阅读说明：本技术 一种固体制剂中维生素c的滴定方法 (Titration method of vitamin C in solid preparation ) 是由 常俊 徐小明 刘晴 张沛霞 徐慧萍 蔡露 盛洁 于 2021-08-20 设计创作，主要内容包括：本发明公开了一种固体制剂中维生素C的滴定方法,精密称取0.1～2.5g经研成细粉的样品(相当于维生素C 100～200mg)于锥形瓶中,加入100～200ml偏磷酸水溶液,振摇使溶解,加入1～2ml淀粉指示液,立即用碘滴定液滴定,滴定至深蓝色或深褐色,溶液保持30s不褪色,根据滴定体积计算样品中维生素C的含量。本发明所述的滴定方法操作简便,测试时间短、准确度高,适用于片剂、硬胶囊、粉剂、预混料等固体制剂中维生素C的测定。(The invention discloses a titration method of vitamin C in a solid preparation, which comprises the steps of precisely weighing 0.1-2.5 g of a sample (equivalent to 100-200 mg of vitamin C) ground into fine powder in a conical flask, adding 100-200 ml of metaphosphoric acid aqueous solution, shaking to dissolve, adding 1-2 ml of starch indicator, immediately titrating with iodometric solution to dark blue or dark brown, keeping the solution fadeless for 30s, and calculating the content of the vitamin C in the sample according to the titration volume. The titration method provided by the invention is simple and convenient to operate, short in testing time and high in accuracy, and is suitable for measuring vitamin C in solid preparations such as tablets, hard capsules, powder, premix and the like.)

1. A titration method of vitamin C in a solid preparation is characterized in that: accurately weighing 0.1-2.5 g of a sample (equivalent to 100-200 mg of vitamin C) ground into fine powder in an erlenmeyer flask, adding 100-200 ml of metaphosphoric acid aqueous solution, shaking to dissolve, adding 1-2 ml of starch indicator, immediately titrating with iodometric solution to dark blue or dark brown, keeping the solution for 30s, and calculating the content of the vitamin C in the sample according to the titration volume.

2. The titration method of vitamin C in a solid preparation according to claim 1, wherein: the calculation formula of the content of the vitamin C is as follows:

in the formula, C: the concentration of the iodometric solution is unit mol/L;

v: volume of iodometric solution consumed, in ml;

w: the samples were weighed in g.

3. The titration method of vitamin C in a solid preparation according to claim 1, wherein: the concentration of the metaphosphoric acid aqueous solution is 20-60 g/L.

4. The titration method of vitamin C in a solid preparation according to claim 1, wherein: the concentration of the iodometric solution is 0.05 mol/L.

Technical Field

The invention relates to the field of detection of functional components of health-care food, food or medicine, in particular to a titration detection method for the content of vitamin C in a solid preparation containing a ferric iron component.

Background

Vitamin C, a water-soluble vitamin, also known as ascorbic acid, is a polyhydroxy compound with acidic properties, has strong reducibility and is easily oxidized into dehydrovitamin C.

At present, the titration methods of vitamin C mainly comprise an iodine titration method and a sodium dichlorophenolate titration method, the sodium dichlorophenolate titration method is complex in operation and long in detection period, and although the iodine titration method is simple and convenient to operate and short in time, for products containing various components, particularly ferric iron, the vitamin C is easily oxidized by the ferric iron due to the strong oxidizing property of the ferric iron, so that the titration result is low, and the actual content of the vitamin C in the products cannot be accurately determined. The method for detecting vitamin C in multi-component health food disclosed at present, for example, in the patent of 'identification method of vitamin C content in vitamin mineral health food' of Jiangsu Elaland nutrient Co., Ltd (application No. 201210450128.9), which uses diethylenetriamine pentaacetic acid and pyrrolidine ammonium dithiocarbamate as metal ion masking agents, but the method cannot mask ferric iron ions, and the used sulfuric acid has strong corrosivity.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the titration method can effectively mask the influence of ferric ions on vitamin C, and accurately, efficiently and conveniently detect the vitamin C in the solid preparation.

