A method for detecting thiourea content in thiourea leaching solution

Abstract

The present invention provides a method for detecting the content of thiourea in a thiourea leaching solution, and relates to the technical field of analysis and detection. The present invention adopts an external standard method for quantitative analysis, and performs high performance liquid chromatography detection on the thiourea leaching solution to obtain the chromatographic peak area of ​​thiourea; the mobile phase used in the high performance liquid chromatography detection is a phosphoric acid aqueous solution; the concentration of thiourea in the thiourea leaching solution is obtained according to the chromatographic peak area of ​​the thiourea and the regression equation of the thiourea standard curve. The present invention uses an external standard method for quantitative analysis, and uses a phosphoric acid aqueous solution as the mobile phase for high performance liquid chromatography (HPLC) detection, and the separation degree of thiourea and dithiocarboxamidine is high, thereby eliminating the interference of dithiocarboxamidine on the detection result of thiourea content, and has high accuracy, high precision, good reproducibility, good repeatability, and good specificity. Moreover, the detection method provided by the present invention does not need to pre-treat the thiourea leaching solution, the analysis and detection time is short, the operation is simple and easy, the detection efficiency is high and the cost is low, and it is worthy of popularization and application.

Description

Technical Field

[0001] The invention relates to the technical field of analysis and detection, and in particular to a method for detecting the thiourea content in a thiourea leaching solution. Background Art

[0002] Thiourea (CSN2H4, TU) is a white and shiny organic substance that decomposes when heated and is easily soluble in water. As an important chemical raw material and organic chemical intermediate, thiourea is widely used in industry, agriculture, pharmaceutical manufacturing and other fields. At present, the main methods for preparing thiourea are thiocyanate amine method, cyanamide method, lime nitrogen method and the use of urea to prepare thiourea. Thiourea reacts with Au in acidic solution. + Formation of AuTU + The reaction is shown in formula (1). 3+ ) in the presence of thiourea, the reaction is shown in formula (2). However, thiourea is unstable in the presence of oxidants and is easily decomposed into dithiocarboxamidine. Since the polarity and properties of dithiocarboxamidine are similar to those of thiourea, it interferes with the analytical detection of thiourea.

[0003] Au + +2TU=AuTU2 + Formula (1)

[0004] Au+2TU+Fe 3+ =AuTU2 + +Fe 2+ Formula (2)

[0005] At present, the main methods for detecting thiourea are chemical titration, electrochemical method, spectrophotometry, and high performance liquid chromatography. Among them, although the chemical titration and electrochemical methods are relatively simple to operate, they have large human errors, and the byproduct disulfide formamidine will interfere with the analysis of thiourea, and cannot be quickly and effectively quantitatively analyzed. High performance liquid chromatography uses liquid as the mobile phase and a high-pressure infusion system to pump a single solvent with different polarities or a mixed solvent of different proportions, a buffer solution and other mobile phases into a chromatographic column equipped with a stationary phase. After the components in the column are separated, they enter the detector for detection, thereby analyzing the sample experimentally. High performance liquid chromatography has the characteristics of fast analysis speed, high separation efficiency, and high sensitivity. This method has become an important separation and analysis technology in the fields of chemistry, medicine, industry, and agronomy.

[0006] For example, Chinese patent CN115128184A discloses a method for determining the thiourea content in a raw material of pramipexole hydrochloride by using an HPLC external standard method, wherein the external standard method is used for quantitative analysis, and the mobile phase A used is: an acetonitrile aqueous solution with a volume fraction of 5%; the mobile phase B is a mixture of a 0.1 volume % trifluoroacetic acid aqueous solution and acetonitrile in a volume ratio of 90:10, wherein the pH of the trifluoroacetic acid aqueous solution is adjusted to 5.0 with triethylamine; the mobile phase is gradient eluted, and the elution procedure is: 0-3 min, the volume fraction of mobile phase A is 100%; 3-4 min, the volume fraction of mobile phase A changes from 100% to 0%; 4-15 min, the volume fraction of mobile phase A is 0%; 15-16 min, the volume fraction of mobile phase A changes from 0% to 100%; 16-22 min, the volume fraction of mobile phase A is 100%. Chinese patent CN107247103A discloses a method for determining the thiourea content in thiourea synthesis by using an HPLC external standard method, wherein the mobile phase is a mixed solution of acetonitrile and 0.25 mol / L ammonium bicarbonate aqueous solution. However, the above test method cannot exclude the interference of dithiocarboxamidine on thiourea. Summary of the invention

