阅读说明：本技术 一种用硫酸小檗碱测定蒙脱石吸附力的方法 (Method for measuring montmorillonite adsorption force by using berberine sulfate ) 是由 石红艳 周建军 刘金磊 曹珍荣 赵颖 于 2019-10-30 设计创作，主要内容包括：本发明提供了一种用硫酸小檗碱测定蒙脱石吸附力的方法,其步骤为：配制硫酸小檗碱标准溶液,取蒙脱石细粉,定量加入pH值为6.8的磷酸盐缓冲液,定量加入硫酸小檗碱标准溶液,使蒙脱石取样量与硫酸小檗碱加入量的比值控制在0.8~1.2,让过量的硫酸小檗碱被蒙脱石充分吸附,再用氧化还原滴定法测定剩余的硫酸小檗碱,然后计算出蒙脱石的吸附力。该方法测定药用蒙脱石的吸附力专属性、线性、准确度、精密度、耐用性等均良好,且安全无毒,购买管理方便,价格低,费用低。(The invention provides a method for measuring montmorillonite adsorption force by using berberine sulfate, which comprises the following steps: preparing a berberine sulfate standard solution, taking montmorillonite fine powder, quantitatively adding a phosphate buffer solution with the pH value of 6.8, quantitatively adding the berberine sulfate standard solution, controlling the ratio of the sampling amount of the montmorillonite to the adding amount of the berberine sulfate to be 0.8-1.2, fully adsorbing excessive berberine sulfate by the montmorillonite, measuring the residual berberine sulfate by using a redox titration method, and calculating the adsorption capacity of the montmorillonite. The method for measuring the adsorption capacity specificity, linearity, accuracy, precision, durability and the like of the medicinal montmorillonite are good, and the method is safe, non-toxic, convenient to purchase and manage, low in price and low in cost.)

1. A method for measuring the adsorption capacity of montmorillonite is characterized by comprising the following steps: the method for measuring the adsorption quantity of berberine sulfate by montmorillonite by redox titration comprises the following steps: preparing a berberine sulfate standard solution with the concentration of 1.5% -2.5%, taking 0.15-0.25 g of montmorillonite fine powder with the granularity of less than 45 mu m, quantitatively adding a phosphate buffer solution with the pH value of 6.8, quantitatively adding the berberine sulfate standard solution, controlling the ratio of the sampling amount of montmorillonite to the adding amount of berberine sulfate to be 0.8-1.2, fully adsorbing excessive berberine sulfate by the montmorillonite, measuring the residual berberine sulfate by using a redox titration method, and then calculating the adsorption capacity of the montmorillonite.

2. The method for measuring the adsorption ability of montmorillonite according to claim 1, characterized in that: the titration solution used in the redox titration method is 0.01667mol/L potassium dichromate titration solution.

3. The method for measuring the adsorption ability of montmorillonite according to claim 1, characterized in that: the ratio of montmorillonite sampling amount to berberine sulfate addition amount is 1.

4. The method for measuring the adsorption ability of montmorillonite according to claim 1, characterized in that:

1) preparing a standard solution of berberine sulfate with the concentration of 2.0 percent: precisely weighing about 2.0g of berberine sulfate, placing into a 100ml measuring flask, adding appropriate amount of water, heating in water bath to dissolve, cooling, diluting with water to scale, and shaking to obtain solution containing 20mg of berberine sulfate per 1 ml;

2) and (3) measuring the adsorption force: taking 0.2g of montmorillonite fine powder with the particle size of less than 45 mu m, precisely weighing, placing in a conical flask with a plug, precisely adding 10ml of phosphate buffer solution with the pH value of 6.8, shaking uniformly, precisely adding 10ml of berberine sulfate standard solution, placing in a water bath at 37 ℃, shaking for 1 hour, filtering, and taking the subsequent filtrate as a sample solution; precisely measuring 10ml of phosphate buffer solution with pH of 6.8, precisely adding 10ml of the berberine sulfate standard solution, placing in water bath at 37 deg.C, and shaking for 1 hrFiltering, taking the subsequent filtrate as a blank test solution, accurately measuring 10ml of the test sample solution or the blank test solution, placing the solution in a 250ml measuring flask, accurately adding 50ml of 0.01667mol/L potassium dichromate titration solution, adding water to dilute the solution to a scale, shaking for 5 minutes, filtering with dry filter paper, accurately measuring 100ml of the subsequent filtrate, placing the subsequent filtrate in a 250ml conical flask with a plug, adding 2g of potassium iodide, shaking to dissolve the subsequent filtrate, adding 10ml of 18% hydrochloric acid solution, sealing the plug, shaking uniformly, placing the subsequent filtrate in the dark for 10 minutes, titrating the subsequent filtrate with 0.lmol/L sodium thiosulfate titration solution, adding 2ml of starch indicator solution when the final end point is reached, continuing to titrate until the blue color disappears, and the solution is bright green, calculating the adsorption force according to the following formula, wherein each lm0.01667 mol/L potassium dichromate titration solution is equivalent to 12.81mg of C₂₀H₁₄NO₄•1/2SO₄；

