477 results about "Phenolphthalein" patented technology

Disclosed herein is a method for producing a 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine. The method comprises forming a reaction mixture comprising at least one substituted or unsubstituted phenolphthalein, at least one substituted or unsubstituted primary hydrocarbyl amine, and an acid catalyst; and heating the reaction mixture to a temperature of less than 180° C. to remove a distillate comprising water and form a crude 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine product; where the 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine has a formula: where R1 is selected from the group consisting of a hydrogen and a hydrocarbyl group, and R2 is selected from the group consisting of a hydrogen, a hydrocarbyl group, and a halogen.

The invention discloses bifidobacterium bifidum capable of remarkably relieving constipation and application thereof and belongs to the technical field of microorganisms. The bifidobacterium bifidum CGMCC NO.13632 can well tolerate simulative gastrointestinal fluid, can be well attached to colon cancer cells HT-29, and can remarkably increase the water content of excrement of constipation mice and shorten the first tarry stool time. On the aspect of increasing the small intestine driving rate, the bifidobacterium bifidum CGMCC NO.13632 is superior to cathartic phenolphthalein, a best effect is shown, secretion of gastrointestinal regulatory peptide relevant to constipation in serum is also adjusted while constipation pathological factors are remarkably improved, and the bifidobacterium bifidum does not have toxic and side effects of medicine for treating constipation, and is a first choice for preventing and treating constipation. The bifidobacterium bifidum CGMCC NO.13632 is used for preparing pharmaceutical compositions and fermented food for relieving constipation, and has very wide application prospects.

Disclosed herein is a method for producing a 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine. The method comprises forming a reaction mixture comprising at least one substituted or unsubstituted phenolphthalein compound, at least one substituted or unsubstituted primary hydrocarbyl amine, and an acid catalyst; and heating the reaction mixture to form 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine. An adduct of the 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine is formed either by using an excess of the primary hydrocarbyl amine in the first heating step, or by isolating crude 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine after the heating step and then reacting with a further amount of the primary hydrocarbyl amine. The 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine has a formula:where R1 is selected from the group consisting of a hydrogen and a hydrocarbyl group, and R2 is selected from the group consisting of a hydrogen, a hydrocarbyl group, and a halogen.

The present invention relates to a polymer blend proton exchange membrane comprising a soluble polymer and a sulfonated polymer, wherein the soluble polymer is at least one polymer selected from the group consisting of polysulfone, polyethersulfone and polyvinylidene fluoride, the sulfonated polymer is at least one polymer selected from the group consisting of sulfonated poly(ether-ether-ketone), sulfonated poly(ether-ketone-ether-ketone-ketone), sulfonated poly(phthalazinone ether keton), sulfonated phenolphthalein poly(ether sulfone), sulfonated polyimides, sulfonated polyphosphazene and sulfonated polybenzimidazole, and wherein the degree of sulfonation of the sulfonated polymer is in the range of 96% to 118%. The present invention further relates to a method for manufacturing the polymer blend proton exchange membrane.

The invention relates to a water alkalinity on-line detection device, a water alkalinity on-line measuring device based on solution image technology and a measuring method thereof, and is characterized in that according to the invention, based on the detection of solution image RGB values during the titration of water to be detected by a HCl solution, an image RGB value-titration solution volume measuring curve is plotted, and the water alkalinity of the solution to be detected is calculated according to the titration solution volume corresponding to an inflection point of the image RGB value measuring curve. With computer image processing technology, the invention establishes a mathematical model of solution RGB values with the change of the titration solution volume during titration, determines the titration end point automatically, establishes a color constancy algorithm model based on a neural network algorithm, and thus increases the precision and reliability of alkalinity measurement. With the device of the invention, on-line measurement of phenolphthalein alkalinity and total alkalinity can be performed optionally, and the operation is convenient. The device is applicable to industry of electric power, petroleum, chemical industry, metallurgy, etc.

