KR101703436B1 - Detecting method of trivalent chromium using EDTA - Google Patents

Abstract

The present invention relates to a method of detecting Cr(III) using EDTA and, more specifically, relates to Cr(III) ions contained in samples such as water first reacted with EDTA and the Cr(III)-EDTA complex bonded to silver nanoparticles; and the silver nanoparticles agglomerated and subjected to a surface enhanced Raman scattering (SERS) method, and Cr(III) ions contained in the sample being able to be detected with a detection limit of 500 nM. In particular, Cr(III) contained in distilled water, tap water, river water and seawater can selectively and easily be detected without an influence of disturbing ions.

Description

{Detecting method of trivalent chromium using EDTA}

The present invention relates to a method for detecting Cr (III) using silver nanoparticles and complexing with EDTA.

Various methodologies for the detection and quantification of heavy metals in aqueous solutions have attracted much attention, and nanoparticles have been introduced to detect heavy metal ions in solution.

Trivalent chromium [Cr (III)] improves the sensitivity of insulin and is therefore used as a diabetic diet and remedy. Quantitation of Cr (III) in water can be carried out using various conventional analytical methods (J. Hazard. Mater. 2011, 186, 169-17; J. Hazard. Mater. 2011, 188, 274-280; Electroanalysis 2011, 23, 287 Recently, a metal nanostructure has been introduced to detect Cr (III), and twin 20, glutathione, 11-mercaptoundecanoic acid, 5,5'- Although a combination of several linker units including dithio-bis- (2-nitrobenzoic acid) and citric acid is used, there is a problem in that the detection method is complicated and the detection sensitivity is low.

However, there is still a need for a method capable of easily and easily detecting Cr (III) in water samples even though the detection sensitivity is high.

Korean Laid-open Patent No. 2015-0034871 (2015.04.06)

An object of the present invention is to provide a detection method of Cr (III) capable of selectively detecting only trivalent chromium ions by an easy and simple method while improving detection sensitivity.

In order to accomplish the above object, the present invention provides a method for preparing a sample, comprising: adding and stabilizing ethylenediaminetetraacetic acid (EDTA) to a sample; Adding silver nanoparticles to the stabilized solution to form a complex; And performing a Raman analysis on the sample.

According to the present invention, after Cr (III) ions contained in a sample such as water are first reacted with EDTA, the Cr (III) -EDTA complex binds with silver nanoparticles and agglomerates the silver nanoparticles to form surface enhanced Raman scattering ) Method can detect the Cr (III) ion contained in the sample with a detection limit of 500 nM, and can selectively and easily remove Cr (III) contained in distilled water, tap water, Can be detected.

FIG. 1A shows a photographic image of EDTA-Cr (III) and UV-Vis absorption spectrum, and FIG. 1B shows FT-IR analysis results of EDTA-Cr (III) at 800-4000 cm ^-1 .
Fig. 2 (a) is a TEM image of silver nanoparticles (AgNPs), Fig. 2 (b) is the result of UV-vis absorption analysis of silver nanoparticles under the bond between Cr (III) and EDTA, TEM image of silver nanoparticles agglomerated after reaction with EDTA in uM.
FIG. 3A shows SERRS (Surface Enhanced Resonance Raman scattering) analysis results for the detection of Cr (III) using Tris-EDTA on silver nanoparticles. FIG. ^-1 , the ratio of the intensity of ~ 563 cm ^{-1 to} the intensity of ^-1 , Figure 3c is a SERS analysis of a mixture of 15 ions to examine the competitive reaction, Figure 3d shows the result of SERS analysis of a mixture of 15 ions The pH-dependent binding behavior of EDTA-Cr ³⁺ is shown by SERS analysis at pH 4.0 and pH 8.0.
Figure 4a shows the concentration dependent SERS spectra of Cr (III) detection using Tris-EDTA and AgNPs at 0.005-10 μM and Figure 4b shows the concentration dependent SERS spectra of Cr (III) concentration dependent SERS spectra between 200 and 750 cm ^-1 And FIG. 4C is a graph showing the ratio of the vibration intensity of ~ 563 cm ^{-1 to} the vibration strength of ~ 918 cm ^-1 .
FIG. 5A is a Raman analysis result for the detection of Cr (III) in an actual seawater sample, and FIG. 5B shows a calculation curve of the vibration band intensity.
6 is a schematic diagram for detection of Cr (III) using silver nanoparticles by confocal Raman spectroscopy.

Hereinafter, the present invention will be described in more detail.

