A kind of detection method of hydrogenated castor oil in detergent

Abstract

The present invention relates to the field of analysis and detection, and discloses a method for detecting hydrogenated castor oil in a detergent. The detection method comprises the following steps: using a mixed solution of ethanol and dichloromethane to perform ultrasonic extraction on a sample to be tested to obtain an extract; performing liquid chromatography detection on the extract, using isopropanol, acetonitrile and ammonium acetate aqueous solution, compounded in a specific ratio at different stages as eluents, and eluting with a specific elution procedure; and performing qualitative and / or quantitative analysis of hydrogenated castor oil in the sample to be tested according to the obtained chromatogram. The present invention can achieve qualitative and quantitative detection of hydrogenated castor oil in a detergent, and can achieve higher detection accuracy.

Description

Technical Field

[0001] The invention relates to the field of analysis and detection, and in particular to a method for detecting hydrogenated castor oil in detergent. Background Art

[0002] In the detergent industry, as consumers' requirements for product performance and sensory experience continue to improve, insoluble additives such as pearlescent agents and microcapsule fragrances have been innovatively introduced into laundry detergents and shampoos to enhance the visual effects and fragrance persistence of the products. However, these insoluble additives will affect the suspension stability of the product. How to ensure that they are evenly distributed in the liquid formula and do not stratify or precipitate for a long time has become the key to formula design.

[0003] Hydrogenated castor oil is a highly efficient suspension stabilizer, the main component of which is trihydroxystearin. At the same time, the industrial raw materials also contain a portion of dihydroxystearin monostearate and trace amounts of triglycerides of fatty acids with different carbon chain lengths. It effectively removes the unsaturated bonds in castor oil through chemical hydrogenation treatment, significantly improving its chemical stability while retaining its original oiliness and lubricity. At the same time, through the hydrogen bonds and interaction forces between molecules, hydrogenated castor oil will form a microscopic network structure inside the detergent. This network structure can not only wrap and fix insoluble particles, effectively resist the influence of gravity and Brownian motion, and maintain the efficient suspension and stability of the formula, but also break in time during the use of the product as it is rubbed and stirred, releasing the wrapped particles, thereby giving full play to its efficacy.

[0004] Although hydrogenated castor oil is increasingly used in detergent products, there is currently a technical gap in the detection of hydrogenated castor oil, and no specific analytical method for detecting its content has been reported, which brings difficulties to product quality control. Summary of the invention

[0005] In order to solve the above technical problem, that is, there is no detection method for hydrogenated castor oil at present, the present invention provides a detection method for hydrogenated castor oil in detergent. The present invention can realize qualitative and quantitative detection of hydrogenated castor oil in detergent and can achieve high detection accuracy.

[0006] The specific technical scheme of the present invention is:

[0007] A method for detecting hydrogenated castor oil in a detergent comprises the following steps:

[0008] S1: using a mixture of ethanol and dichloromethane to perform ultrasonic extraction on the sample to be tested to obtain an extract;

[0009] S2: The extract is subjected to liquid chromatography detection, and the elution procedure is as follows:

[0010] ;

[0011] S3: According to the obtained chromatogram, the hydrogenated castor oil in the sample is qualitatively and / or quantitatively analyzed.

[0012] The elution programs listed in the table above use the conventional expression of elution programs in liquid chromatography, which means:

[0013] The eluent used at the beginning includes the following components by volume percentage: 0% v / v isopropanol, 4-5% v / v ammonium acetate aqueous solution, and the balance is acetonitrile; the eluent formula remains unchanged until 0.1-0.6 min, and then the content of each component gradually changes until it changes to: 25-35% v / v isopropanol, 4-5% v / v ammonium acetate aqueous solution, and the balance is acetonitrile at 0.7-1.2 min; the eluent formula remains unchanged until 2.5-3.5 min, and then the content of each component gradually changes until it changes to 65-85% v / v isopropanol, 4-5% v / v ammonium acetate aqueous solution, and the balance is acetonitrile at 7.5-8.5 min; then the content of each component gradually changes until it changes to 0% v / v isopropanol, 4-5% v / v ammonium acetate aqueous solution, and the balance is acetonitrile at 8.5-9.5 min; the subsequent eluent formula remains unchanged, and the maintenance time is unlimited.

