Methanol extraction-high performance liquid chromatography analysis method for content of salicylaldehyde

Abstract

The invention belongs to the technical field of analysis and detection, and particularly relates to a methanol extraction-high performance liquid chromatography analysis method for the content of salicylaldehyde. The analysis method comprises the following steps: mixing a to-be-detected sample with an extracting agent, carrying out oscillation extraction and ultrasonic-assisted extraction, and separating to obtain supernate, namely a test sample solution; dissolving a salicylaldehyde standard substance with methanol and diluting step by step to prepare a reference substance solution; respectively detecting the reference solution and the test solution by adopting a high performance liquid chromatography to obtain corresponding chromatograms; and calculating the content of salicylaldehyde in the test solution according to the standard curve. The establishment and verification process of the analysis method is systematically elaborated, including instrument conditions, sample pretreatment, various indexes verified by the method and actual sample determination results, so that the method is proved to be suitable for quantitative analysis of salicylaldehyde in industrial by-products, and technical support is provided for quality control and process optimization of related industries.

Description

Technical Field

[0001] This invention belongs to the field of analytical detection technology, specifically relating to a methanol extraction-high performance liquid chromatography method for analyzing salicylaldehyde content. Background Technology

[0002] Salicylic aldehyde (chemical name: o-hydroxybenzaldehyde or 2-hydroxybenzaldehyde) is an important organic chemical intermediate with wide applications in pharmaceuticals, pesticides, fragrances, and dyes. In some industrial production processes, salicylic aldehyde may appear as a byproduct or residue. In particular, the presence of salicylic aldehyde residues in industrial byproducts such as ammonium chloride and ammonium sulfate may pose potential risks to product quality, subsequent processing techniques, and environmental safety. Therefore, establishing an accurate, sensitive, and reliable method for detecting salicylic aldehyde content is of great significance for quality monitoring of related products, production process evaluation, and safety assurance in production.

[0003] Currently, common analytical methods for salicylaldehyde include gas chromatography, high-performance liquid chromatography (HPLC), and ultraviolet spectrophotometry. Among these, HPLC has become the mainstream method for qualitative and quantitative analysis of organic compounds due to its high separation efficiency, good detection sensitivity, and relatively simple operation. However, when this technology is directly applied to the detection of trace salicylaldehyde in industrial by-products (such as ammonium chloride and ammonium sulfate), several technical challenges remain: First, the large number of coexisting inorganic salts and organic impurities in complex matrices can easily interfere with chromatographic separation and detection, affecting the specificity and accuracy of the method. Second, salicylaldehyde itself is chemically unstable and is prone to oxidation or degradation during sample pretreatment and analysis, increasing the risk of errors in quantitative analysis. Third, conventional HPLC methods often lack systematic methodological validation for specific systems, including targeted optimization of chromatographic conditions, adaptive design of sample pretreatment, and comprehensive evaluation of key indicators such as sensitivity, precision, and accuracy, thus making it difficult to ensure its reliability and applicability in industrial quality control scenarios. Summary of the Invention

[0004] The purpose of this invention is to provide a methanol extraction-high performance liquid chromatography (HPLC) method for the analysis of salicylaldehyde content, thereby overcoming the shortcomings of existing technologies. By optimizing the chromatographic column, mobile phase, and detection conditions, an effective sample pretreatment process is developed. The specificity, linear range, limit of detection and limit of quantitation, precision, repeatability, accuracy, and solution stability of the method are fully validated to prove that the method can effectively cope with interference from complex matrices and ensure the accuracy and reliability of salicylaldehyde quantification. This provides practical analytical technology support for process monitoring and product quality assessment in related industries.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: This invention provides a methanol extraction-high performance liquid chromatography (HPLC) method for analyzing salicylaldehyde content, comprising the following steps: The sample to be tested is mixed with the extractant, and after shaking extraction and ultrasonic-assisted extraction, the supernatant obtained is the test solution; the salicylaldehyde standard is dissolved in methanol and diluted stepwise to prepare the reference solution. High-performance liquid chromatography (HPLC) was used to detect the reference solution and the test solution separately, and the corresponding chromatograms were obtained; the content of salicylaldehyde in the test solution was calculated based on the standard curve. The chromatographic conditions for high performance liquid chromatography (HPLC) detection are as follows: C18 column, injection volume 8-12 μL, column temperature 25-30 ℃, flow rate 0.8-1.2 mL / min; mobile phase is one of methanol, acetonitrile, methanol-water-acetic acid, methanol-acetic acid, and acetonitrile-acetic acid, using isocratic elution or gradient elution, and the detection wavelength of the ultraviolet detector is 220-330 nm.

