Pretreatment method of toothpaste and method for detecting content of coloring agent in toothpaste

Abstract

The invention belongs to the technical field of chemical detection and analysis, and particularly relates to a toothpaste pretreatment method and a method for detecting the content of a coloring agent in toothpaste. The toothpaste pretreatment method provided by the invention comprises the following steps: mixing toothpaste to be detected, sea sand and an extracting agent, and performing ultrasonic extraction to obtain an extracting solution; the extracting agent is a mixed solution of methanol, tetrahydrofuran and dimethyl sulfoxide, the volume percentage content of the methanol in the extracting agent is 90-96%, the volume percentage content of the tetrahydrofuran in the extracting agent is 2-5%, and the volume percentage content of the dimethyl sulfoxide in the extracting agent is 2-5%; and filtering the extracting solution through a polytetrafluoroethylene filter membrane to obtain a to-be-detected solution. According to the method, the mixed solution of the methanol, the tetrahydrofuran and the dimethyl sulfoxide with specific volume percentage content is used as the extracting agent, so that the acid yellow 73, the pigment red 4 and the pigment red 49 in the toothpaste can be efficiently extracted, and the pretreatment method is simple and relatively high in separation efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical detection and analysis, and specifically relates to a toothpaste pretreatment method and a method for detecting the colorant content in toothpaste. Background Art

[0002] Toothpaste can present various colors because of the use of colorants; among these colorants, the vast majority are synthetic colorants. Synthetic colorants have strong coloring ability, good stability, and low price. They have been widely used in cosmetics and food. However, some synthetic colorants may cause allergic reactions if used excessively, and even affect liver and kidney function, produce toxicity and carcinogenicity, etc., so they need to be regulated. However, there is currently no detection method for the content of colorants (acid yellow 73, pigment red 4, pigment red 49) in toothpaste. Summary of the invention

[0003] In view of this, the present invention provides a toothpaste pretreatment method and a method for detecting the colorant content in toothpaste. The pretreatment method of the present invention can efficiently separate the colorant in the toothpaste to be tested, thereby improving the accuracy and precision of the colorant content in the toothpaste to be tested.

[0004] In order to solve the above technical problems, the present invention provides a toothpaste pretreatment method, comprising the following steps:

[0005] The toothpaste to be tested, sea sand and an extractant are mixed and then ultrasonically extracted to obtain an extract; the extractant is a mixed solution of methanol, tetrahydrofuran and dimethyl sulfoxide, the volume percentage of methanol in the extractant is 90-96%, the volume percentage of tetrahydrofuran in the extractant is 2-5%, and the volume percentage of dimethyl sulfoxide in the extractant is 2-5%;

[0006] The extract is filtered through a polytetrafluoroethylene filter membrane to obtain a test solution.

[0007] Preferably, the mixing comprises the following steps:

[0008] The toothpaste is dispersed by using sea sand and then first mixed with an extractant;

[0009] The mass ratio of the toothpaste to the sea sand is 1:0.5-3;

[0010] The dispersion method includes vortexing, oscillation, shaking or ultrasound.

[0011] Preferably, the ultrasonic power of the ultrasonic extraction is 480-520 W, the ultrasonic frequency is 52-54 kHz, and the ultrasonic extraction time is 15-25 min.

[0012] Preferably, after the ultrasonic extraction, the method further comprises: centrifuging the system after the ultrasonic extraction, taking the supernatant, and obtaining the extract.

[0013] Preferably, the centrifugal speed is 3000-5000 r / min, and the centrifugal time is 8-12 min.

[0014] Preferably, the pore size of the polytetrafluoroethylene filter membrane is 0.22-0.45 μm.

[0015] The present invention also provides a method for detecting the colorant content in toothpaste, comprising the following steps:

[0016] The mixed standard solution of Acid Yellow 73, Pigment Red 4 and Pigment Red 49 is subjected to high performance liquid chromatography to obtain a standard high performance liquid chromatography spectrum;

[0017] According to the standard high performance liquid chromatography spectrum, standard working curves of acid yellow 73, pigment red 4 and pigment red 49 are respectively obtained; the abscissa of the standard working curve is the mass concentration of acid yellow 73, pigment red 4 or pigment red 49, and the ordinate of the standard working curve is the peak area of ​​acid yellow 73, pigment red 4 or pigment red 49 in the standard high performance liquid chromatography spectrum;

[0018] The liquid to be tested is subjected to high performance liquid chromatography to obtain a high performance liquid chromatography spectrum; the liquid to be tested is the liquid to be tested obtained after being treated according to the pretreatment method described in the above technical solution;

[0019] The peak areas of different colorants in the high performance liquid chromatography spectrum to be tested are respectively substituted into the corresponding standard working curve to obtain the contents of different colorants in the toothpaste.

