A nano-gold array sensor and its method for rapid identification and detection of chromium multimorphic structures.

Abstract

This invention discloses a gold nanoparticle array sensor and its method for rapid identification and detection of multiple chromium species. The gold nanoparticle array sensor includes four probe units: gold nanoparticles modified with small molecule organic compounds containing amino and carboxyl groups, phosphorus-containing inorganic polymers, amino-containing cationic surfactants, and quaternary phosphine-containing cationic surfactants. When rapidly identifying and detecting multiple chromium species, this invention acquires fingerprint spectral information corresponding to different chromium species and uses hierarchical clustering analysis (HCA) and linear discriminant analysis (LDA) algorithms to identify single Cr(III), Cr(VI) ions, Cr(III)-organic complexes, or mixed samples. Simultaneously, it can also perform quantitative analysis of target analytes under low concentration conditions. The method for rapid identification of multiple chromium species using the gold nanoparticle array sensor of this invention has strong identification ability, simple operation, short detection time, high sensitivity, and high selectivity, providing a new approach for the analysis of multiple chromium species in industrial wastewater.

Description

Technical Field

[0001] This invention relates to the field of heavy metal multi-format analysis and detection in typical wastewater, and particularly to a nano-gold array sensor and its method for rapid identification and detection of chromium multi-formats. Background Technology

[0002] Chromium (Cr) is a common heavy metal pollutant in industrial wastewater, mainly originating from industries such as leather tanning, electroplating, paint production, pigment manufacturing, metal processing, wood processing, and steelmaking. Chromium is highly toxic and carcinogenic, posing a serious threat to ecological security and human health. For example, long-term exposure to chromium compounds can cause respiratory cancers and other complications. Common valence states of chromium compounds are trivalent (Cr(III)) and hexavalent (Cr(VI)). In water bodies, hexavalent chromium generally exists as CrO4. 2- Cr2O7 2- HCrO4 - Chromium exists in three anionic forms, influenced by factors such as pH, organic matter, redox substances, temperature, and hardness in the water. Trivalent chromium readily forms complexes with organic complexing agents used extensively in the production process, such as ethylenediaminetetraacetic acid (EDTA), citrate, tartaric acid, cyanide, and humic acid (HA), forming chemically stable and morphologically complex Cr(III)-organic complexes. The widespread presence of these complexes in wastewater severely hinders the efficient treatment of heavy metal pollutants using common processes such as adsorption, ion exchange, and precipitation, making it difficult for treated effluent to meet increasingly stringent discharge standards. Therefore, developing efficient and convenient methods for analyzing the speciation of heavy metal Cr in water is a prerequisite and foundation for understanding the speciation characteristics of heavy metals in water and for innovating advanced wastewater treatment technologies targeting complexed heavy metals.

[0003] Currently, chemical analysis of heavy metal complexes primarily relies on large-scale instrument coupling techniques, including separation technologies such as HPLC, capillary electrophoresis, and solid-phase extraction, as well as elemental characteristic detectors such as mass spectrometry. These methods offer high accuracy and sensitivity, but establishing the methodology is time-consuming and labor-intensive. Furthermore, the instruments are expensive and require specialized personnel, making them unsuitable for widespread use in resource-constrained areas and for real-time on-site monitoring. Developing simple, rapid, and sensitive analytical methods for complexed heavy metals is of significant environmental importance. In recent years, colorimetric analysis methods for pollutants based on the localized surface plasmon resonance effect of gold nanoparticles (Au NPs) have attracted considerable interest from researchers, becoming a current research hotspot in water quality analysis and already being used for the detection of simulated water samples or surface water bodies. In current research, gold nanoparticle probes can identify, semi-quantitatively analyze, and perform single-component quantitative analysis of numerous free heavy metal ions, anions, drug molecules, and small biological molecules. The recognition mechanism of free metal ions mainly involves specific coordination complexation between the metal and functional groups modified on the surface of Au NPs. However, due to their inherent chemical stability and the steric hindrance of organic ligands, complexed heavy metals are unlikely to chemically interact with the recognition units on the surface of gold nanoprobes. To date, there are virtually no research reports on the use of Au NPs nanoprobes to analyze and identify complex metal speciations in simulated or real water samples. Furthermore, in real water bodies, organic ligands are often diverse and vary in content, resulting in diversity and structural uncertainty in the occurrence forms of complexed heavy metals. In addition, the specific recognition capability of a single nanoprobe is insufficient to provide overall variable information about the water sample being tested, nor can it classify and identify similar mixtures. Therefore, constructing a colorimetric analysis method capable of classifying and identifying heavy metal pollutant speciations by modifying the surface of Au NPs with targeted recognition groups remains a significant challenge.

[0004] The sensor array abandons the strict "one-to-one" design philosophy of traditional nanoprobes, instead consisting of a group of sensitive probe units with cross-response characteristics. Based on the differential interactions between each array unit and different target analytes, different response patterns are generated. By aggregating signal data from multiple sensing channels, a fingerprint spectrum containing information on all analytes is generated. Then, chemometric methods such as principal component analysis (PCA), linear discriminant analysis (LDA), or artificial neural networks (ANN) are used to extract and analyze the feature map, enabling pattern recognition of different target analytes. Array analysis evolves the traditional single-point, single-information detection method into simultaneous acquisition of multiple points and multiple information, greatly improving analytical efficiency. It can simultaneously detect and identify multi-component analytes in complex mixtures, and theoretically is more suitable for the speciation analysis of Cr(III)-organic ligand complexes in real water bodies. However, there are currently no reports on the qualitative identification and speciation of Cr multi-species using gold nanoparticle-based array sensors. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a nano-gold array sensor and a method for rapid identification and detection of chromium multi-forms. According to the method of the present invention, not only can single Cr(III), Cr(VI) ions, Cr(III)-organic complexes and their mixed systems be effectively identified, but also Cr(III), Cr(VI) ions and Cr(III)-organic complexes can be quantitatively analyzed.