[0006] This invention employs a high-performance liquid chromatography (HPLC) system, combined with suitable chromatographic columns and detection conditions, to systematically validate the methodology for detecting salicylaldehyde content in industrial byproducts. This ensures that the method meets analytical requirements in terms of specificity, sensitivity, linearity, precision, repeatability, and accuracy, providing a reliable analytical basis for the detection of actual samples.

[0007] In some other embodiments, the extractant is one or more of methanol, acetonitrile, and acetone; the sample to be tested is mixed with the extractant and extracted under a neutral environment; preferably, the extractant is methanol. When methanol is used as the extractant, the extraction efficiency of salicylaldehyde is significantly higher than that of acetonitrile and acetone, exhibiting better elution performance and recovery consistency. Under acidic or alkaline conditions, the extraction efficiency of salicylaldehyde was not improved; instead, it caused a decrease in recovery or an increase in baseline interference, indicating that a neutral extraction environment is more conducive to the stable extraction of this system.

[0008] In some other embodiments, 2-5 mL of extraction reagent is added per gram of sample to be tested, and the extraction time is 8-12 min with shaking, or 15-30 min with ultrasound-assisted extraction.

[0009] In some other embodiments, the chromatographic column is selected from any of the brands Agilent, Waters, and Thermo, preferably an Agilent 5 TC-C18 column. The Agilent 5 TC-C18 column provides the best separation performance for impurities.

[0010] In some other embodiments, the mobile phase is methanol-water-acetic acid, with a volume ratio of 68:30:2. The methanol-water-acetic acid system not only provides good separation but also improves peak shape.

[0011] In some other embodiments, isocratic elution is used, with an elution time of 0-15 min, preferably 3-8 min.

[0012] In some other embodiments, the detection wavelength of the ultraviolet detector is 328 nm. At 328 nm, salicylaldehyde exhibits a considerable response with good peak shape, stable baseline, and minimal background interference. By comparing the signal-to-noise ratio and peak area response at different wavelengths, this wavelength selection effectively improves the detection sensitivity of salicylaldehyde, providing a reliable guarantee for the accurate determination of low-content samples.

[0013] In some other embodiments, the injection volume is 10 μL, the column temperature is 30 °C, and the flow rate is 1.0 mL / min.

[0014] In some other embodiments, in the high-performance liquid chromatography (HPLC) detection, the sample concentration at which the signal-to-noise ratio (SNR) of the salicylaldehyde chromatographic peak is determined as the limit of detection (LOD), and the sample concentration at which the SNR is determined as the limit of quantitation (LOQ) is determined as the limit of quantitation (LOQ). In this analytical method, the LOD of salicylaldehyde is 0.4 mg / kg; the LOQ of salicylaldehyde is 1.0 mg / kg.

[0015] In some other embodiments, the sample to be tested is one or both of the industrial byproducts ammonium chloride and ammonium sulfate. Accurate, sensitive, and reliable determination of the salicylaldehyde content in industrial byproducts ammonium chloride and ammonium sulfate is of great significance for controlling product quality, assessing process cleanliness, and ensuring production safety.

[0016] The beneficial effects of this invention are: (1) This invention achieves efficient and stable release of salicylaldehyde from solid ammonium sulfate samples by using methanol as the extraction solvent, adjusting the pH value of the extraction solvent to affect the extraction effect, and combining oscillation and ultrasonic-assisted extraction. The method recovery rate remains stable at a high level, ensuring the reliability of the pretreatment process. The sample pretreatment steps are simple and quick, and the chromatographic analysis conditions are robust and easy to implement. The entire method is efficient and suitable for routine batch detection of industrial by-product ammonium sulfate, and is easy to promote and apply in routine analytical laboratories.