[0020] Preferably, the conditions for the high performance liquid chromatography detection include: the chromatographic column filler is octadecyl bonded silica gel, the chromatographic column filler particle size is 1.7 to 5 μm, the chromatographic column size is 4.6×250 mm or 2.1×100 mm, the flow rate is 0.8 to 1.2 mL / min, the column temperature is 30 to 50°C, the detection wavelength is 300 to 600 nm, and the injection volume is 1 to 50 μL.

[0021] Preferably, in the HPLC detection process, an ammonium acetate solution with a molar concentration of 20 mmol / L is used as mobile phase A, and acetonitrile is used as mobile phase B;

[0022] The elution method of the high performance liquid chromatography detection is gradient elution;

[0023] The elution conditions of the gradient elution are:

[0024] 0-1min, 20% mobile phase B;

[0025] 1-2 min, 50% mobile phase B;

[0026] 2-10 min, 80% mobile phase B;

[0027] 10-14 min, 95% mobile phase B;

[0028] 14-16.1 min, 20% mobile phase B;

[0029] 16.1~20min, 20% mobile phase B.

[0030] Preferably, the mass concentration of Acid Yellow 73 in the mixed standard solution is 5 μg / mL, 10 μg / mL, 20 μg / mL, 50 μg / mL, 100 μg / mL;

[0031] The mass concentration of Pigment Red 4 in the mixed standard solution is 10 μg / mL, 20 μg / mL, 40 μg / mL, 100 μg / mL, and 200 μg / mL;

[0032] The mass concentrations of Pigment Red 49 in the mixed standard solution are 20 μg / mL, 40 μg / mL, 80 μg / mL, 200 μg / mL, and 400 μg / mL.

[0033] The present invention provides a toothpaste pretreatment method, comprising the following steps: mixing the toothpaste to be tested, sea sand and an extractant, and then ultrasonically extracting to obtain an extract; the extractant is a mixed solution of methanol, tetrahydrofuran and dimethyl sulfoxide, the volume percentage of methanol in the extractant is 90-96%, the volume percentage of tetrahydrofuran in the extractant is 2-5%, and the volume percentage of dimethyl sulfoxide in the extractant is 2-5%; filtering the extractant through a polytetrafluoroethylene filter membrane to obtain a test solution. The present invention uses a mixed solution of methanol, tetrahydrofuran and dimethyl sulfoxide with a specific volume percentage as an extractant to efficiently extract acid yellow 73, pigment red 4 and pigment red 49 in the toothpaste to be tested, and will not have an adverse effect on high performance liquid chromatography detection, thereby improving the accuracy and precision of the detection of acid yellow 73, pigment red 4 and pigment red 49 in toothpaste. The pretreatment method provided by the present invention is simple and has a high separation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is the HPLC spectrum of the fifth mixed standard solution in Example 1;

[0035] Figure 2 is the absorption intensity spectrum of the fifth mixed standard solution in Example 1 within the wavelength range of 300 to 600 nm;

[0036] Figure 3It is a bar chart comparing the extraction rates of different colorants under different ultrasonic extraction times;

[0037] Figure 4 It is a bar chart comparing the extraction rates of different colorants under different sea sand addition amounts;

[0038] Figure 5 It is a bar chart comparing the extraction rates of different colorants in the test solution obtained by filtering through different filter membranes. DETAILED DESCRIPTION

[0039] The present invention provides a toothpaste pretreatment method, comprising the following steps:

[0040] The toothpaste to be tested, sea sand and an extractant are mixed and then ultrasonically extracted to obtain an extract; the extractant is a mixed solution of methanol, tetrahydrofuran and dimethyl sulfoxide, the volume percentage of methanol in the extractant is 90-96%, the volume percentage of tetrahydrofuran in the extractant is 2-5%, and the volume percentage of dimethyl sulfoxide in the extractant is 2-5%;

[0041] The extract is filtered through a polytetrafluoroethylene filter membrane to obtain a test solution.

[0042] In the present invention, unless otherwise specified, all materials are conventional commercially available products.

[0043] The present invention mixes the toothpaste to be tested, sea sand and an extractant and then performs ultrasonic extraction to obtain an extract. As a specific embodiment of the present invention, the mixing may include the following steps:

[0044] The toothpaste to be tested is dispersed with sea sand and then first mixed with the extractant.

[0045] As a specific embodiment of the present invention, the mass ratio of the toothpaste to the sea sand can be 1:0.5-3, specifically 1:0.5, 1:1 or 1:3; the dispersion method can include vortexing, oscillation, shaking or ultrasound; the vortexing time can be 0.8-1.2 minutes, specifically 1 minute. The present invention has no special requirements for the oscillation, shaking and ultrasound, as long as they can be evenly dispersed.