Adsorption capacity g/g = (V)_{Sample (A)}-V_{Air conditioner}）×F×12.81×5/M/10³

V_{Sample (A)}: volume of sodium thiosulfate consumed by test solution

V_{Air conditioner}: consumption of sodium thiosulfate volume by blank solution

F: f value of sodium thiosulfate titration solution

M: the weight of the test sample.

5. The method for measuring the adsorption capacity of montmorillonite according to claim 2, characterized in that: the adsorption capacity of montmorillonite was determined using berberine sulphate.

6. The method for measuring the adsorption capacity of montmorillonite according to claim 2, characterized in that: each lml0.01667mol/L potassium dichromate titration solution is equivalent to 12.81mg of C₂₀H₁₄NO₄•1/2SO₄。

Technical Field

The invention relates to a medicine analysis method, in particular to a method for measuring montmorillonite adsorption force by using berberine sulfate, belonging to the technical field of medicines.

Background

The mineral name of bentonite is montmorillonite (see, Jujiaying, Strin eds., the development and application of bentonite in engineering, 1 st edition of month 07/2003, page 1). Montmorillonite powder is used as an anti-diarrhea drug in the medical field, and is marketed in more than 100 countries and regions around the world. The pharmacological basis of the medicinal montmorillonite is the function of adsorbing pathogenic bacteria, viruses and bacterial toxins, and the magnitude of the adsorption force is a key index of the montmorillonite with low curative effect. Accurate detection of the adsorption force of montmorillonite is a method for controlling the quality of products and ensuring the curative effect.

The method for detecting the montmorillonite adsorption force in the existing national drug standard is to measure the amount of adsorbed strychnine sulfate. The method has the advantages that the adsorption force is measured accurately, but the strychnine sulfate belongs to A-grade organic highly toxic substances, the environment can be polluted when the strychnine sulfate is used, the experimenter can be injured by careless operation in the using process, and great potential safety hazards exist. Moreover, no enterprise produces strychnine sulfate which can meet the experimental requirements in China, and needs to purchase imported reagents, so that the purchase is difficult and the price is high, and the enterprise cost is increased virtually.

In other fields, the content of montmorillonite in the mineral is determined by detecting the methylene blue adsorption capacity of the montmorillonite, which is called blue adsorption amount for short, and the method is widely applied. The method for measuring the blue absorption amount is mainly a halo method in the reported article. The halo method is convenient to operate, simple in instrument and most commonly applied. However, because the liquid drops are taken out from the test paper for multiple times, and the eye is used for observing the green ring to determine the end point, the size of the green ring is greatly different due to human judgment, and the end point judgment is liquid taking observation, the result error is large, and the accuracy and precision of the method are limited.

Zhengxihua notes (see, Zhengxihua main edition, applied technology of bentonite, 1 st edition at 09 month 2001, pages 10 to 11): the adsorption force of bentonite can be divided into three types, namely physical adsorption, chemical adsorption and ion exchange adsorption.

(1) And (4) carrying out physical adsorption. Physical adsorption is produced by intermolecular attraction between the adsorbent and the adsorbate. Physical adsorption is a reversible adsorption process, and the adsorption speed and the desorption speed are in dynamic balance under certain conditions. The main reason for the physical adsorption is that the surface molecules of bentonite have surface energy. The bentonite is highly dispersed in water, so that the physical adsorption phenomenon is very obvious.