[0014] The present invention is based on liquid chromatography and can achieve effective separation and qualitative and quantitative detection of hydrogenated castor oil in detergents by adopting specific eluents, eluent formulas and elution procedures (qualitative detection is to detect whether the sample to be tested contains hydrogenated castor oil, and quantitative detection is to detect the content of hydrogenated castor oil in the sample to be tested), and has high detection accuracy. Specifically:

[0015] (1) Eluent: The present invention uses a mixture of ethanol and dichloromethane as an extractant, which can better extract hydrogenated castor oil and prevent the polymer in the detergent from forming a coagulation precipitate and enveloping more hydrogenated castor oil, thereby achieving a higher detection accuracy.

[0016] (2) Eluent formula and elution procedure: Hydrogenated castor oil is a triglyceride of long-chain fatty acids, which has a low polarity and a strong interaction force with the stationary phase of the chromatographic column, which makes it difficult to elute it. In addition, there are components in the detergent that have a polarity similar to that of hydrogenated castor oil (such as ethylene glycol distearate substances used as pearlescent agents). The eluent formula and elution procedure will have a great impact on the separation effect between hydrogenated castor oil and these components. When the separation degree of hydrogenated castor oil is low, it will cause peak merging in the chromatogram, affecting the detection accuracy. The present invention uses isopropanol, acetonitrile and ammonium acetate aqueous solution, which are compounded in a specific ratio at different stages as eluents, which can better elute the hydrogenated castor oil adsorbed on the chromatographic column. At the same time, it can also achieve a higher separation degree, so that the hydrogenated castor oil is better separated from other components in the detergent, which helps to improve the detection accuracy.

[0017] Preferably, the hydrogenated castor oil comprises trihydroxystearin.

[0018] Preferably, in step S2, the concentration of the aqueous ammonium acetate solution is 40-80 mM.

[0019] In the eluent, when the concentration of the ammonium acetate aqueous solution is controlled within the range of 40-80 mM, the linearity of the standard curve can be improved and the baseline noise of the chromatogram can be reduced, thereby improving the detection accuracy and making the detection results more reliable and repeatable. When the concentration of the ammonium acetate aqueous solution is lower than 40 mM, the linearity of the standard curve is poor, which will affect the detection accuracy; when the concentration of the ammonium acetate aqueous solution is higher than 80 mM, the baseline noise of the chromatogram is large, which will also have an adverse effect on the detection accuracy.

[0020] Preferably, in step S2, the liquid chromatography is ultra-high performance liquid chromatography (UPLC).

[0021] Preferably, in step S2, during the liquid chromatography detection, the chromatographic column used is Waters BEHC18.

[0022] The use of a Waters BEH C18 column can shorten the retention time of hydrogenated castor oil, thereby shortening the detection time. It can also achieve a higher separation of hydrogenated castor oil and reduce baseline fluctuations, which helps to achieve higher detection accuracy.

[0023] Preferably, in step S2, the liquid chromatography detection specifically includes the process of: adding the extract to the chromatographic column, eluting according to the elution procedure, and performing charged aerosol detection on the eluent to obtain a chromatogram.

[0024] Furthermore, during the charged aerosol detection process, the atomization temperature is 35-60°C, the sampling frequency is 5-10 Hz, and the filtration constant is 4-5s.

[0025] Preferably, in step S2, during the liquid chromatography detection, the column temperature is 30-40°C, the injection volume is 2-3 μL, and the flow rate is 0.1-0.3 mL / min.

[0026] Preferably, in step S1, in the mixed solution of ethanol and dichloromethane, the volume ratio of ethanol to dichloromethane is 1:0.8-1.2.

[0027] Preferably, in step S1, the ultrasonic extraction time is not less than 30 minutes, and the ultrasonic power is 45-55 kHz.

[0028] Preferably, step S1 specifically comprises: adding a mixture of ethanol and dichloromethane to the sample to be tested, vortexing and dispersing, performing ultrasonic extraction, and filtering to obtain an extract.

[0029] Furthermore, during the filtering process, the pore size of the filter membrane used is 0.22-0.45 μm.

[0030] Preferably, in step S3, the process of quantitative analysis is: according to the peak area corresponding to hydrogenated castor oil in the obtained chromatogram, substitute it into the standard curve to calculate the content of hydrogenated castor oil in the sample to be tested.