[0006] This invention provides a gold nanoparticle array sensor for rapid identification and detection of multiple chromium species. The array sensor is used for rapid identification and detection of multiple chromium species (including free Cr(III), Cr(VI) ions, and Cr(III)-organic complexes). The gold nanoparticle array sensor includes four probe units, which are modified with four different surface modifiers, as detailed below:

[0007] The first set of probe units contains gold nanoparticles modified with small molecule organic compounds containing amino and carboxyl groups;

[0008] The second set of probe units contains gold nanoparticles modified with phosphorus-containing inorganic polymers;

[0009] The third set of probe units contains gold nanoparticles modified with amino-containing cationic surfactants.

[0010] The fourth probe unit contains gold nanoparticles modified with cationic surfactants containing quaternary phosphine salts.

[0011] The synthesis method of the four probe units described in this invention is as follows: Under stirring conditions (400~600 rpm), haloauric acid solution is used as the gold source and divided into four portions. Four different surface modifier solutions are added to the four portions of gold source respectively. A reducing agent is added, and after thorough mixing, chemical reduction is carried out. The solution color gradually changes from light yellow to orange-red to wine red. The reaction is continued at room temperature for 1.0~3.0 h, and finally four functionalized Au NPs probe units are obtained to form an array sensor.

[0012] The haloauric acid is selected from at least one of fluoroauric acid, chloroauric acid, and bromoauric acid, preferably chloroauric acid, and the final concentration of haloauric acid in the reaction solution is 0.02~1.0 mmol / L, preferably 0.2~0.5 mmol / L;

[0013] The reducing agent is selected from sodium borohydride, trisodium citrate, ascorbic acid, hydroxylamine hydrochloride, or potassium tartrate, with sodium borohydride being preferred. The final concentration of the reducing agent in the reaction solution is 3 to 10 times the final concentration of haloacid.

[0014] Furthermore, the surface modifiers for the first, second, third, and fourth probe units are selected from iminodiacetic acid (IDA) and tripolyphosphate (P3O), respectively. 10 5- Hexadecyltrimethylammonium bromide (CTAB) and hexadecyltributylphosphine bromide (THPB);

[0015] During the synthesis, the final concentrations of each modifier in the reaction solution were as follows: IDA modification concentration ranged from 0.1 to 1.0 mmol / L, preferably 0.5 mmol / L; P3O 10 5- The modification concentration range is 0.1~1.0 mmol / L, preferably 0.5 mmol / L; the CTAB modification concentration range is 0.02~2.0 mmol / L, preferably 0.1 mmol / L; the THPB modification concentration range is 0.01~2.0 mmol / L, preferably 0.1 mmol / L.

[0016] Furthermore, the first, second, third, and fourth groups of probe units were labeled as IDA@Au NPs, P3O, and P3O, respectively. 10 5- @Au NPs, CTAB@Au NPs, and THPB@Au NPs; the pH ranges for detection by the four probe units are as follows: the pH detection range of IDA@Au NPs is 2.0~7.0, preferably 2.0~4.0; P3O 10 5- The pH detection range of @Au NPs is 2.0~9.0, preferably 2.0~4.0; the pH detection range of CTAB@Au NPs is 5.0~12.0, preferably 7.0~11.0; the pH detection range of THPB@Au NPs is 5.0~13.0, preferably 11.0~13.0.

[0017] Furthermore, the four sets of probe units IDA@Au NPs, P3O 10 5- The pH values ​​used for detection by @Au NPs, CTAB@Au NPs, and THPB@Au NPs are 3.0, 3.0, 9.0, and 12.5, respectively.

[0018] This invention provides a method for rapid identification and detection of chromium multi-element speciation, comprising the following steps:

[0019] 1) For different forms of Cr, including free Cr(III), Cr(VI) ions and Cr(III)-organic complexes, a series of standard solutions of different concentrations were prepared with ultrapure water.

[0020] 2) Synthesize each group of probe units of the nano-gold array sensor of the present invention and adjust the pH to the optimal detection range. Add a series of standard solutions of different forms of Cr at different concentrations to each group of probe units after pH adjustment for thorough mixing and reaction.

[0021] 3) Use an ELISA reader to test the absorbance values ​​(A) of the reaction solutions after each group of probe units reacted with the target analyte in the standard solution at a series of different characteristic wavelengths. Also, test the absorbance values ​​(A) of each group of probe units at the corresponding characteristic wavelengths under the same reaction conditions, using an equal volume of ultrapure water as a blank control group. 0 The relative change rate of absorbance values ​​A / A 0 To detect the signal; thus, a multidimensional vector of the detection results of different groups of probe units at different characteristic wavelengths is obtained, and an array sensor fingerprint spectrum for different morphologies of Cr is constructed;

[0022] 4) Use identification and analysis algorithms to analyze the fingerprint spectrum to obtain information about the concentration and speciation of the target substance, including using LDA and / or HCA algorithms to process the relative change rate detection signal of the absorbance value mentioned in step 3) to obtain LDA and / or HCA spectra based on the relative change rate detection signal of absorbance.