[0046] As a specific embodiment of the present invention, the extractant is a mixed solution of methanol (CH3OH), tetrahydrofuran (THF) and dimethyl sulfoxide (DMSO), the volume percentage of methanol in the extractant is 90-96%, which can be specifically 90%, 92%, 94%, 95% or 96%; the volume percentage of tetrahydrofuran in the extractant is 2-5%, which can be specifically 2%, 3%, 4% or 5%; the volume percentage of dimethyl sulfoxide in the extractant is 2-5%, which can be specifically 2%, 3%, 4% or 5%.

[0047] As a specific embodiment of the present invention, the ultrasonic power of the ultrasonic extraction can be 480-520W, specifically 480W, 500W or 520W; the frequency of the ultrasound in the ultrasonic extraction can be 52-54kHZ, specifically 52kHZ, 53kHZ or 54kHZ; the time of the ultrasonic extraction can be 15-25min, specifically 15min, 20min or 25min.

[0048] As a specific embodiment of the present invention, the ultrasonic extraction may further include: centrifuging the system after ultrasonic extraction, taking the supernatant, and obtaining the extract; the centrifugal speed may be 3000-5000 r / min, specifically 3000 r / min, 3500 r / min, 4000 r / min, 4500 r / min or 5000 r / min; the centrifugal time may be 8-12 min, specifically 10 min.

[0049] After obtaining the extract, the present invention filters the extract through a polytetrafluoroethylene filter membrane to obtain a test solution. As a specific embodiment of the present invention, the pore size of the polytetrafluoroethylene filter membrane can be 0.22 to 0.45 μm, specifically 0.22 μm or 0.45 μm.

[0050] The present invention also provides a method for detecting the colorant content in toothpaste, comprising the following steps:

[0051] The mixed standard solution of Acid Yellow 73, Pigment Red 4 and Pigment Red 49 is subjected to high performance liquid chromatography to obtain a standard high performance liquid chromatography spectrum;

[0052] According to the standard high performance liquid chromatography spectrum, standard working curves of acid yellow 73, pigment red 4 and pigment red 49 are respectively obtained; the abscissa of the standard working curve is the mass concentration of acid yellow 73, pigment red 4 or pigment red 49, and the ordinate of the standard working curve is the peak area of ​​acid yellow 73, pigment red 4 or pigment red 49 in the standard high performance liquid chromatography spectrum;

[0053] The liquid to be tested is subjected to high performance liquid chromatography to obtain a high performance liquid chromatography spectrum; the liquid to be tested is the liquid to be tested obtained after being treated according to the pretreatment method described in the above technical solution;

[0054] The peak areas of different colorants in the high performance liquid chromatography spectrum to be tested are respectively substituted into the corresponding standard working curve to obtain the contents of different colorants in the toothpaste.

[0055] The present invention performs high performance liquid chromatography detection on a mixed standard solution of Acid Yellow 73, Pigment Red 4 and Pigment Red 49 to obtain a standard high performance liquid chromatography spectrum. As a specific embodiment of the present invention, the preparation method of the mixed standard solution may include the following steps:

[0056] Dissolve the standard sample of Acid Yellow 73 in methanol to obtain a standard sample solution of Acid Yellow 73 with a mass concentration of 1 mg / mL;

[0057] The standard sample of Pigment Red 4 was dissolved in tetrahydrofuran to obtain a standard sample solution of Pigment Red 4 with a mass concentration of 1 mg / mL;

[0058] Dissolve a standard sample of Pigment Red 49 in dimethyl sulfoxide to obtain a standard sample solution of Pigment Red 49 with a mass concentration of 1 mg / mL;

[0059] The standard sample solution of Acid Yellow 73, the standard sample solution of Pigment Red 4 and the standard sample solution of Pigment Red 49 are mixed and fixed to volume to obtain the mixed standard solution.

[0060] As a specific embodiment of the present invention, the volume-fixing solvent may be an extractant. As a specific embodiment of the present invention, the mass concentration of Acid Yellow 73 in the mixed standard solution may be 5 μg / mL, 10 μg / mL, 20 μg / mL, 50 μg / mL, 100 μg / mL; the mass concentration of Pigment Red 4 in the mixed standard solution may be 10 μg / mL, 20 μg / mL, 40 μg / mL, 100 μg / mL, 200 μg / mL; the mass concentration of Pigment Red 49 in the mixed standard solution may be 20 μg / mL, 40 μg / mL, 80 μg / mL, 200 μg / mL, 400 μg / mL. As a specific embodiment of the present invention, the mixed standard solution may include a first mixed standard solution, a second mixed standard solution, a third mixed standard solution, a fourth mixed standard solution and a fifth mixed standard solution; the mass concentration of Acid Yellow 73 in the first mixed standard solution is 5 μg / mL, the mass concentration of Pigment Red 4 is 10 μg / mL, and the mass concentration of Pigment Red 49 is 20 μg / mL; the mass concentration of Acid Yellow 73 in the second mixed standard solution is 10 μg / mL, the mass concentration of Pigment Red 4 is 20 μg / mL, and the mass concentration of Pigment Red 49 is 40 μg / mL; The mass concentration of acid yellow 73 in the third mixed standard solution is 20 μg / mL, the mass concentration of pigment red 4 is 40 μg / mL, and the mass concentration of pigment red 49 is 80 μg / mL; the mass concentration of acid yellow 73 in the fourth mixed standard solution is 50 μg / mL, the mass concentration of pigment red 4 is 100 μg / mL, and the mass concentration of pigment red 49 is 200 μg / mL; the mass concentration of acid yellow 73 in the fifth mixed standard solution is 100 μg / mL, the mass concentration of pigment red 4 is 200 μg / mL, and the mass concentration of pigment red 49 is 400 μg / mL. In the present invention, the mixed standard solution needs to be prepared on demand.

