CN105067751A - Photocatalysis visualization method for detecting content of silver in ore - Google Patents

Abstract

A method for photocatalytic and visual detection of silver content in ores is to heat and digest ore samples through a simple electric furnace device to decompose silver in ores into Ag ⁺ , and use Ag ⁺ to specifically combine with cytosine (C) in DNA to form C-Ag ⁺ -C hairpin structure, the EB-DNA complex produced by embedding ethidium bromide (EB) in the hairpin structure is oxidized and colorless TMB turns blue under the irradiation of LED light, realizing visual semi-quantitative analysis. This method does not need steps such as separation and enrichment, and can detect Ag ⁺ in the ore sample digestion solution with a concentration as low as 0.1ngmL ^-1 by naked eyes. It is expected to be used for on-site determination of silver content in ore samples, and to evaluate whether the silver content in ore samples meets the mining standard according to the silver deposit mining industry standard (DZ/T0214-2002).

Description

A method of photocatalytic visual detection of silver content in ore

technical field

The invention belongs to the technical field of rock ore analysis, and in particular relates to a visual analysis method for silver content in ore samples.

Background technique

Silver is one of many metals widely used in industry. With the development of science and technology, the consumer demand for silver has greatly increased, and it is no longer limited to traditional currency and jewelry handicrafts, but has shifted its focus to the application and development of industrial technology. As a precious metal, silver must take the analysis results as an important basis in the process of exploration and mining. Therefore, it is particularly important for mining companies to develop rapid methods for determining the silver content in ores.

The existing analysis methods for silver content in silver mines mainly include radioisotope X-rays (P.G.Burkhalter, Analyticalchemistry, 1971, 43, 10-17), atomic absorption spectrometry (Sun Wenjun, Rock and Mineral Testing, 2012, 31, 829-833), inductance Coupled plasma emission spectrometer (G.Chakrapani, P.L.Mahanta, D.S.R.Murty, B.Gomathy, Talanta, 2001, 53, 1139–1147), these methods are relatively mature in determining the content of silver, the measurement results are accurate and have high sensitivity However, these methods require complex instruments and require trained professionals to operate, and when the silver content in the ore sample is low, enrichment and pretreatment are also required. These factors have limited the methods for determining silver to be unable to carry out field analysis and provide analysis results quickly.

In contrast, the visual analysis method can be detected with the naked eye, avoiding the use of large and complex instruments, and is suitable for on-site analysis. The current visual analysis methods for detecting silver content in silver ore mainly include dithizone extraction spectrophotometry (Wang Ye, Cao Lifeng, Jin, 2011, 32, 60-62), Ag ⁺ -phenanthroline-bromopyrogallol red Ternary complex chromogenic method (RM Dagnall, TS West, Talanta, 1964, 11, 1533-1541). However, these two colorimetric methods need to be extracted, the procedures are cumbersome, and the sensitivity is low, and only Ag ⁺ at the mgL-1 level can be detected. Therefore, it is very necessary to develop a method for detecting silver content in ores without enrichment, high sensitivity, and simple and fast.

Contents of the invention

The purpose of the present invention is to utilize the characteristics of the EB-DNA complex with high photocatalytic oxidation ability to be formed by the C-rich base DNA chain and ethidium bromide (EB) in the presence of Ag ⁺ , to provide a simple, A method for rapid, highly sensitive, and highly selective detection of silver content in ore samples. Technical scheme of the present invention is as follows:

(1) Accurately weigh 0.5000g of the mineral sample into a 25mL polytetrafluoroethylene crucible, wet the sample with water, add 5mL of concentrated nitric acid, and after a violent reaction, heat the solution until the volume of the solution is about 3mL. Take off the crucible and let it cool slightly, add 1mL of concentrated perchloric acid and 5mL of hydrofluoric acid, heat on an electric furnace at 200°C until a large amount of white smoke is emitted, turn off the electric furnace, use the residual heat to completely digest the sample, and steam until nearly dry. Add 10mL of 1% nitric acid solution to re-dissolve, transfer the solution to a volumetric flask and dilute it with ultrapure water, and measure after appropriate dilution.

(2) Add DNA solution with sequence 5'-CTCTCTCCAACCTCTCTC-3', silver standard/mineral sample digestion solution, EB solution, PBS buffer solution with pH 4.0 in sequence to a clean culture plate, and incubate at room temperature for 15 minutes;

(3) Add TMB solution to the above mixed solution, and irradiate it with a portable green LED light array for 15 minutes to perform photocatalytic oxidation of TMB to produce a blue solution;

(4) Obtain the solution after the illumination, compare the color of the ore sample digestion solution and the standard series, obtain the ^Ag content in the ore sample semi-quantitatively, according to the measurement results and the silver deposit mining industry standard (DZ/T0214-2002) Mine samples were evaluated.

In the present invention, an ultraviolet-visible spectrophotometer can also be used to measure the absorbance of the solution to accurately measure the silver content in the ore sample.

Invention effect

Compared with prior art, the present invention has following advantage:

(1) The sensitivity is extremely high, and the visual detection of Ag ⁺ as low as 0.02μgL ^-1 in the solution can be realized;

(2) The digestion method of the ore sample is simple, and the digestion can be completed by using an electric furnace;

(3) There is no need for separation and enrichment steps, and it can be directly used to judge whether the silver content in the ore sample reaches the silver deposit mining industry standard;

(4) The method is expected to be used for on-site detection of silver content in ore samples.