The present inventors investigated the method of detecting Cr (III) in a water sample. When silver nanoparticles were treated after EDTA and Cr (III) were combined, aggregation of EDTA-Cr (III) The present inventors have completed the present invention.

The present invention relates to a method for the preparation of a sample, comprising the steps of adding and stabilizing ethylenediaminetetraacetic acid (EDTA) to a sample; Adding silver nanoparticles to the stabilized solution to form a complex; And performing a Raman analysis on the sample.

The EDTA may be a basic EDTA buffer solution having a pH of 8 to 10, for example, a Tris-EDTA solution (pH 8.0). The EDTA is preferably added in an amount of 0.001 to 0.1 part by weight based on 100 parts by weight of the sample. May cause problems when operating the sensor.

The stabilization may be allowed to stand at 25 to 30 DEG C for a period of from several minutes to 60 minutes.

The silver nanoparticles are preferably added in an amount of 0.001 to 0.1 part by weight based on 100 parts by weight of the stabilized solution.

The complex is formed by the coordination bond between Cr (III) and an oxygen atom or nitrogen atom in the carboxyl group of EDTA. In the presence of Cr (III) at a low concentration, Cr (III) (III) -N coordination bonds between the Cr (III) and EDTA nitrogen atoms in the presence of Cr (III) at a high concentration, and then form a complex with silver nanoparticles forms a complex with the particles, the aggregated composites may exhibit a strong Raman bands at ~ 563cm ^-1.

The sample may be water selected from the group consisting of distilled water, tap water, river water and seawater, but is not limited thereto.

The silver nanoparticles may be nanoparticles having an average particle diameter of between 30 and 60 nm.

According to the detection method of the present invention, Cr (III) contained in a water sample at a concentration of less than micromolar such as 500 nM in the water sample can be easily detected within a few minutes without disturbance of other heavy metals.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited by the following examples.

≪ Example 1 >

1. Preparation of reagents

Cr (III) and other ions substrate, _{NaCl, KNO 3, Mg (NO} 3) 2, Ca (NO 3) 2, Cr (NO 3) 3, Mn (NO 3) 2, FeC 2 O 4, Fe (NO _{3) 3, Co (NO 3} ) 2, Ni (NO 3) 2, Cu (NO 3) 2, Zn (NO 3) 2, NH 4 NO 3, Cd (NO 3) 2, Hg (NO 3) 2 , Pb (NO ₃ ) ₂ and K ₂ Cr ₂ O ₇ (or Na ₂ CrO ₄ ), silver nitrate, sodium citrate, Tris-EDTA (pH 8.0) and EDTA acetic acid were dissolved in Sigma Aldrich ). Buffer (pH 4.0) was purchased from Thermo Scientific (Waltham, MA, USA). Seawater samples were collected from the Yellow Sea (Taean, Chungcheongnam-do). Silver colloid substrates stabilized with citric acid were synthesized according to a known method (J. Hazard. Mater. 2014, 265, 89-95).

2. Analysis method

UV-Vis absorption spectra were obtained using a Mecasys UV-3220PC spectrometer (Daejeon, Korea) to observe the resonance process and cohesion characteristics of silver nanoparticles (AgNPs). Projection electron microscopy images of AgNPs were obtained from JEOL (Peabody, MA, USA) using JEM-3010 and JEM-1010. For Fourier Transform Infrared Spectroscopy (FT-IR), one drop of the EDTA-Cr (III) solution sample was transferred onto a MIRacle ZnSe damping totalizer purchased from Pike Technologies (Madison, WI, USA). Infrared spectra were obtained from a Thermo Nicolet (Waltham, MA, USA) using an FT-IR 6700 spectrometer equipped with a narrow-band HgCdTe detector with a cut-off of 800 cm ^-1 . Raman spectra at 632.8 nm were obtained using the conventional method (J. Am. Chem. Soc. 2014, 136, 3833-3841). The resonance Raman spectrum at 532 nm compared to non-resonant near infrared Raman at 785 nm was obtained using Horiba Jovin Yvon (Palaiseau, France) LabRam Aramis. X-ray photoelectron spectra (XPS) spectra were obtained using sigma probe instruments using Al-Kα monochromatic light sources.

3. Sample Processing

For SERS experiments, 10 μL Cr ³⁺ (1 mM of distilled water or sea water) and 50 μL EDTA (Tris-EDTA buffer, pH 8.0) were mixed and stirred at room temperature for 60 minutes or more. Then, 140 μL of AgNPs was added to the above mixture, and the SERS spectrum was observed. The waters were collected from the Yellow Sea in Korea and tested by ICP-OES (Inductively Coupled Plasma Emission Spectroscopy) through an ICAP-7400 analyzer purchased from Thermo Scientiffic and a CETAC M-7500 mercury analyzer purchased from Parma Company.