[0061] As a specific embodiment of the present invention, the conditions for the high performance liquid chromatography detection may include: the chromatographic column filler is octadecyl bonded silica gel, the chromatographic column filler particle size is 1.7-5 μm, the chromatographic column size is 4.6×250mm or 2.1×100mm, the flow rate is 0.8-1.2mL / min, the column temperature is 30-50°C, the detection wavelength is 300-600nm, and the injection volume is 1-50μL; the chromatographic column filler can also be octadecyl bonded silica gel, the chromatographic column filler particle size is 5μm, the chromatographic column size is 4.6×250mm, the flow rate is 1.0mL / min, the column temperature is 30°C, the detection wavelength is 300-600nm, and the injection volume is 10-40μL. As a specific embodiment of the present invention, the detection wavelength of the acid yellow 73 is 493nm, the detection wavelength of the pigment red 4 is 484nm, and the detection wavelength of the pigment red 49 is 493nm.

[0062] As a specific embodiment of the present invention, in the high performance liquid chromatography detection process, an ammonium acetate solution with a molar concentration of 20 mmol / L can be used as mobile phase A, and acetonitrile can be used as mobile phase B; the elution mode of the high performance liquid chromatography detection is gradient elution; the elution conditions of the gradient elution are: 0-1 min, 20% mobile phase B; 1-2 min, 50% mobile phase B; 2-10 min, 80% mobile phase B; 10-14 min, 95% mobile phase B; 14-16.1 min, 20% mobile phase B; 16.1-20 min, 20% mobile phase B.

[0063] After obtaining the standard high performance liquid chromatography spectrum, the present invention obtains the standard working curves of acid yellow 73, pigment red 4 and pigment red 49 according to the standard high performance liquid chromatography spectrum; the abscissa of the standard working curve is the mass concentration of acid yellow 73, pigment red 4 or pigment red 49, and the ordinate of the standard working curve is the peak area of ​​acid yellow 73, pigment red 4 or pigment red 49 in the standard high performance liquid chromatography spectrum. In the present invention, the standard working curve of acid yellow 73 is y=1.22×10 5 x+1.02×10 5 The standard working curve of Pigment Red 4 is y=1.74×10 4 x+3.75×10 4 The standard working curve of Pigment Red 49 is y=1.4×10 4 x+2.67×10 4 .

[0064] The present invention performs high performance liquid chromatography on the liquid to be tested to obtain a high performance liquid chromatography spectrum; the liquid to be tested is the liquid to be tested obtained after being treated according to the pretreatment method described in the above technical scheme. As a specific embodiment of the present invention, the conditions for performing high performance liquid chromatography on the liquid to be tested can be consistent with the conditions for performing high performance liquid chromatography on the mixed standard solution, and will not be repeated here.

[0065] After obtaining the standard working curve and the high performance liquid chromatography spectrum to be tested, the present invention substitutes the peak areas of different colorants in the high performance liquid chromatography spectrum to be tested into the corresponding standard working curve to obtain the content of different colorants in the toothpaste. As a specific embodiment of the present invention, the colorant includes acid yellow 73, pigment red 4 and pigment red 49. In the present invention, if the detection concentration exceeds the linear range, the extract can be diluted by a corresponding multiple and then measured on the machine.

[0066] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0067] Example 1

[0068] Mix 90 mL of methanol, 5 mL of dimethyl sulfoxide and 5 mL of tetrahydrofuran to obtain an extractant;

[0069] 1) Get the standard working curve:

[0070] The standard sample of Acid Yellow 73 was dissolved in methanol to obtain a standard sample solution of Acid Yellow 73 with a mass concentration of 1 mg / mL; the standard sample of Pigment Red 4 was dissolved in tetrahydrofuran to obtain a standard sample solution of Pigment Red 4 with a mass concentration of 1 mg / mL; the standard sample of Pigment Red 49 was dissolved in dimethyl sulfoxide to obtain a standard sample solution of Pigment Red 49 with a mass concentration of 1 mg / mL; the standard sample solution of Acid Yellow 73, the standard sample solution of Pigment Red 4 and the standard sample solution of Pigment Red 49 were stored in a refrigerator at -20°C respectively;

