A fluorescence analysis method for determining p-nitroaniline in a water sample
Patent Information
- Application Number
- CN202311548300.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-20
- Publication Date
- 2026-10-27
- Estimated Expiration
- 2043-11-20
AI Technical Summary
本发明以硫脲为硫源，1,3,5-苯三甲酸(TMA)为保护剂，设计并合成了一种能够高选择性、高灵敏度识别对硝基苯胺的硫量子点荧光探针(SQDS@TMA)，并建立了一种简单、成本低、灵敏度高的对硝基苯胺的荧光测定方法，目前尚没有该方面的相关报道
[0010]本发明与现有技术相比具有以下优点和有益效果：本发明基于对硝基苯胺对硫量子点荧光探针的高选择性荧光猝灭作用，提出了一种简单、低成本、高灵敏度的对硝基苯胺的荧光测定方法，并成功应用于水样中对硝基苯胺的含量测定。
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of fluorescence detection and analysis technology, and relates to a method for detecting p-nitroaniline, specifically a fluorescence analysis method for determining p-nitroaniline in water samples. Background Technology
[0002] p-Nitroaniline (PNA), as an important chemical raw material, is widely used in the pharmaceutical, printing and dyeing industries. Not only is p-nitroaniline highly toxic and difficult to biodegrade, it can also easily enter the human body through various routes, including the skin and digestive tract, posing a significant threat to health. Currently, chromatographic and spectrophotometric methods used for the detection of p-nitroaniline suffer from problems such as cumbersome operation procedures, long analysis times, and complex sample pretreatment.
[0003] Sulfur quantum dots (SQDs) are widely used as fluorescent probes due to their low toxicity and good stability. This invention designs and synthesizes a sulfur quantum dot fluorescent probe (SQDS@TMA) capable of highly selectively and sensitively recognizing p-nitroaniline, using thiourea as the sulfur source and 1,3,5-benzenetricarboxylic acid (TMA) as the protective agent. A simple, low-cost, and highly sensitive fluorescence determination method for p-nitroaniline is also established, a method not previously reported in this area. Summary of the Invention
[0004] The technical problem solved by this invention is to provide a simple, low-cost, and highly sensitive fluorescence analysis method for determining p-nitroaniline in water samples.
[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a fluorescence analysis method for determining p-nitroaniline in water samples, characterized by the following specific steps:
[0006] Step S1, plotting the standard curve: Mix 0.60 mL of sulfur quantum dot fluorescent probe SQDS@TMA with 0.40 mL of BR buffer solution at pH 5.0, then add p-nitroaniline standard working solution, bring the volume to 4.00 mL, shake well, and react at 25℃ for 30 min. Using 380 nm as the excitation wavelength, measure the fluorescence intensity F0 and F of the system before and after adding the p-nitroaniline standard working solution, respectively. Calculate ΔF = F0 - F. For p-nitroaniline concentrations in the range of 0-40 μM, ΔF is related to the p-nitroaniline concentration, i.e., C. PNA There is a good linear relationship between them, and the linear regression equation is: ΔF = 10.81035C PNA +14.757, R 2 =0.99676, the detection limit was 0.79 μM. The parallel determinations of p-nitroaniline systems with concentrations of 10 μM and 30 μM were performed 15 times, and the relative standard deviations were 0.71% and 0.68%, respectively.