[0007] The object of the present invention is to provide a method for detecting the thiourea content in a thiourea leaching solution. The detection method provided by the present invention can eliminate the interference of disulfide formamidine on the thiourea content detection result, thereby quickly and accurately realizing the quantitative detection of thiourea in the thiourea leaching solution.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides a method for detecting the thiourea content in a thiourea leaching solution, which adopts an external standard method for quantitative analysis, comprising the following steps:

[0009] The thiourea leaching solution is subjected to high performance liquid chromatography to obtain the chromatographic peak area of ​​thiourea; the mobile phase used in the high performance liquid chromatography is a phosphoric acid aqueous solution;

[0010] The concentration of thiourea in the thiourea leaching solution is obtained according to the chromatographic peak area of ​​the thiourea and the regression equation of the thiourea standard curve.

[0011] Preferably, the volume concentration of the phosphoric acid aqueous solution is 0.05-1%.

[0012] Preferably, the conditions for the HPLC detection include: the chromatographic column is a Waters X-Bridge C18 column; the column temperature is 30-40°C; the flow rate of the mobile phase is 0.5-1 mL / min; the injection volume is 1-5 μL; and the detection wavelength is 195-236 nm.

[0013] Preferably, the method for preparing the thiourea leachate comprises the following steps:

[0014] Mixing gold-containing ore powder and water to obtain ore powder slurry;

[0015] The pH value of the mineral powder slurry is adjusted to 1-3, and then mixed with ferric sulfate and thiourea to obtain a mixed slurry;

[0016] The pH value of the mixed slurry is adjusted to 1-3, and solid-liquid separation is performed after gold leaching to obtain thiourea leaching solution.

[0017] Preferably, the ratio of the mass of the gold-containing ore powder to the volume of water is 1 g: 2-5 mL.

[0018] Preferably, the ratio of the mass of the ferric sulfate to the volume of the mineral powder slurry is 4-10g:1L.

[0019] Preferably, the ratio of the mass of the thiourea to the volume of the mineral powder slurry is 1-6g:1L.

[0020] Preferably, the acid used to adjust the pH value of the mineral powder slurry is a sulfuric acid solution;

[0021] The acid used to adjust the pH value of the mixed slurry is sulfuric acid solution.

[0022] Preferably, the gold leaching temperature is 20-40° C. and the time is 2-6 hours.

[0023] The present invention provides a method for detecting the content of thiourea in a thiourea leaching solution, and adopts an external standard method for quantitative analysis, comprising the following steps: subjecting the thiourea leaching solution to high performance liquid chromatography detection to obtain the chromatographic peak area of ​​thiourea; the mobile phase adopted in the high performance liquid chromatography detection is a phosphoric acid aqueous solution; and the concentration of thiourea in the thiourea leaching solution is obtained according to the chromatographic peak area of ​​the thiourea and the regression equation of the thiourea standard curve. The present invention uses an external standard method for quantitative analysis, and uses a phosphoric acid aqueous solution as the mobile phase for high performance liquid chromatography (HPLC) detection, and the separation degree of thiourea and dithiocarboxamidine is high, thereby eliminating the interference of dithiocarboxamidine on the detection result of thiourea content, and has high accuracy, high precision, good reproducibility, good repeatability, and good specificity. Moreover, the detection method provided by the present invention does not need to pre-treat the thiourea leaching solution, the analysis and detection time is short, the detection efficiency is high, the operation is simple and easy, convenient and reliable, the cost is low, and it is worthy of promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the liquid chromatogram of disulfide formamidine standard solution;