[0017] (2) By optimizing chromatographic conditions, this invention effectively separates salicylaldehyde from coexisting impurities and potential interfering substances in the ammonium sulfate matrix, ensuring the accuracy and specificity of target peak identification and effectively avoiding interference from complex backgrounds. A comprehensive and systematic methodological validation was conducted on key indicators such as the limit of detection of salicylaldehyde (0.4 mg / kg), the limit of quantitation (1.0 mg / kg), linear range (500-10000.0 ng / mL), precision (relative standard deviation of 0.97%), repeatability (relative standard deviation of 2.66%), and stability (recovery rates of 93.8%–104% with a relative standard deviation of 3.58% for low, medium, and high spikes). This validated the method's good quantitative accuracy and reproducibility, ensuring reliable data and providing a solid basis for quality control. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0019] Figure 1 The chromatograms are of the dilution solvent blank, reference solution, test solution, and spiked test solution in Example 1 of the present invention, wherein a is the dilution solvent blank, b is the reference solution, c is the test solution, and d is the spiked test solution; Figure 2 This is a graph showing the working curve of the method in Embodiment 1 of the present invention. Detailed Implementation

[0020] Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention. Specific conditions not specified in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Components whose manufacturers are not specified are all commercially available conventional products.

[0021] The instruments and materials used are as follows: Instruments: Shimadzu SPD-20A liquid chromatograph (Shimadzu Corporation, Japan), Agilent 5 TC-C18 column (250 mm × 4.6 mm, 5 μm, Agilent Technologies, USA), KQ2202 CNC ultrasonic cleaner (Shanghai Chubai Experimental Equipment Co., Ltd.); Mettle AB265-S electronic analytical balance (Mettler Mettler Instruments, Switzerland). Materials: Salicylic acid aldehyde (purity 100 μg / mL) was purchased from Alta; methanol (chromatographic grade) was purchased from Tiandi Corporation, USA; Wahaha purified water was ordered from a supermarket; and solid samples of ammonium chloride and ammonium sulfate, byproducts of a certain factory.

[0022] Example 1 A methanol extraction-high performance liquid chromatography method for detecting salicylaldehyde content, the specific steps of which are as follows: 1. Chromatographic conditions Chromatographic column: Agilent 5 TC-C18(2) column (250 mm × 4.6 mm, 5 μm), injection volume: 10 μL, column temperature: 30 ℃, flow rate: 1.0 mL / min. Mobile phase: methanol:water:acetic acid volume ratio 68:30:2, isocratic elution: 0–15 min, wavelength: 328 nm, UV detector.

[0023] 2. Solution preparation Preparation of the test solution: Accurately weigh 5.00 g of ammonium sulfate solid, place it in a 10 mL centrifuge tube, add 10 mL of methanol to dissolve it, shake for 10 min, sonicate for 20 min, and take the supernatant to obtain the solution.

[0024] Preparation of reference stock solution: Accurately measure 1 mL of salicylaldehyde standard solution and place it in a 10 mL volumetric flask. Dilute to the mark with methanol solution, shake well, and prepare a 1 mL standard solution containing 10 μg of salicylaldehyde.

[0025] Preparation of reference solution: Take 1.0 mL of the reference stock solution, accurately measure it, place it in a 10 mL volumetric flask, dilute it to the mark with methanol, shake well, and prepare a solution containing 1 μg per mL.

[0026] 3. Condition Optimization (1) Optimization of sample pretreatment methods In sample pretreatment, the choice of extraction solvent is a key factor affecting the extraction efficiency and recovery rate of the target analyte. This embodiment, based on the principle of "like dissolves like" and the acid-base interaction mechanism, systematically investigated the extraction effects of different polar solvents on salicylaldehyde. Methanol, acetonitrile, and acetone, three commonly used organic solvents, were selected for comparative experiments. The elution capacity was evaluated by comparing the chromatographic response and recovery rate of the target analyte under the same treatment conditions. The results showed that when methanol was used as the extraction solvent, the recovery rate of salicylaldehyde was 96.7%; when acetonitrile was used, the recovery rate was 80.5%; and when acetone was used, the recovery rate was 67.2%. Therefore, when methanol was used as the extraction solvent, the extraction efficiency of salicylaldehyde was significantly higher than that of acetonitrile and acetone, exhibiting superior elution performance and consistent recovery rate.