(2) And (4) carrying out chemical adsorption. Chemisorption is generated by the chemical bonding forces between the adsorbent and the adsorbate, and chemisorption is generally irreversible.

(3) And (4) ion exchange adsorption. Bentonite mineral crystals are generally negatively charged and adsorb an equivalent amount of oppositely charged cations, which can exchange with cations in solution, a process known as ion exchange adsorption. The ion exchange adsorption is characterized in that: the same numbers are separated from each other, and the isoelectric values are exchanged. The reaction of ion exchange adsorption is reversible, and the rates of adsorption and desorption are influenced by the ion concentration, which follows the law of mass action.

The factors influencing the bentonite mineral adsorption are:

(1) the effect of the bentonite type. The adsorption capacity of the sodium bentonite is obviously stronger than that of other types of bentonite such as calcium bentonite.

(2) The influence of the size of the crushed particle size of the bentonite particles. According to the theory of solid adsorption, the bentonite mineral adsorption capacity after being crushed is obviously improved, and the finer the crushing is, the stronger the adsorption effect is.

(3) Influence of the solution medium. According to the theory of electric double layer, the mineral crystals of bentonite are negatively charged, ion exchange is carried out when the electric double layer is formed, and if the ion concentration in the solution is too high, the electric double layer of bentonite particles is compressed, dispersion and diffusion of bentonite are inhibited, and even the bentonite is coagulated and agglomerated.

In summary, the adsorption force of montmorillonite includes three types of physical adsorption, chemical adsorption and ion exchange adsorption, wherein the ion exchange adsorption capacity is not influenced by the determined conditions and the concentration of adsorbed ions, is constant and belongs to isoelectric adsorption or stoichiometric reaction; the physical adsorption and chemical adsorption capacity can be determined by measuring the concentration of montmorillonite in the liquid, the dispersion degree of montmorillonite in the liquid, the granularity, the concentration of adsorbed ions, the pH value of the liquid, the temperature of the liquid, the chemical bond force between montmorillonite and adsorbed ions and other factors, and the physical adsorption and chemical adsorption capacity can be changed. An agent is selected to measure the adsorption force of the montmorillonite, and a series of scientific experiments are carried out to determine proper measuring conditions and methods.

The invention patent (CN 102406657 a) discloses (see paragraph 0039 of the specification) that the adsorption force of montmorillonite is derived from its internal charge imbalance. … …, the excess negative charge is compensated by cations adsorbed on the surface of the crystal layer, which are easily exchanged by other cations in the presence of water, known as exchange adsorption. The exchange adsorption has the following characteristics: (1) the same number of ions are exchanged, … … is a stoichiometric reaction, and the mass action law is met; (2) equal electrical quantities (or equal equivalents) are exchanged with each other, … …; (3) the exchange and adsorption of cations is reversible. According to the ion exchange adsorption characteristics of montmorillonite, the adsorbed agent can be a compound capable of dissociating positive ions in water or ethanol solution. These compounds include ammonium acetate, ammonium chloride, methylene blue, quinine sulfate, berberine, betaine, barium chloride, etc., which can dissociate positive ions in water or ethanol solution.

Orefin, norm H, indicates (orefin, usa, lead theory of clay colloid chemistry, 12 months, 1 st edition, 1982, page 169): the adsorption of organic cations is generally not limited by the cation exchange capacity equivalent of the clay. For example, it has been observed that the adsorption of montmorillonite clay to quaternary amine compounds having long chains and three methyl groups is approximately twice and half the cation exchange capacity of the clay.

The invention patent (CN 102406657A) only considers the ion exchange adsorption of montmorillonite, neglects the physical adsorption, the chemical adsorption and other factors influencing the adsorption, and has no general guiding significance. The specification also discloses (see paragraphs 0066 and 0067): experiment seven uses berberine to determine the adsorption force of montmorillonite used in the invention, uses high performance liquid chromatography to determine the adsorption force of montmorillonite to berberine sulfate, calculates the cation exchange capacity of montmorillonite to be 135mmol/100g, namely the adsorption force of montmorillonite used is 135mmol/100 g. The adsorption force of the montmorillonite comprises physical adsorption, chemical adsorption and ion exchange adsorption, and the physical adsorption and the chemical adsorption are influenced by various factors such as the concentration of the montmorillonite in the liquid, the dispersion degree of the montmorillonite in the liquid, the granularity, the concentration of adsorbed ions, the pH value of the liquid, the temperature of the liquid, the chemical bond force between the montmorillonite and the adsorbed ions and the like. The patent only discloses that the adsorption force of montmorillonite can be measured by berberine, and no specific measurement method is disclosed.

