CN115825040A - Method for detecting hydroxyapatite active ingredient in toothpaste - Google Patents

Abstract

The invention relates to the technical field of detection of oral care products, in particular to a method for detecting hydroxyapatite active ingredients in toothpaste, which comprises the following steps of: calcining a sample to be detected, and crushing to obtain sample powder; dispersing sample powder into a buffer solution, and then carrying out stirring treatment, washing and drying to obtain a dry sample; a raman spectrum of the dried sample was obtained. The technical scheme can solve the technical problem that impurities interfere with detection results too much when hydroxyapatite components in oral care products are detected. Hydroxyapatite was selected at 960cm ^‑1 The detection of nearby characteristic peaks can effectively distinguish hydroxyapatite from other friction matrix components; the stability and the signal intensity of the hydroxyapatite are improved through calcination treatment; by selecting acetic acid-acetic acidThe sodium buffer solution dissolves the calcined sample, and impurities such as calcium carbonate and the like are further removed, so that the detection accuracy is improved, and the method has an ideal application prospect.

Description

Method for detecting hydroxyapatite active ingredient in toothpaste

Technical Field

The invention relates to the technical field of detection of oral care products, in particular to a method for detecting hydroxyapatite active ingredients in toothpaste.

Background

Hydroxyapatite (HAP) is an inorganic material with wide applications due to its physical structure and physicochemical properties, and particularly has similar inorganic components to human bones, teeth and the like, and thus has good biocompatibility, and thus has been a hot point for research on materials for oral medicine, particularly hard tissue repair materials. In recent years, more and more attention is paid to the application of HAP in oral care products, and the HAP is reported to be applied to toothpaste and mouthwash products and has the effects of inhibiting the breeding of dental plaque, promoting the remineralization of enamel, whitening teeth, relieving dentin sensitivity and the like. Therefore, quantitative and qualitative evaluation as an efficacy ingredient in oral cleaning care products is also the focus of research.

The detection of HAP usually adopts methods such as freeze drying, high temperature drying, etc., and after the dried finished product is ground, the composition and the crystalline phase structure of the HAP active ingredient are qualitatively characterized by adopting X-ray diffraction (XRD). The XRD diffraction characteristic peak (2 theta) of HAP is positioned at 21-29 degrees, 32-34 degrees, 39-41 degrees and 46-54 degrees, and when the stability of the crystal structure is identified, the types and the intensities of the important characteristic peaks are required to be compared at the same time, so that the existence of the HAP structure is proved. There is a need to develop a method for accurately detecting HAP in an oral care product that eliminates interference from other components of the product.

Disclosure of Invention

The invention aims to provide a method for detecting hydroxyapatite active ingredients in toothpaste, which aims to solve the technical problem that other ingredients greatly interfere with the detection result when the hydroxyapatite ingredients in oral care products are detected in the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for detecting hydroxyapatite active ingredients in toothpaste comprises the following steps in sequence:

s1: calcining a sample to be detected, and crushing to obtain sample powder;

s2: dispersing sample powder into a buffer solution, and then carrying out stirring treatment, washing and drying to obtain a dry sample;

s3: a raman spectrum of the dried sample was obtained.

The principle and the beneficial effects of the technical scheme are as follows:

the technical scheme adopts a method for detecting the HAP active ingredients in the toothpaste by sintering and solidifying the crystal state of the HAP at high temperature, dissolving impurities such as calcium hydrophosphate, calcium carbonate and the like in a weak acid buffer mode and finally combining the advantages of Raman spectrum.