[0031] Furthermore, the standard curve is obtained by the following method: dissolving hydrogenated castor oil in a mixture of ethanol and dichloromethane to prepare standard working solutions of different concentrations, performing liquid chromatography detection using the same method as in step S2, detecting the peak area corresponding to hydrogenated castor oil in the chromatogram, and establishing a standard curve based on the concentration and peak area.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] (1) The present invention establishes for the first time a liquid chromatography analysis and detection method for hydrogenated castor oil in detergents, which can not only accurately determine whether the detergent contains hydrogenated castor oil, but also accurately determine its content, thus filling the current technical gap in the analysis and detection of hydrogenated castor oil, and helping to promote the research and application development of hydrogenated castor oil, as well as the product quality control of detergents.

[0034] (2) The method of the present invention has a low detection limit for hydrogenated castor oil and high detection sensitivity, which can meet the needs of trace analysis; in addition, the method of the present invention has high accuracy and good repeatability, and can reduce the interference of other components in the detergent and other incompletely hydrogenated components in the hydrogenated castor oil raw material, thereby providing a reliable and precise means for the detection and analysis of hydrogenated castor oil in detergents.

[0035] (3) The present invention can achieve efficient separation and determination of hydrogenated castor oil, and the liquid chromatography analysis time is short (hydrogenated castor oil can be eluted out relatively quickly), which can make the detection of hydrogenated castor oil more efficient and meet the demand for rapid detection; and by optimizing the analysis process and shortening the analysis time, the consumption of eluent and the waste of energy can be reduced, which helps to reduce the negative impact on the environment and reduce the detection cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the chromatogram obtained by detecting the standard working solution in Example 1. Among them: the peak labeled "1" (4.632min) is trihydroxystearin, and the peak labeled "2" (7.108min) is dihydroxystearin monostearate.

[0037] Figure 2 This is the chromatogram obtained by testing the homemade shampoo sample in Example 1. Among them: the peak labeled "1" (4.636min) is trihydroxystearin, and the peak labeled "2" (7.114min) is dihydroxystearin monostearate.

[0038] Figure 3 This is the chromatogram obtained by detecting the standard working solution in Example 9. Among them: the peak labeled "1" (7.589 min) is trihydroxystearin, and the peak labeled "2" (8.889 min) is dihydroxystearin monostearate.

[0039] Figure 4 This is a chromatogram obtained by detecting the standard working solution in Example 10. Among them: the peak labeled "1" (4.543min) is trihydroxystearin, and the peak labeled "2" (6.457min) is dihydroxystearin monostearate.

[0040] Figure 5 This is the chromatogram obtained by detecting the standard working solution in Example 14.

[0041] Figure 6 This is the chromatogram obtained by detecting the standard working solution in Example 15.

[0042] Figure 7 This is the chromatogram obtained by detecting the standard working solution in Example 16.

[0043] Figure 8 This is the chromatogram obtained by testing the homemade shampoo sample in Example 17.

[0044] Fig. 9This is the chromatogram obtained by detecting the standard working solution in Example 18.

[0045] Fig.10 This is the chromatogram obtained by detecting the standard working solution in Example 19. DETAILED DESCRIPTION

[0046] The present invention will be further described below in conjunction with the embodiments.

[0047] A method for detecting hydrogenated castor oil in a detergent comprises the following steps:

[0048] S1: using a mixture of ethanol and dichloromethane to perform ultrasonic extraction on the sample to be tested to obtain an extract;

[0049] S2: The extract is subjected to liquid chromatography detection, and the elution procedure is as follows:

[0050] ;

[0051] S3: According to the obtained chromatogram, the hydrogenated castor oil in the sample is qualitatively and / or quantitatively analyzed.

[0052] In some embodiments, the hydrogenated castor oil includes trihydroxystearin.

[0053] In some specific embodiments, step S1 specifically includes: adding a mixture of ethanol and dichloromethane to the sample to be tested, vortexing and dispersing, performing ultrasonic extraction, and filtering with a filter membrane with a pore size of 0.22-0.45 μm to obtain an extract.

[0054] In some specific embodiments, in step S1, in the mixed solution of ethanol and dichloromethane, the volume ratio of ethanol to dichloromethane is 1:0.8-1.2.

[0055] In some specific embodiments, in step S1, the ultrasonic extraction time is not less than 30 minutes, and the ultrasonic power is 45-55 kHz.