Disclosure of Invention

The invention aims to overcome the defects of the existing method for measuring the adsorption capacity of the medicinal montmorillonite preparation and provide a new method for measuring the adsorption capacity of the montmorillonite preparation. The method for measuring the adsorption capacity of the montmorillonite preparation has the advantages of good specificity, linearity, accuracy, precision, reproducibility, durability and the like, safety, no toxicity, convenience in purchase and management, low price and low cost.

The purpose of the invention is realized by the following technical scheme.

A method for measuring the montmorillonite adsorption force by using berberine sulfate is characterized in that: taking a preparation containing 0.15-0.25 g of montmorillonite, adding a phosphate buffer solution with the pH value of 6.8, adding berberine sulfate solution to ensure that the weight ratio of the montmorillonite to the berberine sulfate is 0.8-1.2 and the adsorption time is more than 30 minutes, measuring the residual berberine sulfate, and calculating the adsorption capacity of the montmorillonite preparation.

The invention relates to a method for measuring montmorillonite adsorption force by using berberine sulfate, which is characterized by comprising the following steps: taking a preparation containing 0.15-0.25 g of montmorillonite, wherein the granularity of the montmorillonite is less than 45 mu m, adding a phosphate buffer solution with the pH value of 6.8, adding a berberine sulfate solution to ensure that the weight ratio of the montmorillonite to the berberine sulfate is 0.8-1.2, and the adsorption time is more than 30 minutes, measuring the residual berberine sulfate, and calculating the adsorption force of the montmorillonite preparation;

wherein:

the method for measuring the particle size of the montmorillonite and the particle size range are as follows: taking 10g of montmorillonite, adding 500ml of water, stirring for 15 minutes at 5000 r/min, wetting a 45-micron pore size drug sieve which is dried to constant weight at 105 ℃ with water, pouring the stirred content into the drug sieve, washing the drug sieve with water until no suspension spots exist, drying the drug sieve for 3 hours at 105 ℃, and weighing. The weight of the unscreened granules should not exceed 1%.

The concentration of the berberine sulfate solution is as follows: 1.5% -2.5%;

the invention relates to a method for measuring montmorillonite adsorption force by using berberine sulfate, which is characterized by comprising the following steps: adding berberine sulfate solution to make the weight ratio of montmorillonite and berberine sulfate between 0.8-1.2, and adsorbing for more than 60min, and measuring the rest berberine sulfate to calculate the adsorption force of montmorillonite preparation.

The invention relates to a method for measuring montmorillonite adsorption force by using berberine sulfate, which is characterized by comprising the following steps: adding berberine sulfate solution to make the weight ratio of berberine sulfate to montmorillonite 1.

The invention relates to a method for measuring montmorillonite adsorption force by using berberine sulfate, which is characterized by comprising the following steps: the determination of the remaining berberine sulphate can be determined by titration.

The invention relates to a method for measuring montmorillonite adsorption force by using berberine sulfate, which is characterized by comprising the following steps: the steps of the titration method are as follows:

1) preparing a berberine sulfate solution with the concentration of 2.0 percent: precisely weighing berberine sulfate about 2.0g, placing into a 100ml measuring flask, adding appropriate amount of water, heating in water bath to dissolve, cooling, diluting with water to scale, and shaking to obtain solution containing 20mg berberine sulfate per 1 ml;

2) and (3) measuring the adsorption force: taking 0.2g of montmorillonite fine powder, precisely weighing, placing in a conical flask with a plug, precisely adding 10ml of phosphate buffer solution with the pH value of 6.8, shaking up, precisely adding 10ml of berberine sulfate standard solution, placing in a water bath at 37 ℃, shaking for 1 hour, filtering, and taking the subsequent filtrate as a sample solution;

precisely measuring 10ml of phosphate buffer solution with the pH value of 6.8, precisely adding 10ml of the berberine sulfate standard solution, placing in a water bath at 37 ℃, shaking for 1 hour, filtering, and taking the subsequent filtrate as a blank test solution;