Through high-temperature calcination, impurities such as volatile carbon oxides, nitrogen oxides and the like such as moisture, essence, colloid and the like in a sample can be sufficiently removed. HAP has hexagonal atom skeleton, two cation sites have one leading element (Ca), the third cation site has P, the other structure site is OH, HAP can further strengthen the mechanical strength during high temperature calcination at 700-800 deg.C to avoid subsequent dissolution during acid dissolution, but when the temperature exceeds 800 deg.C, OH ions in HAP structure may shift along channel axis and are located at-3572 cm ^-1 The hydroxyl peak of (A) shows the degree of crystal dehydrogenation, causing structural defects, and therefore, by monitoring 3572cm ^-1 The left and right-OH peaks are calcined at 700-800 ℃ to achieve the purpose of fully removing organic impurities and simultaneously enabling useful component structures to be more stably enriched. Fully grinding the solid after high-temperature calcination to obtain high-dispersion powder, and adopting a weak acid acetic acid-sodium acetate buffer solution with pH of 4.8-5.8 to ensure that impurities such as calcium carbonate, calcium hydrophosphate and the like commonly used in oral care products can be fully dissolved by acid, so that the interference of the impurities such as calcium carbonate, calcium hydrophosphate and the like on HAP determination is overcome, and the qualitative detection of HAP in the oral care products is realized.

Further, in S1, the conditions of the calcination treatment are: heating to 700-800 ℃ at the heating rate of 2-10 ℃/min, and then preserving heat for 1-2h. Calcination at 700-800 ℃ can ensure that the crystal size and the d-spacing value of the main peak (211) are stable, and the stability of-OH ions is good, thereby improving the stability of HAP in a weak acid environment. In addition, organic substances can be removed at 700-800 ℃, and interference factors in the detection process are eliminated. And the dissolving capacities of HAP, calcium carbonate and calcium hydrophosphate in a weak acid environment are differentiated, and the calcium carbonate and the calcium hydrophosphate can be removed through subsequent weak acid treatment.

Further, in S1, the sample powder was sieved through a 200 mesh sieve.

Further, in S2, the mass ratio of the sample powder to the buffer is 1: (5-20).

Further, in S2, the buffer is an acetic acid-sodium acetate buffer. The calcined sample was treated with an acetic acid-sodium acetate buffer solution to remove calcium carbonate and calcium hydrogen phosphate without affecting the structure of HAP and without dissolving HAP.

Further, in S2, the concentration of acetic acid-sodium acetate buffer is 0.2-0.5M, and the pH is 4.8-5.8. Under the condition of the pH value, HAP has good stability in buffer solution, and can fully dissolve calcium carbonate and calcium hydrophosphate. If the pH value is too high or too low, the calcined HAP, calcium carbonate and calcium hydrophosphate cannot be dissolved, or the calcined HAP, calcium carbonate and calcium hydrophosphate are all dissolved, so that the HAP, calcium carbonate and calcium hydrophosphate cannot be separated finally, and the accurate detection of the HAP in the toothpaste cannot be realized.

Further, in S2, the manner of the stirring process is: stirring at the rotation speed of 200-400rpm for 24-60h at the temperature of 25-37 ℃.

Further, in S1, the sample to be tested is toothpaste.

Further, the abrasive matrix of the toothpaste comprises at least one of calcium carbonate, calcium hydrogen phosphate, hydrated silica, and aluminum hydroxide.

Further, in S3, the dried sample was observed to have a Raman spectrum of 950 to 970cm ^-1 Whether or not to occur andcharacteristic peak corresponding to standard hydroxyapatite sample.

The detection by adopting Raman spectrum shows that the HAP structure has a characteristic peak obviously different from substrates such as calcium hydrophosphate, calcium carbonate and the like, and is v 1PO ₄ ^3- The stretching peak is positioned at 950-970cm ^-1 The structural stability of the HAP can be accurately determined by monitoring the characteristic peak with emphasis on showing the ordering of the crystal structure (see fig. 1).

In conclusion, the technical scheme has the following beneficial effects:

(1) The technical proposal carries out Raman spectrum detection research on the friction matrix and HAP in the toothpaste, finds that the HAP is positioned at 950-970cm ^-1 V 1PO of ₄ ^3- Stretching the peak to show the orderliness of the crystal structure, distinguishing the characteristic peaks of substrates such as calcium hydrogen phosphate, calcium carbonate and the like, and accurately judging the structural stability of the HAP by monitoring the characteristic peaks.