[0023] 5) Synthesize the probe units of the gold nanoparticle array sensor of the present invention and adjust the pH to the optimal detection range. Add the Cr solution to be tested to each probe unit after pH adjustment and mix thoroughly. Obtain the absorbance value A of the probe unit after reaction at a series of different characteristic wavelengths and the absorbance value A of the blank control group according to the method in step 3). 0 The test signal of the ratio is processed by the LDA algorithm and / or HCA algorithm, and compared with the known LDA spectrum and / or HCA spectrum in step 3) to obtain the type and content of the Cr to be tested.

[0024] According to the present invention, the preparation method of Cr(III)-organic complex in step 1) is as follows: Cr(III) and organic compound are mixed in ultrapure water at a molar ratio of 1:1, the pH of the solution is adjusted to 4.0~5.0, and the reaction is carried out at 45~60℃ for 30.0~60.0h to prepare a mother liquor of Cr(III)-organic complex. Then, the mother liquor is diluted with water to obtain a series of standard solutions of different concentrations. The final concentration of total Cr in the standard solution is 20.0~1000μmol / L, preferably 30.0~500μmol / L.

[0025] According to the present invention, the organic compound is a common organic acid found in industrial wastewater, such as formic acid, acetic acid, lactic acid, cysteine, glycine, alanine, humic acid, citric acid, tartaric acid, malic acid, aspartic acid, oxalic acid, ethylenediaminetetraacetic acid, succinic acid, aminosulfonic acid, sulfosalicylic acid, etc.

[0026] According to the present invention, the organic acid is preferably one of the following nine: glycine, acetic acid, lactic acid, malonic acid, tartaric acid, citric acid, oxalic acid, ethylenediaminetetraacetic acid, and hydroxyethylidene diphosphonic acid.

[0027] According to the present invention, the reaction time in step 2) is 5.0~20.0 min, preferably 10.0 min. The final concentration of total Cr in the mixed reaction solution of the standard solution and the probe unit in step 2) is 2.0~100 μmol / L, preferably 3.0~50.0 μmol / L.

[0028] According to the present invention, the characteristic wavelength in step 3) is selected from 450, 520, 560, 600, 650 and 700 nm.

[0029] According to the present invention, the preferred method for obtaining the fingerprint spectrum of the array sensor in step 3) is as follows: after the four groups of gold nanoparticle probes react with the target, the absorbance value of the gold nanoparticles at the above wavelength is measured using an enzyme-linked immunosorbent assay (ELISA) reader, and the ratio A of the absorbance value measured at the corresponding wavelength to the absorbance of the blank control group with an equal amount of ultrapure water is used. 450 / A 0 450 A 520 / A 0 520 A 560 / A 0 560 A 600 / A 0 600 A 650 / A 0 650 and A 700 / A 0 700 To detect the signal, the relative rate of change of absorbance is obtained, resulting in a 4×6 dimensional vector, which is then used to construct a fingerprint spectrum.

[0030] According to the present invention, the method can utilize LDA first, second and three-dimensional principal component score plotting to identify multi-component mixed samples of Cr(III), Cr(VI) ions and Cr(III)-organic complexes with different mixing ratios.

[0031] According to the present invention, within a low concentration range, the relationship equation between the first principal component score obtained by LDA and the concentration can be obtained by fitting the equation, thereby achieving quantitative analysis of Cr(III), Cr(VI) ions and Cr(III)-organic complexes. Specifically, when the final concentrations of Cr(III), Cr(VI), and Cr(III)-organic complexes are 2.0–6.0 μmol / L, 3.0–25.0 μmol / L, and 5.0–20.0 μmol / L, respectively, the linear relationship between the first principal component score obtained by LDA and the concentration is significant, and the correlation coefficient (R²) is high. 2 All are greater than 0.95.

[0032] According to the present invention, the final detection concentration range for single Cr(III), Cr(VI) ions and Cr(III)-organic complexes is 3.0~100.0 μmol / L, and the final detection concentration range for Cr element in mixtures of two or more Cr(III), Cr(VI) ions and Cr(III)-organic complexes is 10.0~30.0 μmol / L.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1) In this invention, Cr(III), Cr(VI) ions, and Cr(III)-organic complexes interact with four groups of gold nanoparticle probes in an array sensor through various recognition interactions, including complexation, electrostatic attraction, and hydrophobic interactions, inducing varying degrees of aggregation of the gold nanoparticles. The array sensor then exhibits cross-response characteristics. The change rate of absorbance of the probe units before and after the reaction is collected as the response value. Multivariate statistical methods, such as hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA), are used to analyze the data to explore the array's ability to identify and detect target analytes. LDA results show that in the three-dimensional spatial map, parallel samples of Cr(III) and various Cr(III)-organic complexes can be clearly aggregated, and different analytes can be effectively separated. This indicates that this invention has a significant recognition and differentiation effect on Cr(III) and various Cr(III)-organic complexes. In HCA analysis, Cr(III) and various Cr(III)-organic complexes were classified based on the average Euclidean distance of the data to obtain a dendrogram. The classification results matched the strength of the complexing ability between Cr(III) and organic complexing agents, and were also in good agreement with the distances between analytes in the three-dimensional diagram of LDA analysis.