[0056] In some specific embodiments, in step S2, the concentration of the aqueous ammonium acetate solution is 40-80 mM.

[0057] In some specific embodiments, in step S2, the liquid chromatography is ultra-high performance liquid chromatography (UPLC); during the liquid chromatography detection, the chromatographic column used is Waters BEH C18, the column temperature is 30-40°C, the injection volume is 2-3 μL, and the flow rate is 0.1-0.3 mL / min.

[0058] In some specific embodiments, in step S2, the liquid chromatography detection specifically includes the following process: adding the extract to the chromatographic column, eluting according to the elution procedure, and performing electrospray detection on the eluate to obtain a chromatogram; during the electrospray detection process, the atomization temperature is 35~60°C, the sampling frequency is 5~10Hz, and the filtration constant is 4~5s.

[0059] In some specific embodiments, in step S3, the quantitative analysis process is: according to the peak area corresponding to hydrogenated castor oil in the obtained chromatogram, substituting it into the standard curve, and calculating the hydrogenated castor oil content in the sample to be tested; the standard curve is obtained by the following method: hydrogenated castor oil is dissolved in a mixed solution of ethanol and dichloromethane to prepare standard working solutions of different concentrations, and liquid chromatography detection is performed using the same method as in step S2, the peak area corresponding to hydrogenated castor oil in the chromatogram is detected, and a standard curve is established according to the concentration and peak area.

[0060] The present invention is described below by specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, changes and advantages that can be thought of by those skilled in the art are included in the present invention, and the attached claims and any equivalents thereof are the protection scope of the present invention.

[0061] The tables involving elution procedures in the following embodiments and comparative examples all adopt the conventional representation of elution procedures in liquid chromatography.

[0062] The following provides the main instruments and reagents used in each embodiment and comparative example, but the protection scope of the present invention is not limited thereto:

[0063] (1) Main instruments:

[0064] ACQUITY H-Class UPLC ultra-high performance liquid chromatography (Waters, USA); Corona Veo RS charged aerosol detector (Thermo Fisher, USA); Waters BEH C18 (2.1mm×100mm, 1.7μm); Waters HSST3 (2.1×150mm, 1.7μm); Waters BEH RP18 (2.1×150mm, 1.7μm); MS105 electronic balance (Mettler-Toledo); Heidolph Multi Reax vortex mixer (Heidolph, Germany); KQ5200DE ultrasonic cleaner (Kunshan Ultrasonic Instrument Co., Ltd.); PURELAB flex water purifier (ELGA LabWater, UK).

[0065] (2) Main reagents:

[0066] Isopropyl alcohol (chromatographic grade, Fisher), acetonitrile (chromatographic grade, Merck, Germany), ammonium acetate (chromatographic grade, Fisher), dichloromethane (analytical grade, Cologne Chemicals), ethanol (analytical grade, Cologne Chemicals), hydrogenated castor oil (raw material, Thai Oil, Thailand).

[0067] (3) Homemade laundry detergent:

[0068] The recipe for homemade laundry detergent is as follows:

[0069]

[0070] (4) Homemade shampoo:

[0071] Here is the recipe for homemade shampoo:

[0072]

[0073] Examples 1-3 and Comparative Examples 1-2: Effect of Extraction Agent on Detection Effect

[0074] To test your detergent (homemade laundry detergent and homemade shampoo) for hydrogenated castor oil, follow these steps:

[0075] S1: Preparation of standard working solution:

[0076] Accurately weigh 100 mg of hydrogenated castor oil and place it in a 100 mL volumetric flask. Add ethanol-dichloromethane (volume ratio of 1:1) and dilute to the scale to prepare a standard stock solution with a concentration of 1 mg / mL.

[0077] The standard stock solution was diluted stepwise using ethanol-dichloromethane (volume ratio of 1:1) to prepare standard working solutions with concentrations of 200 μg / mL, 160 μg / mL, 80 μg / mL, 40 μg / mL and 20 μg / mL, respectively.