(2) According to the technical scheme, through high-temperature calcination, organic impurities are fully removed, the HAP component structure is more stable and more enriched, and more ideal peak shape and signal intensity are displayed in Raman spectrum detection. Through the test and research of the inventor, the calcination temperature of 700-800 ℃, the crystal size of HAP and the d spacing of the main peak (211) are stable, and the length is 3572cm ^-1 the-OH stretching vibration has proper frequency and strength, which is beneficial to maintaining the stability of the HAP hexagonal crystal system structure and further improving the stability of the HAP. The stability of HAP is improved, and the detection accuracy can be improved for toothpaste with different friction matrixes.

(3) The technical scheme has better interference elimination effect particularly for toothpaste taking calcium carbonate and calcium hydrophosphate as friction substrates. As the HAP is roasted at 700-800 ℃, the HAP becomes more stable, and can still maintain ideal peak shape and signal intensity in Raman spectrum detection after being treated by subsequent acid buffer solution. At the same time, interfering substances such as calcium carbonate and calcium hydrogen phosphate are removed by the acidic buffer. Roasting treatment at a certain temperature enables calcium carbonate, calcium hydrophosphate and the like to be distinguished from the dissolving performance of HAP in a specific buffer solution, and interference elimination in Raman spectrum detection is further realized. If the buffer solution is directly used for dissolving the toothpaste sample, substances such as calcium carbonate, calcium hydrophosphate and the like are dissolved, HAP is also dissolved, and subsequent Raman spectrum detection cannot be effectively carried out.

(4) The choice of the type of buffer plays a very important role in achieving accurate detection of HAP. Only by using acetic acid-sodium acetate buffer solution, the calcined HAP can be separated from substances such as calcium carbonate, calcium hydrogen phosphate and the like, and the interference on Raman spectrum detection is eliminated. The use of other buffer solutions can cause the calcium carbonate and the calcium hydrophosphate to be incapable of being effectively dissolved or cause characteristic peaks to be shifted, thereby influencing the detection accuracy.

(5) The pH value range of the acetic acid-sodium acetate buffer solution is selected, so that the HAP can be separated from calcium carbonate, calcium hydrogen phosphate and other substances, and the key effect is played. The pH value is too low, so that HAP is dissolved together with substances such as calcium carbonate, calcium hydrophosphate and the like; too high a pH value results in that the interfering substances (calcium carbonate and calcium hydrogen phosphate) are not removed and no characteristic peak of HAP is observed.

Drawings

FIG. 1 is a Raman spectrum of various conventional matrices for toothpaste.

FIG. 2 is a Raman spectrum of examples 1-5 and standard HAP.

FIG. 3 is a Raman spectrum of comparative examples 1-4 and a standard HAP.

FIG. 4 Raman spectra of HAP after calcination at different temperatures excited by 365nm UV light from Experimental example 1.

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following examples and experimental examples are conventional means well known to those skilled in the art, and the materials, reagents and the like used therein are commercially available.

The overall situation of the technical scheme is as follows:

s1: and (3) carrying out high-temperature calcination pretreatment on the toothpaste sample to be tested, controlling the heating rate to be 2-10 ℃/min and the temperature to be 700-800 ℃, keeping the temperature for 1-2h to obtain a calcined sample, grinding the calcined sample, and sieving with a 200-mesh sieve to obtain sample powder.

S2: the sample powder was mixed according to 1: (5-20) in a buffer solution of 0.2-0.5M, pH4.8-5.8, acetic acid-sodium acetate (specifically, in the buffer solution, the total concentration of acetic acid/acetate is 0.2-0.5M). Then stirring at 200-400rpm at 25-37 deg.C for 24-60h, separating powder, washing with water, drying, standing at 70-80 deg.C for 24-48h (due to Raman using laser and infrared spectrum ratio, water has small Raman activity and relatively small interference, and only needs to be dried properly in the test), and obtaining dried sample.

S3: and carrying out conventional Raman spectrum detection on the dried sample and a standard HAP sample, and identifying and analyzing the HAP component in the sample.