[0025] Figure 2 is the liquid chromatogram of thiourea standard solution;

[0026] Figure 3 It is a liquid chromatogram of disulfide formamidine standard solution and -thiourea disulfide formamidine mixed standard solution;

[0027] Figure 4 is the standard curve of thiourea;

[0028] Figure 5 It is the liquid chromatogram of the thiourea leaching solution sample sp-1 in Example 1;

[0029] Figure 6 It is the liquid chromatogram of the thiourea leaching solution sample sp-2 in Example 1;

[0030] Figure 7 It is the liquid chromatogram of the thiourea leaching solution sample sp-2 in Example 1;

[0031] Figure 8 The liquid chromatogram of the thiourea-disulfide formamidine mixed standard solution with the mixed aqueous solution of heptanesulfonic acid-phosphoric acid as the mobile phase in Comparative Example 1;

[0032] Fig. 9 It is a liquid chromatogram of the thiourea-disulfide formamidine mixed standard solution with a trifluoroacetic acid-phosphoric acid mixed aqueous solution as the mobile phase in Comparative Example 2;

[0033] Fig.10 It is the liquid chromatogram of the thiourea-disulfide formamidine mixed standard solution in Comparative Example 3 with a tetraethylammonium hydroxide-phosphoric acid mixed aqueous solution as the mobile phase. DETAILED DESCRIPTION

[0034] The present invention provides a method for detecting the thiourea content in a thiourea leaching solution, which adopts an external standard method for quantitative analysis and comprises the following steps:

[0035] The thiourea leaching solution is subjected to high performance liquid chromatography to obtain the chromatographic peak area of ​​thiourea; the mobile phase used in the high performance liquid chromatography is a phosphoric acid aqueous solution;

[0036] The concentration of thiourea in the thiourea leaching solution is obtained according to the chromatographic peak area of ​​the thiourea and the regression equation of the thiourea standard curve.

[0037] In the present invention, unless otherwise specified, the reagents used are commercially available products well known to those skilled in the art.

[0038] The invention conducts high performance liquid chromatography detection on the thiourea leaching solution to obtain the chromatographic peak area of ​​the thiourea; the mobile phase adopted in the high performance liquid chromatography detection is a phosphoric acid aqueous solution.

[0039] In the present invention, the preparation method of the thiourea leaching solution comprises the following steps:

[0040] Mixing gold-containing ore powder and water to obtain ore powder slurry;

[0041] The pH value of the mineral powder slurry is adjusted to 1-3, and then mixed with ferric sulfate and thiourea to obtain a mixed slurry;

[0042] The pH value of the mixed slurry is adjusted to 1-3, and solid-liquid separation is performed after gold leaching to obtain thiourea leaching solution.

[0043] The present invention mixes gold-containing ore powder and water to obtain ore powder slurry. The present invention has no special limitation on the gold-containing ore powder, and the gold-containing ore powder well known to those skilled in the art can be used; in a specific embodiment of the present invention, the gold-containing ore powder is an oxidized gold ore powder, and the main components of the oxidized gold ore powder include quartz, calcite and dolomite; the particle size of the gold-containing ore powder ≤ 0.074mm accounts for more than 90wt%. In the present invention, the ratio of the mass of the gold-containing ore powder to the volume of water is preferably 1g: 2~5mL, more preferably 1g: 3~5mL, and further preferably 1g: 4~5mL. The present invention has no special limitation on the mixing, and the mixing method well known to those skilled in the art can be used, such as stirring and mixing, and the rotation speed of the stirring and mixing is preferably 200~400r / min, more preferably 300r / min.

[0044] After obtaining the mineral powder slurry, the present invention adjusts the pH value of the mineral powder slurry to 1-3 and then mixes it with ferric sulfate and thiourea to obtain a mixed slurry. In the present invention, the acid used for adjusting the pH value is preferably a sulfuric acid solution, and the mass concentration of the sulfuric acid solution is 10-30%, more preferably 10-20%; the adjusted pH value is more preferably 1.5-2.5, and further preferably 2. In the present invention, the ratio of the mass of the ferric sulfate to the volume of the mineral powder slurry is preferably 6g:1L. In the present invention, the ratio of the mass of the thiourea to the volume of the mineral powder slurry is preferably 2g:1L. The present invention has no special limitation on the mixing, as long as the raw materials can be mixed evenly.