respectively precisely measuring 10ml of a test solution and 10ml of a blank test solution, placing the test solution and the blank test solution into a 250ml measuring flask, precisely adding 50ml of 0.01667mol/L potassium dichromate titration solution, adding water to dilute the solution to scale, shaking for 5 minutes, filtering the solution by using dry filter paper, precisely measuring 100ml of a subsequent filtrate, placing the subsequent filtrate into a 250ml conical flask with a plug, adding 2g of potassium iodide, shaking to dissolve the potassium iodide, adding 10ml of 18% hydrochloric acid solution, sealing the plug, shaking uniformly, placing the subsequent filtrate in a dark place for 10 minutes, and dripping 0.lmol/L sodium thiosulfate into the subsequent filtrateAnd (4) titrating the solution until the end point is reached, adding 2ml of starch indicating solution, and continuously titrating until the blue color disappears, wherein the solution is bright green. The adsorption force was calculated as follows, and 12.81mg of C was equivalent to 0.01667mol/L potassium dichromate titration solution per lml₂₀H₁₄NO₄•1/2SO₄；

Adsorption capacity g/g = (V)_{Sample (A)}-V_{Air conditioner}）×F×12.81×5/M/10³

V_{Sample (A)}: volume of sodium thiosulfate consumed by test solution

V_{Air conditioner}: consumption of sodium thiosulfate volume by blank solution

F: f value of sodium thiosulfate titration solution

M: weight of test article

The method for measuring the adsorption capacity of the montmorillonite preparation has the advantages of good specificity, linearity, accuracy, precision, reproducibility, durability and the like, safety, no toxicity, convenience in purchase and management, low price and low cost.

The advantageous effects of the present invention are further illustrated by the following experimental examples and methodological studies. Experimental examples and methodological studies are intended to further illustrate the beneficial effects of the present invention and are not intended to limit the invention.

Test example: the determination methodology of the adsorption force of the medicinal montmorillonite is verified

1. Test article and reagent

And (3) testing the sample: montmorillonite (Jinan Zhi pure bentonite GmbH production)

Berberine sulfate: (batch No. 36XZM, Taixi Ai-Shanghai Kangcheng Industrial development Co., Ltd.)

2. Test methods and methodological validation

1) Preparing a berberine sulfate solution with the concentration of 2.0 percent: weighing berberine sulfate about 2.0g, accurately weighing, placing into 100ml measuring flask, adding appropriate amount of water, heating in water bath to dissolve, cooling, diluting with water to scale, and shaking to obtain solution containing 20mg berberine sulfate per 1ml

2) And (3) measuring the adsorption force: taking 0.20g of montmorillonite, precisely weighing, placing in a conical flask with a plug, precisely adding 10ml of phosphate buffer solution (pH 6.8), shaking, precisely adding 10ml of berberine sulfate standard solution, placing in a water bath at 37 ℃, shaking for 1 hour, filtering, and taking the subsequent filtrate as a sample solution;

precisely measuring 10ml of phosphate buffer solution (pH6.8), precisely adding 10ml of the berberine sulfate standard solution, placing in water bath at 37 deg.C, shaking for 1 hr, filtering, and collecting the filtrate as blank test solution.

Respectively and precisely measuring 10ml of a test solution and 10ml of a blank test solution, placing the test solution and the blank test solution into a 250ml measuring flask, precisely weighing 50ml of potassium chromate titration solution (0.01667mol/L), adding water to dilute the test solution to a scale, shaking the test solution for 5 minutes, filtering the test solution by using dry filter paper, precisely weighing 100ml of subsequent filtrate, placing the subsequent filtrate into a 250ml conical flask with a plug, adding 2g of potassium iodide, shaking the subsequent solution to dissolve the potassium iodide, adding 10ml of 18% hydrochloric acid solution, sealing the plug, shaking the subsequent solution uniformly, placing the subsequent solution in a dark place for 10 minutes, titrating the subsequent solution by using sodium thiosulfate titration solution (0.lmol/L), adding 2ml of starch indicator solution when the final point is reached, continuing to titrate until blue disappears. The adsorption force was calculated as follows, and 12.81mg of (C) per lml of potassium dichromate titration solution (0.01667mol/L)₂₀H₁₄NO₄）₂•SO₄；

Adsorption capacity (g/g) = (V)_{Sample (A)}-V_{Air conditioner}）×F×12.81×5/M/10³

V_{Sample (A)}: volume of sodium thiosulfate consumed by test solution

V_{Air conditioner}: consumption of sodium thiosulfate volume by blank solution

F: f value of sodium thiosulfate titration solution

M: weight of test article

The method is verified by referring to appendix 9101 of the four parts of the year 2015 of Chinese pharmacopoeia.