[0035] 2) This invention can effectively detect Cr(III) and Cr(VI) ions and Cr(III)-organic complexes at concentrations ranging from 3.0 to 100.0 μmol / L, exhibiting high sensitivity, strong recognition ability, short detection time, and simple operation. Furthermore, this invention can achieve quantitative analysis of Cr(III) and Cr(VI) ions and Cr(III)-organic complexes by fitting the principal component score of the first dimension of LDA to the concentration. In addition, this invention can also perform identification and detection in complex mixed systems.

[0036] 3) This invention is based on common cations in water (Na+). + K + Ba 2+ Ca 2+ Cd 2+ Co 2+ Cu 2+ Hg 2+ Mg 2+ Mn 2 + Ni 2+ Pb 2+ Zn 2+ Fe 3+ ), anion (Cl) - NO3 - CO3 2- SO4 2- The interference is minimal and almost negligible, which also indicates that the present invention has high selectivity for Cr(III), Cr(VI) ions and Cr(III)-organic complexes, and can perform specific recognition. Attached Figure Description

[0037] Figure 1a The response values ​​of the IDA@Au NPs probe of the array sensor of this invention to Cr(III), Cr(VI) and 9 Cr-organic complexes at a final concentration of 20.0 μmol / L are shown.

[0038] Figure 1b It is the P3O of the array sensor of this invention. 10 5- @Au NPs probe response values ​​to Cr(III), Cr(VI) and 9 Cr-organic complexes at a final concentration of 20.0 μmol / L;

[0039] Figure 1c The response values ​​of the CTAB@Au NPs probe of the array sensor of this invention to 20.0 μmol / L final concentrations of Cr(III), Cr(VI) and 9 Cr-organic complexes are shown.

[0040] Figure 1dThe response values ​​of the THPB@Au NPs probe of the array sensor of this invention to 20.0 μmol / L final concentrations of Cr(III), Cr(VI) and 9 Cr-organic complexes are shown.

[0041] Figure 2 This is an LDA diagram of the array sensor of the present invention for Cr(III) and nine Cr-organic complexes at a final concentration of 20.0 μmol / L.

[0042] Figure 3 This is the HCA diagram of the array sensor of the present invention for Cr(III) and nine Cr-organic complexes at a final concentration of 20.0 μmol / L.

[0043] Figure 4 This is the LDA plot of the array sensor of the present invention for a mixed sample of Cr(III) and Cr-citric acid (final concentration 20.0 μmol / L). Detailed Implementation

[0044] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0045] In the embodiments of the present invention, chromium trichloride can be used for Cr(III) salt and potassium chromate can be used for Cr(VI) salt.

[0046] Example 1:

[0047] The synthesis of probe units and the construction of gold nanoarrays include the following steps:

[0048] 1) Synthesis of IDA probe: At room temperature, 5.0 ml of chloroauric acid solution (5.0 mmol / L) was added to 88 ml of ultrapure water, and 5 ml of 10 mmol / L IDA solution was added to the solution. The mixture was stirred at 500 rpm for 5-10 minutes. Then, 2 ml of freshly prepared 0.1 mol / L sodium borohydride solution was added to the solution, and the mixture was stirred for 2.5 h to obtain the IDA@Au NPs probe.

[0049] 2) P3O 10 5- Probe synthesis: At room temperature, 5.0 ml of chloroauric acid solution (5.0 mmol / L) was added to 88 ml of ultrapure water, and 5 ml of 10 mmol / L Na₂P₃O₃ solution was added to the solution. 10 The solution was stirred at 500 rpm for 5-10 minutes. 2 ml of freshly prepared 0.1 mol / L sodium borohydride solution was added, and stirring continued for 2.5 h to obtain P3O. 10 5- @AuNPs probe.

[0050] 3) Synthesis of CTAB probe: At room temperature, 5.0 ml of chloroauric acid solution (5.0 mmol / L) was added to 92 ml of ultrapure water, and 1 ml of 10 mmol / L CTAB solution was added to the solution. The mixture was stirred at 500 rpm for 5-10 minutes. Then, 2 ml of freshly prepared 0.1 mol / L sodium borohydride solution was added to the solution, and the mixture was stirred for 2.5 h to obtain the CTAB@Au NPs probe.

[0051] 3) Synthesis of THPB probe: At room temperature, 5.0 ml of chloroauric acid solution (5.0 mmol / L) was added to 92 ml of ultrapure water, and 1 ml of 10 mmol / L THPB solution was added to the solution. The mixture was stirred at 500 rpm for 5-10 minutes. Then, 2 ml of freshly prepared 0.1 mol / L sodium borohydride solution was added to the solution, and the mixture was stirred for 2.5 h to obtain the THPB@Au NPs probe.

[0052] A gold nanoparticle array sensor was constructed using the above four sets of probes for the detection of Cr multi-forms.

[0053] Example 2:

[0054] The multi-element Cr species at a final concentration of 20 μmol / L were identified using an array sensor. The absorbance response of four probe units to the multi-element Cr species was obtained, and the steps are as follows:

[0055] 1) Constructing a gold nanoparticle array sensor: Four sets of probes were synthesized according to Example 1 to construct a gold nanoparticle array sensor.

[0056] 2) Establishment of absorbance response spectra: Standard sample solutions of Cr(III), Cr(VI) ions, Cr(III)-oxalic acid, Cr(III)-EDTA, Cr(III)-citric acid, Cr(III)-tartaric acid, Cr(III)-acetic acid, Cr(III)-lactic acid, Cr(III)-malonic acid, and Cr(III)-glycine were prepared with ultrapure water to a final concentration of 200.0 μmol / L. The Cr(III)-organic complex was prepared as follows: a 0.1 mol / L Cr(III) salt solution and a 0.1 mol / L organic compound solution were mixed in water at a 1:1 molar ratio. The pH of the solution was adjusted to 4.0–5.0 using 0.1 mol / L sodium hydroxide. The reaction was carried out at 45–60 °C for 48.0 h. The solution was then diluted with water to a final volume to prepare a stock solution containing 10 mmol / L Cr(III)-organic complex. The mother liquor was further diluted with water to a fixed volume to prepare a standard sample solution containing 200.0 μmol / L Cr(III)-organic complex.