[0045] After obtaining the mixed slurry, the present invention adjusts the pH value of the mixed slurry to 1-3, performs solid-liquid separation after gold leaching, and obtains thiourea leaching solution. In the present invention, the acid used for adjusting the pH value is preferably a sulfuric acid solution, and the mass concentration of the sulfuric acid solution is preferably 10-30%, more preferably 10-20%; the adjusted pH value is more preferably 1.5-2.5, and more preferably 2. In the present invention, the temperature of the gold leaching is preferably 20-40°C, more preferably 25-30°C; the time of the gold leaching is preferably 2-6h, more preferably 3-5h, and more preferably 4h; the gold leaching is preferably carried out under stirring conditions, and the stirring speed is preferably 200-400r / min, more preferably 300r / min. The present invention has no special limitation on the solid-liquid separation, and a solid-liquid separation method well known to those skilled in the art can be used, such as centrifugal separation, filtration or suction filtration, and the liquid component obtained by the solid-liquid separation is a thiourea leaching solution, that is, a thiourea leaching solution. In the present invention, the concentration of thiourea in the thiourea leaching solution is preferably 2 to 100 mg / L.

[0046] In the present invention, the conditions for the high performance liquid chromatography detection include: the mobile phase is a phosphoric acid aqueous solution, the volume concentration of the phosphoric acid aqueous solution is preferably 0.05-1%, more preferably 0.05-0.5%, and further preferably 0.05-0.25%; the chromatographic column is preferably a Waters X-Bridge C18 column; the column temperature is preferably 30-40°C, more preferably 32-38°C, and further preferably 35-36°C; the flow rate of the mobile phase is preferably 0.5-1 mL / min, more preferably 0.5-0.8 mL / min; the injection volume is preferably 1-5 μL, more preferably 1-2 μL; the detector is preferably CTO-10AS; the detection wavelength is preferably 195-236 nm, more preferably 236 nm.

[0047] After the chromatographic peak area of ​​thiourea is obtained, the concentration of thiourea in the thiourea leaching solution is obtained according to the chromatographic peak area of ​​thiourea and a regression equation of a thiourea standard curve.

[0048] In the present invention, the method for obtaining the regression equation of the thiourea standard curve preferably includes the following steps: preparing a series of thiourea standard solutions, performing high performance liquid chromatography detection on the series of thiourea standard solutions, obtaining a series of thiourea standard peak areas, linearly fitting the series of thiourea standard peak areas with the concentrations of the series of thiourea standard solutions, and using the external standard method to draw a concentration-peak area standard curve of thiourea to obtain a thiourea standard curve regression equation. In the present invention, the concentrations of the series of thiourea standard solutions are preferably 10 mg / L, 20 mg / L, 25 mg / L, 50 mg / L and 100 mg / L, respectively; the method for preparing the series of thiourea standard solutions preferably includes the following steps: dissolving the thiourea standard in the mobile phase to obtain a thiourea standard stock solution with a concentration of 1000 mg / L; using the mobile phase to dilute the thiourea standard stock solution and then fix the volume to obtain a series of thiourea standard solutions with concentrations of 10 mg / L, 20 mg / L, 25 mg / L, 50 mg / L and 100 mg / L, respectively. In the present invention, the detection conditions of the HPLC are the same as those of the above-mentioned HPLC, which will not be described in detail. In the present invention, the regression equation of the standard curve of thiourea is preferably y=8178.92x-7413.71, R 2 =0.99965, and the linear range is preferably 2-80 mg / L.