The invention discloses bifidobacterium longum and applications thereof, and belongs to the technical field of microorganisms. The bifidobacterium longum is deposited in the China General Microbiological Culture Collection Center in Institute of Microbiology, Chinese Academy of Sciences at number 3, No.1 yard, Beichenxi road, Chaoyang district, Beijing on December 7, 2017, and the accession numberis CGMCC NO.15032. The bifidobacterium longum has good growth, acid production, and acid resistant properties, and high adhesive capacity, can significantly increase the water content of faeces and the pushing rate of small intestine of mice with constipation, shortens the first black stool evacuation time, relieves inflammation of colonic mucosas, and regulates contents of gastrointestinal peptides related to constipation in serum. A constipation relieving effect of the bifidobacterium longum is equivalent to that of bifidobacterium animalis BB12, but an effect of the bifidobacterium longumon the pushing rate of small intestine is superior to those of bifidobacterium animalis BB12 and phenolphthalein. Accordingly, the bifidobacterium longum strain CCFM760 can be widely applied in various foods or medicine matrixes.

The invention relates to a preparation method of triethyl citrate. The preparation method is as follows: by deeply studying the preparation process of triethyl citrate, setting a reaction feed ratio; then adding catalyst to perform reflux reaction; then utilizing phenolphthalein as an indicator and sodium hydroxide to perform titration to determine the reaction end point; utilizing weak base to neutralize less acidic materials in the obtained product, and eluting sodium carbonate with purified water; and finally utilizing activated carbon to decolor, thus obtaining the pure triethyl citrate product. Compared with the prior art, the preparation method provided by the invention has the advantages that the reaction end point is strictly controlled, unnecessary side reactions are reduced, thereduction of the product quality and the waste of cost caused by inadequate reaction or too long reaction time can be avoided; by controlling the temperatures of the processing steps, the damages caused by side reactions are reduced as far as possible; by selecting the decoloring mode, an ideal, colorless and transparent liquid product can be obtained; and the product quality is above the national standard: especially the acid value is controlled to be about 0.2 while the acid value of the national standard is 1.0, and the stability of the product when stored for a long time is higher than those of the like products.

The invention discloses a benzoxazine intermediate, composition and method for preparation, phenolphthalein type benzoxazine intermediate has a structural formula disclosed in the specification, wherein R is C3-C20 alicyclic hydrocarbon and its derivative, C3-C20 aliphatic hydrocarbon and its derivative, or C3-C20 unsaturated aliphatic hydrocarbon and its derivative. The intermediate is prepared by using phenothalin, primary amine and aldehyde as raw material through through solution synthesizing process or melting synthesizing process.

Disclosed herein is a method for producing a 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine. The method comprises forming a reaction mixture comprising at least one substituted or unsubstituted phenolphthalein compound, at least one substituted or unsubstituted primary hydrocarbyl amine, and an acid catalyst; and heating the reaction mixture to form 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine. An adduct of the 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine is formed either by using an excess of the primary hydrocarbyl amine in the first heating step, or by isolating crude 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine after the heating step and then reacting with a further amount of the primary hydrocarbyl amine. The 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine has a formula: where R1 is selected from the group consisting of a hydrogen and a hydrocarbyl group, and R2 is selected from the group consisting of a hydrogen, a hydrocarbyl group, and a halogen.

The invention discloses a method for preparing sulfonated polymer films, which comprises the following steps: preparing a casting solution and film-forming on the basis of phase-inversion. The sulfonation reaction is carried out between one or two of polyether-ether-ketone (PEEK), phenolphthalein polyaryl ether sulfone (PES-C) or polystyrene (PS) and concentrated sulfuric acid, fuming sulfuric acid or chlorosulfonic acid to obtain a sulfonated polymer solution in the preparation of the casting solution; and then, the film is directly formed on the basis of the phase-inversion method. The sulfonated polymer film prepared by the invention has higher pure water flux and protein retention rate, furthermore, the method has the advantages of good anti-pollution performance, higher mechanical strength and simple preparation process.

The invention provides a method for performing non-destructive detection on evolution of the three-dimensional carbonation depth of a cement-based material through X-ray computerized tomography and relates to a novel detection method for the carbonation depth of a cement-based material. The main principle is that: an image is reconstructed by acquiring ray attenuation information of a rotary object based on an X-ray source; a carbonized region and a non-carbonized region of the cement-based material are distinguished according to difference of gray value; and the defects in the traditional pHmethod of phenolphthalein alcohol solution are overcome. Under the condition of not damaging a test piece, the evolution process of the three-dimensional carbonation depth of the cement-based material along with the time is detected. By the method, flaw space distribution in the carbonation process, the flaw volume, the flaw closing area, the evolution law of porosity and hole dimensional distribution and the topological properties, such as connectivity, sinuosity and the like, of the hole can be achieved.