Wherein, 0.2-0.5M, pH4.8-5.8 acetic acid-sodium acetate buffer solution specifically refers to: the total concentration of acetic acid/acetate is 0.2-0.5M. Glacial acetic acid and sodium acetate are usually selected for preparation in the prior art, the dosage of the glacial acetic acid and the sodium acetate is calculated according to the required pH value and the existing formula, and the preparation can be completed by using water as a solvent, which is not described herein again. The acetic acid-sodium acetate buffer solution described above can also be obtained directly in a commercial manner.

The toothpaste contains a large amount of organic additives which can interfere the detection of the hydroxyapatite, and the organic additives can be removed by high-temperature calcination, thereby ensuring the improvement of the stability of the hydroxyapatite.

In FIG. 1, various tribological matrices were tested in pure form, including: silica standards, aluminum hydroxide, calcium carbonate, calcium hydrogen phosphate and HAP standards are commonly used for toothpaste. As is clear from this figure, in the presence of each of the friction substrates independently, the characteristic peaks of the respective substances are different from each other, and hence the discrimination determination can be made by the positions of the characteristic peaks (at 950 to 970 cm) ^-1 V 1PO of ₄ ^3- Stretching peak). However, the characteristic peaks of calcium carbonate and calcium hydrogen phosphate are relatively close to those of HAP, so when a large amount of calcium carbonate or calcium hydrogen phosphate is present in the toothpaste powder, the following may occur: when a large amount of calcium carbonate or calcium hydrophosphate exists, the characteristic peak of HAP is completely covered by the strong peak of impurities and cannot appear; calcium carbonate or calcium hydrogen phosphateRelatively rarely, both combine with HAP (e.g., dibasic calcium phosphate and HAP) to become a broader peak, causing the peak shape to change or shift. Therefore, calcium carbonate or calcium hydrogen phosphate needs to be removed as much as possible.

Example 1

Weighing 5g of a commercially available sample 1 (HAP-containing toothpaste with calcium carbonate as a substrate) and carrying out high-temperature calcination pretreatment, wherein the heating rate is 2 ℃/min, and the temperature is controlled at 700 ℃ and kept for 2h to obtain a calcined sample. Grinding the powder, and mixing the ground powder according to the weight ratio of 1: dispersing in buffer solution of acetic acid-sodium acetate with concentration of 0.2M and pH of 5.8 at 5 mass ratio, stirring at 25 deg.C for 60 hr, separating to obtain powder, washing with water, and drying; subjecting the dried sample to Raman spectroscopy with a standard HAP sample, shown in FIG. 2, of 960cm ^-1 The peaks at the left and right positions correspond to the standard peaks, and the HAP component is detected.

Example 2

Weighing 5g of a commercially available sample 2 (HAP-containing toothpaste with calcium hydrophosphate as a substrate) and carrying out high-temperature calcination pretreatment, wherein the heating rate is 4 ℃/min, and the temperature is controlled at 750 ℃ and is kept for 1h to obtain a calcined sample. Grinding the powder, and mixing the ground powder according to the proportion of 1: dispersing in buffer solution of acetic acid-sodium acetate with concentration of 0.3M and pH of 4.8 at a mass ratio of 10, stirring for 48h at 30 ℃, separating out powder, fully washing and drying with water, and then drying; subjecting the dried sample to Raman spectroscopy with a standard HAP sample at 960cm as shown in FIG. 2 ^-1 The peak at the position corresponds to the standard peak, and it is determined that it contains the HAP component.

Example 3

Weighing 5g of a commercially available sample 3 (HAP-containing toothpaste with hydrated silica as a matrix) and carrying out high-temperature calcination pretreatment, wherein the heating rate is 6 ℃/min, and the temperature is controlled at 800 ℃ and is kept for 1.5h to obtain a calcined sample; subjecting the dried and ground sample to Raman spectroscopy with a standard HAP sample, 960cm, as shown in FIG. 2 ^-1 The peak at the position corresponds to the standard peak, and it is determined that it contains the HAP component.