[0049] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] Example 1

[0051] 1. HPLC chromatographic detection conditions

[0052] High performance liquid chromatograph: Agilent high performance liquid chromatograph LC-20AD;

[0053] Chromatographic column: Waters X-Bridge C18 (150 mm × 3.0 mm × 3.5 μm);

[0054] Column temperature: 35°C;

[0055] Mobile phase: 0.05v / v% phosphoric acid aqueous solution;

[0056] Mobile phase flow rate: 0.5 mL / min;

[0057] Detector: CTO-10AS (variable wavelength detector);

[0058] Detection wavelength: 236nm;

[0059] Injection volume: 2 μL;

[0060] Flushing fluid: water.

[0061] 2. Reagents and samples

[0062] Thiourea standard (purity>99.7%, purchased from Sinopharm Group Shanghai Co., Ltd.), disulfide formamidine standard (purity>99.7%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.).

[0063] Preparation of thiourea leaching solution: In a 250mL beaker, add water and oxidized gold ore powder (more than 90wt% of the particle size ≤0.074mm) according to a liquid-to-solid ratio of 5:1 (mL:g) to obtain a ore powder slurry, adjust the pH value to 2.0 with a 10wt% sulfuric acid solution, add Fe2(SO4)3 and thiourea and mix evenly, adjust the pH value of the obtained slurry to 2.0 with a 10% sulfuric acid solution, stir and leach at 300r / min for 4h, filter the obtained slurry, and the obtained filtrate is a thiourea leaching solution; wherein, the concentration of Fe2(SO4)3 in the ore powder slurry is 6g / L, and the concentration of thiourea in the ore powder slurry is 2g / L.

[0064] Preparation of thiourea leaching solution samples: Pipette three portions of 2.5 mL of the thiourea leaching solution into 100 mL volumetric flasks respectively, and dilute to volume with 0.05 v / v% phosphoric acid aqueous solution to obtain thiourea leaching solution samples sp-1, sp-2 and sp-3.

[0065] Preparation of thiourea-disulfide formamidine mixed standard solution: accurately weigh 2.0 mg of thiourea standard and 2.0 mg of disulfide formamidine standard, dissolve them in 0.5 v / v% phosphoric acid solution and make up to 100 mL to obtain a thiourea-disulfide formamidine mixed standard solution with a concentration of 20 mg / L.

[0066] Preparation of thiourea standard solution: accurately weigh 100.0 mg of thiourea standard into a beaker, dissolve it in 0.5 v / v% phosphoric acid solution and dilute to 100 mL to obtain a thiourea standard stock solution with a concentration of 1000 mg / L; accurately pipette 1 mL, 2 mL, 2.5 mL, 5 mL and 10 mL of thiourea standard stock solution into a 100 mL volumetric flask, dilute to the scale with 0.5 v / v% phosphoric acid to obtain a series of thiourea standard solutions with concentrations of 10 mg / L, 20 mg / L, 25 mg / L, 50 mg / L and 100 mg / L, respectively.

[0067] Preparation of disulfide formamidine standard solution: accurately weigh 100.0 mg of disulfide formamidine standard in a beaker, dissolve it in 0.5 v / v% phosphoric acid solution and dilute to 100 mL to obtain a disulfide formamidine standard stock solution with a concentration of 1000 mg / L; accurately transfer 1 mL, 2 mL, 2.5 mL, 5 mL and 10 mL of the disulfide formamidine standard stock solution into a 100 mL volumetric flask, respectively, and dilute to the scale with 0.5 v / v% phosphoric acid to obtain a series of disulfide formamidine standard solutions with concentrations of 10 mg / L, 20 mg / L, 25 mg / L, 50 mg / L and 100 mg / L, respectively.