[0071] 1 mL of the standard sample solution of Acid Yellow 73, 2 mL of the standard sample solution of Pigment Red 4 and 4 mL of the standard sample solution of Pigment Red 49 were placed in a 10 mL volumetric flask, fixed to volume with an extractant and shaken to obtain a fifth mixed standard solution with a mass concentration of 100 μg / mL for Acid Yellow 73, 200 μg / mL for Pigment Red 4 and 400 μg / mL for Pigment Red 49; the fifth mixed standard solution was diluted 2 times with an extractant to obtain a fourth mixed standard solution with a mass concentration of 50 μg / mL for Acid Yellow 73, 100 μg / mL for Pigment Red 4 and 2 ... The third mixed standard solution with the mass concentration of Acid Yellow 73 of 20 μg / mL, the mass concentration of Pigment Red 4 of 40 μg / mL, and the mass concentration of Pigment Red 49 of 80 μg / mL was obtained by diluting the fifth mixed standard solution 10 times with the extractant to obtain the second mixed standard solution with the mass concentration of Acid Yellow 73 of 20 μg / mL, the mass concentration of Pigment Red 4 of 40 μg / mL, and the mass concentration of Pigment Red 49 of 80 μg / mL; the first mixed standard solution with the mass concentration of Acid Yellow 73 of 5 μg / mL, the mass concentration of Pigment Red 4 of 10 μg / mL, and the mass concentration of Pigment Red 49 of 20 μg / mL was obtained by diluting the fifth mixed standard solution 20 times with the extractant;

[0072] The first mixed standard solution, the second mixed standard solution, the third mixed standard solution, the fourth mixed standard solution and the fifth mixed standard solution were respectively subjected to high performance liquid chromatography detection to obtain standard high performance liquid chromatography spectra; the conditions for high performance liquid chromatography detection were as follows: the chromatographic column filler was octadecyl bonded silica gel with a particle size of 5 μm, the chromatographic column size was 4.6×250 mm, the flow rate was 1.0 mL / min, the column temperature was 30°C, the injection volume was 10 μL, the detection wavelength of Acid Yellow 73 was 493 nm, the detection wavelength of Pigment Red 4 was 484 nm, and the detection wavelength of Pigment Red 49 was The measuring wavelength is 493 nm; the high performance liquid chromatography detection uses an ammonium acetate solution with a molar concentration of 20 mmol / L as the mobile phase A, and acetonitrile as the mobile phase B; the elution mode of the high performance liquid chromatography detection is gradient elution; the elution conditions of the gradient elution are: 0-1 min, 20% mobile phase B; 1-2 min, 50% mobile phase B; 2-10 min, 80% mobile phase B; 10-14 min, 95% mobile phase B; 14-16.1 min, 20% mobile phase B; 16.1-20 min, 20% mobile phase B;

[0073] The standard working curves of Acid Yellow 73, Pigment Red 4 and Pigment Red 49 were obtained according to the standard HPLC spectra. The standard working curve of Acid Yellow 73 is y=1.22×10 5 x+1.02×10 5 ; Pigment Red 4 standard working curve is y = 1.74 × 10 4 x+3.75×10 4 ; The standard working curve of Pigment Red 49 is y=1.4×10 4 x+2.67×10 4 ;

[0074] 2) Pretreatment of toothpaste samples to be tested:

[0075] After squeezing out the toothpaste sample to be tested for 20 mm, accurately weigh 1.0 g (accurate to 0.01 g), place it in a 15 mL centrifuge tube, add 0.5 g of sea sand, vortex for 1 min, add 8 mL of extractant, perform ultrasonic extraction for 20 min at 500 W power and 53 kHz, centrifuge at 4000 r / min for 10 min, take the supernatant into a 10 mL volumetric flask, make up the volume with the extractant, and shake well to obtain an extract; filter the extract through a polytetrafluoroethylene filter membrane with a pore size of 0.22 μm to obtain a test solution;

[0076] 3) Detect the content of colorant in the toothpaste to be tested:

[0077] The liquid to be tested is subjected to high performance liquid chromatography to obtain a high performance liquid chromatography spectrum to be tested; the conditions for high performance liquid chromatography detection are: the chromatographic column filler is octadecyl bonded silica gel with a particle size of 5 μm, the chromatographic column size is 4.6×250 mm, the flow rate is 1.0 mL / min, the column temperature is 30° C., the injection volume is 10 μL, the detection wavelength of Acid Yellow 73 is 493 nm, the detection wavelength of Pigment Red 4 is 484 nm, and the detection wavelength of Pigment Red 49 is 493 nm; the high performance liquid chromatography detection is carried out at 493 nm. Ammonium acetate solution with a molar concentration of 20mmol / L was used as mobile phase A, and acetonitrile was used as mobile phase B; the elution mode of HPLC detection was gradient elution; the elution conditions of gradient elution were: 0-1min, 20% mobile phase B; 1-2min, 50% mobile phase B; 2-10min, 80% mobile phase B; 10-14min, 95% mobile phase B; 14-16.1min, 20% mobile phase B; 16.1-20min, 20% mobile phase B;

[0078] The peak areas of different colorants in the HPLC spectrum to be tested are substituted into the corresponding standard working curve to obtain the contents of different colorants in the toothpaste.

