Preparation method of accurate pH test paper

Abstract

The invention relates to a preparation method of accurate pH test paper. An indicator is prepared by dissolving Metanil yellow, malachite green, acid turquoise blue, bromphenol blue, cresol red, m-cresol purple and bromocresol green in a 30% ethanol water solution. The preparation method comprises the following steps: previously impregnating base paper of pH test paper in the prepared indicator solution, and drying with heating steam of 95-105 DEG C at normal pressure. The preparation method of accurate pH test paper is simple in process, stable in product quality and higher in sensitivity and accuracy in comparison with the common accurate test paper, and the accuracy can be up to 0.2 level. Thus, the preparation method can be widely used in the fields of scientific research, industry, agriculture, environmental protection, medicine and food.

Description

technical field [0001] The invention belongs to the technical field of detection test papers, and in particular relates to a preparation method of pH precision test papers for testing the pH values ​​of liquids and gases. Background technique [0002] pH test paper is widely used in scientific research, industry, agriculture, environmental protection, medicine and food fields to determine the pH value of liquids and gases. The reaction principle of pH is based on the pH indicator method. At present, the general pH analysis test paper contains methyl red [pH4.2 (red) ~ 6.2 (yellow)], bromocresol green [pH3.6 (yellow) ~ 5.4 (green)], bromothymol blue [pH6.7 (yellow) ~ 7.5 (blue)], these mixed acid-base indicators can reflect the variation range of pH 4.5 ~ 9.0. However, the precision of the pH precision test papers currently on the market is relatively poor. The error of the general precision test paper pH measurement is about ±1, and it is easily affected by the indoor envir...

AI Technical Summary

Problems solved by technology

However, the precision of the pH precision test papers currently on the market is relatively poor. The error of the general precision test paper pH measurement is about ±1, and it is easily affected by the indoor environment, especially the time. When the test paper leaves the test solution, it will Rapid changes, if not judged quickly, are likely to introduce large errors

[0003] A high-sensitivity pH test paper and its preparation method (CN102519959A) are disclosed on the website of the Intellectual Property Office of the People's Republic of China. This method solves the human factor by using digital advanced offset printing technology instead of manual screen printing to print standard color plates. Caused the same batch of color plates to reappear, uneven color, and then affect the accuracy of the test, but the sensitivity and accuracy of the pH test paper itself has not been well resolved

Moreover, the above-mentioned literature records that in order to ensure that the pH base paper is not affected by acid and alkali corrosion and improve the stability of the pH test paper, water-based color-fixing agent, cotton wood fiber anti-mold agent, and special paper anti-mold agent are added to the indicator formula. , and a buffer neutralizer prepared by sodium hydroxide and phosphoric acid, which not only makes the production process complicated, but also may affect the accuracy of the test when determining certain substances