In HAP-containing toothpastes based on hydrated silica, there is no need to carry it in as much as the hydrated silica does not interfere with the Raman spectroscopic detection of HAPAnd (3) performing acid treatment to remove the interfering matrix. However, in order to obtain better detection results of Raman spectrum, impurities in the toothpaste should be sufficiently removed to obtain uniform powder, and a water centrifugal resuspension method or a high-temperature calcination method can be generally adopted; when the centrifugal resuspension method is adopted, because the HAP generally belongs to the nanometer level, the colloid in the toothpaste can carry away the HAP when the centrifugal resuspension method is adopted, so that a certain amount of loss is caused, and the centrifugal resuspension method is not recommended. When high-temperature calcination is adopted, when the temperature reaches 400-500 ℃, the volatile essence, spice, colloid and other impurities in the sample can be carbonized. When the temperature reaches 700-800 ℃, the stability of the HAP crystal structure can be further improved, and a better detection result, namely 960cm, can be obtained ^-1 The peak shape of the peak at the position is better, narrow and sharp, and the intensity is high. Therefore, in the embodiment 3, after calcination at 800 ℃, the interfering impurities can be sufficiently and effectively removed, and the crystal structure property of the HAP is enhanced, so that a better Raman spectrum result is obtained.

Example 4

5g of a commercially available sample 4 (HAP-containing toothpaste with a matrix of hydrated silica and aluminum hydroxide) was weighed, subjected to a high-temperature calcination pretreatment at a temperature rise rate of 8 ℃/min and a temperature control of 750 ℃ for 2 hours to obtain a calcined sample, and the calcined sample was ground. Performing Raman spectroscopy on the ground sample and a standard HAP sample, as shown in FIG. 2, 960cm ^-1 The peak at the position corresponds to the standard peak, and it is determined that it contains the HAP component.

Example 5

Weighing 5g of a commercially available sample 5 (HAP-containing toothpaste with calcium carbonate and calcium hydrophosphate as matrixes) and carrying out high-temperature calcination pretreatment, wherein the heating rate is 10 ℃/min, the temperature is controlled at 750 ℃ and is kept for 2h to obtain a calcined sample, and the calcined sample is ground. Grinding the powder according to the proportion of 1: dispersing in buffer solution of acetic acid-sodium acetate with concentration of 0.5M and pH of 5.5 at 20 mass ratio, stirring at 25 deg.C for 48h, separating to obtain powder, washing with water, and drying; subjecting the dried sample to Raman spectroscopy with a standard HAP sample, shown in FIG. 2, of 960cm ^-1 The peak at the position corresponds to the standard peak, and it is determined that it contains the HAP component.

Experimental example 1

HAP (HAP), usually written as (Ca) ₁₀ (PO ₄ ) ₆ (OH) ₂ ) So as to highlight the two parts of hydroxyl and apatite. Research shows that the lattice point of hydroxyl is an important path for proton and oxygen ion conduction, and the stability of the HAP hexagonal crystal system structure is closely related to the stability of-OH ions in the structure. Under high temperature conditions, dehydration is easily caused by low partial pressure of water to generate O-HAP, and apatite is easily decomposed into tricalcium phosphate and tetracalcium phosphate.

In the experiment, standard pure HAP samples are calcined at different temperatures, structural information of-OH of the HAP is observed through ultraviolet Raman spectroscopy, the structure of the sintered HAP at different temperatures is measured through XRD, the d-spacing of a main peak is obtained at the same time, and the crystal size is calculated by adopting a Scherrer method so as to comprehensively reveal the structure and the performance of the HAP.