The invention relates to a method for simultaneously detecting seven slimming chemical components which are illegally added to traditional Chinese medicine, health food or cosmetics. According to the method, an appropriate mobile phase and a reasonable elution gradient are adopted during liquid-phase separation, so that the slimming components needing to be detected are effectively separated within 12 min, the analysis time of a sample instrument is shortened by 88%, and the work efficiency is greatly increased. Additionally, the advantages of high separation ability of the HPLC (High Performance Liquid Chromatography) technology, high sensitivity and stronger qualitative ability of the mass spectrum and the like are combined, so screening and confirmation can be simultaneously completed during one operation. By using the method disclosed by the invention, the seven chemical components including sibutramine, fenfluramine, phenolphthalein, ephedrine, caffeine, N,N-bi-demethylation sibutramine and furosemide can be effectively separated, the inspection time can be shortened, and the slimming chemical components which are illegally added to the traditional Chinese medicine, the health food or the cosmetics can be accurately and effectively distinguished.

A thermosetting resin composition and a prepreg or laminate using the same are provided. The thermosetting resin composition includes an epoxy resin and a curing agent, in which the curing agent is a dual-curing agent system formed with a multi-functional aromatic polyester curing agent in combination with a phenolphthalein benzoxazine phenol aldehyde or a poly(styrene-co-maleic anhydride). An organic or inorganic fiber reinforced material is impregnated with the thermosetting resin composition to form a prepreg, and the prepreg is bonded to a substrate with a metal foil disposed thereon, to form a laminate.

Method for detecting a basic target species in a fuel composition, by (i) adding a spectroscopically active indicator which is capable of reacting with the target species, and (ii) detecting the spectroscopic response (suitably a colour change) of the fuel composition to the presence of the indicator. The method may be used to detect an additive such as a detergent or dispersant additive, in particular in an automotive gasoline or diesel fuel or a lubricating oil. Also provided is a kit for carrying out the method, in particular in the field. The indicator may be a phenolphthalein indicator such as tetrabromophenolphthalein ethyl ester (HTBPE).

The invention relates to carboxyl-side-group-containing polyarylether copolymers and a preparation method thereof, and application of the copolymers in the aspect of ultrafiltration membrane hydrophilic modification, belonging to the technical field of ultrafiltration membrane preparation. By adopting nucleophilic polycondensation and one-step feeding, the mole ratio of the phenolphthalin bisphenol monomer to the total bisphenol monomer is changed to prepare a series of polyarylether copolymers with different carboxylation degrees; and the polyarylether copolymers are used as the membrane material preparation membrane casting solution to prepare a series of ultrafiltration membranes by an impregnation precipitated-phase conversion process. The hydrophilicity and water flux of the carboxyl-side-group-containing modified polyarylether ultrafiltration membranes are obviously enhanced. The modified monomer phenolphthalin can be obtained only by hydrolyzing / reducing phenolphthalein, so the experimental operation is simple, and the raw material price is low. In addition, the technique has the advantages of enduring chemical hydrophilic modification, high repetitiveness and the like, and is easy to operate.

The invention discloses a high-stability allochroic solid adhesive and a preparation method thereof. The allochroic solid adhesive is prepared by the method according to the following steps: adding all the following raw materials in portion by weight into a reaction kettle of which the temperature is between 50 and 100 DEG C: 50 to 75 portions of dispersant water, 10 to 45 portions of bonding agent such as polyvinyl pyrrolidone, 5 to 18 portions of excipient such as sodium stearate, 5 to 15 portions of humectant such as glycerol, 0.1 to 1 portion of developer phenolphthalein, and proper amount of color stabilizer; stirring the raw materials at a temperature of between 80 and 100 DEG C for one hour, and then adjusting the pH to between 9 and 11; and then standing the mixture at a constant temperature, and bottling the mixture to obtain a purple solid adhesive. The allochroic solid adhesive has a reasonable and simple formulation, easy manufacture and production and low cost; the colloid is purple when the allochroic solid adhesive is coated on a substrate material, and the purple disappears in a short time to meet the requirements in specific fields; besides, the allochroic solid adhesive has the most prominent characteristic that the color is stable during storage and is basically unchanged for more than two years.

