ES2556156B2 - Polymeric material for speciation of inorganic mercury and methylmercury - Google Patents

Abstract

Polymeric material for the speciation of inorganic mercury and methylmercury. # Mercury is a heavy element of high toxicity due mainly to its high bioavailability and bioaccumulation in the body. This accumulation depends on its chemical form being organic species, such as methylmercury, which represent a greater danger to health, which makes it necessary to have simple analytical methodologies to control mercury in food. # The present invention shows a new material polymer for speciation and selective analysis of mercury allowing a separation between inorganic mercury and methylmercury in environmental and food samples.

Description

Polymeric material for speciation of inorganic mercury and methylmercury

Technical Sector The present invention belongs to the field of analytical methods for the analysis of mercury. More specifically, it refers to the manufacture of polymeric materials for the prc-conccntration and determination of mercury species, especially in environmental and food samples.

State of the art Mercury is a heavy element of high toxicity due mainly to its high bioavailability and bioaccumulation in the body. This accumulation depends on its chemical form being organic species, such as methylmercury, which represent a greater danger to health. Current legislation limits the content of mercury in food, especially fish, which makes it necessary to have simple analytical methodologies to control mercury in food.

Also the cspeciación and analysis of the different species of mercury in environmental samples is today a topic of great interest.

Numerous analytical procedures and techniques have been developed in recent years (Noal, EM al. Chem. Rev. 108 (2008) 3443-3480; Liu, z. Al. Ana /. Chem. 81 (2012) 10170-10174 ; Gao, W. al. J. Ana /. Al. Speclrom. 26 (2011) 126-132).

Among the most widespread methods of analysis, the use of Atomic Absorption Spectroscopy (AAS) (Ignacio, LG et al. Anal. Chim. Acla 743 (2012) 6974), Fluorescence Spectrometry (AFS) (Ai, X. al. Ana / ysl 138 (2013) 3494350; Da Silva, MJ el. Anal. Chim. Acta 667 (20tO) 43-48), Liquid Chromatography (LC) (Gao, Z. el al. Chim. Acta 702 ( 2011) 50-55; Yin, YG et al. J. Anal. Al. Spectrom. 24 (2009) 1575-1578), Gas Chromatogram (OC) coupled to various detectors (Carro, M. el al. Chromalographia 56 ( 2002) 733; Lagar, M. et al. Ana /. Bioana /. Chem. 374 (2002) 1015; Berzas Nevado, J. el al. J Chramalagr. A 12 18 (2011) 4545-4551; Mishra, S. et al. Anal. Chim. Acla 551 (2005) 192-198), Capillary Elecrophoresis (EC) (Chen, C. et al. Anal. Methods (2012) 1185-1191; Lai, E.l. et al. Anal. Chim. Acta 264 (1998) 63-74; Li, Y. et al. Electrophoeresis 26 (2005) 661667) or ICP-MS (Jo Souza, SS et al. J. Anul. At. Speclrom. 25 (2010 ) 79-83; Debeljak, M. et a l. Anal. Chim. Minutes 787 (2013) 155-162). In general, the use of these techniques requires complex sample treatment procedures.

There are other approaches to mercury speciation, including the design of fluorescent sensors (FL) using "quantum dots" (QDs), "meta [organic dOls" (MOFs) or gold nanoparticles (AuNp), among others ( Yuan, C. al. Anal. Chenl. 84 (2012) 9792-9801; Wang, H. el al. Anal. Chem. 80 (2008) 902 19028; Park, M. et al. Chem. Commun. 46 ( 2010) 4478-4480; Lin, YW et al. Analyst 136 (2011) 3323-3328; Wang, C. 1. et al. Anal. Chim. Acta 745 (2012) 124-1 30; Ma,

C. et al. Anal. Chim. Acla 73 4 (2012) 69-78; Xu, F. et al. Anal. Chim. Acla 804 (2013) 240-245; Sener, G. al. Anal. Chem. 86 (2014) 51 4-520; An, J. H. al. ACS Nano 7 (2013) 10563-10571).

The direct determination of these species in a simple way and using techniques that provide high sensitivity remains of interest since SOn numerous problems associated with virtually all the proposed methodologies. Their sensitivity and selectivity are usually insufficient for low levels of analyte concentration.

In this sense, the use of molecular printed polymers (MIPs) is a novel technique for the recognition of species since it offers a series of analytical advantages: they allow a clean-up of the sample quickly and efficiently, allow preconcentrate the analytes They are at low concentrations, are very selective with the analyte (s) of interest, their synthesis is simple and low cost, they can be robust and durable and can be reusable. However, although they are widely used for the recognition of organic molecules, the same is not true for the recognition of ions and / or metallic species. To date, there are very few developed polymers capable of retaining metals and metals.

with selective ability to recognize different species thereof. Therefore, the development of selective materials remains of great interest.

