A UV detection method for simultaneous detection of trace and ultraviolet benzyl quaternary ammonium salts

Abstract

This invention relates to a UV detection method for simultaneously detecting trace and ultraviolet (UV) levels of benzyl quaternary ammonium salts, comprising: preparing standard solutions for trace and ultraviolet (UV) levels of benzyl quaternary ammonium salts; determining the UV detection wavelength; plotting a standard curve; and detecting the sample. The UV detection method provided by this invention avoids operational errors caused by dilution or concentration steps during sample detection, and has advantages such as simple operation, fast analysis speed, and good accuracy, enabling the simultaneous detection of trace and ultraviolet components.

Description

Technical Field

[0001] This invention relates to the field of content analysis and detection technology, and in particular to an ultraviolet detection method for simultaneously detecting trace and ultra-trace amounts of benzyl quaternary ammonium salts. Background Technology

[0002] Benzyl quaternary ammonium salts are a class of quaternary ammonium cationic surfactants that are readily soluble in water. They form micelles in water, exhibiting certain degreasing and detergency capabilities. They can also disrupt cell membrane integrity, possessing broad-spectrum and potent antibacterial activity with low toxicity. Therefore, as preservatives, antibacterial agents, and disinfectants, benzyl quaternary ammonium salts are widely used in medical, daily cosmetic, textile, and water treatment fields. Furthermore, benzyl quaternary ammonium salts are also used as anion exchange membrane materials in fuel cells, exhibiting good ionic conductivity and alkali stability, thus extending membrane lifespan.

[0003] Quantitative methods for benzyl quaternary ammonium salts are divided into chemical methods and instrumental methods. The commonly used chemical method is titration, suitable for macro-level analysis, but prone to large errors and low accuracy for micro- and trace analysis. Commonly used instrumental methods include organic solvent extraction-UV-Vis spectrophotometry, liquid chromatography, liquid chromatography-tandem mass spectrometry, and matrix-assisted laser desorption / ionization time-of-flight mass spectrometry.

[0004] CN116223673A discloses a method for detecting benzyl chloride in benzylated quaternary ammonium salts by HS-GC-MS. The method includes the following steps: (1) Sample pretreatment: dissolve the benzylated quaternary ammonium salt sample to be tested in ethanol to obtain a sample solution; (2) Preparation of standard solution: weigh the benzyl chloride standard, dilute to 25 mL with ethanol in a volumetric flask, and then prepare a standard working solution with a concentration gradient; (3) Headspace-gas chromatography-mass spectrometry analysis of the standard working solution in step (2): plot the standard curve of benzyl chloride with the concentration of benzyl chloride as the abscissa and the measured peak area as the ordinate; perform headspace-gas chromatography-mass spectrometry analysis on the sample solution in step (1), and substitute the obtained peak area into the linear regression equation of the standard curve obtained above to obtain the content of benzyl chloride in the sample to be tested.

[0005] CN114014798A discloses a method for detecting bispyridine quaternary ammonium salts. The method includes the following steps: (1) measuring the maximum ultraviolet absorption wavelength of the bispyridine quaternary ammonium salt sample to be tested using an ultraviolet-visible spectrophotometer; (2) preparing standard samples of bispyridine quaternary ammonium salts at different concentrations, measuring the absorbance of the standard samples at the maximum ultraviolet absorption wavelength, and plotting a standard curve between concentration and absorbance; (3) measuring the absorbance of the sample to be tested using an ultraviolet-visible spectrophotometer, and calculating the concentration of bispyridine quaternary ammonium salts based on the standard curve.