[0078] S2: Drawing of standard curve:

[0079] Five standard working solutions of different concentrations were taken respectively, and analyzed in order from low concentration to high concentration by ultra-high performance liquid chromatography. The chromatographic conditions were as follows: a Waters BEH C18 column was used, the column temperature was 40°C, the injection volume was 2 μL, and the flow rate was 0.3 mL / min; the detector was a CAD charged aerosol detector, the atomization temperature was 35°C, the sampling frequency was 10 Hz, and the filtration constant was 5 s; during the elution process, the mobile phase A was isopropanol, the mobile phase B was acetonitrile, and the mobile phase C was 80 mM ammonium acetate aqueous solution. The gradient elution program was as follows:

[0080]

[0081] A typical chromatogram of hydrogenated castor oil is obtained as shown in Figure 1 According to the qualitative identification of UPLC-Q-TOF / MS, peak 1 (retention time of 4.632 min) was determined to be trihydroxystearin, and peak 2 (retention time of 7.108 min) was determined to be dihydroxystearic acid monostearin.

[0082] According to the peak area measured by the standard working solution of each concentration (the peak area corresponding to trihydroxystearate), the standard curve was drawn with the concentration (c) as the abscissa and the corresponding peak area (A) as the ordinate. The results are as follows:

[0083]

[0084] S3: Extraction of the sample to be tested:

[0085] 1g of homemade laundry detergent and 1g of homemade shampoo were accurately weighed in 25mL stoppered colorimetric tubes as samples to be tested, 10mL of extractant was added to each, and vortexed for 2min; then the volume was adjusted to the scale, and fully extracted by 45kHz ultrasound at room temperature for 30min, and the obtained extract was filtered through a 0.22μm microporous filter membrane to obtain a test solution for standby use. In the above process, the extractants used in Examples 1 to 3 and Comparative Examples 1 to 2 are as follows:

[0086]

[0087] S4: Testing of samples to be tested:

[0088] The method in step S2 is used to perform ultra-high performance liquid chromatography analysis on the test solution prepared in step S3. The chromatogram obtained by measuring the homemade shampoo sample in Example 1 is shown in FIG. Figure 2 , peak 1 (retention time is 4.636min) is trihydroxystearin, and peak 2 (retention time is 7.114min) is dihydroxystearin monostearate. According to the peak area corresponding to trihydroxystearin in the chromatogram, it is substituted into the standard curve and the hydrogenated castor oil content in the sample to be tested is obtained after calculation. The test results of Examples 1 to 3 and Comparative Examples 1 to 2 are as follows:

[0089]

[0090] Results analysis and conclusion:

[0091] (1) Comparative Example 1 uses ethanol as the extractant. During the extraction process, it was observed that the laundry detergent sample was well dispersed, and the shampoo sample had flocculent precipitation, which was presumably due to the precipitation of high molecular weight. The test results of hydrogenated castor oil content were significantly lower than the theoretical value (especially in the homemade laundry detergent), which was presumably due to the incomplete extraction of ester components by ethanol.

[0092] (2) Comparative Example 2 used ethanol-dichloromethane (1:1) as the extractant. During the extraction process, it was observed that the laundry detergent sample had agglomerated precipitation, and the shampoo sample had flocculent coagulation precipitation, which was presumed to be the precipitation of polymers. The test results of the hydrogenated castor oil content in the homemade laundry detergent and homemade shampoo were significantly lower than the theoretical value, which was presumed to be because the coagulation precipitation would wrap the hydrogenated castor oil.

[0093] (3) Examples 1 to 3 use ethanol-dichloromethane (volume ratio of 1:0.8 to 1.2) as the extractant. During the extraction process, a small amount of precipitation was observed in the laundry detergent sample, which was presumed to be the precipitation of inorganic salts; and a flocculent dispersed precipitate appeared in the shampoo sample, which was presumed to be the precipitation of polymers. The test results of the hydrogenated castor oil content in the homemade laundry detergent and homemade shampoo were close to the theoretical value, indicating that the use of the extractant can better extract hydrogenated castor oil and avoid the formation of condensed precipitation to wrap more hydrogenated castor oil, thereby achieving a higher detection accuracy.

[0094] Examples 4-5: Effect of extraction temperature on detection results

[0095] In Examples 4-5, the content of hydrogenated castor oil in detergents (homemade laundry detergent and homemade shampoo) was detected according to the steps of Example 1, and the only difference from Example 1 was that the temperature during the ultrasonic extraction process was changed. The ultrasonic extraction temperatures of Examples 1 and Examples 4-5 were as follows:

[0096]

[0097] In Examples 1 and 4-5, the test results of the content of hydrogenated castor oil in homemade laundry detergent and homemade shampoo are as follows:

[0098]

[0099] Results analysis and conclusion:

[0100] According to the test results of Example 1 and Examples 4-5, it can be seen that the warm administration of ultrasonic extraction has no significant effect on the detection accuracy of the hydrogenated castor oil content.