[0007] Step S2, detection of p-nitroaniline in water sample: Mix 0.60 mL of sulfur quantum dot fluorescent probe SQDS@TMA with 0.40 mL of BR buffer solution with pH = 5.0, add the water sample to be tested, make up to 4.00 mL, shake well, react at 25℃ for 30 min, use 380 nm as the excitation wavelength, measure the fluorescence intensity F0 and F of the system before and after adding the water sample to be tested, calculate ΔF = F0 - F, substitute the calculated ΔF into the linear regression equation obtained in step S1, and calculate the concentration of p-nitroaniline in the water sample to be tested;
[0008] The specific preparation process of the sulfur quantum dot fluorescent probe SQDS@TMA is as follows: Under room temperature conditions, 2.50 mL of 0.20 mol / L thiourea, 0.15 mL of 1 mol / L NaOH solution, 11.85 mL of H2O and 5.5 mL of 10 mmol / L 1,3,5-benzenetricarboxylic acid were added sequentially to the reaction vessel and stirred for 5 min. Then, 1.8 mL of 3 wt% hydrogen peroxide solution was added dropwise and mixed thoroughly. Subsequently, the mixture was stirred at 80 °C for 4.5 h to finally obtain the sulfur quantum dot fluorescent probe SQDS@TMA.
[0009] Further defining the assay system formed by the sulfur quantum dot fluorescent probe SQDS@TMA, it is effective against high concentrations of Al. 3+ Fe 3+ Cu 2+ Only Cr(VI) exhibits a significant response. This sulfur quantum dot fluorescent probe, SQDS@TMA, demonstrates a unique characteristic of highly selective recognition of PNA and strong anti-interference ability in the p-nitroaniline assay system. It can also eliminate Fe by adding sodium fluoride to the water sample for masking. 3+ Al 3+ Interference from Cu can be masked and eliminated by adding sodium bromide to the water sample to be tested. 2+ Interference.
[0010] Compared with the prior art, the present invention has the following advantages and beneficial effects: Based on the highly selective fluorescence quenching effect of p-nitroaniline on sulfur quantum dot fluorescent probes, the present invention proposes a simple, low-cost, and highly sensitive fluorescence determination method for p-nitroaniline, which has been successfully applied to the determination of p-nitroaniline content in water samples. Attached Figure Description
[0011] Figure 1 To explore the feasibility of synthesizing the sulfur quantum dot fluorescent probe SQDS@TMA.
[0012] Figure 2 The effect of storage time on the stability of sulfur quantum dot fluorescent probes.
[0013] Figure 3The effect of pH on the stability of sulfur quantum dot fluorescent probes.
[0014] Figure 4 The effect of ionic strength on the stability of sulfur quantum dot fluorescent probes.
[0015] Figure 5 The standard curve is plotted.
[0016] Figure 6 shows the selectivity and anti-interference performance of the p-nitroaniline determination system. Detailed Implementation
[0017] The following examples further illustrate the above-described content of the present invention, but it should not be construed as limiting the scope of the subject matter of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention.
[0018] Example
[0019] Synthesized sulfur quantum dot fluorescent probe SQDS@TMA:
[0020] At room temperature, 2.50 mL of thiourea (0.20 mol / L), 0.15 mL of NaOH solution (1 mol / L), 11.85 mL of H2O, and 5.5 mL of 1,3,5-benzenetricarboxylic acid (TMA, 10 mmol / L) were added sequentially to a round-bottom flask and stirred for 5 min. Then, 1.8 mL of hydrogen peroxide solution (3 wt%) was added dropwise and mixed thoroughly. The mixture was then stirred at 80 °C for 4.5 h to obtain a sulfur quantum dot fluorescent probe, denoted as SQDS@TMA.
[0021] The sulfur quantum dot fluorescent probe SQDS@TMA was used to detect p-nitroaniline (PNA) in water samples:
[0022] Plotting the standard curve: Mix 0.60 mL of sulfur quantum dot fluorescent probe SQDS@TMA with 0.40 mL of BR buffer solution (pH = 5.0), then add a certain amount of p-nitroaniline standard working solution, and bring the volume to 4.00 mL. Shake well and react at 25℃ for 30 min. Using 380 nm as the excitation wavelength, measure the fluorescence intensity F0 and F1 before and after adding PNA, respectively, and calculate ΔF = F0 - F1. For PNA concentrations in the range of 0-40 μM, ΔF is related to the PNA concentration (C10-C20-D1). PNA The two equations show a good linear relationship, and the linear regression equation is: ΔF = 10.81035C. PNA +14.757, R 2 =0.99676, the detection limit was 0.79 μM. Parallel determinations were performed 15 times for PNA concentrations of 10 μM and 30 μM, and the relative standard deviations were 0.71% and 0.68%, respectively.