In the present invention a new polymer synthesized is presented through a precipitation polymerization process and is selective towards mercury, allowing a separation between inorganic mercury and methylmercury, thus constituting a tool to facilitate the speciation of Hg in routine laboratories for food speciation. The developed polymer can also be used in aqueous media.

Description of the invention The polymeric material is synthesized by radical polymerization using as reagents a monomer derived from 8-hydroxyquinoline of Formula 1 (quinolin-8-yl vinylbenzoates), a cross-linking agent and a polymerization initiator in presence of a solvent.

The polymer thus obtained is characterized by studying in solid phase extraction cartridges (MIPS E procedure), previously optimizing all stages.

The quantification of mercury is carried out using the CV-AFS (Cold Vapor-Atomic Fluorescence Spectroscopy) technique.

The polymer obtained has a high affinity towards mercury (in its different chemical forms) and a high preconcentration factor. It has high efficiency towards the retention of species of both inorganic mercury and methylmercury both in salt matrices and seawater, without the need for prior treatment of the sample. It allows, therefore, the speciation of methylmercury and inorganic mercury

by sequential elution of the species and constitutes a novel tool to facilitate the speciation of Hg in routine laboratories for its speciation in foods and samples of environmental interest.

Description of the figures Figure 1 shows the general scheme of inorganic mercury speciation, Hg

(H) And methylmercury, MeI-lg, following the MISPE procedure: 1) conditioning, 2) sample loading, 3) washing, 4) inorganic mercury elution, I-Ig (H) and 5) methylmercury elution, MeHg

Embodiment of the invention

The present invention is further illustrated by the following examples, which are not intended to be limiting in scope.

Example I In this example it shows the synthesis of the quinoline-8 p-vinylbenzoate monomer

ilo (Scheme [).

On an aqueous solution of p-vinylbenzoic acid (830 mg, 5.6 mmo!) In anhydrous TI-IF (15 mL) DMF (12 drops) is isolated. The mixture is cooled to 0 ° C and oxalyl chloride (0.7 mL, 8.02 mmo!) Is added dropwise. The mixture is stirred 3 h at 20 ° C, then the solvent and excess oxalyl chloride are removed in vacuo. The residue is dissolved in anhydrous THF (15 mL), and 8-hydroxyquinoline (0.82 g,

5.6 mmo!) And triethylamine (lml, 7.2 mmo!). The mixture is stirred for 4 h at 20 ° C. Subsequently, it is extracted with dichloromethane, washed with water and dried over MgSO4. The solvent is removed in vacuo and the solid obtained is purified by chromatography to obtain a white solid (0.78 g, 50%).

'H NMR (CDCI,): 5.43 (d, J ~ II Hz, IH), 5.92 (d, J ~ 17.7 Hz, IH), 6.82 (dd, J ~ 17.7, J ~ II Hz, IH), 7.42 ( dd, J ~ 8.3, J ~ 4.2 Hz, IH), 7.57 (m, 4H), 7.76 (m, IH), 8.19 (dd, J ~ 8.3 Hz, J ~ 1.7 Hz, IH), 8.31 (d, J ~ 8.3 Hz, 2H), 8.89 (dd, J ~ 4.3, J ~ 1.7 Hz IH). "c NMR (CDCI): 165.2 (C ~ O), 150.6 (CH), 147.8 (Cq), 142.5 (CH), 141.4 (Cq), 136.1 (Cq), 135.9 (CH), 130.9 (CH), 129.6 (Cq), 128.6 (Cq), 126.3 (CH), 126.2 (CH), 125.9 (CH), 121.7 (CH),

121.6 (CH), I 16.7 (CH,). IR (KB,): 1736, 1604, 1499, 1266, 1234, I 173, 1096 cm. "MS (E l)

miz: 275.09 (M '"66%), 132.05 (52%), 131.05 (100%), 103.05 (73%), 77.04 (68%). Elemental analysis: e, 78.53; 1-1.4.76; N, 5.09 CSI-l13N02 requires e, 78.60; 1-1.4.73; N, 5. 13.

5

Scheme I

Example 2

This example represents the synthesis of the polymer of formula IV (Scheme TI)

the

The polymeric material is synthesized by polymerization.

radicalaria using

as reagents a monomer of Formula II (p-vinylbcnzoate of quinoli n-8-yl), a

cntrccrucing agent of Formula III (2-acrylolamidoethyl acrylate, NOBE) and

a

polymerization initiator (2,2'-azobis-isobutyronitrile, AlBN) in the presence of a

fifteen

solvent (acctonitrile).

The

polymerization be carries to cape in bowls of topaz in atmosphere from argon,

using a heating plate with stirring, maintaining a temperature of 65 ° C

for 24 h. 0.13 mmol (35 mg) of monomer 1 dissolved in 4 mL of

twenty

acetonitrile (HPLC purity), 3 mmol of N013E (600 mg) and subsequently the initiator

(AIBN). The mixture is stirred at 65 ° C for 24 h. The precipitate obtained is weighed,

getting

around from 600 mg from a solid White in every process from

polymerization.