[0079] The toothpaste samples to be tested in Example 1 are 20 batches of toothpaste purchased in supermarkets or retail stores. According to the above detection method, 5 batches of samples were found to contain colorants, of which 3 batches contained acid yellow 73, with the mass percentages of 3.52%, 4.24%, and 1.87%, respectively; 1 batch contained pigment red 4, with the mass percentage of 1.12%, and 1 batch contained pigment red 49, with the mass percentage of 1.53%.

[0080] Figure 1 is the standard HPLC spectrum of the fifth mixed standard solution, Figure 1 It can be seen that using acetonitrile and 20 mmol / L ammonium acetate as the mobile phase can well separate Acid Yellow 73, Pigment Red 49 and Pigment Red 4.

[0081] The fifth mixed standard solution was scanned in the wavelength range of 300-600nm using a diode array detector to obtain an absorption intensity graph as shown in FIG. Figure 2 As shown. Figure 2 It can be seen that Acid Yellow 73 has the strongest absorption at 493nm, Pigment Red 4 at 484nm, and Pigment Red 49 at 493nm, indicating that 300-600nm can be selected as the absorption wavelength for HPLC detection.

[0082] The toothpaste samples in Examples 2 to 7 and Comparative Examples 1 to 7 are samples obtained by adding 50.0 mg / kg of Acid Yellow 73 standard sample, 100 mg / kg of Pigment Red 49 standard sample and 200 mg / kg of Pigment Red 4 standard sample to blank toothpaste (toothpaste without colorant).

[0083] Example 2

[0084] The toothpaste sample was pretreated according to the method of Example 1; the content of the colorant in the toothpaste sample was detected according to the method of Example 1; the difference was that the composition of the extractant was different, specifically, 96 mL of methanol, 2 mL of dimethyl sulfoxide and 2 mL of tetrahydrofuran were evenly mixed to obtain the extractant.

[0085] Example 3

[0086] The toothpaste sample was pretreated according to the method of Example 1; the content of the colorant in the toothpaste sample was detected according to the method of Example 1; the difference was that the composition of the extractant was different, specifically, 94 mL of methanol, 3 mL of dimethyl sulfoxide and 3 mL of tetrahydrofuran were evenly mixed to obtain the extractant.

[0087] Example 4

[0088] The toothpaste sample was pretreated according to the method of Example 1; the content of the colorant in the toothpaste sample was detected according to the method of Example 1; the difference was that the composition of the extractant was different, specifically, 92 mL of methanol, 4 mL of dimethyl sulfoxide and 4 mL of tetrahydrofuran were evenly mixed to obtain the extractant.

[0089] Example 5

[0090] The toothpaste sample was pretreated according to the method of Example 1; the content of the colorant in the toothpaste sample was detected according to the method of Example 1; the difference was that 1.0 g of sea sand was added to 1.0 g of the toothpaste sample.

[0091] Example 6

[0092] The toothpaste sample was pretreated according to the method of Example 1; the content of the colorant in the toothpaste sample was detected according to the method of Example 1; the difference was that 3.0 g of sea sand was added to 1.0 g of the toothpaste sample.

[0093] Example 7

[0094] The toothpaste sample was pre-treated according to the method of Example 1; the content of the colorant in the toothpaste sample was detected according to the method of Example 1.

[0095] Comparative Example 1

[0096] The toothpaste sample was pretreated according to the method of Example 1; the content of the colorant in the toothpaste sample was detected according to the method of Example 1; the difference was that the ultrasonic extraction time was 10 minutes.

[0097] Comparative Example 2

[0098] The toothpaste sample was pretreated according to the method of Example 1; the content of the colorant in the toothpaste sample was detected according to the method of Example 1; the difference was that the ultrasonic extraction time was 30 minutes.

[0099] Comparative Example 3

[0100] The toothpaste sample was pretreated according to the method of Example 1; the colorant content in the toothpaste sample was detected according to the method of Example 1; the difference was that the filter membrane used for filtering the extract was replaced with a nylon filter membrane with a pore size of 0.22 μm.

[0101] Comparative Example 4

[0102] The toothpaste sample was pretreated according to the method of Example 1; the content of the colorant in the toothpaste sample was detected according to the method of Example 1; the difference was that the composition of the extractant was different, specifically, 50 mL of methanol, 25 mL of dimethyl sulfoxide and 25 mL of tetrahydrofuran were evenly mixed to obtain the extractant.