The invention discloses a preparation method of phenolphthalein polyether sulfone containing a tertiary amine side group, which comprises the following steps of: (a) adding a halogenated organic matter monomer or a nitrified organic matter monomer, a catalyst and a solvent into a prepared phenolphthalein bisphenol monomer containing the tertiary amine side group to form a mixed solution; and (b) leading the mixed solution to react at 80-220 DEG C. The invention also discloses a phenolphthalein polyether sulfone homopolymer containing the tertiary amine side group and a phenolphthalein polyether sulfone copolymer containing the tertiary amine side group. The phenolphthalein or the phenolphthalein polyether sulfone is adopted as a raw material to generate substitution reaction with asymmetric amine to obtain the phenolphthalein polyether sulfone containing the tertiary amine side group. Because a tertiary amine group is a polar group and has higher hydrophily, the application limitation of the phenolphthalein polyether sulfone is overcome, and particularly, the adverse effect of the phenolphthalein polyether sulfone used as an ultrafiltration membrane or a reverse osmosis support base membrane applied to water treatment is eliminated. Meanwhile, the tertiary amine group has higher activity, is easy to convert into other groups, such as a quaternary amine group, and the like, and is beneficial to the further functionalization of the phenolphthalein polyether sulfone and the modification of a polyether sulfone product.

The invention discloses a temperature-changeable microcapsule coating which comprises the following components in parts by mass: 20-50 parts of temperature-changeable microcapsules, 2-8 parts of a spacing agent, 2-10 parts of an adhesive and 100-250 parts of water, wherein each temperature-changeable microcapsule comprises a core material and a capsule wall coating the core material; the core material comprises a solvent, a color former and a color developing agent; and the color former is a phenolphthalein or fluoran compound containing a lactonic ring structure. The temperature-changeable microcapsule coating disclosed by the invention is relatively wide in color changing temperature range, and can be subjected to color changing reaction in a temperature range of 30-80 DEG C, and urea is added during the preparation of microcapsule powder to absorb formaldehyde in a capsule wall material, so that the maximization of the material utilization rate is realized, and the surrounding environment is protected.

This invention relates to one rapid test method of sodium sulfoxylate formaldehyde in food, which comprises the following steps: a, preparing sample and smashing the food to be tested for dipping and filtering for use; b, formaldehyde testing and using the reaction between the formaldehyde and sodium sulfite to generate OH- and according to the characteristics of product, judging by the color developing method of thymol phthalein and semi-determining the content by electrometric method; c, sodium acid sulfite testing: using amidon as indicator and generating Na2SO4 and I- to turning the solution from blue to none to judge whether there is NaHSO3.

The invention provides a measuring method for fluorine ion content in glass. The measuring equipment adapting the measuring method comprises selecting electrode of fluorine ion, reference electrode, PH acidimeter and magnetic stirrer. Reagent comprises sodium hydroxide, phenolphthalein indicator, hydrochloride and regulating buffering solution of total ion intensity. The measuring method comprises following procedures that sample is washed and dried; sample of sodium hydroxide is melted; melted sample is immerged by hot de-ionized water; the regulating and buffering solution of total ion intensity is added; potential value is measured by the selecting electrode of fluorine ion; logarithm value of fluorine ion concentration is found on the calibration curve; fluorine ion concentration is calculated according to the formula of F-%=[(VXCX10) / (GX1000)]X100=(VXC) / G. Where: V--cubage of sample detecting solution (ml); G--sample weight (g); C-logarithm value of fluorine ion concentration found on the calibration curve. The invention is simple, quick and low cost compared with prior technology.