AlBN

X = O, Y = NH m

m ~ 1

X: NHY = Q

n2: 1

X = O, Y = NH

r ~ 1

IV

Scheme 11

Example 3 5 In this example the characterization of the polymer of example 2 is shown by MIPSE procedure (Figure 1).

The polymeric material is used as a support in 6 mL glass cartridges equipped with 0.22 micron Teflon frits. The amount deposited in the cartridges is 50

10 rng of polymer, the following steps of the procedure being carried out. Conditioning of the material with 5 mL of He! 2M in methanol and 5 mL H20 Milli-Q Load: 1 rnL of 25 ~ g.L·l of Hg (11) and CI-hHg, in water, both individually and together.

15 Washing: with 1 rnL of acetonitrile to eliminate possible interference and nonspecific junctions.

Elution: in the case of loading only inorganic mercury, its elution is performed with 5 mL of Hel 2M in methanol; if it has been loaded with methylmercury, elution is performed with 5 rnL of 20% NaCIO in 1M He !. And in the case of loading both analytes, the sequential elution of the species is carried out (eluting inorganic mercury first).

Example 4 Selectivity of the polymer of example 2 towards mercury.

Cross-reactivity studies are carried out following the MIPSE procedure using other elements that are present in the environment, such as As, Cd and Pb and allow to demonstrate the high selectivity of this material towards mercury. A preconcentration factor1 of 40 applied in seawater for inorganic and organic mercury is achieved, having a recovery efficiency of 100% in the case of inorganic mercury and 80% for methylmercury. In addition, the MIPSE procedure allows to differentiate between both species in consecutive stages of elution, obtaining a sequential separation.

Example 5 The application of the polymeric material of Example 2 to real biological or fish samples is shown.

First, the samples of swordfish and tuna, previously purchased at the supermarket, are freeze dried. An extraction with 5M HCI is performed for 30 minutes in an ultrasonic bath; It is then centrifuged to collect the supernatant, being the extract of interest. Before performing the MISPE procedure, the extract is diluted so that its final concentration is 2.5 M HCL. After this, the procedure described above is carried out.

In this way the methylmercury content can be evaluated directly, without the need to pre-concentrate the extract. The procedure is validated by the analysis of a BCR-646 reference material (tuna methylmercury).

Claims (16)

one.

Monochrome derived from 8-hydroxyquinoline of formula l:

2.

Monochrome derived from 8-hydroxyquinoline (quinolin-8-yl p-vinylbenzoate), according to claim 1, of formula JI:

3.

Method of obtaining the monomcro p-vinylbcnzoate of quinolin-8-yl, according to claim 2, from p-vinylbenzoic acid and 8-hydroxyquinoline.

Four.

Method of obtaining the monomer p-vinylbenzoalo of quinolin-8-yl, according to claim 3, characterized in that it is carried out in two claps:

a) Dissolution of p-vinylbenzoic acid in anhydrous THF and subsequent addition of anhydrous DMF and oxalyl chloride. b) Removal of solvent and excess oxalyl chloride, dissolution in anhydrous THF and addition of 8-hydroxyquinoline and triethylene amine. The white solid obtained is recovered and purified.

5.

Polymeric material comprising the quinoline-8yl p-vinylbenzoate monomer.

6.

Polymeric material according to claim 5, comprising the quinoline-8-yl pvinylbenzoate monomer and a crosslinking agent.

7.

Polymeric material, according to claim 6, characterized in that the crosslinking agent is 2-acrylolamidoethyl acrylate (NOBE).

8.

Method of obtaining polymeric material, according to claims 5, and 6,

characterized in that it comprises: Dissolving the monomer (quinolin-8-yl p-vinylbenzoate) in a solvent pathogen. Add a crosslinking agent Add a polymerization initiator Recover the product obtained

9.

Method of obtaining polymeric material, according to claim 8, wherein the crosslinking agent is 2-acrylolamomethyl (NO BE).

10.

Method of obtaining polymeric material, according to claims 8 and 9, wherein the polymerization initiator is AIBN.

eleven.

Method of obtaining polymeric material according to claims 8, 9 and 10, wherein the porogenic solvent is acetonitrile.

12.

Method of obtaining polymeric material, according to claims 8 to 11, wherein the polymerization is carried out by precipitation.

13.

Use of the polymeric material claimed for the preconcentration and selective speciation of inorganic and organic mercury species.

14.

Use of the polymeric material according to claim 13, wherein the mercury species come from natural waters.

fifteen.

Use of the polymeric material according to claim 13, wherein the mercury species come from food.

16. Use of the polymeric material according to claim 15, wherein the mercury species come from fish.