[0027] Based on this, the effect of adjusting the pH value of the extraction solution on the extraction efficiency was further investigated. The experiment found that under both acidic and alkaline conditions, the extraction efficiency of salicylaldehyde was less than 75%, and the recovery rate was not improved; instead, it led to a decrease in recovery rate or an increase in baseline interference, indicating that a neutral extraction environment is more conducive to the stable extraction of this system.

[0028] Based on the above results, methanol was ultimately selected as the optimized solvent for salicylaldehyde extraction. This condition ensures efficient extraction while also being simple and reproducible, making it suitable for subsequent analytical methodology validation and actual sample testing.

[0029] (2) Wavelength condition optimization In liquid chromatography, the choice of ultraviolet (UV) detection wavelength directly affects the response sensitivity and specificity of target compounds. To determine the optimal detection wavelength for salicylaldehyde, this study first referred to relevant literature reports, finding that the maximum UV absorption wavelengths of common salicylaldehyde and its analogues are mostly concentrated around 220 nm and 300 nm. Based on this, to further optimize detection conditions and improve method sensitivity and signal-to-noise ratio, this study systematically investigated multiple wavelengths, including 220 nm, 300 nm, and 328 nm (under initial conditions), and extended the screening to longer wavelengths where UV absorption might be enhanced.

[0030] Experimental results show that the signal response is significantly improved at a wavelength of 328 nm, with good peak shape, stable baseline, and minimal background interference. By comparing the signal-to-noise ratio and peak area response at different wavelengths, 328 nm was ultimately determined to be the optimal detection wavelength for this method. The selection of this wavelength effectively improves the detection sensitivity of salicylaldehyde, providing a reliable guarantee for the accurate determination of low-content samples.

[0031] (3) Optimization of chromatographic column and mobile phase Through column selection (screening different brands of Agilent, Waters, and Thermo, and different specifications of columns, the recoveries of salicylaldehyde were 96.7%, 78.8%, and 83.5%, respectively, with the Agilent 5 TC-C18 column showing the best separation effect for impurities), changing the composition of the organic phase (screening the effects of methanol, acetonitrile, methanol-acetic acid, and acetonitrile-acetic acid systems on impurity separation, with recoveries of salicylaldehyde of 89.3%, 80.1%, 101%, and 85.1%, respectively, showing that the methanol-water-acetic acid system not only had good separation but also improved peak shape), and adjusting the mobile phase ratio (screening the effects of gradient elution and isocratic elution on impurity separation), the recovery rate of salicylaldehyde was 84.6% when sampling with gradient elution and 93.4% when sampling with isocratic elution. Therefore, the chromatographic elution condition for this method was determined to be isocratic elution.

[0032] By further optimizing each chromatographic parameter, the chromatographic conditions were finally determined, achieving good separation between impurities and the main component, as well as among the impurities themselves. This also enables accurate detection of the impurity content in the sample, ensuring the reliability of the detection results.

[0033] 4. Effect Verification (1) Specificity verification Methanol reagent was used as the diluent and the test solution for injection to demonstrate that the diluent blank and the test solution did not interfere with the analyte test. The reference solution and the spiked test solution were then injected. The corresponding spectra are shown below. Figure 1 .

[0034] Depend on Figure 1 The comparison between the two methods shows that the diluted solution does not interfere with the detection of the target compound, and other impurities in the sample do not interfere with the detection of the target compound, indicating that the method has strong specificity.

[0035] (2) Validation of limit of quantitation and limit of detection The concentration with a signal-to-noise ratio (S / N) of 3 to 5 is the limit of detection concentration; the concentration with a S / N of 10 to 15 is the limit of quantitation concentration, and the relative standard deviation of the S / N corresponding to the limit of quantitation for 6 needles should be ≤10.0%.

[0036] Accurately transfer 2 mL of the reference solution into a 10 mL volumetric flask, dilute to the mark with methanol to prepare a 200 ng / mL solution, which will be used as the detection limit verification concentration.

[0037] Accurately transfer 5 mL of the reference solution into a 10 mL volumetric flask, dilute to the mark with methanol to prepare a 500 ng / mL solution, which will be used as the limit of quantitation verification concentration.

[0038] The test results are shown in Tables 1 and 2.

