryness, rediss. in 10 mL MeOH sol., pH adjust to 4.0 | not given | 1.0 mL sample sol., inj. 0.3 mL MeOH (DS) + 70 μL [BMIM]TFSI (ES); shake, US (2 min); centrif.; sedim. phase dissolved in 0.5 mL MeOH | not given for overall method (just for DLLME) | [64] |
| IL-DLLME | HPLC-FLD | soil | 5 pesticides 2 metabol. |
3 g s.s. + 20 mL MeOH + 2.5% NaCl; manual shaking + US; centrif. + filtr.; repeat; evaporated to dryness, rediss. in 10.0 mL w., pH adjust to 5.2 |
extraction solvent, Vsolv, NaCl add., US time, amount of sample | add. NaCl to 30%; MeOH (DS) + IL ([HMIm][PF6], ES); centrif.; 80 µL sedim. phase dissolved in 1120 µL ACN-phosphate buffer |
central composite experimental design for optimization of IL-DLLME conditions; η 88%–119%; LOD 0.02–27.1 ng/g |
[65] |
| IL-DLLME | HPLC-FLD | soil | 7 pesticides and metabol. | 3 g s.s. + 20 mL MeOH + 2.5% NaCl; manual shaking + US (10 min), centrif. + filtr.; repeat; evaporated to dryness, rediss. in 10.0 mL w., pH adjust to 5.2 |
not given | comparison of 2 IL as ES: [PPIm][PF6] and [HMIm][PF6]; add. NaCl (2.5 g); MeOH (DS) 418 μL + IL 117.5 mg (ES); VA 1 min; centrif.; 80 µL sedim. phase dissolved in 1120 µL ACN-phosphate buffer |
η 93%–118%; RSD < 20%; LOD 0.02–60.5 ng/g |
[66] |
| DLLME | sweeping MEKC-DAD |
soil | 5 sulfonylurea herbicides | 10 g s.s. + 10 mL ACN (5% HCOOH, pH 3.0), shaking; added 4 g MgSO4 + 1 g NaCl, shaking; centrif.; 5 mL supernatant + 250 mg C18 + 1.5 g MgSO4, shaking; centrif., filtered | extraction solvent, pH of sample solution for DSPE, DSPE sorbent | 1.0 mL extract (DS) + 50 µL ClBz inj. into 5.0 mL w. (pH 2.0, HCl), VA (5 s); centrif.; sedim. phase evaporated, rediss. in 20.0 µL phosphate buffer (pH 10.0) | η 76.0%–93.5% (3 levels); RSD < 6.8%; LOD 0.5–1.0 ng/g |
[67] |
| DLLME | HPLC-DAD | soil | 4 sulfonylurea herbicides | 10 g s.s. + 20 mL AC/0.15 M NaHCO3 (2:8), shaking 30 min; filtered; 10 mL filtrate + 0.15 g C18, shaking 5 min; filtered; pH adj. to 2.0 and dil. to 25 mL with AC/w. (2:8, pH 2.0) | organic solvent, DSPE sorbent | 5.0 mL solution (with AC 20% as DS) + 60 µL ClBz (ES), VA 5 s; centrif.; sedim. phase evaporated, rediss. in 15 µL ACN | η 78.0%–92.5% (3 levels); RSD < 7.2%; LOD 0.5–1.2 ng/g; some interferences present in chromatograms |
[68] |
| DLLME | GC-MS/MS | sediment | 4 PBDEs | 0.25 g s.s. + 1.5 mL AC; US (35 °C) 6 × 5 min; centrif.; 1.2 mL leachate + 100 mg SiO2, VA (30 s); centrif. | leaching solvent, Vsolv, DSPE sorbent, US time & mode, US-transmitting liq., leaching T | 1.0 mL AC extract (DS) + 60 µL CCl4 (ES) inj. into 5.0 mL w.; shaking, 5 min in bath (35 °C); centrif.; direct injection | η 80%–112% (2 levels); RSD < 9.8%; LOD 0.02–0.06 ng/g; extraction method comparable efficiency with Soxhlet's |
[69] |
| DLLME | GC-MS/MS | sediment | 4 PBDEs | 1 g s.s. + 1.2 mL MeOH; US (40 °C) 2 × 9.2 min; centrif. | leaching solvent type (also a DS) & V, T, US time & cycles | 0.1 mL MeOH (DS) + 22 mg 1-dodecanol (ES) inj. into 0.4 mL leachate + 1.0 mL 6.15 M NaCl + 4.4 mL w. at 40 °C; SFOD form. at 10 min in ice bath; collected, melt, add. 3 µL i-octane; direct injection | factorial (2k) screening & central composite design for optimization; η 71%–104% (2 levels); RSD < 9.2%; LOD 0.5–1.8 pg/g |