Parameter determination for an adsorption force determination method

2.1.1 determination of the adsorption time

Taking 7 parts of sample, testing according to the above method, setting reaction time at 1min, 5min, 10min, 30min, 60min, 90min and 120min, and measuring the time curve of adsorption force, wherein the results are as follows (the adsorption force curve of different reaction times is shown in figure 1):

TABLE 1 results of adsorption force at different reaction times

Reaction time (min)	0	1	5	10	30	60	90	120
									Adsorption capacity (g/g)	0	0.352	0.405	0.408	0.424	0.435	0.436	0.434

As a result, it was found that when the adsorption force of montmorillonite was measured with 2.0% berberine sulfate solution, the adsorption force became large as the time elapsed, and about 93% of the total adsorption amount was reached at 5min and about 97% or more of the total adsorption amount was reached at 30min, and thereafter the increase of the adsorption force became gentle and balanced at 60min, and therefore, the adsorption time was determined to be 30min, preferably 60min or more.

2.1.2 determination of berberine sulfate concentration (addition amount)

Taking 7 parts of sample, precisely adding 19ml, 18ml, 16ml, 12ml, 10ml, 8ml and 5ml of phosphate buffer solution (pH6.8) and 1ml, 2ml, 4ml, 8ml, 10ml, 12ml and 15ml of berberine sulfate solution (20 mg/ml) according to the test of the measuring method of the adsorption force, and measuring the relation between the adsorption force and the reaction concentration, wherein the results are as follows (the relation curve between the concentration of the berberine sulfate solution and the adsorption force is shown in figure 2):

TABLE 2 relationship between initial reaction concentration and adsorption force

Serial number	1	2	3	4	5	6	7
								Initial concentration (mg/ml)	1	2	4	8	10	12	15
Adsorption force g/g	0.403	0.405	0.408	0.431	0.435	0.437	0.439

The test results show that the adsorption capacity is increased with the increase of the added berberine sulfate, and when the amount of the berberine sulfate solution with 2.0 percent of the added berberine sulfate is more than 8ml, the adsorption capacity still continues to increase, but the increase of the adsorption capacity is reduced, so that the adsorption capacity of the montmorillonite is determined to be measured by using the berberine sulfate solution with 2.0 percent and the method, and the added berberine sulfate solution is 10 ml.

2.1.3 method for measuring adsorption force

The provisional adsorption capacity was measured by the above test as follows:

1) preparing a berberine sulfate solution with the concentration of 2.0 percent: precisely weighing about 2.0g of berberine sulfate, placing into a 100ml measuring flask, adding appropriate amount of water, heating in water bath to dissolve, cooling, diluting with water to scale, and shaking to obtain solution containing 20mg of berberine sulfate per 1ml

2) And (3) measuring the adsorption force: taking 0.20g of montmorillonite, precisely weighing, placing in a conical flask with a plug, precisely adding 10ml of phosphate buffer solution (pH 6.8), shaking, precisely adding 10ml of berberine sulfate standard solution, placing in a water bath at 37 ℃, shaking for 1 hour, filtering, and taking the subsequent filtrate as a sample solution;

precisely measuring 10ml of phosphate buffer solution (pH6.8), precisely adding 10ml of the berberine sulfate standard solution, placing in water bath at 37 deg.C, shaking for 1 hr, filtering, and collecting the filtrate as blank test solution.