[0068] 3. Detection

[0069] (1) Retention time of thiourea and disulfide formamidine: A 20 mg / L thiourea standard solution, a 20 mg / L disulfide formamidine standard solution, and a thiourea-disulfide formamidine mixed standard solution were analyzed and tested by HPLC. The liquid chromatogram of the disulfide formamidine standard solution is shown in FIG. Figure 1 As shown in Figure 1, disulfide formamidine is easily hydrolyzed and decomposes into thiourea when it enters the solution. Therefore, the standard curve of disulfide formamidine shows a thiourea peak. The liquid chromatogram of the thiourea standard solution is shown in Figure 1. Figure 2 As shown, the liquid chromatogram of the thiourea-disulfide formamidine mixed standard solution is as follows Figure 3 As shown. Figures 1 to 3 It can be seen that the retention time of thiourea is 3.579 min, and the retention time of disulfide formamidine is 2.742 min, indicating that in the detection method provided by the present invention, the separation degree of thiourea and disulfide formamidine is high, and disulfide formamidine will not affect the determination of the content of thiourea.

[0070] (2) Standard curve regression equation of thiourea: After the series of thiourea standard solutions are shaken well, HPLC analysis is performed according to the concentration from small to large, and the peak area of ​​thiourea is recorded. The concentration-peak area standard curve of thiourea is drawn by the external standard method, such as Figure 4 As shown, the standard curve regression equation of thiourea is y=8178.92x-7413.71, R 2 =0.99965, linear range is 2~80mg / L.

[0071] (3) Determination of thiourea content in thiourea leaching solution samples: thiourea leaching solution samples sp-1, sp-2 and sp-3 were analyzed respectively, and the peak areas of thiourea and dithiocarbamidine were recorded. The concentration of thiourea was calculated according to the regression equation of the standard curve of thiourea, as shown in Table 1. The liquid chromatogram of thiourea leaching solution sample sp-1 is shown in Figure 5 As shown, the liquid chromatogram of the thiourea leaching solution sample sp-2 is as follows Figure 6 As shown, the liquid chromatogram of the thiourea leaching solution sample sp-3 is as follows Figure 7 shown.

[0072] Table 1 Thiourea concentration in thiourea leaching solution samples

[0073] Thiourea leachate sample sp-1 sp-2 sp-3 average value Concentration (g / L) 1.21 1.20 1.21 1.21

[0074] According to the average concentration of thiourea in the thiourea leaching solution sample, the consumption rate of thiourea was calculated to be 39.67%. The consumption rate of thiourea = 1-(C0-C1) / C0, where C0 is the initial concentration of thiourea and C1 is the concentration of thiourea after the reaction (gold leaching) is completed.

[0075] Example 2

[0076] The concentration of thiourea in the thiourea leaching solution sample and the consumption rate of thiourea were tested according to the method of Example 1. The only difference from Example 1 was that the concentration of Fe2(SO4)3 in the mineral powder slurry was 10 g / L, the concentration of thiourea in the mineral powder slurry was 4 g / L, and the column temperature was 32°C. The test results of thiourea concentration in the thiourea leaching solution sample are shown in Table 2:

[0077] Table 2 Thiourea concentration in thiourea leaching solution samples

[0078] Thiourea leachate sample sp-1 sp-2 sp-3 average value Concentration (g / L) 2.39 2.39 2.38 2.39

[0079] According to the average concentration of thiourea in the thiourea leaching solution samples, the consumption rate of thiourea was calculated to be 40.25%.

[0080] Example 3

[0081] The concentration of thiourea in the thiourea leaching solution sample and the consumption rate of thiourea were tested according to the method of Example 1. The only difference from Example 1 was that the concentration of Fe2(SO4)3 in the mineral powder slurry was 15 g / L, the concentration of thiourea in the mineral powder slurry was 6 g / L, and the column temperature was 37°C. The test results of thiourea concentration in the thiourea leaching solution sample are shown in Table 3:

[0082] Table 3 Thiourea concentration in thiourea leaching solution samples

[0083] Thiourea leachate sample sp-1 sp-2 sp-3 average value Concentration (g / L) 3.54 3.53 3.53 3.53

[0084] According to the average concentration of thiourea in the thiourea leaching solution samples, the consumption rate of thiourea was calculated to be 41.17%.