[0103] Comparative Example 5

[0104] The toothpaste sample was pretreated according to the method of Example 1; the content of the colorant in the toothpaste sample was detected according to the method of Example 1; the difference was that the composition of the extractant was different, specifically, 60 mL of methanol, 20 mL of dimethyl sulfoxide and 20 mL of tetrahydrofuran were evenly mixed to obtain the extractant.

[0105] Comparative Example 6

[0106] The toothpaste sample was pretreated according to the method of Example 1; the content of the colorant in the toothpaste sample was detected according to the method of Example 1; the difference was that the composition of the extractant was different, specifically, 70 mL of methanol, 15 mL of dimethyl sulfoxide and 15 mL of tetrahydrofuran were evenly mixed to obtain the extractant.

[0107] Comparative Example 7

[0108] The toothpaste sample was pretreated according to the method of Example 1; the content of the colorant in the toothpaste sample was detected according to the method of Example 1; the difference was that the composition of the extractant was different, specifically, 80 mL of methanol, 10 mL of dimethyl sulfoxide and 10 mL of tetrahydrofuran were evenly mixed to obtain the extractant.

[0109] The extraction efficiencies of different colorants in the test solutions prepared in Examples 2 to 4 and 7 were calculated based on the test results. The results are listed in Table 1. Six parallel experiments were performed for each example and the average results were taken.

[0110] Table 1 The extraction efficiency results of different colorants in the test solution prepared in Examples 2, 3, 4, and 7 (n=6)

[0111]

[0112] The recovery rates of different colorants in the test solutions prepared in Comparative Examples 4 to 7 were calculated based on the test results, and the results are listed in Table 2.

[0113] Table 2 Extraction rate of different colorants in the test solution prepared in Comparative Examples 4 to 7

[0114]

[0115]

[0116] Combining the results of Table 1 and Table 2, it can be seen that the extraction rate of pigment red 4 by the extractants in Comparative Examples 4 to 7 is too high, which does not meet the detection requirements, and the content of THF and DMSO is too high, which will damage the chromatographic column during the high-performance liquid chromatography detection process. The mixed solution composed of CH3OH, THF and DMSO in a specific volume ratio provided by the present invention is used as an extractant to have a good extraction efficiency for the colorant in the toothpaste, and reduces the damage to the chromatographic column during the high-performance liquid chromatography detection process.

[0117] The extraction efficiencies of different colorants in the test solutions prepared in Example 7 and Comparative Examples 1-2 were calculated based on the test results, and the results are listed in Table 3.

[0118] Table 3 Extraction rate of different colorants in the test solution prepared in Example 7 and Comparative Examples 1-2

[0119]

[0120] According to Table 3, a bar chart comparing the extraction rates of different colorants under different ultrasonic extraction times is drawn, such as Figure 3 Combining Table 3 and Figure 3 It can be seen that when the ultrasonic extraction time is 20 minutes, the extraction rate of the colorant is higher, and the extraction rate does not increase significantly with the increase of time.

[0121] The extraction efficiencies of different colorants in the test solutions prepared in Examples 5, 6 and 7 were calculated based on the test results, and the results are listed in Table 4.

[0122] Table 4 Extraction rate of different colorants in the test solution prepared in Examples 5, 6 and 7

[0123]

[0124] According to Table 4, a column comparison chart of different colorant extraction rates under different sea sand addition amounts is drawn, such as Figure 4 Combining Table 4 and Figure 4 It can be seen that the sample extracts obtained by adding different amounts of sea sand are all clear and have little effect on the extraction rate.

[0125] The extraction efficiencies of different colorants in the test solutions prepared in Example 7 and Comparative Example 3 were calculated based on the test results, and the results are listed in Table 5.

[0126] Table 5 Extraction rate of different colorants in the test solution prepared in Example 7 and Comparative Example 3

[0127]

[0128] According to Table 5, a bar chart comparing the extraction rates of different colorants in the test solution obtained by filtering with different filter membranes is drawn, such as Figure 5 Combining Table 5 and Figure 5 It can be seen that the test results of the sample after filtration through the nylon filter membrane are slightly lower than those of the sample solution filtered through the polytetrafluoroethylene filter membrane, indicating that the nylon filter membrane has a certain adsorption on the target substance. Therefore, the polytetrafluoroethylene filter membrane is selected as the filtration membrane.

[0129] Detection of linearity, detection limit and quantification limit:

[0130] The mixed standard solution in Example 1 was subjected to HPLC detection according to the HPLC detection conditions of Example 1 to obtain its linear equation and linear correlation coefficient r; 3S / N was used as the detection limit and 10S / N was used as the quantification limit, and combined with the spiked recovery of the blank sample, the detection limit and quantification limit of Acid Yellow 73, Pigment Red 4, and Pigment Red 49 in toothpaste were confirmed, and the results are shown in Table 6.

