CN103411962B - A kind of cobalt ions colorimetric determination kit and detection method thereof - Google Patents

Abstract

The present invention relates to environment and bioassay technique field, specifically a kind of cobalt ions colorimetric determination kit and detection method thereof.Kit comprises, hydrogen peroxide, potassium rhodanide, gold nanorods solution, standard color comparison card F and color comparison tube molten containing cetyl ammonium bromide (CTAB) borate buffer solution, sodium bicarbonate; Described containing cetyl ammonium bromide (CTAB) borate buffer solution, pH is 7.4-9.6, and concentration is 10-200mM; Described sodium bicarbonate solution concentration is 0.01-1M; Described H ₂o ₂solution concentration is 0.01-1M; Described potassium thiocyanate solution concentration is 0.01-1M.Utilize the present invention to detect cobalt ions, have clever lightness high, selectivity is good, and fast, naked eyes such as easily to observe at the advantage, under the experiment condition optimized, can realize the detection of environment and biological sample cobalt ions.

Description

A kind of cobalt ion colorimetric detection kit and its detection method

technical field

The invention relates to the technical field of environmental and biological analysis, in particular to a cobalt ion colorimetric detection kit and a detection method thereof.

Background technique

As one of the essential elements of living organisms, cobalt ions play a very important role in living organisms. It is one of the components of vitamin B12. It may be for this reason that the research on the detection of cobalt ions has not received much attention. However, , It has been reported that when the cobalt ion in the blood plasma has a certain concentration, it will cause some serious diseases. Cobalt and its complexes have been pointed out as possible pathogenic toxins and carcinogenic tendencies. In addition, as a metal ion, cobalt ion cannot be decomposed, so it has the effect of bioaccumulation and biomagnification, which increases the risk of humans at the top of the food chain, so the detection of cobalt ion is very necessary.

Traditional methods to detect cobalt ions include atomic absorption spectroscopy (AAS), inductively coupled plasma-mass spectrometry (ICP-MS), voltammetry, and so on. Both AAS and ICP-MS require large instruments, which are expensive and not suitable for on-site detection, while voltammetry is relatively simple and fast, but often requires toxic mercury membrane electrodes or complex chemically modified electrodes. Compared with the above methods, the advantage of the colorimetric analysis method is that it is easy to observe with the naked eye, is very suitable for on-site real-time detection, and is easy to operate and cheap. In recent years, gold nanoparticles have been widely used in colorimetric analysis. This is due to the surface plasmon resonance absorption of gold nanoparticles, which makes its good molar extinction coefficient. The present invention uses cobalt ions to catalyze superoxide radicals to etch gold nanorods. The purpose of high sensitivity and rapid detection of cobalt ions, the method of detecting cobalt ions in this way, has not been reported in China at present.

Contents of the invention

The purpose of the present invention is to provide a cobalt ion colorimetric detection kit and a detection method thereof.

To achieve the above object, the technical solution adopted in the present invention is:

A cobalt ion colorimetric detection kit, the kit includes cetyl ammonium bromide (CTAB) borate buffer solution, sodium bicarbonate solution, hydrogen peroxide, potassium thiocyanate, gold nanorod solution, standard Color comparison card F and color comparison tube;

The borate buffer solution containing cetyl ammonium bromide (CTAB) has a pH of 7.4-9.6 and a concentration of 10-200mM;

The concentration of the sodium bicarbonate solution is 0.01-1M;

The concentration of the H ₂ O ₂ solution is 0.01-1M;

The concentration of the potassium thiocyanate solution is 0.01-1M.

The concentration of CTAB in the borate buffer solution containing cetyl ammonium bromide (CTAB) is 0.1-20mM.

Further, the borate buffer containing cetyl ammonium bromide (CTAB) in the kit has a pH of 9.0 and a concentration of 50 mM, and the concentration of CTAB is 2 mM; the gold nanorod solution has a concentration of 2.3 nM A gold nanorod solution with an aspect ratio of 2:1; a sodium bicarbonate solution with a concentration of 0.1M; a H ₂ O ₂ solution with a concentration of 0.1M; and a potassium thiocyanate solution with a concentration of 0.1M.

Centrifuge the gold nanorod solution at 6000-10000 rpm for 5-30min, collect the precipitate and dilute it with secondary water, then centrifuge at 5000-9000 rpm for 5-30min after dilution, then dilute the precipitate with secondary water for use .