The technical scheme adopted by the invention for solving the technical problems is as follows: a titration method of vitamin C in a solid preparation is characterized in that: accurately weighing 0.1-2.5 g of a sample (equivalent to 100-200 mg of vitamin C) ground into fine powder in an erlenmeyer flask, adding 100-200 ml of metaphosphoric acid aqueous solution, shaking to dissolve, adding 1-2 ml of starch indicator, immediately titrating with iodometric solution to dark blue or dark brown, keeping the solution for 30s, and calculating the content of the vitamin C in the sample according to the titration volume.

The calculation formula of the content of the vitamin C is as follows:

in the formula, C: the concentration of the iodometric solution is unit mol/L;

v: volume of iodometric solution consumed, in ml;

w: the samples were weighed in g.

The concentration of the metaphosphoric acid aqueous solution is 20-60 g/L.

The concentration of the iodometric solution is 0.05 mol/L.

The method has the advantages that the metaphosphoric acid aqueous solution is used as the extraction solvent of the sample, the metaphosphoric acid can effectively mask the influence of ferric ions on vitamin C, the stability of the vitamin C in the solvent is improved, the metaphosphoric acid is stable in property and non-volatile, and cannot be decomposed under the conventional condition.

Drawings

Figure 1 is a comparison of the recovery using the present method with the results of the conventional pharmacopoeia method for examples 7-10.

Detailed Description

The present invention will now be described in further detail with reference to examples.

Example 1:

precisely weighing 1.1g of a sample (about equivalent to 100mg of vitamin C, product name: Fe, Zn and multi-vitamin tablets, code: MT1L, source: Jiangsu Ailan nutritional products Co., Ltd.) which is ground into fine powder, adding 100ml of 20g/L aqueous solution of metaphosphoric acid into a 250ml conical flask, shaking to dissolve, adding 1ml of starch indicator, immediately titrating with 0.05mol/L iodometric solution, titrating to dark blue or dark brown, keeping the solution for 30s, and calculating according to the titration volume to obtain that the content of the vitamin C in the sample is 65.1 mg/g.

Example 2:

precisely weighing 1.1g of a sample (about equivalent to 100mg of vitamin C, product name: Fe, Zn and multi-vitamin tablets, code: MT1L, source: Jiangsu Ailan nutritional products Co., Ltd.) which is ground into fine powder, adding 100ml of 40g/L aqueous solution of metaphosphoric acid into a 250ml conical flask, shaking to dissolve, adding 1ml of starch indicator, immediately titrating with 0.05mol/L iodometric solution, titrating to dark blue or dark brown, keeping the solution for 30s, and calculating according to the titration volume to obtain that the content of the vitamin C in the sample is 65.2 mg/g.

Example 3:

precisely weighing 1.1g of a sample (about equivalent to 100mg of vitamin C, product name: Fe, Zn and multi-vitamin tablets, code: MT1L, source: Jiangsu Ailan nutritional products Co., Ltd.) which is ground into fine powder, adding 100ml of 60g/L aqueous solution of metaphosphoric acid into a 250ml conical flask, shaking to dissolve, adding 1ml of starch indicator, immediately titrating with 0.05mol/L iodometric solution, titrating to dark blue or dark brown, keeping the solution for 30s, and calculating according to the titration volume to obtain that the content of the vitamin C in the sample is 65.2 mg/g.

Example 4:

precisely weighing 1.5g of a sample (about 100mg of vitamin C, product name: Fe + vitamin C capsule, code: MTPF, source: Jiangsu Ailan nutritional products Co., Ltd.) which is ground into fine powder, adding 100ml of 20g/L aqueous solution of metaphosphoric acid into a 250ml conical flask, shaking to dissolve, adding 1ml of starch indicator, immediately titrating with 0.05mol/L iodometric solution, titrating to dark blue or dark brown, keeping the solution for 30s, and calculating the content of the vitamin C in the sample to be 86.3mg/g according to the titration volume.

Example 5:

precisely weighing 1.5g of a sample (about 100mg of vitamin C, product name: Fe + vitamin C capsule, code: MTPF, source: Jiangsu Ailan nutritional products Co., Ltd.) which is ground into fine powder, adding 100ml of 40g/L aqueous solution of metaphosphoric acid into a 250ml conical flask, shaking to dissolve, adding 1ml of starch indicator, immediately titrating with 0.05mol/L iodometric solution, titrating to dark blue or dark brown, keeping the solution for 30s, and calculating the content of the vitamin C in the sample to be 86.3mg/g according to the titration volume.