[0006] Organic solvent extraction is complex, polluting, and often incomplete; liquid chromatography and mass spectrometry are expensive, complex, and time-consuming, with poor accuracy in detecting trace and ultra-trace components; conventional ultraviolet or infrared spectroscopy uses only a single standard curve to detect the content of the sample, resulting in a mismatch between the absorption wavelength and the sample concentration, large detection errors, or exceeding the detection limit, and cannot simultaneously detect the content of trace and ultra-trace components. Especially for the determination of trace collectors, due to their low concentration, detection may exceed the measurement range or be interfered with by other substances, while concentration methods are prone to inaccurate measurements due to operational errors and require additional steps, which is not conducive to testing large batches of samples. Therefore, there is a need to invent a rapid, simple, inexpensive method that directly measures trace and ultra-trace reagents without requiring additional reagents or procedures. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a UV detection method for simultaneously detecting trace and ultraviolet (UV) levels of benzyl quaternary ammonium salts. This UV detection method offers advantages such as speed, no need for dilution or concentration, high accuracy, and the ability to simultaneously detect trace and ultraviolet (UV) levels of benzyl quaternary ammonium salts.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] This invention provides a UV detection method for simultaneously detecting trace and ultraviolet amounts of benzyl quaternary ammonium salts, the method comprising the following steps:

[0010] (1) Prepare a series of trace and ultra-trace benzyl quaternary ammonium salt standard solutions;

[0011] (2) Determine the ultraviolet detection wavelength: The ultraviolet-visible spectrophotometer was used to perform spectral scanning on a series of trace and ultra-trace benzyl quaternary ammonium salt standard solutions to determine the ultraviolet detection wavelength of trace and ultra-trace benzyl quaternary ammonium salt.

[0012] (3) Plotting standard curves: Using a UV-Vis spectrophotometer, the photometric measurements of the series of trace and ultraviolet benzyl quaternary ammonium salt standard solutions described in step (1) were performed at the UV detection wavelength described in step (2), and standard curves between the concentration of trace and ultraviolet benzyl quaternary ammonium salt and absorbance were established respectively.

[0013] (4) Test sample: The UV-Vis spectrophotometer described in step (3) is used to measure the photometric properties of the sample under the UV detection wavelength described in step (2). Then, the content of benzyl quaternary ammonium salt in the sample solution is determined according to the standard curve drawn in step (3).

[0014] The ultraviolet detection method described in this invention uses ultrapure water as a background and employs an ultraviolet-visible spectrophotometer for full-spectrum scanning. Taking into account factors such as baseline, peak stability, sensitivity, and detection limit, and based on the unique ultraviolet spectral characteristics of benzyl quaternary ammonium salts, the most suitable absorption wavelength is selected as the detection wavelength for trace and ultra-trace detection. Different detection wavelengths are used to perform photometric measurements on trace and ultra-trace solutions, establishing standard curves between the concentration and absorbance of trace and ultra-trace benzyl quaternary ammonium salt solutions. The absorbance of the sample is measured at different detection wavelengths, and the benzyl quaternary ammonium salt content in the sample solution is calculated based on the standard curves. This method has advantages such as simple operation, fast analysis speed, no need for dilution and concentration, high accuracy, simultaneous detection of trace and ultra-trace components, and low cost, and has broad application prospects.

[0015] As a preferred embodiment of the present invention, step (1) of preparing a series of trace and ultra-trace benzyl quaternary ammonium salt standard solutions includes:

[0016] Weigh out benzyl quaternary ammonium salt solid, dissolve the weighed benzyl quaternary ammonium salt solid in ultrapure water, and make up to volume to obtain standard benzyl quaternary ammonium salt stock solution. Take a series of volumes of standard benzyl quaternary ammonium salt stock solution, dilute and make up to volume to obtain standard solution.

[0017] Preferably, the resistivity of the ultrapure water used is 18.5 MΩ·cm.

[0018] Preferably, the concentration range of the series of trace benzyl quaternary ammonium salt standard solutions in step (1) is 5-100 ppm. For example, with a concentration gradient of 20 ppm, the concentration of the trace benzyl quaternary ammonium salt standard solutions can be 20 ppm, 40 ppm, 60 ppm, 80 ppm, or 100 ppm; or with a non-equal concentration gradient, the concentration of the trace benzyl quaternary ammonium salt standard solutions can be 5 ppm, 10 ppm, 40 ppm, 60 ppm, 80 ppm, or 100 ppm, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0019] Preferably, the concentration range of the series of trace benzyl quaternary ammonium salt standard solutions in step (1) is 0.1-5 ppm. For example, with a concentration gradient of 0.2 ppm, the concentration of the trace benzyl quaternary ammonium salt standard solutions can be 0.2 ppm, 0.4 ppm, 0.6 ppm, 0.8 ppm, or 1 ppm; or with a non-equal concentration gradient, the concentration of the trace benzyl quaternary ammonium salt standard solutions can be 0.1 ppm, 1 ppm, 2 ppm, 4 ppm, or 5 ppm, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0020] As a preferred technical solution of the present invention, the specific steps of the spectral scanning in step (2) include: using an ultraviolet-visible spectrophotometer, with ultrapure water as the background, to perform spectral scanning on a series of trace and ultra-trace benzyl quaternary ammonium salt standard solutions in the wavelength range of 185 to 800 nm.