[0057] The four probe units, IDA@Au NPs and P3O, were adjusted using 0.1 mol / L hydrochloric acid and 0.1 mol / L sodium hydroxide, respectively. 10 5- The detection pH values ​​for @Au NPs, CTAB@Au NPs, and THPB@Au NPs were 3, 3, 9, and 12.5, respectively. The standard sample solutions and probes were mixed thoroughly at a volume ratio of 1:9, and ultrapure water was used as a blank control and mixed thoroughly with the probes at the same volume ratio of 1:9. After reacting for 10.0 min, the absorbance values ​​A corresponding to the standard sample detection and the blank control detection were measured using a microplate reader at wavelengths of 450 nm, 520 nm, 560 nm, 600 nm, 650 nm, and 700 nm. 0 The relative change rate of absorbance at different characteristic wavelengths (A) 450 / A 0 450 A 520 / A 0 520 A 560 / A 0 560 A 600 / A 0 600 A 650 / A 0 650 and A 700 / A 0 700 Using the detection signal, absorbance response spectra of the array sensor of the present invention for Cr(III), Cr(VI) ions and Cr(III)-organic complexes are plotted.

[0058] Figure 1a , Figure 1b , Figure 1c and Figure 1d These are IDA@Au NPs probes and P3O, respectively. 10 5- Absorbance response spectra of @Au NPs probe, CTAB@Au NPs probe, and THPB@Au NPs probe for Cr(III), Cr(VI) ions, and the above nine Cr(III)-organic complexes. Figures 1a-1d In the study, the probe's absorbance response to various Cr species yielded six bar graphs, which, from left to right, correspond to detection results at wavelengths of 450 nm, 520 nm, 560 nm, 600 nm, 650 nm, and 700 nm (A). 450 / A 0 450 A520 / A 0 520 A 560 / A 0 560 A 600 / A 0 600 A 650 / A 0 650 and A 700 / A 0 700 ).from Figures 1a-1d As can be seen, the probe responds differently to the absorbance of different morphologies of Cr.

[0059] Example 3:

[0060] LDA and HCA analyses were performed on a standard substance of Cr multi-forms with a final concentration of 20 μmol / L using a gold nanoparticle array sensor. The LDA spectrum and HCA analysis chromatogram were obtained. The steps are as follows:

[0061] 1) Construct a gold nanoparticle array and react it with Cr multi-elemental forms respectively: obtain the relative change rate of absorbance of the four probe arrays with respect to Cr multi-elemental forms according to the steps of Example 2.

[0062] 2) Establishment of LDA spectra: using the relative change rate of absorbance (A) 450 / A 0 450 A 520 / A 0 520 A 560 / A 0 560 A 600 / A 0 600 A 650 / A 0 650 and A 700 / A 0 700 Using the detection signal as the basis, the obtained data were analyzed by linear discriminant analysis (LDA) using SPSS software, and an LDA spectrum of the array sensor for the multi-element speciation of Cr at a final concentration of 20.0 μmol / L was constructed with the scores of the first, second, and third principal components as coordinate axes.

[0063] 3) HCA result analysis: Based on the relative change rate of absorbance obtained in step 1), hierarchical cluster analysis (HCA) was performed on the data using SPSS software to obtain the phylogenetic diagram.

[0064] Figure 2For the obtained LDA analysis plot, from Figure 2 The results clearly show that parallel samples of the same type of substance can cluster together, while different types of substances can be clearly distinguished spatially. This demonstrates that the present invention can effectively distinguish multiple forms of Cr. Figure 3 The obtained HCA analysis chart, Figure 3 The Cr multi-forms can be divided into three major categories, and the distinction is matched with the strength of Cr(III) complexation ability with organic compounds.

[0065] Example 4:

[0066] LDA analysis of a mixed sample of Cr(III) and Cr-citric acid (total Cr concentration of 20 μmol / L) was performed using a gold nanoparticle array sensor. The steps are as follows:

[0067] 1) Constructing a gold nanoparticle array sensor: Four sets of probes were synthesized according to Example 1 to construct a gold nanoparticle array sensor.

[0068] 2) Preparation of mixed samples: Cr-citric acid solution and Cr(III) solution, both with a concentration of 10 mmol / L, were mixed at volume ratios of 0:1, 1:0, 1:1, 1:2, 2:1, 1:3, 3:1, 1:5, 5:1, 1:7, and 7:1, respectively, and diluted with water to ensure that the total Cr concentration after mixing was 200 μmol / L.