[0023] Detection of p-nitroaniline in water samples: 0.60 mL of sulfur quantum dot fluorescent probe SQDS@TMA was mixed thoroughly with 0.40 mL of BR buffer solution (pH = 5.0). A certain volume of the water sample to be tested was added, and the volume was adjusted to 4.00 mL. The mixture was shaken well and reacted at 25℃ for 30 min. The fluorescence intensity F0 and F of the system before and after adding the water sample were measured using 380 nm as the excitation wavelength. ΔF = F0 - F was calculated. The calculated ΔF was substituted into the linear regression equation to calculate the concentration of p-nitroaniline in the water sample.
[0024] Figure 1 To investigate the feasibility of synthesizing the sulfur quantum dot fluorescent probe SQDS@TMA, the optimal conditions for synthesis were as follows: 2.50 mL of thiourea (0.20 mol / L), 0.15 mL of NaOH solution (1 mol / L), 11.85 mL of H₂O, and 5.5 mL of 1,3,5-benzenetricarboxylic acid (TMA, 10 mmol / L) were sequentially added to a round-bottom flask at room temperature and stirred for 5 min. Then, 1.8 mL of hydrogen peroxide solution (3 wt%) was added dropwise and thoroughly mixed. The reaction was then carried out at 80 °C with stirring for 4.5 h, ultimately yielding the sulfur quantum dot fluorescent probe SQDS@TMA. Under optimal experimental conditions, such as keeping the reaction temperature, time, and reaction system volume (20.00 mL) constant, and to investigate the indispensability of thiourea, hydrogen peroxide, and 1,3,5-benzenetricarboxylic acid, the fluorescence properties of the reaction systems were further examined (e.g., thiourea + hydrogen peroxide, 1,3,5-benzenetricarboxylic acid + hydrogen peroxide, thiourea + 1,3,5-benzenetricarboxylic acid, thiourea + 1,3,5-benzenetricarboxylic acid + hydrogen peroxide). Figure 1 (As shown). By Figure 1 It is known that sulfur quantum dot fluorescent probe SQDS@TMA can only be successfully synthesized under the condition that thiourea, 1,3,5-benzenetricarboxylic acid and hydrogen peroxide coexist.
[0025] Figure 2 The effect of storage time on the stability of sulfur quantum dot fluorescent probes. Figure 2 It can be seen that the fluorescence performance of the sulfur quantum dot fluorescent probe SQDs@TMA remains basically unchanged after 30 days of storage at room temperature and away from light.
[0026] Figure 3 The effect of pH on the stability of sulfur quantum dot fluorescent probes. Figure 3 It can be seen that the fluorescence performance of sulfur quantum dot fluorescent probe SQDs@TMA remains stable within the pH range of 2-7. Further increasing the pH value of the system reduces the fluorescence performance of sulfur quantum dot fluorescent probe SQDs@TMA.
[0027] Figure 4The effect of ionic strength on the stability of sulfur quantum dot fluorescent probes. Figure 4 The effects of sodium chloride concentrations of 10 mmol / L, 20 mmol / L, 30 mmol / L, 40 mmol / L, 50 mmol / L, 60 mmol / L, 80 mmol / L, 100 mmol / L, 150 mmol / L, 200 mmol / L, 250 mmol / L, 300 mmol / L, and 500 mmol / L on the fluorescence properties of the sulfur quantum dot fluorescent probe SQDs@TMA were presented. Under higher ionic strength conditions, the fluorescence properties of the sulfur quantum dot fluorescent probe SQDs@TMA remained unchanged.