AgNPs-EDTA showed selective turn-on Raman intensity response to Cr ³⁺ in seawater (50 μM). The reaction behavior was observed in AgNPs-EDTA in the presence of metal ions associated with various environments. The Raman spectral characteristics of AgNPs-EDTA-Mn ⁺ are determined by the following ^equation : K ⁺ , Cd ²⁺ , Mg ²⁺ , Ca ²⁺ , Mn ²⁺ , Co ²⁺ , Na ⁺ , Cu ²⁺ , NH ⁴⁺ , Hg ²⁺ , Ni There was no change in the presence of ²⁺ , Fe ³⁺ , Pb ²⁺ , Fe ²⁺ and Zn ²⁺ ions (both at a concentration of 50 μM). Of all tested metal ions, only Cr ³⁺ ions increased Raman intensity in the presence of AgNPs-EDTA.

For XPS experiments, 1.0 mL of the mixture was placed in a 1.5 mL centrifuge tube and centrifuged at 10,000 rpm for 10 minutes at 4 ° C to recover AgNPs-EDTA-Cr ³⁺ until the residue became 20 μL The supernatant was carefully removed. AgNPs-EDTA-Cr ^{3 +} 20 μL was placed on a Deckglaser (Sondheim / Rhon, Germany) cover glass (5 mm x 5 mm size) and dried overnight at 75 ° C and then the XPS spectrum was observed.

4. Experimental results

FIG. 1A shows a photographic image and UV-Vis absorption spectrum of EDTA-Cr (III). When Cr (III) was bound, the absorbance value increased at 500 to 700 nm and the color changed to purple. The excitation wavelength was 633 nm. FIG. 1B shows FT-IR (FT-IR) analysis of EDTA-Cr (III) at 800 to 4000 cm ^-1 .

The UV-Vis spectrum of EDTA appeared similar to known literature ( Inorg . Chem . 1984, 23 , 3798-3802). 1622, 1522 and 1387 ^cm-1 band, ν (C = O), ν as (COO -) ^respectively is assigned to the band, and ν _s (COO). This spectral change means that the COO ^- band becomes a stronger symmetric vibration instead of an asymmetric vibration.

Fig. 2 (a) is a TEM image of silver nanoparticles (AgNPs), Fig. 2 (b) is the result of UV-vis absorption analysis of silver nanoparticles under the bond between Cr (III) and EDTA, TEM images of silver nanoparticles agglomerated after reaction with EDTA in uM. According to Fig. 2, when Cr (III) is increased in the complex, the UV-Vis spectrum of AgNPs is red shifted toward 600 to 800 nm, which means agglomeration of AgNPs. These results indicate that EDTA with high concentration of Cr (III) can induce plasmon changes in AgNPs.

FIG. 3A shows the results of SERRS (Surface Enhanced Resonance Raman scattering) analysis for detecting Cr (III) using Tris-EDTA on silver nanoparticles. As a result, the increase in absorbance at 633 nm can be confirmed, SERRS observation over 532 nm instead of nm was attempted. We observed ~ 563 cm ^-1 oscillation band at excitation of 532 nm, but it was confirmed that this peak was not observed at 785 nm. This result means that there can be a strong Raman band at ~ 564 cm ^-1 due to the resonant Raman effect through the absorption band of 500-600 nm.

FIG. 3b is shown as a of ~ 563 cm ^-1 for the 16 varieties of ~ 918 cm ^-1 in the ionic species of the strength intensity ratio in a bar graph, Cr ³⁺ ion, such as only a 918 and 1381 cm ^-1 Along with the reduction of the band, it showed intrinsic strong peaks at ~ 563 cm ^-1 of the metal-N stretching band.

FIG. 3c is a graph showing SERS analysis of a mixture of 15 ions in order to examine a competitive reaction. FIG. 3c shows the results of SERS analysis of K ⁺ , Cd ²⁺ , Mg ²⁺ , Ca ²⁺ , Mn ²⁺ , Co ^{2 +,} in the case of ^{Na +, Cu 2+, NH 4+} , Hg 2+, Ni 2+, Fe 3+, Pb 2+, Fe 2+, and the other 15 of the mixed ion is Zn ²⁺ Cr ³⁺ , While the Cr3 ⁺ was mixed in 15 ions, the 563 cm- ¹ band was further enhanced. These results indicate that competitive ions at high ion concentrations of 10 μM do not substantially interfere with the detection of Cr ³⁺ ions by other ions.