Example 6:

precisely weighing 1.5g of a sample (about 100mg of vitamin C, product name: Fe + vitamin C capsule, code: MTPF, source: Jiangsu Ailan nutritional products Co., Ltd.) which is ground into fine powder, adding 100ml of 60g/L aqueous solution of metaphosphoric acid into a 250ml conical flask, shaking to dissolve, adding 1ml of starch indicator, immediately titrating with 0.05mol/L iodometric solution, titrating to dark blue or dark brown, keeping the solution for 30s, and calculating the content of the vitamin C in the sample to be 86.2mg/g according to the titration volume.

Examples 1-3 and 4-6 the content of vitamin C in MT1L and MTPF of the samples (the determination results are shown in the following table), respectively, were maintained at about 65.2mg/g for MT1L and about 86.3mg/g for MTPF, and the conclusion was that: the concentration of metaphosphoric acid in the same sample had a negligible effect on the results of the vitamin C assay.

And the content of the vitamin C in the two samples is measured by adopting a traditional pharmacopoeia detection method (namely dilute acetic acid is adopted as an extraction solvent), and the recovery rate is calculated, and compared with the measurement result of the method, the method has the following steps:

as can be seen from the table above, in the process of developing the method, the metaphosphoric acid aqueous solution is used as the extraction solvent of the sample, so that the influence of ferric ions on vitamin C can be effectively masked, the content determination of the vitamin C in the solid preparation is more accurate, and the recovery rate is higher.

Example 7:

precisely weighing 2.5g of a powder sample (product name: multi-vitamin mineral powder, code: OP51, source: Jiangsu Elaland nutriment Co., Ltd.) ground into fine powder, adding 100ml of 60g/L metaphosphoric acid aqueous solution into a 250ml conical flask, shaking to dissolve, adding 1ml of starch indicator, immediately titrating with 0.05mol/L iodometric titration solution, titrating to dark blue or dark brown, keeping the solution for 30s, and calculating according to the titration volume to obtain the content of vitamin C in the sample to be 35.9 mg/g.

Example 8:

precisely weighing 0.7g of a finely ground premix sample (product name: vitamin complex premix, code: VP05, source: Jiangsu Elatio Nutrition Co., Ltd.) in a 250ml conical flask, adding 100ml of 40g/L aqueous solution of metaphosphoric acid, shaking for dissolution, adding 1ml of starch indicator, immediately titrating with 0.05mol/L iodometric titration solution, titrating to dark blue or dark brown, keeping the solution from fading for 30s, and calculating according to the titration volume to obtain the content of vitamin C in the sample of 140.7 mg/g.

Example 9:

precisely weighing 2.5g of a tablet sample (product name: multi-vitamin mineral tablet, code: DD9945, source: Hewlett-packard pharmaceutical company, Ltd.) ground into fine powder into a 250ml conical flask, adding 100ml of 60g/L aqueous solution of metaphosphoric acid, shaking to dissolve, adding 1ml of starch indicator, immediately titrating with 0.05mol/L iodometric titration solution to dark blue or dark brown, keeping the solution from fading for 30s, and calculating according to the titration volume to obtain the content of the vitamin C in the sample to be 36.3 mg/g.

Example 10:

precisely weighing 0.9g of a finely ground tablet sample (product name: multi-vitamin mineral tablet, code: S120123, source: Zhejiang New Vision Biotechnology Ltd.) in a 250ml conical flask, adding 100ml of 20g/L metaphosphoric acid aqueous solution, shaking for dissolving, adding 1ml of starch indicator, immediately titrating with 0.05mol/L iodometric solution, titrating to dark blue or dark brown, keeping the solution for 30S, and calculating according to the titration volume to obtain the content of vitamin C in the sample of 111.5 mg/g.

In examples 7 to 10, the method is used to perform titration detection of vitamin C content on samples of different forms and different sources (the recovery rate is compared with the results of the conventional pharmacopoeia method and is shown in figure 1), and it can be seen that the detection recovery rate of vitamin C can be effectively improved in the concentration range of 20-60 g/L in the metaphosphoric acid solution, so that the content of vitamin C in the product can be truly reflected.

The titration method provided by the invention is simple and convenient to operate, short in testing time and high in accuracy, and is suitable for measuring vitamin C in solid preparations such as tablets, hard capsules, powder, premix and the like.

In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.