[0039] Table 1 Detection Limit Experiment Results

[0040] Table 2 Results of Limit of Quantitation Experiment

[0041] The results in Tables 1 and 2 show that the detection limit of salicylaldehyde in this analytical method is 0.4 mg / kg; the quantitation limit of salicylaldehyde is 1.0 mg / kg, and the relative standard deviation of the signal-to-noise ratio of the 6-needle quantitation limit is 1.75%, which is less than 10%.

[0042] (3) Linear range verification Take an appropriate amount of the reference standard stock solution and dilute it stepwise with methanol to prepare standard solutions with concentrations of 500 ng / mL, 1000 ng / mL, 2000 ng / mL, 5000 ng / mL, and 10000 ng / mL, as linearity range verification solutions. Inject 10 μL of each of the above solutions and record the chromatograms. The linearity results of the compounds are shown in Table 3. Plot the working curve with concentration on the x-axis and the integral area on the y-axis as shown in the figure. Figure 2 As shown.

[0043] Table 3 Linearity results of salicylaldehyde

[0044] The results in Table 3 show that, in the mass concentration range of 500–10000.0 ng / mL, the linear equation for salicylaldehyde using this analytical method is y = 20486.6x - 294.2, with a linear correlation coefficient of [missing value]. R ² = 0.9999; exhibiting a good linear relationship.

[0045] (4) Method precision verification The reference solution was used as the method precision test solution, and the injection was repeated 6 times. The peak area response values ​​were recorded, and the relative standard deviation was calculated, as shown in Table 4. The results in Table 4 show that the relative standard deviation of the salicylaldehyde peak area in this analytical method is 0.97%, proving that the method has high precision.

[0046] Table 4. Results of Method Precision Test

[0047] (5) Repeatability verification Accurately weigh 5.00 g of ammonium sulfate and place it in a 50 mL centrifuge tube. Then, accurately add 1 mL of salicylaldehyde reference standard stock solution, followed by 9 mL of methanol. Shake for 10 min, then sonicate for 20 min. Collect the supernatant to obtain a mixed solution containing a salicylaldehyde standard concentration of 1 μg / mL. Use this solution for repeatability testing. Perform six parallel analyses, injecting 10 μL of each solution. Record the measured concentrations and calculate the relative standard deviations. The results are shown in Table 5. Table 5 shows that the relative standard deviation of the measured concentrations of the analyte in the six parallel samples was 2.66%. The results indicate that this analytical method has good repeatability for salicylaldehyde.

[0048] Table 5 Repeatability Test Results

[0049] (6) Validation of spiked recovery rate Accurately weigh 5.00 g of ammonium sulfate and place it in a 50 mL centrifuge tube. Then, accurately add 0.8 mL of salicylaldehyde reference standard stock solution, followed by 9.2 mL of methanol. Shake for 10 min, then sonicate for 20 min. Collect the supernatant to obtain a mixed solution containing a salicylaldehyde standard concentration of 0.8 μg / mL, which serves as the 80% salicylaldehyde standard concentration test solution. Prepare three aliquots. Alternatively, accurately weigh 5.00 g of ammonium sulfate and place it in a 50 mL centrifuge tube. Then, accurately add 1 mL of salicylaldehyde reference standard stock solution, followed by 9.0 mL of methanol. Shake for 10 min, then sonicate for 20 min. Collect the supernatant to obtain a mixed solution containing a salicylaldehyde standard concentration of 1 μg / mL, which serves as the 100% salicylaldehyde standard concentration test solution. Prepare three aliquots. Finally, accurately weigh 5.00 g of ammonium sulfate and place it in a 50 mL centrifuge tube. Then, accurately add 1.2 mL of salicylaldehyde reference standard stock solution, followed by 8.8 mL of methanol. Shake for 10 min, then sonicate for 20 min. After a period of time, the supernatant was collected to obtain a mixed solution containing a salicylaldehyde standard concentration of 0.8 μg / mL. This solution was used as a 120% salicylaldehyde standard concentration test solution, and three aliquots were prepared. The recovery rate and relative standard deviation of the salicylaldehyde content were calculated. The difference between the measured results and the true values ​​was verified to determine whether the analytical method could obtain accurate test results. The salicylaldehyde spiked recovery test results are shown in Table 6.