FIG. 3D shows the SERS analysis of pH-dependent binding behavior of EDTA-Cr ³⁺ bound to silver nanoparticles at pH 4.0 and pH 8.0, wherein the Raman spectra at pH 4.0 varied considerably from pH 8.0, and pH 4.0 Did not produce peaks equal to 563 cm < ^-1 > peaks at pH 8.0. These results indicate that the basic pH value of the silver nanoparticles is essential for producing EDTA-Cr ³⁺ -induced spectral changes.

According to X-ray photoelectron spectroscopy (XPS), the atomic ratios of Cr and K EDTA compounds on AgNPs were measured to be 1.41% and 0.24%, respectively. The relative ratios of Cr and K to Ag were 3.93% and 0.77%, respectively. For Fe ^{3 +} ions, no iron species could be observed in the entire spectral range between 1000 and 0 eV. Accordingly, it would mean that the Cr ^{3 +} ions can be strongly adsorbed on the Ag surface, as compared with other ions and by the EDTA-Cr ³⁺ compounds more strongly bonded to the AgNPs induced a strong dose-dependently SERS spectrum. It can be interpreted that EDTA represents a carboxylation band at low concentrations of Cr (III) and other ions. The marker band of the Cr (III) -EDTA compound at high concentrations of Cr (III) can be enhanced in the SERRS spectrum.

Figure 4a shows the concentration dependent SERS spectra of Cr (III) detection using Tris-EDTA and AgNPs at 0.005-10 μM and Figure 4b shows the concentration dependent SERS spectra of Cr (III) concentration dependent SERS spectra between 200 and 750 cm ^-1 will showing an enlarged view of the band, Figure 4c is - as shown in the graph was calculated the ratio of vibration intensity of the ~ 563 cm ^-1 on the vibration intensity of 918 cm ^-1, at least 500 nM in the 563cm ^-1 band of distilled water , Respectively. The SERRS band between 200 and 300 cm ^-1 assigned to Ag-N and Ag-COO showed different binding of EDTA-Cr (III) compounds on AgNPs.

Based on the results, detection of Cr (III) in the applicable seawater samples was carried out. The following table 1 shows the elemental composition of the seawater used: K, Mg, Ca, and Na ion concentrations of ~ 13.3 mM, ~43.6 mM, ~ 8.61 mM and ~ 435 mM, respectively.

[Table 1]

FIG. 5A clearly shows bands observed at 563 cm ^-1 , which is a marker band capable of quantifying Cr (III) concentration, as a result of Raman analysis for detection of Cr (III) in an actual seawater sample, The detection limit of the band intensity was found to be as low as 500 nM from the calibration curve of the vibration band intensity of ~ 563 cm ^-1 depending on the Cr (III) concentration in seawater samples.

FIG. 6 is a schematic diagram for detection of Cr (III) using silver nanoparticles by confocal Raman spectroscopy. In the presence of Cr (III) at a low concentration, Cr (III) (III) -N coordination between the nitrogen atoms of Cr (III) and EDTA in the presence of a high concentration of Cr (III) To form a complex with the silver nanoparticles, and the agglomerated complex exhibited a strong Raman band at ~ 563 cm <" ^{1 &} gt ;.

The present invention provides a novel method for detecting Cr (III) at a submicromolar level using Tris-EDTA buffer and silver nanoparticles. Tris-EDTA, in particular, is sensitive to Cr (III) in the presence of silver nanoparticles (III) as low as 500 nM can be detected effectively. In actual seawater samples, low concentrations of Cr (III) can be effectively detected without interfering with other ions.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (6)

Adding ethylenediaminetetraacetic acid (EDTA) to the sample and stabilizing the sample;
Adding silver nanoparticles to the stabilized solution to form a complex; And
Determine whether or not the band at 563 cm ^-1 and by performing a Raman analysis,
Wherein the complex binds to silver nanoparticles after coordination bond between the carboxyl group or nitrogen atom of EDTA and Cr (III) in the sample to form a coagulated complex. delete The method for detecting Cr (III) ions in a sample according to claim 1, wherein the EDTA is a basic EDTA buffer solution having a pH of 8 to 10. delete The method according to claim 1, wherein the sample is water selected from the group consisting of distilled water, tap water, river water and seawater. The method according to claim 1, wherein the silver nanoparticles are nanoparticles having an average particle diameter of between 30 nm and 60 nm.

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