[0085] Example 4

[0086] Precision experiment

[0087] Using the HPLC chromatographic conditions of Example 1, the thiourea leaching solution sample sp-1 prepared in Example 1 was shaken and injected into HPLC for analysis 6 times and the peak areas were recorded simultaneously, as shown in Table 4:

[0088] Table 4 Precision test results

[0089]

[0090] As shown in Table 4, RSD is less than 0.5%, indicating that the detection method provided by the present invention has good precision.

[0091] Example 5

[0092] Stability test

[0093] Using the HPLC chromatographic conditions of Example 1, the thiourea leaching solution sample sp-2 prepared in Example 1 was placed at 3°C, and the sample was injected into the HPLC analysis at 0h, 6h, 12h, 24h, 48h and 72h, and the peak area was recorded at the same time, as shown in Table 5:

[0094] Table 5 Stability test results

[0095]

[0096] As shown in Table 5, RSD is less than 0.5%, indicating that the thiourea leaching solution sample provided by the present invention has good stability and the detection method has high stability.

[0097] Example 6

[0098] Reproducibility experiment

[0099] The thiourea leachate sample sp-3 prepared in Example 1 was used as the research object. Different experimenters in different laboratories conducted HPLC analysis 6 times on the same instrument to determine the reproducibility of the method. The HPLC chromatographic conditions were the same as those in Example 1, and the peak area ratios were recorded as shown in Table 6:

[0100] Table 6 Reproducibility test results

[0101]

[0102]

[0103] As shown in Table 6, RSD is less than 0.08%, indicating that the detection method provided by the present invention has good reproducibility.

[0104] Example 7

[0105] Spike recovery experiment

[0106] Accurately weigh 40.0 mg of thiourea standard (purity 99.7%) in a beaker, dissolve the sample with 100 mL of 5 v / v% phosphoric acid aqueous solution, transfer to a 1000 mL volumetric flask, dilute to scale with 5 v / v% phosphoric acid aqueous solution, and prepare a thiourea mother solution with a concentration of 40.0 mg / L. Accurately transfer 5.00 mL, 10.00 mL and 20.00 mL of thiourea mother solution to a 100 mL volumetric flask, respectively, add 0.5 mg, 1.0 mg and 2.0 mg of thiourea standard to scale, respectively, and mark them as thiourea leaching solution samples St-1, St-2 and St-3, respectively, measure each sample in parallel 3 times, shake well, and perform HPLC analysis, record the sample peak area, and calculate its spike recovery rate based on the peak area, as shown in Table 7:

[0107] Table 7 Spiked recovery

[0108] Thiourea leachate sample Base amount / mg Addition amount / mg Average measured amount / mg Average recovery rate St-1 4.0 0.5 4.49 99.8％ St-2 4.0 1.0 5.11 102.2％ St-3 4.0 2.0 6.08 101.3％

[0109] As shown in Table 7, the sample recovery rate is between 99.8% and 102.2%, which can meet the accuracy requirements of daily analysis, indicating that the improved detection method of the present invention can accurately determine the content of thiourea and can be used as an analysis method for thiourea content.

[0110] Comparative Example 1

[0111] The retention time of thiourea and dithiocarboxamidine in the thiourea-dithiocarboxamidine mixed standard solution was tested according to the method of Example 1. The only difference from Example 1 was that the mobile phase was a 10 v / v% heptanesulfonic acid-0.05 v / v% phosphoric acid mixed aqueous solution. The liquid chromatogram of the thiourea-dithiocarboxamidine mixed standard solution is shown in FIG. Figure 8 As shown by Figure 8 It can be seen that the retention time of thiourea is 3.58 min, while disulfide formamidine does not appear in the chromatogram, indicating that thiourea cannot be separated from disulfide formamidine when a 10 v / v% heptanesulfonic acid-0.05 v / v% phosphoric acid mixed aqueous solution is used as the mobile phase, and disulfide formamidine will affect the determination of thiourea content.