[0021] Preferably, the ultraviolet detection wavelength range of the trace amount of benzyl quaternary ammonium salt in step (2) is 200-220nm, such as 200nm, 205nm, 210nm, 215nm, 220nm, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0022] More preferably, when detecting trace amounts of hexadecyl dimethyl benzyl ammonium chloride, the ultraviolet detection wavelength is 216 nm; when detecting trace amounts of dodecyl dimethyl benzyl ammonium chloride, the ultraviolet detection wavelength is 208.5 nm.

[0023] Preferably, the ultraviolet detection wavelength range of the trace benzyl quaternary ammonium salt in step (2) is 185-200nm, such as 185nm, 190nm, 195nm, 200nm, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0024] More preferably, when detecting trace amounts of hexadecyl dimethyl benzyl ammonium chloride, the ultraviolet detection wavelength is 192.5 nm; when detecting trace amounts of dodecyl dimethyl benzyl ammonium chloride, the ultraviolet detection wavelength is 189.5 nm.

[0025] As is well known to those skilled in the art, when using a UV spectrophotometer with ultrapure water as a background to perform spectral scans on a series of trace and ultra-trace benzyl quaternary ammonium salt standard solutions in the wavelength range of 185–800 nm, the maximum absorption wavelength λ of the maximum absorption peak of the benzyl quaternary ammonium salt within the experimental concentration range is... max Within the wavelength range of 187–194 nm, the second largest absorption peak λ max At 216 nm, the B-band absorption generated by the π→π* transition of the benzene ring occurs in the range of 250–270 nm.

[0026] When the concentration of benzyl quaternary ammonium salt is 5-100 ppm, the maximum absorption peak red-shifts with increasing concentration, and its λ... max The peak position shifts towards longer wavelengths, becoming unstable, with the maximum absorption peak λ. max The three absorption peaks of the benzene ring at 257 nm, 262.5 nm, and 268.5 nm are too weak, resulting in low sensitivity, large error, and low data confidence when used as detection wavelengths. The second absorption peak is stable, has high sensitivity, and is less susceptible to interference from other sources; therefore, the second absorption peak λ is not suitable as a detection wavelength. maxThe value is the most suitable ultraviolet detection wavelength for trace amounts of benzyl quaternary ammonium salts.

[0027] When the concentration of benzyl quaternary ammonium salt is 0.1-5 ppm, the second largest absorption peak, which is suitable as the UV detection wavelength for trace benzyl quaternary ammonium salt, is not suitable for trace analysis because its intensity is weak. The largest absorption peak, which is unstable at trace amounts, can be stably emitted, with a strong peak intensity and high sensitivity. Therefore, its largest absorption peak is the most suitable as the UV detection wavelength for trace benzyl quaternary ammonium salt.

[0028] As a preferred technical solution of the present invention, the R value of the standard curve between the concentration and absorbance of trace and ultra-trace benzyl quaternary ammonium salts established in step (3) is... 2 It reaches 0.999 or higher.

[0029] The standard curve R between trace and ultra-trace benzyl quaternary ammonium salt concentration and absorbance in this invention 2 A value of 0.999 or higher indicates that the UV detection method of the present invention is feasible and can simultaneously detect trace and ultra-trace amounts of benzyl quaternary ammonium salt components.

[0030] As a preferred technical solution of the present invention, the sample to be tested in step (4) is a water sample containing benzyl quaternary ammonium salt components.

[0031] Preferably, the water sample can be a test sample prepared using the method for preparing the standard solution described in step (1), or it can be other water samples containing benzyl quaternary ammonium salt components, requiring only the filtration of solid components and no additional dilution or concentration steps.