[0050] Table 6. Salicylaldehyde Recovery Rate Test Results

[0051] The results in Table 6 show that the recovery rates of salicylaldehyde at low, medium, and high spikes in this analytical method range from 93.8% to 104%, with a relative standard deviation of 3.58%, indicating good recovery results.

[0052] 5. Determination of content in actual samples Take solid ammonium chloride (ammonium sulfate) for each of the following samples: Sample 1, Sample 2, and Sample 3. Accurately weigh 5.00 g of ammonium chloride (ammonium sulfate) and place it in a 50 mL centrifuge tube. Then accurately add 9 mL of methanol, shake for 10 min, sonicate for 20 min, and collect the supernatant. Inject 10 μL of each sample. The results are shown in Table 7.

[0053] Table 7 Sample Test Results

[0054] The verification of the above indicators shows that the analytical method for determining the salicylaldehyde content in ammonium sulfate solid by high performance liquid chromatography has high specificity, high sensitivity, good recovery rate, accuracy, reliability, and simple operation, and can meet the technical requirements for detection.

[0055] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A methanol extraction-high performance liquid chromatography method for analyzing salicylaldehyde content, characterized in that, Includes the following steps: The sample to be tested is mixed with the extractant, and after shaking extraction and ultrasonic-assisted extraction, the supernatant obtained is the test solution. The salicylaldehyde standard was dissolved in methanol and diluted stepwise to prepare a reference solution. High-performance liquid chromatography (HPLC) was used to detect the reference solution and the test solution separately, and the corresponding chromatograms were obtained; the content of salicylaldehyde in the test solution was calculated based on the standard curve. The chromatographic conditions for high performance liquid chromatography (HPLC) detection are as follows: C18 column, injection volume 8-12 μL, column temperature 25-30 ℃, flow rate 0.8-1.2 mL / min; mobile phase is one of methanol, acetonitrile, methanol-water-acetic acid, methanol-acetic acid, and acetonitrile-acetic acid, using isocratic elution or gradient elution, and the detection wavelength of the ultraviolet detector is 220-330 nm.

2. The methanol extraction-high performance liquid chromatography method for analyzing salicylaldehyde content according to claim 1, characterized in that, The extractant is one or more of methanol, acetonitrile, and acetone; the sample to be tested is mixed with the extractant and extracted under a neutral environment; preferably, the extractant is methanol.

3. The methanol extraction-high performance liquid chromatography method for analyzing salicylaldehyde content according to claim 1, characterized in that, Add 2-5 mL of extraction reagent per gram of sample to be tested, and extract by shaking for 8-12 min, or extract by ultrasound-assisted extraction for 15-30 min.

4. The methanol extraction-high performance liquid chromatography method for analyzing salicylaldehyde content according to claim 1, characterized in that, The chromatographic column is selected from any of the brands Agilent, Waters, and Thermo, preferably an Agilent 5 TC-C18 column.

5. The methanol extraction-high performance liquid chromatography method for analyzing salicylaldehyde content according to claim 1, characterized in that, The mobile phase is methanol-water-acetic acid, and the volume ratio of methanol-water-acetic acid is (65-68):(25-30):(2-5), preferably 68:30:

2.

6. The methanol extraction-high performance liquid chromatography method for analyzing salicylaldehyde content according to claim 1, characterized in that, Isocratic elution was used, with an elution time of 0-15 min.

7. The methanol extraction-high performance liquid chromatography method for analyzing salicylaldehyde content according to claim 1, characterized in that, The detection wavelength of the ultraviolet detector is 328 nm.

8. The methanol extraction-high performance liquid chromatography method for analyzing salicylaldehyde content according to claim 1, characterized in that, The injection volume was 10 μL, the column temperature was 30 ℃, and the flow rate was 1.0 mL / min.

9. The methanol extraction-high performance liquid chromatography method for analyzing salicylaldehyde content according to claim 1, characterized in that, In high-performance liquid chromatography (HPLC), the sample concentration with a signal-to-noise ratio (SNR) of 3-5 for the salicylaldehyde chromatographic peak is determined as the limit of detection, and the sample concentration with a SNR of 10-15 is determined as the limit of quantitation.

10. The methanol extraction-high performance liquid chromatography method for analyzing salicylaldehyde content according to claim 1, characterized in that, The sample to be tested is one or both of the industrial byproducts ammonium chloride and ammonium sulfate.

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