[0112] Comparative Example 2

[0113] The retention time of thiourea and dithioformamidine in the thiourea-dithioformamidine mixed standard solution was tested according to the method of Example 1. The only difference from Example 1 was that the mobile phase was a 5 v / v% trifluoroacetic acid-0.05 v / v% phosphoric acid mixed solution. The liquid chromatogram of the thiourea-dithioformamidine mixed standard solution is shown in FIG. Fig. 9 As shown by Fig. 9 It can be seen that the retention time of thiourea is 3.58min, while disulfide formamidine does not appear in the chromatogram, indicating that thiourea cannot be separated from disulfide formamidine when a 5v / v% trifluoroacetic acid-0.05v / v% phosphoric acid mixed aqueous solution is used as the mobile phase, and disulfide formamidine will affect the determination of thiourea content.

[0114] Comparative Example 3

[0115] The retention time of thiourea and dithiocarboxamidine in the thiourea-dithiocarboxamidine mixed standard solution was tested according to the method of Example 1. The only difference from Example 1 was that the mobile phase was a 2.5 v / v% tetraethylammonium hydroxide-0.05 v / v% phosphoric acid mixed aqueous solution. The liquid chromatogram of the thiourea-dithiocarboxamidine mixed standard solution is shown in FIG. Fig.10 As shown by Fig.10 It can be seen that the retention time of thiourea is 3.5 minutes, while disulfide formamidine does not appear in the chromatogram, indicating that when a mixed aqueous solution of 2.5 v / v% tetraethylammonium hydroxide-0.05 v / v% phosphoric acid is used as the mobile phase, thiourea cannot be separated from disulfide formamidine, and disulfide formamidine will affect the determination of the thiourea content.

[0116] It can be seen from the above precision, stability, reproducibility and spike recovery tests that the method for detecting thiourea content using high performance liquid chromatography provided by the present invention is feasible. The detection method provided by the present invention has high precision, good reproducibility, high accuracy and good repeatability, and can realize direct detection of samples without special pretreatment of the samples, thereby greatly reducing the time for analysis and detection.

[0117] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for detecting thiourea content in thiourea leaching solution, characterized in that: The quantitative analysis was performed using the external standard method, which included the following steps: The thiourea leaching solution is subjected to high performance liquid chromatography to obtain the chromatographic peak area of ​​thiourea; the mobile phase used in the high performance liquid chromatography detection is a phosphoric acid aqueous solution; the volume concentration of the phosphoric acid aqueous solution is 0.05-1%; the chromatographic column used in the high performance liquid chromatography detection is a Waters X-Bridge C18 column, and the detection wavelength is 236nm; The concentration of thiourea in the thiourea leaching solution is obtained according to the chromatographic peak area of ​​the thiourea and the regression equation of the thiourea standard curve; The preparation method of the thiourea leachate comprises the following steps: Mixing gold-containing ore powder and water to obtain ore powder slurry; The pH value of the mineral powder slurry is adjusted to 1-3, and then mixed with ferric sulfate and thiourea to obtain a mixed slurry; The pH value of the mixed slurry is adjusted to 1-3, and solid-liquid separation is performed after gold leaching to obtain thiourea leaching solution.

2. The detection method according to claim 1, characterized in that: The conditions for the high performance liquid chromatography detection include: a column temperature of 30-40° C.; a flow rate of the mobile phase of 0.5-1 mL / min; and an injection volume of 1-5 μL.

3. The detection method according to claim 1, characterized in that: The ratio of the mass of the gold-containing ore powder to the volume of water is 1g:2-5mL.

4. The detection method according to claim 1 or 3, characterized in that: The ratio of the mass of the ferric sulfate to the volume of the mineral powder slurry is 4-10 g:1 L.

5. The detection method according to claim 1 or 3, characterized in that: The ratio of the mass of the thiourea to the volume of the mineral powder slurry is 1-6 g:1 L.

6. The detection method according to claim 1 or 3, characterized in that: The acid used to adjust the pH value of the mineral powder slurry is sulfuric acid solution.

7. The detection method according to claim 1, characterized in that: The acid used to adjust the pH value of the mixed slurry is sulfuric acid solution.

8. The detection method according to claim 1 or 7, characterized in that: The gold leaching temperature is 20-40° C. and the time is 2-6 hours.

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