The invention provides quaternary ammonium lateral groups-containing phenolphthalein type polyarylether and the method for preparing the same. The preparation method comprises the following steps of: dissolving a bisphenol monomer and a di-halogen monomer of tertiary amine lateral groups-containing phenolphthalein, which serve as raw materials, into an aprotic polar solvent to perform a reaction to obtain the tertiary amine lateral groups containing polyarylether; and after the reaction is ended, dissolving the obtained tertiary amine lateral groups-containing polyarylether in the aprotic polar solvent to perform a reaction with halogenated hydrocarbons. The preparation method can accurately control the positions and number of the quaternary ammonium functional groups, avoids the use of chloromethylation reagent(such as methylchloromethyl ether) which is highly poisonous and a strong carcinogen; and the obtained quaternary ammonium lateral groups containing phenolphthalein type polyarylether has good dissolvability and contributes to the further functionalized application; and the tertiary amine groups contained in the intermediate product of the tertiary amine lateral group-containing polyarylether easily make other similar reactions so as to derive other functional groups.

The present invention is solution pH value detecting test paper and its preparation process. The test paper includes color developing test paper sheet with test function, and the test paper sheet is soaked in the mixed ethanol and water solution of soap yellow, methyl red, bromcresol green, nitrate nitrogen yellow, phenolphthalein, Alizarine Yellow and Dadan yellow. The mixed solution has pH value of 5-8. The test paper is used in testing the pH value of solution, or the concentration of hydrogen ion and hydroxide radical ion. It is suitable for various solution, including ground water, underground water, industrial waste water, etc.

The invention provides an erasable bluish dark writing liquid. The writing liquid mainly comprises the following components: alpha-naphtholphthalein, phenolphthalein, sodium hydroxide, ethanol, formaldehyde, a thickener, a surfactant and distilled water. The writing liquid is prepared by a complementary color principle, and has no toxicity, no penetrating odor and no corrosion. The writing liquid can not only be applied to a teaching board but also be applied to water-color brushes for children. The preparation process is simple and the writing liquid has convenient use. The writing liquid can be erased by water solution, and is a writing liquid without environmental pollution and harm to human bodies.

The invention relates to a new fluorine polyaryletheretherketone soluble high-performance material, process for preparation and the blend film material formed by the epoxide resin. The process for preparation comprises the following procedures: regarding 4,4'- difluorobenzophenone or 4,4'-difluorotribenzodiketone and mixing bisphenol monomer as the material; controlling the proportion of bisphenol hexaflurate A ( or trifluoromethyl phenyl eldopaque) and bisphenol A ( or fenolftaleina) in the segment of polymer via the way of nucleophilic substitution reaction; getting the new fluorine polyaryletheretherketone soluble high-performance material; furthermore, selecting the immobilized liquid epoxide resin and the functional polymer blend film prepared by the new fluorine polyaryletheretherketone soluble high-performance material in order to achieve the functionalization of polyaryletheretherketone material for meeting the aim of the different applying range and extending the processing window. The blend film material is suitable for high-performance composite material resin base field, microelectronic insulating material field, optical waveguide device field and air permoselective membrane field and the like.

The invention discloses a carbonation depth detector. The carbonation depth detector comprises a staff, a microscope, a lighting source, a camera, a detector housing, a bulge on the end of the staff, a precision gear, a signal cable, a current supply cable, an image collecting and processing chip, a video display, a roller with a spring, a power switch, a power work indicating lamp, a diode and a camera power supply module. The carbonation depth detector can clearly and truly display the color change of concrete after phenolphthalein is sprayed on concrete; and the carbonation dividing line can be accurately found through the displayed image video, thus avoiding the error caused by oblique visual observation. Therefore, the measurement is fast and the operation is simple.

The invention relates to a piece of highly sensitive pH test paper and a preparation method thereof, wherein a developing strip is in the form of a piece of pH body paper, which is dipped in a reagent solution and then dried by hot air at constant temperature; the reagent solution contains an indicator; the formula of the indicator contains bromothymol blue, thymol blue, metanil yellow, m-methyl red, bromocresol green, nitrazine yellow, cresol red, phenolphthalein, para-nitrophenylazosalicylate sodium, titan yellow, fluorescent pigment orange red, 5% 4-nitrobenzenediazo-1-naphthol-3.6-sodium disulfonate solution and 30% dissolved ethanol aqueous solution; and the formula of the indicator further contains an aqueous colour fixing agent, a cotton wooden fibre mildew preventive, a special paper mildew preventive and a buffer neutralizer formed by modulating sodium hydroxide and phosphoric acid. The preparation method comprises the following steps of: adjusting the reagent solution till a pH value is up to 6-7.5, uniformly wetting the pH body paper, and drying through hot air at constant temperature. According to the invention, the reagent solution can be adjusted, so that the pH value is up to 6-7.5; steady and precise high sensitivity of the pH1-14 test paper is effectively increased; and the test paper is convenient and simple to use.