The method for detecting copper ions in the cobalt ion colorimetric method detection kit is to add borate buffer solution containing CTAB to the colorimetric tube of the sample to be tested, add sodium bicarbonate, H ₂ O ₂ and potassium thiocyanate to shake and mix Mix well, then add gold nanorod solution, shake well; then incubate at 60-100°C for 2-20 minutes, observe the color with the naked eye or an ultraviolet-visible spectrometer, and compare it with the standard color card F to determine the cobalt ion content.

Furthermore, adjust the pH of the sample to be tested with borate buffer containing CTAB, and keep the final volume at 800-900 μL, add sodium bicarbonate, H ₂ O ₂ and potassium thiocyanate to shake and mix well, after mixing Then add 200-300 μL of gold nanorod solution, shake well; then incubate at 60-100°C for 2-20 minutes, observe the color with the naked eye or an ultraviolet-visible spectrometer, and compare it with the standard color card F to determine the cobalt ion content.

The preparation of the standard color card F is to take _0-300nM cobalt standard color scale solutions with different concentrations and place them in colorimetric tubes respectively, add borate buffer solution containing CTAB, _sodium bicarbonate, H2O2 and sulfur Shake and mix potassium cyanate, then add gold nanorods after mixing, shake well; then incubate at 50-100°C for 2-30 minutes for color reaction, use a professional camera to record the color results, collect pictures, Use pictures with color gradients to compose cobalt standard color card F.

The borate buffer solution containing cetyl ammonium bromide (CTAB) has a pH of 7.4-9.6 and a concentration of 10-200mM; the concentration of the sodium bicarbonate solution is 0.01-1M; the H ₂ O ₂ solution The concentration is 0.01-1M; the concentration of the potassium thiocyanate solution is 0.01-1M.

Further, the pH of the borate buffer solution containing cetyl ammonium bromide (CTAB) is 9.0, the concentration is 50mM, and the concentration of CTAB is 2mM; the gold nanorod solution has a long diameter of 2.3nM A gold nanorod solution with a ratio of 2:1; a sodium bicarbonate solution with a concentration of 0.1M; a H ₂ O ₂ solution with a concentration of 0.1M; and a potassium thiocyanate solution with a concentration of 0.1M.

Centrifuge the gold nanorod solution at 6000-10000 rpm for 5-30min, collect the precipitate and dilute it with secondary water, then centrifuge at 5000-9000 rpm for 5-30min after dilution, then dilute the precipitate with secondary water for use .

The principle of the present invention (see Figure 1) is that in a borate buffer solution containing sodium bicarbonate, cobalt ions catalyze hydrogen peroxide to generate superoxide radicals with strong oxidative properties, thereby accelerating the oxidative dissolution of gold nanorods to make them A blue shift in the radial absorption spectrum (see Figure 3) is accompanied by a distinct color change, which is positively correlated with the concentration of cobalt ions (see Figure 5).

Advantages of the present invention: the present invention utilizes cobalt ion catalytic etching gold nanorod colorimetric method to detect cobalt ion, has high sensitivity (detection limit is 1.0nM), good selectivity (see Figure 4), fast speed, no It requires instruments and is suitable for on-site real-time detection.

Description of drawings

Fig. 1 is the principle of cobalt ion catalyzed production of superoxide free radicals etched gold nanorods provided by the present invention.

Figure 2 is a transmission electron microscope image before and after cobalt ions catalyzed to produce superoxide radicals to etch gold nanorods provided by the present invention, in which cobalt ions catalyze to produce superoxide radicals before (left) and after (right) to etch gold nanorods.

Fig. 3 is an absorption spectrum diagram of cobalt ions (concentration from low to high) provided by the present invention after catalytic etching of gold nanorods.

Figure 4 is the selectivity experimental results and corresponding photos for detecting cobalt ions provided by the present invention.

Fig. 5 is the standard color card C provided by the present invention.

Fig. 6 is a flowchart for detecting cobalt ions provided by the present invention.

Fig. 7 is the linear range for detecting cobalt ions in drinking water provided by the present invention.

Fig. 8 is an effect diagram of the detection of cobalt ions (marking) in drinking water provided by the present invention.