Precisely measuring 10ml of a test solution and a blank test solution, placing the test solution and the blank test solution into a 250ml measuring flask, precisely weighing 50ml of a potassium chromate titration solution (0.01667mol/L), adding water to dilute the test solution to a scale, shaking for 5 minutes, filtering the test solution by using dry filter paper, precisely weighing 100ml of a subsequent filtrate, placing the subsequent filtrate into a 250ml conical flask with a plug, adding 2g of potassium iodide, shaking to dissolve the potassium iodide, adding 10ml of 18% hydrochloric acid solution, sealing the plug, shaking uniformly, placing the subsequent filtrate in a dark place for 10 minutes, titrating the subsequent filtrate by using a sodium thiosulfate titration solution (0.lmol/L), adding 2ml of a starch indicator solution when the final point is reached, continuing to titrate until the blue disappears, and the solution is bright green. The adsorption force was calculated as follows, and 12.81mg of (C) per lml of potassium dichromate titration solution (0.01667mol/L)₂₀H₁₄NO₄）₂•SO₄；

Adsorption capacity (g/g) = (V)_{Sample (A)}-V_{Air conditioner}）×F×12.81×5/M/10³

V_{Sample (A)}: volume of sodium thiosulfate consumed by test solution

V_{Air conditioner}: consumption of sodium thiosulfate volume by blank solution

F: f value of sodium thiosulfate titration solution

M: weight of test article

2.2 methodological validation

The method is verified by referring to appendix 9101 of the four parts of the year 2015 of Chinese pharmacopoeia.

2.2.1 specificity

Preparing a test solution: taking 0.20g of montmorillonite, precisely weighing, placing in a conical flask with a plug, precisely adding 10ml of phosphate buffer solution (pH6.8), shaking up, precisely adding berberine sulfate solution (taking about 2g of berberine sulfate with known content, precisely weighing, placing in a 100ml measuring flask, adding a proper amount of water, heating on a water bath to dissolve, cooling, diluting with water to scale, shaking up to obtain solution containing 20mg of berberine sulfate per 1 ml), placing in a water bath at 37 ℃, shaking up for 1 hour, filtering, and taking the subsequent filtrate as a test sample solution;

precisely measuring 10ml of phosphate buffer solution (pH6.8), precisely adding 10ml of the above 20mg/ml berberine sulfate solution, placing in water bath at 37 deg.C, shaking for 1 hr, filtering, and collecting the filtrate as blank test solution.

Preparation of negative solution: taking 0.20g of montmorillonite, precisely weighing, placing in a conical flask with a stopper, precisely adding 10ml of phosphate buffer solution (pH 6.8), precisely adding 10ml of water, and preparing a negative solution by the same method from 'placing in a water bath at 37 ℃ and shaking for 1 hour' according to the preparation method of the test solution.

The determination method comprises the following steps: accurately measuring 10ml of a test solution or a negative solution or a blank test solution, placing the test solution or the negative solution or the blank test solution into a 250ml measuring flask, accurately weighing 50ml of potassium chromate titration solution (0.01667mol/L), adding water to dilute the solution to a scale, shaking for 5 minutes, filtering the solution by using dry filter paper, accurately measuring 100ml of a subsequent filtrate, placing the filtrate into a 250ml conical flask with a plug, adding 2g of potassium iodide, shaking to dissolve the potassium iodide, adding 10ml of 18% hydrochloric acid solution, sealing the plug, shaking uniformly, placing the mixture in a dark place for 10 minutes, titrating the mixture by using sodium thiosulfate titration solution (0.lmol/L), adding 2ml of starch indicator solution when the endpoint is reached, continuing to titrate until blue disappears, and the solution is bright green.

As a result: the negative solution does not consume the potassium dichromate titration solution, which shows that the method has good specificity.

2.2.2 Linear Range test

Taking 0.1g, 0.2g, 0.3g, 0.4g and 0.5g of berberine sulfate, precisely weighing, placing in a 250ml measuring flask, adding appropriate amount of water to dissolve, precisely weighing 50ml of potassium chromate titration solution (0.01667mol/L), adding water to dilute to scale, shaking for 5min, filtering with dry filter paperPrecisely measuring 100ml of subsequent filtrate, placing the subsequent filtrate in a 250ml conical flask with a plug, adding 2g of potassium iodide, shaking to dissolve the subsequent filtrate, adding 10ml of 18% hydrochloric acid solution, sealing the plug, shaking uniformly, standing in the dark for 10 minutes, titrating by using sodium thiosulfate titration solution (0.lmol/L), adding 2ml of starch indicator solution when the end point is reached, and continuing to titrate until the blue color disappears, so that the solution is bright green. 12.81mg of (C) per lml of potassium dichromate titration solution (0.01667mol/L)₂₀H₁₄NO₄）₂•SO₄. The results are given in Table 3 below:

TABLE 3 results of the Linear relationship test

Sample volume (g)	0.1021	0.1992	0.3013	0.3988	0.5019
						Volume of titration solution (ml)	17.2	14.8	12.1	9.6	6.9

Taking the sample amount as an abscissa and the volume of the sodium thiosulfate consumption titration solution as an ordinate, a linear regression equation y = -25.823x + 19.884 is obtained, and the correlation coefficient r =0.9999 is obtained (the linear relation graph is shown in figure 3).