[0101] Examples 6-8: Effect of extraction time on detection effect

[0102] In Examples 6 to 8, the content of hydrogenated castor oil in detergents (homemade laundry detergent and homemade shampoo) was detected according to the steps of Example 1, and the only difference from Example 1 was that the ultrasonic extraction time was changed. The ultrasonic extraction time of Examples 1 and Examples 6 to 8 was as follows:

[0103]

[0104] In Examples 1 and 6-8, the test results of the content of hydrogenated castor oil in homemade laundry detergent and homemade shampoo are as follows:

[0105]

[0106] Results analysis and conclusion:

[0107] According to the test results of Example 1 and Examples 6-8, it can be seen that when the ultrasonic extraction time is 10 min, the extraction of hydrogenated castor oil is not thorough, and thus the test result is low; when the ultrasonic extraction time is 30 min or more, the hydrogenated castor oil in the detergent sample is completely extracted, and the test result is close to the theoretical value, and further extending the ultrasonic extraction time has no significant effect on the extraction effect of hydrogenated castor oil.

[0108] Examples 9-10: Effect of chromatographic column on detection results

[0109] In Examples 9-10, the preparation of the standard working solution and the ultra-high performance liquid chromatography analysis were performed according to steps S1 and S2 of Example 1, and the only difference from Example 1 was that the selection of the chromatographic column was changed. The chromatographic columns used in Examples 1 and Examples 9-10 were as follows:

[0110]

[0111] In Example 9, when the 200 μg / mL standard working solution was subjected to ultra-high performance liquid chromatography, the chromatogram obtained was shown in Figure 3 Peak 1 (retention time 7.589min) is trihydroxystearin, and peak 2 (retention time 8.889min) is dihydroxystearin monostearate. Figure 1 and Figure 3, it can be seen that: when performing ultra-high performance liquid chromatography analysis, when using Waters HSS T3, the retention time of hydrogenated castor oil is shifted back and the baseline fluctuates greatly compared to using Waters BEH C18 as the chromatographic column. Waters BEH C18 and Waters HSS T3 are both reverse-phase bonded chromatographic columns, and HSS T3 has stronger retention. This may be because the latter has a longer chromatographic column specification and the pore size of the stationary phase particles is 100Å, while the former has a slightly shorter chromatographic column specification and the pore size of the stationary phase particles is 130Å - the shorter the chromatographic column, the larger the pore size, and the shorter the retention time.

[0112] In Example 10, when the 200 μg / mL standard working solution was subjected to ultra-high performance liquid chromatography, the chromatogram obtained was shown in Figure 4 Peak 1 (retention time 4.543min) is trihydroxystearin, and peak 2 (retention time 6.457min) is dihydroxystearin monostearate. Figure 1 and Figure 4 It can be seen that when using Waters BEH RP18 as a chromatographic column, the retention time of hydrogenated castor oil is shifted forward when using Waters BEH C18, and the separation of hydrogenated castor oil is poor, and there is a phenomenon of peak merging. Although the chromatographic column of Waters BEH RP18 is longer than that of Waters BEH C18, the retention time of hydrogenated castor oil is shorter under the same elution procedure. This may be due to the polar carbamate functional group embedded in the stationary phase of Waters BEH RP18, which reduces the molecular interaction with hydrogenated castor oil.

[0113] Examples 11-13: Effect of mobile phase C concentration on detection results

[0114] In Examples 11 to 13, the standard working solution was prepared and the standard curve was drawn according to steps S1 and S2 of Example 1, and the only difference from Example 1 was that the concentration of the mobile phase C (ammonium acetate aqueous solution) was changed. The concentrations of the mobile phase C (ammonium acetate aqueous solution) in Examples 1 and Examples 11 to 13 were as follows:

[0115]

[0116] In Example 1 and Examples 11 to 13, the baseline noise in the chromatogram obtained with the 200 μg / mL standard working solution and the correlation coefficient r measured when drawing the standard curve are as follows:

[0117]

[0118] Results analysis and conclusion:

[0119] (1) Example 11 Based on Example 1, the concentration of the ammonium acetate aqueous solution was adjusted from 80 mM to 0 mM. Compared with Example 1, this concentration adjustment improved the baseline noise of the spectrum and made the background signal clearer. However, the linearity of the hydrogenated castor oil standard curve deteriorated, and the correlation coefficient r was only 0.99722, which would have an adverse effect on the detection accuracy.