[0032] Preferably, the photometric measurement in step (4) includes at least three parallel measurements and taking the average value.

[0033] As a preferred technical solution of the present invention, the method includes the following steps:

[0034] (1) Prepare a series of trace and ultra-trace benzyl quaternary ammonium salt standard solutions: Weigh benzyl quaternary ammonium salt solid, dissolve the weighed benzyl quaternary ammonium salt solid in ultrapure water, and make up to volume to obtain standard benzyl quaternary ammonium salt stock solution. Take a series of volumes of standard benzyl quaternary ammonium salt stock solution, dilute and make up to volume to obtain standard solutions.

[0035] The concentration range of the series of trace benzyl quaternary ammonium salt standard solutions is 5-100 ppm; the concentration range of the series of ultra-trace benzyl quaternary ammonium salt standard solutions is 0.1-5 ppm.

[0036] (2) Determine the ultraviolet detection wavelength: Using an ultraviolet-visible spectrophotometer with ultrapure water as the background, a series of trace and ultra-trace benzyl quaternary ammonium salt standard solutions were spectrally scanned in the wavelength range of 185-800 nm.

[0037] The ultraviolet detection wavelength range of the trace amount of benzyl quaternary ammonium salt is 200-220 nm; the ultraviolet detection wavelength range of the ultraviolet detection of the trace amount of benzyl quaternary ammonium salt is 185-200 nm.

[0038] (3) Plotting standard curves: A series of trace benzyl quaternary ammonium salt standard solutions were measured photometrically in the range of 200-220 nm using a UV-Vis spectrophotometer, and a series of ultra-trace benzyl quaternary ammonium salt standard solutions were measured photometrically in the range of 185-200 nm. Standard curves between the concentration of trace and ultra-trace benzyl quaternary ammonium salts and absorbance were established respectively.

[0039] Among them, the R value of the standard curve between the concentration and absorbance of trace and ultra-trace benzyl quaternary ammonium salts is... 2 Achieve 0.999 or higher;

[0040] (4) Test sample: The photometric determination of the sample containing benzyl quaternary ammonium salt component is carried out using a UV-Vis spectrophotometer within the UV detection wavelength range described in step (2). The measurement is performed in parallel at least 3 times, and the average value is taken. Then, the content of benzyl quaternary ammonium salt in the sample solution is determined according to the standard curve between trace and ultra-trace benzyl quaternary ammonium salt concentration and absorbance.

[0041] Compared with the prior art, the present invention has at least the following beneficial effects:

[0042] This invention provides a UV detection method for simultaneously detecting trace and ultraviolet (UV) levels of benzyl quaternary ammonium salts. This method avoids operational errors caused by dilution or concentration steps during sample detection, offering advantages such as ease of operation, fast analysis speed, and good accuracy. It can simultaneously detect trace and ultraviolet components. Furthermore, this invention selects the most suitable absorption wavelength as the detection wavelength for each of the trace and ultraviolet (UV) levels, achieving simultaneous detection of both components without requiring complex sample pretreatment. The UV-Vis spectrophotometer used in this invention is low-cost, and the operation process does not use organic reagents for extraction or color development, making it green and pollution-free, with broad application prospects. Attached Figure Description

[0043] Figure 1 The ultraviolet spectra of trace and ultra-trace amounts of hexadecyl dimethyl benzyl ammonium chloride.

[0044] Figure 2 Standard curves for trace and ultra-trace amounts of hexadecyl dimethyl benzyl ammonium chloride.

[0045] Figure 3 The ultraviolet spectra of trace and ultra-trace amounts of dodecyl dimethyl benzyl ammonium chloride.

[0046] Figure 4 Standard curves for trace and ultra-trace amounts of dodecyl dimethyl benzyl ammonium chloride. Detailed Implementation

[0047] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0048] Instruments and working conditions

[0049] Instrument used: UV-2600i UV-Vis spectrophotometer

[0050] Instrument operating conditions: temperature 15-35℃, humidity 30-80%, power supply AC100V-240V, 50 / 60Hz. In a dim and quiet environment, avoid sunlight and other strong light interference.

