<p> Electronic Supplementary Material</p><p>Table 1S Effect of the foreign ions on the recovery of the analytes a</p><p>Foreign Ce Dy Hf La Sm Th Y Yb Zr ion Alkaline 100 b 100 20 100 100 20 100 100 100 metals (107%) c (106%) (114%) (94%) (109%) (105%) (104%) (103%) (92%) Alkaline 100 100 20 100 100 20 100 100 20 earth (105%) (104%) (101%) (108%) (109%) (85%) (105%) (107%) (89%) metals 1 1 1 1 1 1 1 1 1 Al3+ (94%) (97%) (95%) (93%) (96%) (112%) (95%) (91%) (91%)</p><p>25 25 50 20 20 20 25 25 25 Ni2+ (108%) (108%) (93%) (89%) (111%) (99%) (105%) (105%) (98%)</p><p>Mn2+ 25 25 15 15 25 15 25 25 15 (97%) (947%) (113%) (113%) (96%) (90%) (94%) (90%) (92%)</p><p>5 5 5 5 5 5 5 5 5 Cu2+ (90%) (95%) (92%) (88%) (108%) (93%) (92%) (90%) (94%)</p><p>10 10 5 5 15 5 10 10 5 Zn2+ (95%) (99%) (84%) (97%) (108%) (104%) (96%) (93%) (96%)</p><p>10 10 10 10 10 10 10 10 10 Fe3+ (96%) (97%) (114%) (96%) (96%) (107%) (98%) (95%) (114%)</p><p>20 20 20 20 20 20 20 20 20 Hg2+ (105%) (102%) (88%) (115%) (107%) (95%) (105%) (108%) (100%)</p><p>30 30 20 10 30 10 20 20 20 Co2+ (91%) (89%) (100%) (96%) (87%) (94%) (109%) (107%) (108%) 10 10 10 10 10 10 10 10 10 Cr3+ (105%) (104%) (90%) (93%) (114%) (90%) (99%) (95%) (90%) a Three replicate measurements were done and RSDs in the range of 2-10% were obtained b Concentration of the foreign ions as mg L-1 c Recovery respect to the solution containing no foreign ion Table 2S Analysis of the real samples</p><p>Sample Ce Dy Hf La Sm Th Y Yb Zr Determined (µg L-1) a a a a a a a a a Well Spiked (µg L-1) 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.37 b 9.87 8.90 10.55 10.08 9.58 10.12 10.03 9.63 water 1c Found (µg L-1) ± 0.95 ± 0.48 ± 0.24 ± 0.56 ± 0.85 ± 0.15 ± 0.49 ± 0.58 ± 0.38</p><p>Recovery (%) 103.7 98.7 89.0 105.5 100.8 95.9 101.2 100.3 96.3 1.02 Determined (µg L-1) a a a a a a a a ± 0.15 Well Spiked (µg L-1) 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00</p><p> d 11.06 10.11 10.25 10.75 10.69 10.35 9.56 9.99 10.94 water 2 Found (µg L-1) ± 0.60 ± 0.29 ± 0.51 ± 1.05 ± 0.62 ± 0.61 ± 1.15 ± 0.53 ± 0.35 Recovery (%) 110.6 101.1 102.5 97.3 106.9 103.5 95.6 99.9 109.4 0.30 ± Determined (µg L-1) a a a a a a a a 0.02 Sea Spiked (µg L-1) 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.46 5.52 4.16 5.65 5.35 5.18 5.56 5.43 4.23 Water e Found (µg L-1) ± 0.17 ± 0.39 ± 0.33 ± 0.34 ± 0.18 ± 0.29 ± 0.39 ± 0.34 ± 0.46 Recovery (%) 109.2 110.5 83.2 107.0 107.0 103.6 111.2 108.6 84.6 Determined (µg L-1) a a a a a a a a a -1 Tap Spiked (µg L ) 5.00 5.00 --- 5.00 5.00 --- 5.00 5.00 --- 4.62 4.46 4.91 4.50 4.80 4.32 -1 c Found (µg L ) ------Water ± 0.32 ± 0.07 ± 0.25 ± 0.25 ± 0.16 ± 0.15 Recovery (%) 92.4 89.2 --- 98.2 90.0 --- 96.0 86.4 --- a Analytes were not detected b Each result is mean of three replicate extractions ± standard deviation c Obtained from Tarbiat Modares University, Tehran, Iran d Obtained from Anomaly, Bandar Abbas, Iran e Obtained from Caspian Sea</p>