Weighing 2g of standard HAP powder sample, respectively carrying out calcination pretreatment at different temperatures, heating at a rate of 10 ℃/min, and carrying out heat preservation at different temperatures for 1-2h to obtain a calcined sample. And grinding the sample, and carrying out ultraviolet Raman and XRD detection on the dried and ground sample. Since the vibration mode of the atoms in the HAP is strongly dependent on the crystal structure and composition, raman scattering is sensitive to oxygen atoms, and the experimental results are shown in FIG. 4, wherein 3572cm is observed with the increase of temperature ^-1 The frequency and intensity of the-OH stretching vibration are gradually reduced, OH moves along the channel axis at high temperature, and when the temperature reaches 800 ℃, the-OH does not have a definite position on the channel axis. As shown in Table 1, the crystal size and d-spacing of the main peak (211) are preferably stabilized at a calcination temperature of about 700 ℃ to 800 ℃. The crystal size and d-spacing of the main peak (211) are the main parameters of the HAP unit cell, and the stable values indicate that the HAP crystal structure is stable. More specifically, with a calcination temperature of 700-900 ℃, the crystal size is stabilized at 22.6nm; the d-spacing of the main peak (211) is maintained at 2.714 by adopting the calcining temperature of 600-800 ℃; therefore, at the calcination temperature of 700-800 ℃, two main parameters of the crystal size and the d spacing of the main peak (211) are stable, and the stability of the crystal structure is characterized. In addition, the position of-OH is on the channel of unit cell (i.e. branched structure), and-OH is in HAP structure although it does not affect the main structure of crystalThe intensity and position of the peaks of the inseparable important component also indicate that this part of the "branched structure" in the crystals of HAP is stable. Therefore, in the case where the main structure and the branch structure are stable, the overall structure of the HAP is stable.

As described above, in order to obtain a stable HAP structure, the calcination temperature is preferably controlled to 700 to 800 ℃. At this calcination temperature range, the crystal size of HAP and the d-spacing of the main peak (211) were maintained at a stable value and 3572cm ^-1 The frequency and intensity of the-OH stretching vibration are suitable (the frequency and intensity of the-OH stretching vibration are too low due to the temperature rise of more than 800 ℃), and the stability of the-OH ions is closely related to the stability of the HAP hexagonal crystal structure. At the calcining temperature of 700-800 ℃, the obtained calcined sample can be kept stable in a specific buffer solution, and is distinguished from the dissolving performance of the calcium-containing toothpaste friction matrix such as calcined calcium carbonate in the specific buffer solution, so that impurities influencing the detection effect are effectively removed.

Table 1: crystal size and lattice spacing of HAP at different calcination temperatures

Calcination temperature/. Degree.C	Crystal size (nm)	D spacing of main peak (211)
			100	7.8	2.878
300	12.7	2.759
			600	15.4	2.714
700	22.6	2.714
			800	22.6	2.714
900	22.6	2.712
			1100	22.9	2.711

Comparative example 1

Weighing 5g of a commercial sample 5 (HAP-containing toothpaste with calcium carbonate and calcium hydrophosphate as matrixes) to carry out high-temperature calcination pretreatment, controlling the temperature rise rate to be 10 ℃/min and the temperature to be 750 ℃ and keeping the temperature for 2h to obtain a calcined sample, and grinding the calcined sample. Grinding the powder according to the proportion of 1: dispersing in buffer solution of acetic acid-sodium acetate with concentration of 0.5M and pH of 4.5 at 20 mass ratio, stirring at 25 deg.C for 48h, separating to obtain powder, washing with water, and drying; the dried sample and a standard HAP sample are subjected to Raman spectrum detection at the same time, and the experimental result shows that after acid treatment, the residual solid powder is less, and the Raman spectrum of the sample is compared with 960cm of HAP ^-1 The characteristic peak shifts and the peak intensity is greatly reduced (see figure 3), which shows that under the condition, HAP is dissolved and the structure of the HAP is changed, thus influencing the qualitative detection of the HAP, and particularly under the condition of less HAP content in the toothpaste, the detection of the substance component is difficult to realize.

Comparative example 2

Weighing 5g of a commercially available sample 5 (HAP-containing toothpaste with calcium carbonate and calcium hydrophosphate as matrixes) and carrying out high-temperature calcination pretreatment, wherein the heating rate is 10 ℃/min, and the temperature is controlled at 750 ℃ and is kept for 2h to obtain a calcined sample; grinding the mixture; grinding the powder according to the proportion of 1: dispersing in buffer solution of acetic acid-sodium acetate with concentration of 0.5M and pH of 6.2 at a mass ratio of 20, stirring at 25 deg.C for 48h, separating out powder, washing with water, and drying; the dried sample and a standard HAP sample are subjected to Raman spectrum detection (see figure 3), and under the condition of higher pH close to neutral, interferents (calcium carbonate and calcium hydrophosphate) are not removed, and a characteristic peak of the HAP cannot be observed.