Detailed ways

Example 1

Accurately weigh 0.5000g of the ore sample into a 25mL polytetrafluoroethylene crucible, wet the sample with water, add 5mL of concentrated nitric acid, and after a violent reaction, heat until the solution is about 3mL. Take off the crucible and let it cool slightly, add 1mL of concentrated perchloric acid and 5mL of hydrofluoric acid, heat on an electric furnace at 200°C until a large amount of white smoke is emitted, turn off the electric furnace, use residual heat to completely digest the sample, and steam until nearly dry. Add 10mL of 1% nitric acid solution to redissolve, transfer the solution to a 50mL volumetric flask and dilute to volume with ultrapure water. and dilute appropriately. Add 10 μL of 10 μM DNA solution (sequence 5'-CTCTCTCCAACCTCTCTC-3'), 1 mL of different concentrations of Ag ⁺ standard solution/diluted solution of standard environmental mineral samples, and 1 mL of PBS with a concentration of 0.1 molL ^-1 in a clean culture plate. Buffer solution (pH=4.0), 20 μL of ethidium bromide solution with a concentration of 100 mM, incubate at room temperature for 30 min; add 40 μL of TMB solution with a concentration of 10 mgmL ^-1 , and irradiate with a green LED light for 15 min; compare the mineral sample digestion solution with the standard A series of colors, conduct semi-quantitative analysis, and evaluate the ore sample according to the obtained results.

Example 2

Accurately weigh 0.5000g of the ore sample into a 25mL polytetrafluoroethylene crucible, wet the sample with water, add 5mL of concentrated nitric acid, and after a violent reaction, heat until the solution is about 3mL. Take off the crucible and let it cool slightly, add 1mL of concentrated perchloric acid and 5mL of hydrofluoric acid, heat on an electric furnace at 200°C until a large amount of white smoke is emitted, turn off the electric furnace, use residual heat to completely digest the sample, and steam until nearly dry. Add 10mL of 1% nitric acid solution to re-dissolve, transfer the solution to a volumetric flask and dilute it with ultrapure water, and measure after appropriate dilution. Add 10 μL of 10 μM DNA solution (sequence 5'-CTCTCTCCAACCTCTCTC-3'), 1 mL of Ag ⁺ standard solution/environmental mineral sample digestion solution of different concentrations, and 1 mL of PBS with a concentration of 0.1 molL ^-1 in a clean culture plate. Buffer solution (pH=4.0), 20 μL of ethidium bromide solution with a concentration of 10 mM (final concentration of 100 μM), incubate at room temperature in the dark for 15 min; add 40 μL of TMB solution with a concentration of 10 mgmL ^-1 , and irradiate with a green LED light for 30 min ; Compare the color of the ore sample digestion solution with the standard series for semi-quantitative analysis. The ore samples were evaluated according to the measurement results and the silver deposit mining industry standard (DZ/T0214-2002).

Adopt embodiment 1,2 to record the content of silver in environment ore sample 1,2,3,4,5 and standard ore sample (GBW07256) see Table 1, semi-quantitative measurement result and graphite furnace atomic absorption method measured value or standard ore sample The reference values are in good agreement, indicating that the determination results are reliable. The ore samples were evaluated according to the measurement results and the silver deposit mining industry standard (DZ/T0214-2002).

The detection detection result of silver content in the actual sample of table 1

sample Visualization (gt ^-1 ) Graphite furnace atomic absorption measured value or reference value (gt ^-1 ) Sample evaluation Environmental Mineral Sample 1 40–80 52.88±0.17 reserves can be calculated Environmental Mineral Sample 2 80–400 117.8±0.16 Potential mining value Environmental Mineral Sample 3 80–400 155.0±0.19 Potential mining value Environmental Mineral Sample 4 40–80 76.10±0.14 reserves can be calculated

Environmental Mineral Sample 5 0-40 not detected waste rock Standard Environmental Mineral Sample 80-400 112±4 (standard value) —

Table 2 Silver Deposit Mining Industry Standards (DZ/T0214-2002)

project index cut-off grade gt ^-1 40～50 Minimum Industrial Grade GT ^-1 80～100 Average grade of ore deposit gt ^-1 >150 Minimum recoverable thickness m 0.8～1 Stone removal thickness m 2～4

Claims (5)

1. A method for photocatalytic visual detection of silver content in ore, characterized in that it comprises the following four steps: (1) Accurately weigh an appropriate amount of ore sample in a polytetrafluoroethylene crucible, moisten the sample with water, and then add concentrated nitric acid; after a violent reaction, heat until the solution volume is about 3mL; remove the crucible and cool slightly, add perchloric acid, Heat the hydrofluoric acid on the electric furnace until a large amount of white smoke is emitted, turn off the electric furnace, and use the residual heat to completely dissolve the sample in the solution until it is completely evaporated; (2) Add aptamer solution, Ag ⁺ standard solution/environmental mineral sample digestion solution, ethidium bromide solution (EB), potassium dihydrogen phosphate (PBS) to a clean culture plate in sequence Buffer solution, incubated at room temperature for a period of time; (3) Add 3,3',5,5'-tetramethylbenzidine (TMB) solution into the mixed solution described in (2), and use LED light Irradiate for a period of time to realize photocatalytic oxidation of TMB color development; (4) Take the solution described in (3) for observation, compare the color of the ore sample digestion solution with the standard series, and obtain the Ag ⁺ content in the ore sample semi-quantitatively. According to the measurement results and the silver deposit mining industry standard (DZ/T0214- 2002) to evaluate the ore samples. 2. The method according to claim 1, wherein the selected mismatched aptamer sequence is 5'-CTCTCTCCAACCTCTCTC-3'. 3. The method according to claim 1, characterized in that the incubation time in the dark is 10-40min. 4. The method according to claim 1, wherein the pH of the solution is 3.5-5.0 when illuminated. 5. The method according to claim 1, characterized in that the color of the LED light is green, and the illumination time is 10-40min.