[0131] Table 6 Linearity, detection limit and quantification limit of each colorant

[0132]

[0133] The precision and recovery rate of the detection method provided by the present invention are:

[0134] The amount of each colorant added to the blank toothpaste sample was 1 times the quantitation limit, 2 times the quantitation limit, 10 times the quantitation limit and the standard solution of the limit value. Each added amount was measured in parallel 6 times. The recovery and precision results are shown in Table 7. The recovery rate of the target compound was 79.7% to 109%, and the relative standard deviation was 0.99% to 9.45%, which met the test requirements.

[0135] Table 7 Precision and recovery of each colorant (n=6)

[0136]

[0137]

[0138] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A toothpaste pretreatment method, characterized in that: The following steps are involved: The toothpaste to be tested, sea sand and an extractant are mixed and then ultrasonically extracted to obtain an extract; the extractant is a mixed solution of methanol, tetrahydrofuran and dimethyl sulfoxide, the volume percentage of methanol in the extractant is 90-96%, the volume percentage of tetrahydrofuran in the extractant is 2-5%, and the volume percentage of dimethyl sulfoxide in the extractant is 2-5%; The extract is filtered through a polytetrafluoroethylene filter membrane to obtain a test solution.

2. The toothpaste pretreatment method according to claim 1, characterized in that: The mixing comprises the following steps: The toothpaste is dispersed by using sea sand and then first mixed with an extractant; The mass ratio of the toothpaste to the sea sand is 1:0.5-3; The dispersion method includes vortexing, oscillation, shaking or ultrasound.

3. The toothpaste pretreatment method according to claim 1, characterized in that: The ultrasonic power of the ultrasonic extraction is 480-520W, the ultrasonic frequency is 52-54kHZ, and the ultrasonic extraction time is 15-25min.

4. The toothpaste pretreatment method according to claim 1 or 3, characterized in that: After the ultrasonic extraction, the method further comprises: centrifuging the system after the ultrasonic extraction, taking the supernatant, and obtaining the extract.

5. The toothpaste pretreatment method according to claim 4, characterized in that: The centrifugal speed is 3000-5000 r / min, and the centrifugal time is 8-12 min.

6. The toothpaste pretreatment method according to claim 1, characterized in that: The pore size of the polytetrafluoroethylene filter membrane is 0.22-0.45 μm.

7. A method for detecting the colorant content in toothpaste, characterized in that: The following steps are involved: The mixed standard solution of Acid Yellow 73, Pigment Red 4 and Pigment Red 49 is subjected to high performance liquid chromatography to obtain a standard high performance liquid chromatography spectrum; According to the standard high performance liquid chromatography spectrum, standard working curves of acid yellow 73, pigment red 4 and pigment red 49 are respectively obtained; the abscissa of the standard working curve is the mass concentration of acid yellow 73, pigment red 4 or pigment red 49, and the ordinate of the standard working curve is the peak area of ​​acid yellow 73, pigment red 4 or pigment red 49 in the standard high performance liquid chromatography spectrum; The liquid to be tested is subjected to high performance liquid chromatography to obtain a high performance liquid chromatography spectrum; the liquid to be tested is the liquid to be tested obtained after being treated according to the pretreatment method according to any one of claims 1 to 6; The peak areas of different colorants in the high performance liquid chromatography spectrum to be tested are respectively substituted into the corresponding standard working curve to obtain the contents of different colorants in the toothpaste.

8. The detection method according to claim 7, characterized in that: The conditions for the high performance liquid chromatography detection include: the chromatographic column filler is octadecyl bonded silica gel, the chromatographic column filler particle size is 1.7 to 5 μm, the chromatographic column size is 4.6×250 mm or 2.1×100 mm, the flow rate is 0.8 to 1.2 mL / min, the column temperature is 30 to 50°C, the detection wavelength is 300 to 600 nm, and the injection volume is 1 to 50 μL.

9. The detection method according to claim 7 or 8, characterized in that: In the HPLC detection process, an ammonium acetate solution with a molar concentration of 20 mmol / L is used as mobile phase A, and acetonitrile is used as mobile phase B; The elution method of the high performance liquid chromatography detection is gradient elution; The elution conditions of the gradient elution are: 0-1min, 20% mobile phase B; 1-2 min, 50% mobile phase B; 2-10 min, 80% mobile phase B; 10-14 min, 95% mobile phase B; 14-16.1 min, 20% mobile phase B; 16.1~20min, 20% mobile phase B.

10. The detection method according to claim 7, characterized in that: The mass concentration of Acid Yellow 73 in the mixed standard solution is 5 μg / mL, 10 μg / mL, 20 μg / mL, 50 μg / mL, and 100 μg / mL; The mass concentration of Pigment Red 4 in the mixed standard solution is 10 μg / mL, 20 μg / mL, 40 μg / mL, 100 μg / mL, and 200 μg / mL; The mass concentrations of Pigment Red 49 in the mixed standard solution are 20 μg / mL, 40 μg / mL, 80 μg / mL, 200 μg / mL, and 400 μg / mL.

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