Comparative example 3

Weighing 5g of a commercial sample 5 (HAP-containing toothpaste with calcium carbonate and calcium hydrophosphate as matrixes) to carry out high-temperature calcination pretreatment, controlling the temperature rise rate to be 10 ℃/min and the temperature to be 750 ℃ and keeping the temperature for 2h to obtain a calcined sample, and grinding the calcined sample. And (3) grinding the powder according to the proportion of 1: dispersing 20 mass ratio in citric acid-sodium citrate buffer solution with concentration of 0.5M and pH of 5.5 (citric acid/citrate ion concentration of 0.5M, prepared by citric acid solution and sodium citrate solution; or obtained by commercial means), stirring at 25 deg.C for 48h, separating to obtain powder, washing with water, and drying; performing Raman spectrum detection on the dried sample and a standard HAP sample, and finding 960cm by referring to the attached figure 3 ^-1 The characteristic peak shifts and does not coincide with the characteristic peak of the standard HAP any more, which indicates that the crystal structure of the HAP changes, and the detection method of the comparative example is not suitable for detecting the HAP in the toothpaste and is easy to generate errors. The inventors further analyzed the cause of the above phenomenon, probably due to adsorption bonding with HAP in a citric acid-sodium citrate buffer solution at pH 5.0, due to the large polarity of citrate ion, resulting in 960cm ^-1 The characteristic peaks are shifted.

Comparative example 4

Weighing 5g of a commercially available sample 5 (HAP-containing toothpaste with calcium carbonate and calcium hydrophosphate as matrixes) and carrying out high-temperature calcination pretreatment, wherein the heating rate is 10 ℃/min, the temperature is controlled at 750 ℃ and is kept for 2h to obtain a calcined sample, and the calcined sample is ground. Grinding the powder according to the proportion of 1:20 mass ratio in a 0.5M pH5.5 disodium hydrogen phosphate-citric acid buffer solution (the sum of the concentrations of disodium hydrogen phosphate and citric acid is 0.5M, prepared from disodium hydrogen phosphate solution and citric acid solution; or obtained by commercial means), stirring at 25 deg.C for 48h, separating to obtain powder, washing with water, and drying; the dried sample and a standard HAP sample are subjected to Raman spectrum detection, and a characteristic peak of HAP cannot be observed (see figure 3). The reason for the analysis by the inventors may be: in the disodium hydrogen phosphate-citric acid buffer, hydrogen phosphate ions and citrate ions exist in the solution at the same time, so that the dissolution of calcium hydrogen phosphate is prevented, and the peak of HAP is completely covered by the peak of calcium hydrogen phosphate, so that the characteristic peak of HAP cannot be observed. Further, if the pH of the disodium hydrogenphosphate-citric acid buffer solution is adjusted to be slightly high (pH 5.8) or low (pH 4.8, etc.), the problem that the characteristic peak of HAP cannot be observed cannot be solved, and the interference of calcium hydrogenphosphate and calcium carbonate cannot be eliminated.

Comparative example 5

This comparative example 5g of a commercial sample 5 (HAP-containing toothpaste with calcium carbonate and calcium hydrogen phosphate as bases) was mixed at a ratio of 1: dispersing 10 mass ratio in 0.5M acetic acid-sodium acetate buffer solution with pH5.5, stirring at 25 deg.C for 48 hr, separating out powder, washing with water, and drying; and carrying out Raman spectrum detection on the dried sample and a standard HAP sample. The powder substance separated by the above operation is very little, and a remarkable sharp 960cm could not be observed under Raman spectrum ^-1 Characteristic peak. This indicates that, in the case of the non-calcined product, calcium carbonate and calcium hydrogen phosphate were dissolved in a large amount in the acetic acid-sodium acetate buffer solution, and HAP was also partially dissolved, so that less powdery substance was separated. And the crystal structure of the separated powder substance is damaged to a certain extent under the action of acid, and the thickness of the powder substance is 960cm ^-1 Neither side showed a significant characteristic peak. In addition, since HAP had not been subjected to calcination treatment and had poor stability, the structure thereof was destroyed during stirring, and 960cm was therefore used ^-1 The characteristic peak is difficult to observe, or 960cm appears even barely ^-1 Characteristic peak, the peak width of which is widened and shifted, and960cm of HAP standard ^-1 The characteristic peaks show a large difference.