[0051] Example 1

[0052] This embodiment provides a UV detection method for simultaneously detecting trace and ultraviolet amounts of benzyl quaternary ammonium salts, the method comprising the following steps:

[0053] (1) Preparation of a series of trace and ultra-trace benzyl quaternary ammonium salt standard solutions: Weigh 0.1000 g of hexadecyl dimethyl benzyl ammonium chloride solid using an analytical balance. Dissolve the weighed hexadecyl dimethyl benzyl ammonium chloride solid in ultrapure water. Transfer the solution to a 1000 mL volumetric flask. Transfer the washing solution used to clean the beaker and glass rod into the volumetric flask. Add ultrapure water to the mark and mix well to obtain a 1000 ppm hexadecyl dimethyl benzyl ammonium chloride standard stock solution. The resistivity of the ultrapure water used is 18.5 MΩ·cm.

[0054] Take 0.5 mL, 1 mL, 2 mL, 4 mL, 6 mL, 8 mL, and 10 mL of 1000 ppm hexadecyl dimethyl benzyl ammonium chloride standard stock solution into 100 mL volumetric flasks, respectively, dilute to the mark with ultrapure water, and shake well. The concentrations of the prepared series of trace hexadecyl dimethyl benzyl ammonium chloride standard solutions are 5 ppm, 10 ppm, 20 ppm, 40 ppm, 60 ppm, 80 ppm, and 100 ppm, respectively.

[0055] Take 1 mL, 2 mL, 4 mL, 6 mL, 8 mL, and 10 mL of 10 ppm hexadecyl dimethyl benzyl ammonium chloride standard solution into 100 mL volumetric flasks, respectively, dilute to the mark with ultrapure water, and shake well. The concentrations of the prepared series of trace hexadecyl dimethyl benzyl ammonium chloride standard solutions are 0.1 ppm, 0.2 ppm, 0.4 ppm, 0.6 ppm, 0.8 ppm, and 1 ppm, respectively.

[0056] (2) Determining the UV detection wavelength: Using a UV-2600i UV-Vis spectrophotometer with ultrapure water as the background, a series of trace and ultra-trace cetyldimethylbenzylammonium chloride standard solutions were spectrally scanned in the wavelength range of 185–800 nm. The UV spectra are as follows: Figure 1 As shown. Considering factors such as baseline, peak stability, sensitivity, and detection limit, 216 nm was selected as the UV detection wavelength for trace amounts of hexadecyl dimethyl benzyl ammonium chloride, and 192.5 nm was selected as the UV detection wavelength for ultraviolet detection of trace amounts of hexadecyl dimethyl benzyl ammonium chloride.

[0057] (3) Plotting Standard Curves: A UV-2600i UV-Vis spectrophotometer was used to measure the absorbance of a series of trace hexadecyl dimethyl benzyl ammonium chloride standard solutions at 216 nm and a series of ultra-trace hexadecyl dimethyl benzyl ammonium chloride standard solutions at 192.5 nm. Standard curves were established between the concentration and absorbance of trace and ultra-trace hexadecyl dimethyl benzyl ammonium chloride, respectively. The standard curves are shown below. Figure 2 As shown.

[0058] (4) Sample Testing: The UV-2600i UV-Vis spectrophotometer was used to measure the absorbance of the two test samples at 216 nm and 192.5 nm, respectively. Three parallel measurements were performed, and the average value was taken. The absorbance results are shown in Table 1. Based on the standard curve between the concentration of trace and ultra-trace hexadecyl dimethyl benzyl ammonium chloride and absorbance, the concentration of hexadecyl dimethyl benzyl ammonium chloride in the test samples was calculated to be 5.34 × 10⁻⁶. -7 g / mL and 1.51×10 -5 g / mL.

[0059] Table 1. Absorbance values ​​of hexadecyl dimethyl benzyl ammonium chloride in the test samples.

[0060]

[0061] from Figure 1 It can be seen that, within the experimental concentration range, the maximum absorption wavelength λ of the maximum absorption peak of hexadecyl dimethyl benzyl ammonium chloride is... max Within the wavelength range of 187–194 nm, the second largest absorption peak λ max At 216 nm, the B-band absorption generated by the π→π* transition of the benzene ring occurs in the range of 250–270 nm.