[0028] Figure 5 To plot the standard curve, 0.60 mL of sulfur quantum dot fluorescent probe SQDS@TMA was mixed thoroughly with 0.40 mL of BR buffer solution (pH = 5.0), and then a certain amount of p-nitroaniline (PNA) standard working solution was added to bring the volume to 4.00 mL. The mixture was shaken well and reacted at 25 °C for 30 min. The fluorescence intensity F0 and F2 of the system before and after the addition of PNA were measured using 380 nm as the excitation wavelength, and ΔF = F0 - F2 was calculated. For PNA concentrations in the range of 0-40 μM, ΔF was related to the PNA concentration (C20-40 μM). PNA The two equations show a good linear relationship, and the linear regression equation is: ΔF = 10.81035C. PNA +14.757, R 2 =0.99676, the detection limit was 0.79 μM. Parallel determinations were performed 15 times for PNA concentrations of 10 μM and 30 μM, and the relative standard deviations were 0.71% and 0.68%, respectively.
[0029] Figure 6 shows the selectivity and anti-interference performance of the p-nitroaniline assay system. 0.60 mL of sulfur quantum dot fluorescent probe SQDS@TMA was mixed with 0.40 mL of BR buffer solution (pH = 5.0), p-nitroaniline and interfering substances were added, and the volume was adjusted to 4.00 mL. The mixture was shaken well and reacted at 25 °C for 30 min. The fluorescence intensity of the system before and after the addition of p-nitroaniline and interfering substances was measured using 380 nm as the excitation wavelength. To investigate the selectivity and anti-interference performance of the p-nitroaniline assay system, the PNA concentration was determined to be 30 μM, and the concentration of all interfering substances was 100 μM. The ions and interfering substances investigated included: Na... + NH4 + K + Ni 2+ Ca 2+ Cd 2+ Al 3+ Cr 3+ Co 2+ Ba 2+ Hg2+ Mn 2+ Fe 3+ Fe 2+ Cr(VI), Pb 2+ Ag + Sn 2+ Mg 2+ and anion F - ,Br - HCO3 - CO3 2- NO3 - Cl - SO4 2- SO3 2- Common surfactants in water include hexadecyltrimethylammonium bromide (CTMAB), tetradecyltrimethylammonium bromide (TTMAB), sodium dodecyl sulfonate (SBS), sodium dodecyl sulfate (SDS), and dodecylbenzene sulfonic acid (SDBS). Amino acids include tryptophan (Trp), histidine (His), aspartic acid (Asp), glutamic acid (Glu), lysine (Lys), L-leucine (Leu), L-isoleucine (Ile), and glycine (Gly). Sugars include sucrose (SUC), glucose (GLC), and starch (ST). Imidazoles include 1,2-dimethylimidazole, 1-methylimidazole, imidazole, and 2-methylimidazole. The test results included azole), 4-methylimidazole, phenols such as 3-chlorophenol, p-cresol, o-cresol, 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 4-chlorophenol, resorcinol, bisphenol A, 1-catechol, as well as m-nitroaniline, melamine, thiosemicarbazide, ammonium iron(III) sulfate, ammonium vanadate, pyrophosphoric acid, formaldehyde, ascorbic acid (AA), and other interfering substances. Figures 6A-6E As shown in the figure. It can be seen from the figure that the measurement system is effective against high concentrations of Al. 3+Fe 3+ Cu 2+ Only substances such as Cr(VI) show a significant response, indicating that the p-nitroaniline assay system provided by this invention has the unique characteristic of highly selective recognition of PNA and strong anti-interference ability. Fe can be eliminated by masking with sodium fluoride. 3+ Al 3+ Interference from Cu is eliminated by masking with sodium bromide. 2+ Interference.