Therefore, calcination at 700-800 ℃ plays a triple role: the stability of the weak acid environment of the HAP is enhanced; so that the dissolving capacities of HAP, calcium carbonate and calcium hydrophosphate in a weak acid environment are differentiated, and the calcium carbonate and the calcium hydrophosphate are removed; meanwhile, organic impurities in the toothpaste can be removed.

Comparative example 6

This comparative example is substantially the same as example 5 except that the calcination temperature was 600 ℃ or 900 ℃ and that under these two temperature conditions, after stirring with buffer, less powdery material was separated than in example 5 and 960cm was observed in Raman spectrum ^-1 The intensity of the characteristic peak was inferior to that of example 5, and the peak height was lower than that of example 5, and the peak width was wider than that of example 5, and the characteristic peak was shifted to some extent. This indicates that the calcination temperature is not in the range of 700-800 ℃, the stability of HAP is not ideal, and happened dissolution and structural change during the acid buffer solution treatment, which is not good for realizing accurate detection of HAP in toothpaste.

The foregoing is merely an example of the present invention and common general knowledge in the art of designing and/or characterizing particular aspects and/or features is not described in any greater detail herein. It should be noted that, for those skilled in the art, without departing from the technical solution of the present invention, several variations and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.

Claims (10)

1. A method for detecting hydroxyapatite active ingredients in toothpaste is characterized by comprising the following steps: comprises the following steps in sequence:

s1: calcining a sample to be detected, and crushing to obtain sample powder;

s2: dispersing sample powder into a buffer solution, and then carrying out stirring treatment, washing and drying to obtain a dry sample;

s3: a raman spectrum of the dried sample was obtained.

2. The method for detecting hydroxyapatite active ingredients in toothpaste according to claim 1, characterized in that: in S1, the conditions of the calcination treatment are: heating to 700-800 ℃ at the heating rate of 2-10 ℃/min, and then preserving heat for 1-2h.

3. The method for detecting hydroxyapatite active ingredients in toothpaste according to claim 2, characterized in that: in S1, the sample powder was passed through a 200 mesh screen.

4. The method for detecting hydroxyapatite active ingredients in toothpaste according to claim 1, wherein in S2, the mass ratio of the sample powder to the buffer solution is 1: (5-20).

5. The method for detecting hydroxyapatite active ingredients in toothpaste according to claim 4, wherein in S2, the buffer is acetic acid-sodium acetate buffer.

6. The method of claim 5, wherein the concentration of the acetate-sodium acetate buffer solution in S2 is 0.2-0.5M and the pH is 4.8-5.8.

7. The method for detecting hydroxyapatite active ingredient in toothpaste according to claim 6, wherein in S2, the stirring treatment is performed by: stirring at 25-37 deg.C and 200-400rpm for 24-60h.

8. The method for detecting hydroxyapatite active ingredients in toothpaste according to claim 1, wherein in S1, the sample to be detected is toothpaste.

9. The method for detecting hydroxyapatite active ingredients in toothpaste according to claim 1, wherein, in S3, the frictional base of the toothpaste includes at least one of calcium carbonate, calcium hydrogen phosphate, hydrated silica and aluminum hydroxide.

10. The method for detecting hydroxyapatite active ingredients in toothpaste according to claim 9, wherein the method comprises the following steps: in S3, the dried sample is observed at 950-970cm in Raman spectrum ^-1 Whether a characteristic peak corresponding to a standard hydroxyapatite sample appears.

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