[0062] When the concentration of hexadecyl dimethyl benzyl ammonium chloride is 5-100 ppm, the maximum absorption peak red-shifts with increasing concentration, and its λ... max The peak position shifts towards longer wavelengths, becoming unstable, with the maximum absorption peak λ. maxThe three absorption peaks of the benzene ring at 257 nm, 262.5 nm, and 268.5 nm are too weak, resulting in low sensitivity, large errors, and low data confidence. The second largest absorption peak at 216 nm is stable, has high sensitivity, and is less susceptible to interference from other sources. Therefore, the second largest absorption peak λ is not suitable as a detection wavelength. max The value is the most suitable ultraviolet detection wavelength for trace amounts of hexadecyl dimethyl benzyl ammonium chloride.

[0063] When the concentration of hexadecyl dimethyl benzyl ammonium chloride is 0.1-1 ppm, the second largest absorption peak, which is suitable as the UV detection wavelength for trace amounts of hexadecyl dimethyl benzyl ammonium chloride, is not suitable for trace analysis due to its weak intensity. The largest absorption peak, which is unstable at trace amounts, is stable at 192.5 nm, with a strong peak intensity and high sensitivity. Therefore, 192.5 nm is the most suitable UV detection wavelength for trace amounts of hexadecyl dimethyl benzyl ammonium chloride.

[0064] Depend on Figure 2 It can be seen that when the concentration is 0.1-1 ppm, the standard curve of hexadecyl dimethyl benzyl ammonium chloride is y = 568099.54x, and the coefficient of determination R is... 2 The coefficient of determination is 0.99908; when the concentration is 5-100 ppm, the standard curve of hexadecyl dimethyl benzyl ammonium chloride is y = 19879.66x, and the coefficient of determination R is 0.99908. 2 The value is 0.99998. The R-values ​​of the two standard curves are... 2 The results all reached 0.999 or higher, indicating that the ultraviolet detection method of the present invention is feasible and can simultaneously detect trace and ultra-trace amounts of benzyl quaternary ammonium salt components.

[0065] Example 2

[0066] This embodiment provides a UV detection method for simultaneously detecting trace and ultraviolet amounts of benzyl quaternary ammonium salts, the method comprising the following steps:

[0067] (1) Preparation of a series of trace and ultra-trace benzyl quaternary ammonium salt standard solutions: Weigh 0.1000 g of dodecyl dimethyl benzyl ammonium chloride solid using an analytical balance, dissolve the weighed dodecyl dimethyl benzyl ammonium chloride solid in ultrapure water, transfer the solution to a 1000 mL volumetric flask, transfer the washing solution used to clean the beaker and glass rod into the volumetric flask, add ultrapure water to the mark, and shake well to obtain a 1000 ppm dodecyl dimethyl benzyl ammonium chloride standard stock solution. The resistivity of the ultrapure water used is 18.5 MΩ·cm.

[0068] Take 2 mL, 4 mL, 6 mL, 8 mL, and 10 mL of 1000 ppm dodecyl dimethyl benzyl ammonium chloride standard stock solution into 100 mL volumetric flasks, respectively, dilute to the mark with ultrapure water, and shake well. The concentrations of the prepared series of trace dodecyl dimethyl benzyl ammonium chloride standard solutions are 20 ppm, 40 ppm, 60 ppm, 80 ppm, and 100 ppm, respectively.

[0069] Take 1 mL, 2 mL, 3 mL, 4 mL, and 5 mL of 100 ppm dodecyl dimethyl benzyl ammonium chloride standard solution respectively into 100 mL volumetric flasks, dilute to the mark with ultrapure water, and shake well. The concentrations of the prepared series of trace dodecyl dimethyl benzyl ammonium chloride standard solutions are 1 ppm, 2 ppm, 3 ppm, 4 ppm, and 5 ppm, respectively.