Detailed ways

Example 1: Detection of Cobalt Ions (Spending) in Drinking Water

The kit includes boric acid buffer solution, sodium bicarbonate solution, hydrogen peroxide, potassium thiocyanate, gold nanorod solution containing cetyl ammonium bromide (CTAB), standard color card F and colorimetric tube;

Described borate buffer solution is to prepare with secondary water with analytically pure borax and boric acid, and the buffer solution pH after preparation is 9.0, and concentration is 50mM; Then add the CTAB of high concentration, make CTAB concentration in the buffer solution be 2mM;

The concentration of the sodium bicarbonate solution is 0.1M, which is obtained by dissolving analytically pure sodium bicarbonate in secondary water;

The concentration of the H ₂ O ₂ solution is 0.1M, which is obtained by diluting analytically pure 30% hydrogen peroxide with secondary water;

The concentration of the potassium thiocyanate solution is 0.1M, which is obtained by dissolving analytically pure potassium thiocyanate in secondary water. Preparation of gold nanorod solution containing cetyl ammonium bromide (CTAB):

1) Gold nanorods are obtained as follows:

Synthesis of gold seed solution: Add chloroauric acid solution to cetyl ammonium bromide (CTAB) solution and stir evenly, then add ice-cold sodium borohydride to the mixed solution to make the mixed solution from bright yellow to purple gray, Then, at 26°C, let stand for 2 hours, and set aside;

Nanorod synthesis: Add 1200 μL of chloroauric acid (50 mM) solution to 100 mL of 0.1 M cetyl ammonium bromide (CTAB) solution and mix well, add 300 μL of silver nitrate (0.01 M) solution and mix well, then add 960 μL of ascorbic acid (0.1M) solution, at this time the solution changes from yellow-brown to colorless, and finally add 200 μL of gold seed solution (the first step of synthesis), about 10-20 minutes, the color of the solution gradually changes from five colors to blue-green, stop stirring , use after standing for 20 hours. The radial absorption peak of the ultraviolet-visible absorption spectrum is at 670nM (see figure 3 absorption spectrum figure 0). According to Lambert-Beer's law, the concentration of nanorods is estimated to be 2.3nM.

2) Obtain the gold nanorod solution required by this method: centrifuge the synthesized gold nanorods at 6000-10000 rpm for 5-30 min, collect the precipitate and dilute it with secondary water, and then centrifuge at 5000-9000 rpm 5-30min, the precipitate is diluted with secondary water, and the product is obtained.

The preparation of the standard color card F is as follows: take 10 μL cobalt standard color scale solution with concentrations of 0, 5, 40, 50, 60, 100 and 300 nM respectively, and add it to a colorimetric tube containing 800 μL boric acid buffer solution containing CTAB , shake well, then add 25 μL sodium bicarbonate, 20 μL H ₂ O ₂ and 7.5 μL potassium thiocyanate, shake and mix well, then add gold nanorods containing CTAB, shake well; then incubate at 95°C for 6 Minutes, carry out color reaction, use a professional camera to record the color development results, after collecting pictures, use the pictures with color gradients to form the cobalt standard color card F (Figure 5).

i.e. the kit:

Borate buffer, pH 9.0, concentration 0.2M;

Sodium bicarbonate solution, the concentration is 0.1M;

H ₂ O ₂ solution, the concentration is 0.1M;

Potassium thiocyanate solution, the concentration is 0.1M;

Colorimetric tube, 1.5mL;

glass graduated straw;

Cobalt standard color scale solution;

Cobalt standard color chart.

Cobalt ion (spiked) detection in drinking water

(1) Take three 1.5mL colorimetric tubes, add 200 μL of boric acid buffer solution (0.2M) from reagent bottle A to each colorimetric tube, then add 25 μL of sodium bicarbonate in reagent bottle B, 20 μL of reagent Mix H ₂ O ₂ in bottle C and 7.5 μL potassium thiocyanate in reagent bottle D, then add 600 μL of spiked samples containing three different concentrations of cobalt ions (5nM, 50nM, 100nM) respectively, mix well, and mark 1 , No. 2 and No. 3, and then add 200 μL of gold nanorods containing CTAB in E reagent bottle respectively, and shake well.

(2) Incubate at 95°C for 6 minutes.

(3) Observe the color change (as shown in Figure 8), compare the colorimetric tube with the standard color card F (see Figure 5), and determine the concentration range of cobalt ions in the drinking water spiked sample. The corresponding concentrations are very consistent; at the same time, the peak shift can be obtained through the visible spectrum, and the definite content of cobalt ions can be determined according to the standard curve. The reliability of the practical application of this method.