[0069] 3) Establishment of LDA spectra: The four probe units, IDA@Au NPs and P3O, were adjusted with 0.1 mol / L hydrochloric acid and 0.1 mol / L sodium hydroxide, respectively. 10 5- The detection pH values ​​for @Au NPs, CTAB@Au NPs, and THPB@Au NPs were 3, 3, 9, and 12.5, respectively. The mixed sample from step 2) was mixed with the probe at a volume ratio of 1:9, and ultrapure water was used as a blank control and mixed with the probe at the same volume ratio of 1:9. After reacting for 10.0 min, the absorbance values ​​at wavelengths of 450 nm, 520 nm, 560 nm, 600 nm, 650 nm, and 700 nm were measured using a microplate reader. The relative change rate of absorbance (A0) was expressed as the percentage change. 450 / A 0 450 A 520 / A 0 520 A 560 / A 0 560 A 600 / A 0 600 A 650 / A0 650 and A 700 / A 0 700 Using the detection signal as the basis, the obtained data were analyzed by linear discriminant analysis (LDA) using SPSS software, and a mixed LDA spectrum at a final concentration of 20.0 μmol / L was constructed with the scores of the first, second, and third principal components as coordinate axes.

[0070] Figure 4 The LDA chromatogram of the obtained mixed sample is shown below. Figure 4 As can be seen, parallel samples with the same volume ratio can cluster together, while substances with different volume ratios can be clearly distinguished spatially. At the same time, as the concentration of Cr(III) in the mixed sample increases (or decreases) and the concentration of Cr(III)-citric acid decreases (or increases), the spatial distribution of mixed samples with different proportions in the LDA diagram shows obvious trends.

[0071] Example 5:

[0072] Quantitative analysis of Cr(III), Cr(VI) ions and Cr-citric acid (final concentration 20 μmol / L) was performed using a gold nanoparticle sensor, as follows:

[0073] 1) Constructing a gold nanoparticle array sensor: Four sets of probes were synthesized according to Example 1 to construct a gold nanoparticle array sensor.

[0074] 2) Preparation of samples with different concentration gradients: 10 mmol / L Cr(III) solution, Cr(VI) ion solution and Cr-citric acid solution were diluted to obtain Cr(III) solution with concentration gradients of 20, 30, 40, 50 and 60 μmol / L; Cr(VI) solution with concentration gradients of 30, 60, 100, 150 and 250 μmol / L; and Cr-citric acid solution with concentration gradients of 50, 80, 100, 150 and 200 μmol / L.

[0075] 3) Quantitative analysis: The four probe units, IDA@Au NPs and P3O, were adjusted with 0.1 mol / L hydrochloric acid and 0.1 mol / L sodium hydroxide, respectively. 10 5-The detection pH values ​​for @Au NPs, CTAB@Au NPs, and THPB@Au NPs were 3, 3, 9, and 12.5. Using ultrapure water as a blank, Cr(III) solution, Cr(VI) ion solution, and Cr-citric acid solution of different concentration gradients were mixed with the probes at a volume ratio of 1:9. After reacting for 10.0 min, the absorbance values ​​at wavelengths of 450 nm, 520 nm, 560 nm, 600 nm, 650 nm, and 700 nm were measured using a microplate reader. The relative change rate of absorbance (A0) was used as the percentage of absorbance measured. 450 / A 0 450 A 520 / A 0 520 A 560 / A 0 560 A 600 / A 0 600 A 650 / A 0 650 and A 700 / A 0 700 Using the detection signal as the basis, the obtained data were analyzed by linear discriminant analysis (LDA) using SPSS software. Two-dimensional graphs were plotted for the three Cr species with the first principal component score (Factor 1) as the y-axis and the concentration gradient as the x-axis, and linear fitting was performed.

[0076] As shown in Table 1, the first-dimensional principal component scores obtained from LDA analysis of the Cr(III), Cr(VI) ion, and Cr-citric acid data exhibit a high degree of linearity with their corresponding concentrations. Specifically, the fitting curve between Factor 1 and concentration for Cr-citric acid is y = 11.3x - 205.0, R0. 2 = 0.99; The fitted curve of Factor 1 and concentration for Cr(III) is y = 20.4x - 122, R 2 = 0.99; The fitted curve of Factor 1 and concentration for Cr(VI) is y = 5.76x - 52.1, R 2 =0.99. Based on the fitting results, R0.99 2 All values ​​are greater than 0.95, indicating that the array sensor of the present invention can perform quantitative analysis of Cr in different morphologies.

[0077]

[0078] Example 6:

[0079] The speciation of chromium in chromium plating wastewater (raw water) was analyzed and identified.

[0080] The same LDA spectrum was constructed as in Example 3 with a final concentration of 20.0 μmol / L.

[0081] The chromium plating wastewater (raw water) was diluted approximately 100 times (maintaining a total Cr content of 200.0 μmol / L). Using ultrapure water as a blank, it was mixed with each group of probes at a volume ratio of 1:9. After reacting for 10.0 min, the absorbance values ​​at wavelengths of 450 nm, 520 nm, 560 nm, 600 nm, 650 nm, and 700 nm were measured using a microplate reader. The relative change rate of absorbance (A) was then used as the statistical measure. 450 / A 0 450 A 520 / A 0 520 A 560 / A 0 560 A 600 / A 0 600 A 650 / A 0 650 and A 700 / A 0 700 The signal is used for detection, and the obtained data is summarized into the LDA standard library for prediction, thereby determining the main type of chromium complex contained in the tannery wastewater.

[0082] Example 7:

[0083] The speciation of chromium in tanning wastewater was analyzed and identified.

[0084] The same LDA spectrum was constructed in Example 3 with a final concentration of 20.0 μmol / L.