[0070] (2) Determining the UV detection wavelength: Using a UV-2600i UV-Vis spectrophotometer with ultrapure water as the background, a series of trace and ultra-trace dodecyl dimethyl benzyl ammonium chloride standard solutions were spectrally scanned in the wavelength range of 185–800 nm. The UV spectra are as follows: Figure 3 As shown. Considering factors such as baseline, peak stability, sensitivity, and detection limit, 208.5 nm was selected as the UV detection wavelength for trace amounts of dodecyl dimethyl benzyl ammonium chloride, and 189.5 nm was selected as the UV detection wavelength for ultraviolet (UV) detection of trace amounts of dodecyl dimethyl benzyl ammonium chloride.

[0071] (3) Plotting Standard Curves: A UV-2600i UV-Vis spectrophotometer was used to measure the absorbance of a series of trace amounts of dodecyl dimethyl benzyl ammonium chloride standard solutions at 208.5 nm and a series of ultra-trace amounts of dodecyl dimethyl benzyl ammonium chloride standard solutions at 189.5 nm. Standard curves were established between the concentration and absorbance of trace and ultra-trace amounts of dodecyl dimethyl benzyl ammonium chloride, respectively. The standard curves are shown below. Figure 4 As shown.

[0072] (4) Sample Testing: The UV-2600i UV-Vis spectrophotometer was used to measure the absorbance of the two test samples at 208.5 nm and 189.5 nm, respectively. Three parallel measurements were performed, and the average value was taken. The absorbance results are shown in Table 2. Based on the standard curve between the concentration of trace and ultra-trace dodecyl dimethyl benzyl ammonium chloride and absorbance, the concentration of dodecyl dimethyl benzyl ammonium chloride in the test samples was calculated to be 1.52 × 10⁻⁶. -6 g / mL and 5.63×10 -5 g / mL.

[0073] Table 2 Absorbance values ​​of dodecyl dimethyl benzyl ammonium chloride in the test samples

[0074]

[0075]

[0076] Depend on Figure 4 It can be seen that when the concentration is 0.5-5 ppm, the standard curve of dodecyl dimethyl benzyl ammonium chloride is y = 133376.99x, and the coefficient of determination R is... 2 The coefficient of determination is 0.99991; when the concentration is 5-100 ppm, the standard curve of dodecyl dimethyl benzyl ammonium chloride is y = 21510.66x, and the coefficient of determination R is 0.99991. 2 The value is 0.99990. The R-values ​​of the two standard curves are... 2 The results all reached 0.999 or higher, indicating that the ultraviolet detection method of the present invention is feasible and can simultaneously detect trace and ultra-trace amounts of benzyl quaternary ammonium salt components.

[0077] In summary, this invention provides a UV detection method for simultaneously detecting trace and ultra-trace amounts of benzyl quaternary ammonium salts. Using ultrapure water as a background, a UV-Vis spectrophotometer performs a full-spectrum scan. Considering factors such as baseline, peak stability, sensitivity, and detection limit, the most suitable absorption wavelength is selected based on the unique UV spectral characteristics of benzyl quaternary ammonium salts as the detection wavelengths for both trace and ultra-trace amounts. This method achieves simultaneous detection of trace and ultra-trace benzyl quaternary ammonium salt components without requiring complex sample pretreatment, avoiding operational errors caused by dilution or concentration steps during sample detection. It offers advantages such as simple operation, fast analysis speed, and good accuracy. Furthermore, the UV-Vis spectrophotometer used in this invention is low-cost, and the operation does not use organic reagents for extraction or color development, making it green and pollution-free, with broad application prospects.

[0078] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for the simultaneous detection of trace and ultratrace amounts of benzyl quaternary ammonium salts by UV detection, characterized in that, The method comprises the following steps: (1) configuring a series of trace and trace benzyl quaternary ammonium salt standard solutions; (2) determining the ultraviolet detection wavelength: using an ultraviolet visible spectrophotometer to scan the spectrum of a series of trace and trace benzyl quaternary ammonium salt standard solutions, and determining the ultraviolet detection wavelength of the trace and trace benzyl quaternary ammonium salt; the ultraviolet detection wavelength of the trace benzyl quaternary ammonium salt in step (2) is 200-220 nm; the ultraviolet detection wavelength of the trace benzyl quaternary ammonium salt in step (2) is 185-200 nm; (3) draw a standard curve: using an ultraviolet visible spectrophotometer to measure the light intensity of the series of trace and trace benzyl quaternary ammonium salt standard solutions in step (1) at the ultraviolet detection wavelength in step (2), and establish a standard curve between the concentration and the absorbance of the trace and trace benzyl quaternary ammonium salt, respectively; (4) detecting the sample: using the ultraviolet visible spectrophotometer in step (3) to measure the light intensity of the sample to be measured at the ultraviolet detection wavelength in step (2), and determining the content of benzyl quaternary ammonium salt in the sample to be measured according to the standard curve drawn in step (3).