The invention discloses a device and a method for continuously analyzing pH value, phenolphthalein end-point alkalinity, total alkalinity and chloridion concentration. The method comprises the following steps: a. using a standard acid liquid adding unit to perform alkalinity titration to a sample to be detected, and sequentially performing the alkalinity titration: phenolphthalein end-point alkalinity titration and total alkalinity titration, and respectively reading corresponding liquid volume values for titration in the titration end-point, calculating the phenolphthalein end-point alkalinity and the total alkalinity, wherein the initial pH value acquired by a pH electrode is the pH value of the sample to be detected; and b. performing chloridion potentiometric titration to the sample to be detected after the total alkalinity is completed, reading the liquid volume value for the titration when in the titration end-point and calculating the chloridion concentration. The device for continuously analyzing the pH value, the phenolphthalein end-point alkalinity, the total alkalinity and the chloridion concentration comprises a potentiometric titrimeter main machine with double electrode interfaces, the pH electrode (1), the standard acid liquid adding unit (2), a silver electrode (3), a silver nitrate standard liquid adding unit (4) and a control system. According to the invention, the detection time is greatly shortened, the working efficiency of the device is improved, and the sample consumption and the standard acid liquid consumption are saved.

The invention discloses a method for preparing sodium carboxymethylcellulose by abandoned cotton fabrics, which includes cleaning, drying and cutting up the abandoned cotton fabrics, placing the abandoned cotton fabrics into a pretreating agent solution for heating and stirring, and filtering out after the abandoned cotton fabrics faded; placing and heating the abandoned cotton fabrics in a sodium hydroxide solution for 45-90 minutes at the temperature from 75 DEG C to 100DEG C until colors of the abandoned cotton fabrics are completely faded, and obtaining celluloses; submerging the celluloses into the sodium hydroxide solution, heating the celluloses for 1.5-2 hours at the temperature from 30 DEG C to 50 DEG C, and then removing the sodium hydroxide solution to obtain alkali celluloses; shredding the alkali celluloses and adding absolute ethyl alcohol and the sodium hydroxide solution; dropwise adding a chloroacetic acid ethanol solution at the temperature from 50 DEG C to 60 DEG C; heating for 80-100 minutes at the temperature from 70 DEG C to 80 DEG C; performing a suction filtration and washing; and adding a phenolphthalein indicator, dropwise adding hydrochloric acid for a neutralization until the solution is colorless, washing 1-2 times, and drying after a suction filtration to obtain a finished product.

The invention relates to a method for determining the content of calcium fluoride in fluorite. The method comprises the steps that 1, a calcium-containing acetic acid solution with the calcium content ranging from 0.8 mg / mL to 2.0 mg / mL is prepared; 2, a fluorine-containing washing solution with the fluorine content ranging from 10 micrograms per milliliter to 20 micrograms per milliliter; 3, a fluorit sample is soaked with the calcium-containing acetic acid solution, then filtering is performed with low-speed filter paper, a beaker and precipitate are washed with the fluorine-containing washing solution, the low-speed filter paper and the precipitate are placed in a muffle furnace to be incinerated and burnt, a mixed solution of sodium carbonate and boric acid is added after the low-speed filter paper and the precipitate are cooled, the mixture is put in a high-temperature furnace to be fused and then put in a hydrochloric acid solution, a saturated boric acid solution is added for leaching, and the liquid is diluted with water to obtain a test solution after being cooled; 4, a magnesium sulfate solution, water, a triethanolamine solution, a mixed solution of sodium sulfide and hydroxylamine hydrochloride and a potassium hydroxide solution are added in the test solution, the mixture is shaken evenly, a calcein-thyme mixed phenolphthalein indicator is added, the mixed solution is titrated with an EDTA standard titration solution until the mixed solution turns into prunosus, and then the content of the calcium fluoride is calculated according to the volume number of the standard titration solution.