[0085] Tannery wastewater was diluted 2 times (maintaining a total Cr content of 200.0 μmol / L). Using ultrapure water as a blank, it was mixed with each probe group at a volume ratio of 1:9. After reacting for 10.0 min, the absorbance values ​​at wavelengths of 450 nm, 520 nm, 560 nm, 600 nm, 650 nm, and 700 nm were measured using a microplate reader. The relative change rate of absorbance (A) was used as the statistical measure. 450 / A 0 450 A 520 / A 0 520 A 560 / A 0 560 A 600 / A 0 600 A650 / A 0 650 and A 700 / A 0 700 The signal is used for detection, and the obtained data is summarized into the LDA spectrum for prediction, thereby determining the main type of chromium complex contained in the leather tanning wastewater.

[0086] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. A nano-gold array sensor for rapid identification and detection of multiple chromium species, characterized in that... The array sensor is used to identify and detect different forms of Cr, including free Cr(III), Cr(VI) ions, and Cr(III)-organic complexes. The array sensor of the gold nanoparticles includes four probe units, which are modified with four different surface modifiers, as detailed below: The first set of probe units contains gold nanoparticles modified with small molecule organic compounds containing amino and carboxyl groups; The second set of probe units contains gold nanoparticles modified with phosphorus-containing inorganic polymers; The third set of probe units contains gold nanoparticles modified with amino-containing cationic surfactants. The fourth probe unit contains gold nanoparticles modified with cationic surfactants containing quaternary phosphine salts; The surface modifiers for the first, second, third, and fourth groups of probe units were selected from iminodiacetic acid (IDA) and tripolyphosphate (P3O4), respectively. 10 5- Hexadecyltrimethylammonium bromide (CTAB) and hexadecyltributylphosphine bromide (THPB).

2. The nano-gold array sensor for rapid identification and detection of chromium multi-morphology as described in claim 1, characterized in that... The synthesis method of the four probe units is as follows: Under stirring conditions of 400~600 rpm, haloauric acid solution is used as gold source and divided into four portions. Four different surface modifier solutions are added to the four portions of gold source respectively. A reducing agent is added, and after thorough mixing, chemical reduction is carried out. The solution color gradually changes from light yellow to orange-red to wine red. The reaction is continued at room temperature for 1.0~3.0 h, and finally four functionalized Au NPs probe units are obtained to form an array sensor. The haloauric acid is selected from at least one of fluoroauric acid, chloroauric acid, and bromoauric acid, and the final concentration of haloauric acid in the reaction solution is 0.02~1.0 mmol / L; The reducing agent is selected from sodium borohydride, trisodium citrate, ascorbic acid, hydroxylamine hydrochloride, or potassium tartrate. The final concentration of the reducing agent in the reaction solution is 3 to 10 times the final concentration of haloacid.

3. A nano-gold array sensor for rapid identification and detection of chromium multi-morphology as described in claim 2, characterized in that... The haloauric acid is selected as chloroauric acid, and the final concentration of haloauric acid in the reaction solution is 0.2~0.5 mmol / L; the reducing agent is sodium borohydride.

4. A nano-gold array sensor for rapid identification and detection of chromium multi-morphology as described in claim 2, characterized in that... During the synthesis, the final concentrations of each modifier in the reaction solution were as follows: IDA modification concentration ranged from 0.1 to 1.0 mmol / L; P3O 10 5- The modification concentration range was 0.1–1.0 mmol / L; the CTAB modification concentration range was 0.02–2.0 mmol / L; and the THPB modification concentration range was 0.01–2.0 mmol / L.

5. A nano-gold array sensor for rapid identification and detection of chromium multi-morphology as described in claim 4, characterized in that... During the synthesis, the final concentrations of each modifier in the reaction solution were as follows: IDA modification concentration range was 0.5 mmol / L; P3O 10 5- The modification concentration range was 0.5 mmol / L; the CTAB modification concentration range was 0.1 mmol / L; and the THPB modification concentration range was 0.1 mmol / L.

6. A nano-gold array sensor for rapid identification and detection of chromium multi-morphology as described in claim 2, characterized in that... The first, second, third, and fourth groups of probe units were labeled as IDA@Au NPs, P3O, and P3O, respectively. 10 5- @Au NPs, CTAB@Au NPs and THPB@Au NPs; The four probe units are used to detect pH ranges as follows: IDA@Au NPs have a pH detection range of 2.0~7.0; P3O 10 5- The pH detection range for @Au NPs is 2.0~9.0; the pH detection range for CTAB@Au NPs is 5.0~12.0; and the pH detection range for THPB@Au NPs is 5.0~13.

0.

7. A nano-gold array sensor for rapid identification and detection of chromium multi-morphology as described in claim 6, characterized in that... The four probe units are used to detect pH ranges as follows: IDA@Au NPs have a pH detection range of 2.0~4.0; P3O 10 5- The pH detection range for @Au NPs is 2.0–4.0; the pH detection range for CTAB@Au NPs is 7.0–11.

0. The pH detection range of THPB@Au NPs is 11.0~13.

0.

8. A nano-gold array sensor for rapid identification and detection of multiple chromium morphologies as described in claim 7, characterized in that... The four probe units IDA@Au NPs, P3O 10 5- The pH values ​​used for detection by @Au NPs, CTAB@Au NPs, and THPB@Au NPs are 3.0, 3.0, 9.0, and 12.5, respectively.