[70] |
| HLLE | GC-ECD | soil | 3 organo-phosph. & pyrethroid pesticides | 4.0 g s.s. + 10 mL AC; mech. shaking (30 min); supernatant decanted | extraction solvent, Vsolv | 1.0 mL AC extract (CS) + 40 µL CCl4 (ES) inj. into 5.0 mL w.; phase separation by 0.3 g NaCl; centrif.; direct injection | η 79.2%–113.1%; RSD < 9.6%; LOD 0.01–0.04 ng/g |
[71] |
| USA-EME | GC-FID | soil | diazinon, chlorpyrifos | 2 g s.s. + 2.5 mL MeOH; US (2 min pulse on/off); centrif., filtered | not given | 1.5 mL extract + 10.5 mL w.; 14 µL toluene slowly injected during US, US (30 s); centrif.; upper phase collection, direct injection | η 90.0%–105%; RSD < 9.2%; LOD not given for soil; several interferences in the chromatogram |
[72] |
| HF-LPME | GC-ICP-MS | soil, dust | 4 PBDEs | 0.5 g soil/0.05 g dust + 3 mL MeOH; US (30 min); centrif.; supernatant diluted to 10 mL with w. | not given | 3.0 mL extract, 4 µL decane (ES) in 1.5-cm HF; stirring 20 min at 40 °C & 1000 rpm; direct injection | η 86.7%–110.9%; RSD < 10.4%; LOD not given for soil & dust; several interferences present in the chromatogram (brominated compounds?) |
[73] |
| HF-LPME | GC-ECD | sediment | vinclozoline | 5 g s.s. + 10 mL ACN-MeOH (9:1); US 30 min; centrif., evapor. to 0.05 mL | extraction solvent | extract + 5 mL w., 3 µL toluene (ES) in 1.3-cm HF; stirring 20 min at 800 rpm; direct injection | η 94%–96% (2 levels); RSD 6.1%; LOD 0.5 ng/g |
[74] |
| HF-LPME | HPLC-FLD | soil | 7 pesticides and metabol. | 3 g s.s. + 20 mL MeOH + 2.5% NaCl; manual shaking + US (10 min); centrif. + filtr.; repeat; evaporated to dryness, rediss. in 10.0 mL w., filtered |
not given | extract (pH adj. to 9.0, NaCl to 20%), 20 µL 1-octanol (ES) in 2.0-cm HF; stirring 30 min at 1440 rpm; ES evaporated, rediss. in 50 µL mobile phase for HPLC | η 85%–117%; RSD variable, up to 71% at low levels; LOD 0.001–6.94 ng/g |
[75] |
| HF-LLLME | GC-ECD | soil | chlorophenols | 2 g s.s. + 3 mL MeOH; US (2 min pulse on/off); centrif., filtered | not given except for MeOH effect on HF-LLLME | 2 mL extract dil. to 20 mL with w., dodecane in 8-cm HF wall (ES) & 25 µL ACN (AS) + IS in HF lumen; stirring 30 min at 400 rpm; direct injection | η 86.3%–110%; RSD < 9.3%; LOD not given for soil |
[58] |
| HF-LLLME, dynamic |
GC-FID | soil | PAHs | 2 g s.s. + 3 mL MeOH; US (2 min pulse on/off); centrif., filtered | not given except for MeOH effect on HF-LLLME | 2 mL extract dil. to 20 mL with w. + dodecane in 8-cm HF wall (ES) & 25 µL ACN (AS) in HF lumen; stirring 20 min at 1000 rpm; dynamic extr. (syringe plunger); direct injection | η 84.4%–110%; RSD < 9.3%; LOD not given for soil |
[36] |
Abbreviations: ES—extraction solvent; DS—disperser solvent in DLLME; CS—co-solute solvent in HLLE; AS—acceptor solvent in HF-LLLME; HLLE—homogeneous LLE; DSPE—dispersive solid phase extraction; IS—internal standard; s.s.—solid sample. Solvents: AC—acetone; ACN—acetonitrile; ClBz—chlorobenzene; MeOH—methanol; TCE—trichloroethylene; TtCE—tetrachloroethane; w.—water (ultrapure/double deionized/MilliQ); [HMIm][PF6]—1-hexyl-3-methylimidazolium hexafluorophosphate; [PPIm][PF6]—1,3-dipentylimidazolium hexafluorophosphate.