[0030] Application of the determination method:
[0031] Tap water (sample 1), groundwater (sample 2), river water (sample 3), and lake water (sample 4) were collected, filtered, and set aside. 0.60 mL of sulfur quantum dot fluorescent probe SQDS@TMA was mixed thoroughly with 0.40 mL of BR buffer solution (pH = 5.0), and a certain volume of the water sample to be tested was added. The volume was then adjusted to 4.00 mL, shaken well, and reacted at 25℃ for 30 min. The fluorescence intensity F0 and F of the system before and after adding the water sample were measured using 380 nm as the excitation wavelength, and ΔF = F0 - F was calculated. PNA was not detected in any of the water samples. Further spiked recovery experiments were conducted, with 5 μM, 10 μM, and 30 μM of PNA added, respectively. The experimental results are shown in Table 1. The spiked recoveries ranged from 97.8% to 100.27%, and the RSDs ranged from 0.06% to 0.82%. This indicates that the fluorescence determination method based on the sulfur quantum dot fluorescent probe SQDS@TMA provided by this invention can be successfully applied to the detection and analysis of PNA in water samples.
[0032] Table 1. Measurement of actual water samples
[0033]
[0034] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the scope of the principles of the present invention, and all such changes and modifications fall within the protection scope of the present invention.
Claims
1. A fluorescence analysis method for determining p-nitroaniline in water samples, characterized in that... The specific steps are as follows: Step S1, plotting the standard curve: Mix 0.60 mL of sulfur quantum dot fluorescent probe SQDS@TMA with 0.40 mL of BR buffer solution at pH=5.0, then add p-nitroaniline standard working solution, bring the volume to 4.00 mL, shake well, and react at 25℃ for 30 min. Using 380 nm as the excitation wavelength, measure the fluorescence intensity F0 and F of the system before and after adding the p-nitroaniline standard working solution, respectively. Calculate ΔF = F0 - F. For p-nitroaniline concentrations in the range of 0-40 µM, ΔF is related to the p-nitroaniline concentration, i.e., C. PNA A good linear relationship is observed between them, and the linear regression equation is: ΔF = 10.81035C PNA +14.757, R 2 =0.99676, the detection limit was 0.79 µM. Fifteen parallel determinations were performed on systems with p-nitroaniline concentrations of 10 µM and 30 µM, with relative standard deviations of 0.71% and 0.68%, respectively. Step S2, detection of p-nitroaniline in water sample: Mix 0.60 mL of sulfur quantum dot fluorescent probe SQDS@TMA with 0.40 mL of BR buffer solution at pH=5.0, add the water sample to be tested, bring the volume to 4.00 mL, shake well, and react at 25℃ for 30 min. Use 380 nm as the excitation wavelength to measure the fluorescence intensity F0 and F of the system before and after adding the water sample to be tested, respectively, and calculate ΔF=F0-F. Substitute the calculated ΔF into the linear regression equation obtained in step S1 to calculate the concentration of p-nitroaniline in the water sample to be tested. The specific preparation process of the sulfur quantum dot fluorescent probe SQDS@TMA is as follows: 2.50 mL of 0.20 mol / L thiourea, 0.15 mL of 1 mol / L NaOH solution, 11.85 mL of H2O and 5.5 mL of 10 mmol / L 1,3,5-benzenetricarboxylic acid were added sequentially to the reaction vessel at room temperature and stirred for 5 min. Then, 1.8 mL of 3wt% hydrogen peroxide solution was added dropwise and mixed thoroughly. Subsequently, the reaction was stirred at 80℃ for 4.5 h to finally obtain the sulfur quantum dot fluorescent probe SQDS@TMA. The assay system formed by the sulfur quantum dot fluorescent probe SQDS@TMA is effective for high concentrations of Al. 3+ Fe 3+ Cu 2+ The sulfur quantum dot fluorescent probe SQDS@TMA exhibits a significant response to Cr(VI) and possesses unique characteristics of high selectivity in recognizing PNA and strong anti-interference ability in the p-nitroaniline determination system. It can also eliminate Fe by masking with sodium fluoride added to the water sample. 3+ Al 3 + Interference from Cu can be masked and eliminated by adding sodium bromide to the water sample to be tested. 2+ Interference.