9. A method for rapid identification and detection of chromium multi-element speciation, characterized in that... Includes the following steps: 1) For different forms of Cr, including free Cr(III), Cr(VI) ions and Cr(III)-organic complexes, a series of standard solutions of different concentrations were prepared with ultrapure water. 2) Synthesize each group of probe units of the gold nanoarray sensor described in claim 1 and adjust the pH to the optimal detection range. Add a series of standard solutions of different forms of Cr at different concentrations to each group of probe units after pH adjustment for thorough mixing and reaction. 3) Use an ELISA reader to test the absorbance values ​​(A) of the reaction solutions after each group of probe units reacted with the target analyte in the standard solution at a series of different characteristic wavelengths. Also, test the absorbance values ​​(A) of each group of probe units at the corresponding characteristic wavelengths under the same reaction conditions, using an equal volume of ultrapure water as a blank control group. 0 The relative change rate of absorbance values ​​A / A 0 To detect the signal; thus, a multidimensional vector of the detection results of different groups of probe units at different characteristic wavelengths is obtained, and an array sensor fingerprint spectrum for different morphologies of Cr is constructed; 4) Use identification and analysis algorithms to analyze the fingerprint spectrum to obtain information about the concentration and speciation of the target substance, including using LDA and / or HCA algorithms to process the relative change rate detection signal of the absorbance value mentioned in step 3) to obtain LDA and / or HCA spectra based on the relative change rate detection signal of absorbance. 5) Synthesize each group of probe units of the gold nanoparticle array sensor described in claim 1 and adjust the pH to the optimal detection range. Add the Cr solution to be tested to each group of probe units after pH adjustment for thorough mixing and reaction. Obtain the absorbance value A of the probe units after reaction at a series of different characteristic wavelengths and the absorbance value A of the blank control group according to the method in step 3). 0 The test signal of the ratio is processed by the LDA algorithm and / or HCA algorithm, and compared with the known LDA spectrum and / or HCA spectrum in step 3) to obtain the type and content of the Cr to be tested.

10. The method for rapid identification and detection of chromium multi-element speciation as described in claim 9, characterized in that... In step 1), the preparation method of Cr(III)-organic complex is as follows: Cr(III) and organic compound are mixed in ultrapure water at a molar ratio of 1:1, the pH of the solution is adjusted to 4.0~5.0, and the reaction is carried out at 45~60℃ for 30.0~60.0h to prepare the mother liquor of Cr(III)-organic complex. Then, the mother liquor is diluted with water to obtain a series of standard solutions with different concentrations. The final concentration of total Cr in the standard solutions is 20.0~1000μmol / L. The organic compounds are common organic acids found in industrial wastewater, selected from formic acid, acetic acid, lactic acid, cysteine, glycine, alanine, humic acid, citric acid, tartaric acid, malic acid, aspartic acid, oxalic acid, ethylenediaminetetraacetic acid, succinic acid, aminosulfonic acid, or sulfosalicylic acid. The reaction time in step 2) is 5.0~20.0 min; In step 2), the final concentration of total Cr in the mixed reaction solution of the standard solution and the probe unit is 2.0~100μmol / L.

11. The method for rapid identification and detection of chromium multi-element speciation as described in claim 10, characterized in that... The final concentration of total Cr in the standard solution is 30.0~500 μmol / L; The organic compounds are common organic acids found in industrial wastewater, selected from glycine, acetic acid, lactic acid, malonic acid, tartaric acid, citric acid, oxalic acid, ethylenediaminetetraacetic acid, or hydroxyethylidene diphosphonic acid. The reaction time in step 2) is 10.0 min; In step 2), the final concentration of total Cr in the mixed reaction solution of the standard solution and the probe unit is 3.0~50.0 μmol / L.

12. The method for rapid identification and detection of chromium multi-morphology as described in claim 9, characterized in that... In step 3), the characteristic wavelengths are selected as 450, 520, 560, 600, 650, and 700 nm. Step 3) The fingerprint spectrum acquisition method of the array sensor is as follows: After the four groups of gold nanoparticle probe units react with the target, the absorbance value of the gold nanoparticles at the above wavelength is measured by an enzyme-linked immunosorbent assay (ELISA) reader. The ratio A of the absorbance value measured at the corresponding wavelength to the absorbance of the blank control group with an equal amount of ultrapure water is used. 450 / A 0 450 A 520 / A 0 520 A 560 / A 0 560 A 600 / A 0 600 A 650 / A 0 650 and A 700 / A 0 700 To detect the signal, the relative rate of change of absorbance is obtained, resulting in a 4×6 dimensional vector, which is then used to construct a fingerprint spectrum.

13. The method for rapid identification and detection of chromium multi-element speciation as described in claim 9, characterized in that... In steps 4) and 5), the first, second and third-dimensional principal component scores of LDA are used to identify multi-component mixed samples of Cr(III), Cr(VI) ions and Cr(III)-organic complexes under different mixing ratios. Quantitative analysis of multiple Cr species can be achieved. When the final concentrations of Cr(III), Cr(VI), and Cr(III)-organic complexes are 2.0–6.0 μmol / L, 3.0–25.0 μmol / L, and 5.0–20.0 μmol / L, respectively, the linear relationship obtained by fitting the first principal component score of LDA with the concentration of the corresponding Cr species is obvious, and the correlation coefficient R is high. 2 All values ​​are greater than 0.

95. Based on this, the concentration of the sample can be predicted in the linear fitting graph using the analytical score of the sample to be tested.

14. The method for rapid identification and detection of chromium multi-element speciation as described in claim 9, characterized in that... The final detection concentration range for single Cr(III), Cr(VI) ions and Cr(III)-organic complexes is 3.0~100.0 μmol / L, and the final detection concentration range for Cr element in mixtures of two or more Cr(III), Cr(VI) ions and Cr(III)-organic complexes is 10.0~30.0 μmol / L.

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