The result shows that the berberine sulfate concentration and the volume of the titration solution of consumed sodium thiosulfate have good linear relation within the sampling amount range of 0.1-0.5.

2.2.3 precision

2.2.3.1 repeatability

6 parts of the sample are taken, and a repeatability test is carried out according to an adsorption force measuring method, and the result is shown in a table 4.

TABLE 4 results of the repeatability tests

Test No	1	2	3	4	5	6	Average	RSD%
									Adsorption capacity (g/g)	0.428	0.436	0.431	0.427	0.433	0.432	0.431	0.77%

The result RSD% is less than 2.0%, which shows that the method has good repeatability.

2.2.3.2 different analysts

The test samples were taken and tested by different testers, and the results are shown in Table 5.

TABLE 5 precision of different experimenters

The result RSD% is less than 2.0%, which shows that the precision of different testers is good.

2.2.3.3 different dates of analysis

The test samples were taken and measured on different days, and the results are shown in Table 6.

TABLE 6 results of different dates of analysis

Date	Date 1	Date 2	Date 3	Average	RSD%
						Adsorption capacity (g/g)	0.432	0.434	0.438	0.435	0.71%

The result RSD% is less than 2.0%, indicating that the precision is good at different analysis dates.

2.2.4 accuracy

Preparation of 1% berberine sulfate solution: taking 1.0g of berberine sulfate, precisely weighing, and dissolving with water to 100ml to obtain 10.224mg/ml berberine sulfate solution.

Taking 6 parts of conical flask with plug, respectively adding 10ml of phosphate buffer solution (pH 6.8) precisely, then adding 10ml of the above 0.01g/ml berberine sulfate solution precisely and 0.1g of berberine sulfate reference substance precisely, shaking up to dissolve, taking 0.20g of montmorillonite with known adsorption capacity of 0.431g/g, precisely weighing 6 parts, placing in the conical flask, and measuring according to the adsorption capacity measuring method from 'placing in water bath at 37 ℃ and shaking for 1 hour', the results are as follows:

TABLE 7 recovery results

The result shows that the method has good accuracy.

2.2.5 range

The amount of the test sample in the range of 80-120% of the test amount of the product is taken and tested according to the method for measuring the adsorption force, and the results are shown in table 8:

TABLE 8 Range of test results

The result shows that the sampling is carried out within the range of +/-20% of the testing amount, and the determination result is reliable.

The result of the above methodology verification shows that the method for determining the adsorption capacity of the medicinal montmorillonite is good in specificity, linearity, accuracy, precision, durability and the like, safe, nontoxic, convenient to purchase and manage, low in price and low in cost.

The method for measuring the adsorption capacity of the medicinal montmorillonite can be used for montmorillonite raw materials and montmorillonite preparations. The montmorillonite preparation comprises clinically acceptable dosage forms such as powder, tablets, capsules, granules, suspension, gels, dispersible tablets and the like.

Drawings

Figure 1, adsorption force versus time curve. The graph shows that the adsorption force of montmorillonite is measured by using 2.0% berberine sulfate solution, and the adsorption force result becomes larger with the time.

FIG. 2 is a graph showing the relationship between the concentration of berberine sulfate solution and the adsorption force. As shown in the figure, the adsorption capacity is increased with the increase of the added amount of berberine sulfate, and when the added amount of 2.0% berberine sulfate solution is more than 10ml, the adsorption capacity still continues to increase, but the increase of the adsorption capacity is reduced.

Fig. 3, a linear range inspection diagram. The figure shows that the concentration of berberine sulphate remaining titrated with sodium thiosulphate titrant (0.lmol/L) is in a good linear relationship in the range of 0.04% (g/ml) to 0.2% (g/ml).

The invention is further illustrated by the following specific examples.

Detailed Description