Supporting Information for:

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1 Electronic Supplementary Material (ESI) for Analytical Methods. This journal is The Royal Society of Chemistry 2014 Supporting Information for: Quantification of rare earth elements using cloud point extraction with diglycolamide and ICP-MS for environmental analysis Charles Labrecque a, and Dominic Larivière a a Laboratoire de radioécologie, Département de chimie, Université Laval, 1045 Avenue de la Médecine, Québec, QC, Canada, G1V 0A6 To whom correspondence should be addressed: dominic.lariviere@chm.ulaval.ca Département de chimie, Faculté des sciences et de génie Université Laval 1045, avenue de la Médecine, Bureau 1250D Pavillon Alexandre-Vachon Québec, QC, Canada G1V 0A6 Phone: Fax : dominic.lariviere@chm.ulaval.ca Content 1. Soil digestion S2 2. Fusion protocol S3 3. Cloud Point Extraction protocol S4 4. Equations used S5 5. Extraction behavior for all REEs S7 S1

2 Soil digestion The soil solutions were prepared using fluxer digestion (0.5 g of soil was dissolved in 3.4 g of flux) for soil and sediment. For solid matrices that contained high amounts of iron, such as red sludge, a mixture of lithium metaborate, LiMBO 2, and lithium tetraborate, LiTBO 2 (in a ratio of 0.3 g of red sludge with 1.5 g of LiMBO 2 and 1.5 g LiTBO 2 ) was used. The fluxes were purchased from Corporation Scientifique Claisse and are composed of ultrapure lithium metaborate:lithium bromide (98.5:1.5) and lithium tetraborate:lithium bromide (99:1). (Bouchard, M., Rivard, S., Ness, S. ISO Simplified Borate Fusion & WDXRF Analytical Method for Iron Ores Analysis Including Exploration Samples; Technical Report from Corporation Scientifique Claisse: Quebec, QC, 2013) Lithium bromide was added to prevent the flux from sticking to the crucibles. A revised method (Table S1) from the protocol, as suggested by the M4 fluxer manufacturer, was used throughout the experiments. The fluxer parameters used allowed the complete and stable dissolution of solid environmental matrices in 3 M HNO 3, and the samples remained stable for weeks following fusion. The parameters remained the same regardless of the flux mixture used. To facilitate cloud point extraction, the solutions were treated with PEG-6000 to eliminate the silica in solution. (Dai, X.; Kramer-Tremblay S. Health Phys. 2011, 101, ) The silica was eliminated for instrumental reasons, i.e., to limit the ICP-MS nebulizer clogging and to ease the surfactant rich phase (SRP) redispersion. S2

3 Fusion Protocol Table S1 : Fusion protocol used for the dissolution of environmental samples Function Steps Time (min) Proposed Protocol 0 Pre-heating 00:05 1 Oxidation 00:30 2 First dissolution 00:30 3 Cooling 4 Heating 01:00 5 Final dissolution 03:00 6 Cooling - 7 Pouring 00:10 8 Stirring 10:00 Total 15:15 S3

4 CPE conditions Table S2: Optimised CPE system conditions Parameter Condition Unit Sample 6.5 ml [HNO 3 ] M [TTX-114] 1.07 mmol L -1 [DGA] 165 µmol L -1 [CTAB] 100 µmol L -1 [KBr] 10 mmol L -1 [KBrO 3 ] 1,5 mmol L -1 T extraction 4 C T phase separation 20 C RCF average G S4

5 Equations used The method s figures of merit were calculated using the following equations. The principal parameters evaluated were: extraction efficiencies, chemical recovery, detection limits, and quantification limits. The chemical recovery (CR, %) was determined using the following equation, proposed in a previous report (Labrecque, C. et al. Anal. Chem. 2013, 85, ): CR = C SRP x V SRP redisp C spiked x V Spiked 100 Eq.1 where C SRP redisp is defined as the concentration found in the surfactant-rich phase, C spiked is the spiked concentration, V SRP redisp is the volume (analysed) of the SRP, and V spiked is the spiked volume. The equations were slightly modified from the previous report as the chemical recoveries were done with alpha spectrometry instead of ICP-MS, hence the measured properties are different and required different data analysis. The extraction efficiencies (EE, %) were calculated using the following equation, proposed in a previous report (Labrecque, C. et al. Talanta 2013, 107, ), based on the equations of Favre-Réguillon et al. (Favre-Reguillon, A. et al. Talanta 2004, 63, ) EE = C SRP redisp C SRP redisp + C supernatant V supernatant V SRP redisp Eq.2 where C SRP redisp and V SRP redisp are the same as defined above, whereas V supernatant and C supernatant represent the volume and concentration in the isolated supernatant after the extraction, respectively. S5

6 The preconcentration factor (PF) was determined using the following equation reported in a previous communication: PF = C initial V initial C supernatant V supernatant C supernatant V supernatant Eq.3 V supernatant and C supernatant are the same as defined above and C initial and V initial are the concentration and volume prior to the extraction, respectively. S6

7 Figure S1 a) Influence of various parameters [a) nitric acid, b) hydrochloric acid, c), ligand d) TTX-114 e) KBrO3 and f) CTAB concentrations] on the extraction of REEs with other parameters being kept constant (at the concentration shown in Table S4), using nitric acid. S7