[0120] (2) Example 13 is based on Example 1, but the concentration of the aqueous ammonium acetate solution is adjusted from 80 mM to 100 mM. Compared with Example 1, this concentration adjustment causes a larger baseline noise in the chromatogram, which affects the reliability and repeatability of the detection results.

[0121] Examples 14-15: Effect of mobile phase A on detection results

[0122] In Example 14, the preparation of the standard working solution and the ultra-high performance liquid chromatography analysis were carried out according to steps S1 and S2 of Example 1, and the only difference from Example 1 was that the mobile phase A was not used. The gradient elution procedure of Example 14 was as follows:

[0123]

[0124] In Example 14, when the 200 μg / mL standard working solution was subjected to ultra-high performance liquid chromatography, the chromatogram obtained was shown in Figure 5 , the target component of hydrogenated castor oil did not elute. This is because hydrogenated castor oil is a triglyceride of long-chain fatty acids, which has a relatively small polarity and a strong interaction with the stationary phase of the reversed-phase chromatography column, while the mobile phase used in Example 14 has insufficient elution capacity to elute the target substance.

[0125] In Example 15, the preparation of the standard working solution and the ultra-high performance liquid chromatography analysis were carried out according to steps S1 and S2 of Example 1, and the only difference from Example 1 was that the mobile phase A was replaced with methanol. The gradient elution procedure of Example 15 was as follows:

[0126]

[0127] In Example 15, when the 200 μg / mL standard working solution was subjected to ultra-high performance liquid chromatography, the chromatogram obtained was shown in Figure 6 , the target component of hydrogenated castor oil did not elute, and the baseline fluctuated greatly. This is because hydrogenated castor oil is a triglyceride of long-chain fatty acids, which has a low polarity and a strong interaction with the stationary phase of the reversed-phase chromatography column, while the mobile phase used in Example 15 has insufficient elution capacity to elute the target substance.

[0128] Examples 16-19: Effect of elution procedure on detection results

[0129] In Examples 16 to 19, the content of hydrogenated castor oil in detergents (homemade laundry detergent and homemade shampoo) was detected according to the steps of Example 1, and the only difference from Example 1 was that the gradient elution procedure was changed. The gradient elution procedure of Examples 16 to 19 was as follows:

[0130]

[0131] In Example 16, when the 200 μg / mL standard working solution was subjected to ultra-high performance liquid chromatography, the chromatogram obtained was shown in Figure 7 Compared with Example 1, the retention time of hydrogenated castor oil in Example 16 was shifted back, the overall analysis time was prolonged, and the peak of hydrogenated castor oil was wider. This is because although the initial (0-0.5 min) ratio of the mobile phase did not change, the ratio of isopropanol in the subsequent mobile phase was low, and its elution ability was weakened to a certain extent.

[0132] In Example 17, when the homemade shampoo sample was subjected to ultra-high performance liquid chromatography analysis, the chromatogram obtained was shown in Figure 8 Compared with Example 1, the separation degree between the hydrogenated castor oil chromatographic peak and the interfering substances in the laundry detergent in Example 17 is poor, which affects the detection accuracy of hydrogenated castor oil. The interfering substances are presumed to be pearlescent agents (ethylene glycol distearate substances), which have a polarity close to that of hydrogenated castor oil. When the acetonitrile content in the second stage (1.0-3.0 min) of the eluent is increased and the elution capacity is enhanced, the separation effect of substances with similar polarity will be affected.

[0133] In Example 18, when the 200 μg / mL standard working solution was subjected to ultra-high performance liquid chromatography, the chromatogram obtained was shown in Fig. 9 Compared with Example 1, in Example 18, the retention time of trihydroxystearin remained basically unchanged, the retention time of dihydrogenated ricinoleyl monostearate shifted back, and the overall analysis time was prolonged.

