1. Development of an ionic imprinted polymer for the selective preconcentration of lanthanide ions
Manel Moussa1, Clarisse Mariet2,Thomas Vercouter2, Valérie Pichon1,3, Nathalie Delaunay1*
1 Laboratory of Analytical and Bioanalytical Sciences and Miniaturization, UMR CBI 8231 CNRS/ESPCI ParisTech, PSL Research University, Paris, France
2 CEA Saclay, DEN, DANS, DPC, SEARS, LANIE, Gif-sur-Yvette, France
3 Sorbonne Universités, UPMC, Paris, France
*Corresponding author
Introduction
Lanthanides comprise the elements between lanthanum (Z=57) to lutetium (Z=71), commonly encountered at the +III oxidation state (a few exceptions occur especially with Ce4+ and Eu2+). Thanks to their remarkable chemical, electronic, and magnetic properties, their fields of applications are various and extending, which induce a dramatic increase in the global consumption of these elements. However, recent studies showed some toxicity of these compounds [1,2]. Therefore the detection and monitoring of their environmental release require their analysis at trace level in soil extracts or water samples. This project aims to develop a new selective sorbent, an ionic imprinted polymer (IIP), for the selective extraction and preconcentration of the lanthanide ions.
Materials and methods
ICP-MS operating conditions
Complexation
Polymerization
Removal of the
template ion
Cross-linker
Schematic representation of an IIP synthesis
: template ion
: Ligand
Synthesis of neodymium imprinted polymers (Nd-IIPs)
Styrene (St)
Divinylbenzene (DVB)
5 ,7-dichloroquinoline-8-ol (DCQ)
4-vinylpyridine (4-VP)
Nd3+
Nd-IIP
An Agilent Technologies 7700x ICP-MS instrument was used for the analyses of all the fractions of the removal of the template ion and the SPE process
Optimization of the removal of the template ion after synthesis
Tested solutions : 6 M HCl or 100 mM EDTA (pH 10)
Magnetic stirring : 3h/cycle
6 M HCl
100 mM EDTA (pH 10)
6 M HCl is more suitable than EDTA(elimination of 81% of the template ion)
Nd3+
ICP-MS Plasma
Rf power
1550 W
Plasma gas (Ar) flow rate
15 L min−1
Carrier gas (Ar) flow rate
1.01 L min−1
Sampling depth
10 mm
Sampler/skimmer cones
Nickel
Data acquisition
Scanning mode
Full quant
Replicates 5
Sweeps/replicate
100
Isotopes
139La, 140Ce, 
143Nd, 147Sm, 154Gd, 
161Dy,  166Er, 175Lu
Polymers of the study
Nd3+ (mmol)
DCQ (mmol)
VP (mmol)
Styrene (mmol)
DVB (mmol)
Porogen
DCQ+4VPM 1 3 2 20
2-methoxyethanol[3]
DCQ+4VPD
DMSO
DCQ -
2-methoxyethanol
2-VP
Packing of an IIP synthetized in bulk in a SPE cartridge cartirge cartridge
Grinding
Sieving
Sedimentation
Packing in
cartridge
First grinding of the polymer
A non-imprinted polymer (NIP) is synthesized in the same conditions as the IIP but in absence of the template ion, in order to evaluate the imprinting effect
Removal of the template ion
Results 1
Characterization by gradual pH elution of the DCQ-4VPM, 2-VP and DCQ polymers by SPE
SPE steps
Conditions
Loading
1 mL of Bis-tris pH 7.5 containing 100 ng of Sm3+
Gradual elution
3 x 1 mL of Bis-Tris (pH 6.9, pH 6.5, pH 6) , 2 x 1 mL of creatinine (pH 5, pH 4),
3 x 1 mL of HCl (pH 3, pH 2, pH 0.2) Nd
30 mg of IIP and NIP 3
IIP DCQ+4VPM
Analysis of the liquid fraction by ICP-MS
The IIP DCQ+4-VPM retains more than the IIP 2-VP, that itself retains more than the IIP DCQ
Selectivity between the NIP and the IIP for the DCQ+4-VPM and the DCQ polymers but not for the 2-VP polymer Nd Nd
n=2
Optimization of the loading condition for SPE
Study of the pH of Bis-Tris for the loading of 1 mL containing 100 ng of Sm3+ ions
Optimum loading pH: 7.5!
30 mg of IIP
Conditioning: 3 mL of Bis-Tris (I = 0.02), pH 6 - 8
Loading: 1 mL of Bis-Tris (I = 0.02), pH 6 – 8 containing 100 ng of Sm3+
Washing: 1 mL of Bis Tris pH= 6 - 8
Elution: 3 mL of 100 mM EDTA 2 Nd M M
Recoveries (%) Nd
NIP DCQ
IIP DCQ+4VPM
Recoveries (%)
n=2
DCQ favors selectivity
A higher selectivity is obtained with the ternary complex than with the secondary complex
Perspectives
[1] J. E. Allison et al, Chemosphere 96 (2014) 57-66
[2] S. Hirano et al, Environ. Health Perspect. 140 (1996) 85-95
[3] T. Prasado Rao et al, Anal. Chimica Acta 478 (2003) 43-51
Optimization of the SPE procedure (especially the washing step) for the polymer synthesized in DMSO in order to improve selectivity between NIP and IIP
Application to real samples
Study of the porogen nature effect on the selectivity of the resulting polymers 4
SPE steps
Conditions
Loading
1 mL of Bis-tris pH 7.5 containing 100 ng of Sm3+
Gradual elution
3 x 1 mL of Bis-Tris (pH 6.9, pH 6.5, pH 6) , 2 x 1 mL of creatinine (pH 5, pH 4), 3 x 1 mL of HCl (pH 3, pH 2 , pH 0.2)
30 mg of IIP and NIP
Recoveries (%)
Higher selectivity at pH 6 for the IIP DCQ+4-VP synthetized in DMSO than for the IIP DCQ+4-VP synthetized in 2- methoxyethanol
Evaluation of the selectivity of the DCQ+4VPD polymers towards different lanthanides
30 mg of IIP and NIP
SPE steps
Conditions
Loading
30 ng (each) of La3+ ,Ce3+, Nd3+, Sm3+, Gd3+, Dy3+ , Er3+ and Sm3+ in 1 mL of Bis-Tris (pH 7.5)
Washing 1-2
2 x 1 mL of Bis-Tris (pH 7)
Elution
3 mL of 1 M HCl
Selectivity obtained only for the Light Rare Earth Elements (LREE)
DCQ+4VPD polymers 5
Solid phase extraction (SPE) process
Loading
Washing
: Interferences
Elution
Conditioning
: Analytes a)
Recoveries (%)