2. The method of claim 1, wherein, The step (1) of configuring a series of trace and trace benzyl quaternary ammonium salt standard solutions comprises: Take the benzyl quaternary ammonium salt solid, dissolve the weighed benzyl quaternary ammonium salt solid with ultrapure water as the solvent, and after constant volume, obtain the standard benzyl quaternary ammonium salt stock solution, take a series of volumes of the standard benzyl quaternary ammonium salt stock solution, dilute and constant volume to obtain the standard solution.

3. The method according to claim 1 or 2, characterized in that, The concentration range of the series of trace benzyl quaternary ammonium salt standard solutions in step (1) is 5-100 ppm.

4. The method of claim 1, wherein, The concentration range of the series of trace benzyl quaternary ammonium salt standard solutions in step (1) is 0.1-5 ppm.

5. The method of claim 1, wherein, The specific steps of the spectrum scanning in step (2) include: Using an ultraviolet visible spectrophotometer, taking ultrapure water as the background, and scanning the spectrum of a series of trace and trace benzyl quaternary ammonium salt standard solutions in the wavelength range of 185-800 nm.

6. The method of claim 1, wherein, The R2 of the standard curve between the micro and trace benzyl quaternary ammonium salt concentration and absorbance established in step (3) is 2 0.999 or more.

7. The method of claim 1, wherein, The sample to be measured in step (4) is a water sample containing benzyl quaternary ammonium salt component.

8. The method of claim 1, wherein, The light intensity measurement in step (4) includes at least 3 parallel measurements, and the average value is taken.

9. The method of claim 1, wherein, The method comprises: (1) configuring a series of trace and trace benzyl quaternary ammonium salt standard solutions: taking the benzyl quaternary ammonium salt solid, dissolving the weighed benzyl quaternary ammonium salt solid with ultrapure water as the solvent, and after constant volume, obtaining the standard benzyl quaternary ammonium salt stock solution, taking a series of volumes of the standard benzyl quaternary ammonium salt stock solution, diluting and constant volume to obtain the standard solution; The concentration range of the series of trace benzyl quaternary ammonium salt standard solutions is 5-100 ppm; the concentration range of the series of trace benzyl quaternary ammonium salt standard solutions is 0.1-5 ppm; (2) determining the ultraviolet detection wavelength: using an ultraviolet visible spectrophotometer to scan the spectrum of a series of trace and trace benzyl quaternary ammonium salt standard solutions in the wavelength range of 185-800 nm; The ultraviolet detection wavelength of the trace benzyl quaternary ammonium salt is 200-220 nm; the ultraviolet detection wavelength of the trace benzyl quaternary ammonium salt is 185-200 nm; (3) Drawing standard curve: using ultraviolet visible spectrophotometer in the range of 200-220nm to carry out photometric determination on series of trace benzyl quaternary ammonium salt standard solution, and in the range of 185-200nm to carry out photometric determination on series of trace benzyl quaternary ammonium salt standard solution, and respectively establishing the standard curve between trace and trace benzyl quaternary ammonium salt concentration and absorbance; The R of the standard curve between the established trace and micro amounts of benzyl quaternary ammonium salt concentration and absorbance is 0.999 or above. 2 0.999 or above. (4) Detecting sample: using ultraviolet visible spectrophotometer to carry out photometric determination on the sample to be detected containing benzyl quaternary ammonium salt component in the ultraviolet detection wavelength range described in step (2), parallel measurement at least 3 times, taking the average value, and then according to the standard curve between trace and trace benzyl quaternary ammonium salt concentration and absorbance, determining the content of benzyl quaternary ammonium salt in the sample solution to be detected.

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