[0134] In Example 19, when the 200 μg / mL standard working solution was subjected to ultra-high performance liquid chromatography, the chromatogram obtained was shown in Fig.10 Compared with Example 1, in Example 19, although the overall analysis time is shortened, the system pressure is relatively high, which is not conducive to the long-term operation of the instrument and will affect the durability of the chromatographic column. This is because the viscosity of isopropanol is relatively high, and when its proportion is increased, the viscosity of the mobile phase will increase, thereby increasing the operating pressure of the liquid phase system.

[0135] Example 20: Method repeatability and recovery rate investigation

[0136] The repeatability of the method was investigated by the following method: 6 samples of homemade laundry detergent and homemade shampoo were taken, and the hydrogenated castor oil content was tested according to the method in Example 1. The results were as follows:

[0137]

[0138] The above results show that the method for detecting the content of hydrogenated castor oil of the present invention has good repeatability.

[0139] The recovery rate of the method was investigated by the following method: According to the method in Example 1, the standard working solution was added to the homemade laundry detergent sample and the homemade shampoo sample, and the spiked recovery was determined. The spiked levels were divided into three levels: low (20 mg / L), medium (80 mg / L), and high (200 mg / L). Each spiked level was measured 6 times. The recovery test results are as follows:

[0140]

[0141] The above results show that the method for detecting the content of hydrogenated castor oil of the present invention can meet the requirement of spiked recovery rate.

[0142] Example 21: Actual sample testing

[0143] The method in Example 1 was used to test the content of hydrogenated castor oil in 5 actual detergent samples. The results were as follows:

[0144]

[0145] When testing actual detergent samples, the chromatographic peak of hydrogenated castor oil was not interfered by impurity peaks and had good parallelism.

[0146] Unless otherwise defined, all technical terms and scientific terms used in the present invention have the same meanings as those commonly understood by ordinary technicians in the field to which the present disclosure belongs. Unless otherwise specified, the raw materials and equipment used in the present invention are conventional raw materials and equipment in the field and can be obtained from conventional commercial channels; unless otherwise specified, the methods used in the present invention are conventional methods in the field.

[0147] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for detecting hydrogenated castor oil in a detergent, characterized in that: The following steps are involved: S1: using a mixture of ethanol and dichloromethane to perform ultrasonic extraction on the sample to be tested to obtain an extract; S2: The extract is subjected to liquid chromatography detection, and the elution procedure is as follows: ； S3: According to the obtained chromatogram, the hydrogenated castor oil in the sample is qualitatively and / or quantitatively analyzed.

2. The detection method according to claim 1, characterized in that: The hydrogenated castor oil includes trihydroxystearin.

3. The detection method according to claim 1, characterized in that: In step S2, the concentration of the ammonium acetate aqueous solution is 40-80 mM.

4. The detection method according to claim 1, characterized in that: In step S2, during the liquid chromatography detection, the chromatographic column used is Waters BEH C18.

5. The detection method according to claim 1, characterized in that: In step S2, the liquid chromatography detection specifically includes the following processes: adding the extract to the chromatographic column, eluting according to the elution procedure, and performing charged aerosol detection on the eluent to obtain a chromatogram.

6. The detection method according to claim 1, characterized in that: In step S2, during the liquid chromatography detection, the column temperature is 30-40°C, the injection volume is 2-3 μL, and the flow rate is 0.1-0.3 mL / min.

7. The detection method according to claim 1, characterized in that: In step S1, in the mixed solution of ethanol and dichloromethane, the volume ratio of ethanol to dichloromethane is 1:0.8-1.

2.

8. The detection method according to claim 1, characterized in that: Step S1 specifically includes: adding a mixture of ethanol and dichloromethane to the sample to be tested, vortexing and dispersing, performing ultrasonic extraction, and filtering to obtain an extract.

9. The detection method according to claim 1, characterized in that: In step S3, the process of the quantitative analysis is: according to the peak area corresponding to hydrogenated castor oil in the obtained chromatogram, it is substituted into the standard curve to calculate the content of hydrogenated castor oil in the sample to be tested.

10. The detection method according to claim 9, characterized in that: The standard curve is obtained by the following method: dissolving hydrogenated castor oil in a mixture of ethanol and dichloromethane to prepare standard working solutions of different concentrations, performing liquid chromatography detection in the same manner as in step S2, detecting the peak area corresponding to hydrogenated castor oil in the chromatogram, and establishing a standard curve according to the concentration and the peak area.

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