Table 1 Cobalt ion spiked test results

Claims (10)

1. A cobalt ion colorimetric method detection kit is characterized in that: the kit includes cetyl ammonium bromide (CTAB) borate buffer solution, sodium bicarbonate solution, hydrogen peroxide, potassium thiocyanate , gold nanorod solution, standard color card F and colorimetric tube; The borate buffer solution containing cetyl ammonium bromide (CTAB) has a pH of 7.4-9.6 and a concentration of 10-200mM; The concentration of the sodium bicarbonate solution is 0.01-1M; The concentration of the H ₂ O ₂ solution is 0.01-1M; The concentration of the potassium thiocyanate solution is 0.01-1M. 2. The cobalt ion colorimetric detection kit according to claim 1, characterized in that: the concentration of CTAB in the borate buffer containing cetylammonium bromide (CTAB) is 0.1-20mM. 3. by the described cobalt ion colorimetric method detection kit of claim 1 or 2, it is characterized in that: containing cetyl ammonium bromide (CTAB) borate buffer solution pH is 9.0 in the described kit, concentration 50mM, the concentration containing CTAB is 2mM; the gold nanorod solution is a gold nanorod solution with a concentration of 2.3nM and an aspect ratio of 2:1; the concentration of sodium bicarbonate solution is 0.1M; the concentration of H ₂ O ₂ solution is 0.1 M; the concentration of potassium thiocyanate solution is 0.1M. 4. by the described cobalt ion colorimetric method detection kit of claim 1, it is characterized in that: gold nanorod solution is centrifugal 5-30min at 6000-10000 rev/min, collects precipitation and dilutes with secondary water, after dilution Centrifuge at 5000-9000 rpm for 5-30min, and dilute the precipitate with secondary water for later use. 5. the method for the detection cobalt ion of a kind of cobalt ion colorimetric method detection kit described in claim 1, it is characterized in that: in the sample colorimetric tube to be tested, add containing cetyl ammonium bromide (CTAB) Borate buffer solution, add sodium bicarbonate, H ₂ O ₂ and potassium thiocyanate, shake and mix well, then add gold nanorod solution, shake well; then incubate at 60-100°C for 2-20 Minutes, observe the color with the naked eye or an ultraviolet-visible spectrometer, and compare it with the standard color card F to determine the cobalt ion content. 6. by the method for the detection cobalt ion of cobalt ion colorimetric method detection kit described in claim 5, it is characterized in that: the borate buffer containing cetyl ammonium bromide (CTAB) is used to test sample Adjust the pH and keep the final volume at 800-900 μL, add sodium bicarbonate, H ₂ O ₂ and potassium thiocyanate, shake and mix well, then add 200-300 μL gold nanorod solution, shake well; then at 60 Incubate at -100°C for 2-20 minutes, observe the color with the naked eye or an ultraviolet-visible spectrometer, and compare it with the standard color card F to determine the cobalt ion content. 7. by the method for the detection cobalt ion of the cobalt ion colorimetric method detection kit described in claim 5 or 6, it is characterized in that: the preparation of described standard colorimetric card F is, get 0-300nM different concentration cobalt standard color Place the step solutions in colorimetric tubes respectively, add borate buffer solution containing cetyl ammonium bromide (CTAB), _sodium bicarbonate, _H2O2 and potassium thiocyanate, shake and mix well, and then Add gold nanorods and shake well; then incubate at 50-100°C for 2-30 minutes for color reaction, use a professional camera to record the color results, collect pictures, and use pictures with color gradients to form a cobalt standard colorimetric Card F. 8. by the method for the detection cobalt ion of the cobalt ion colorimetric method detection kit described in claim 5 or 6, it is characterized in that: described borate buffer containing cetyl ammonium bromide (CTAB), pH 7.4-9.6, the concentration is 10-200mM; the concentration of the sodium bicarbonate solution is 0.01-1M; the concentration of the H ₂ O ₂ solution is 0.01-1M; the concentration of the potassium thiocyanate solution is 0.01-1M. 9. by the method for the detection cobalt ion of cobalt ion colorimetry detection kit described in claim 7, it is characterized in that: described containing cetyl ammonium bromide (CTAB) borate buffer solution pH is 9.0, The concentration is 50mM, and the concentration containing CTAB is 2mM; the gold nanorod solution is a gold nanorod solution with a concentration of 2.3nM and an aspect ratio of 2:1; the concentration of sodium bicarbonate solution is 0.1M; the concentration of H ₂ O ₂ solution is 0.1M; the concentration of potassium thiocyanate solution is 0.1M. 10. The method for detecting cobalt ions by the cobalt ion colorimetric method detection kit described in claim 5 or 6 is characterized in that: the gold nanorod solution is centrifuged at 6000-10000 rpm for 5-30min, and the precipitate is collected and used Dilute with water for the second time, centrifuge at 5000-9000 rpm for 5-30 minutes after dilution, and dilute the precipitate with secondary water for further use.