SU1269007A1 - Method of preparing indicator paper for ascorbic acid - Google Patents

Abstract

The invention relates to analytical chemistry, in particular the preparation of indicator paper (IB). for ascorbic acid, and can be used in the chemical and pharmaceutical industries of vitamin C. Increasing the storage time of IB is achieved by using other filter paper processing. and sodium nitroprusside. Then the paper is dried and cut into strips. Store t IB in tightly closed cardboard boxes. The determination of ascorbic acid is carried out by wetting the IB with the test solution. The appearance of rust-brown color indicates the presence of ascorbino (L of acid. The storage time of the IB without changing the properties is more than 2 years. Table 3.

Description

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This invention relates to analytical chemistry, in particular to a method for preparing indicator paper for ascorbic acid.

The purpose of the invention is to increase the storage time of indicator paper.

The method is carried out as follows.

Ammonia or trisodium citrate solution is added to the copper sulfate or copper chloride solution. When ammonia is added, the blue suspension first dissolves easily to form a blue solution. A solution of sodium nitroprusside is added to the resulting solution.

Ammonia or brownish in citrate is obtained through the resulting green-colored solutions of ammonium color, filter paper strips, for example, 60 mm wide, are slowly drawn. I dry the impregnated strips in the air to avoid direct sunlight. Dried pieces of paper are cut into strips suitable for use and stored in tightly closed cardboard boxes.

In the determination of ascorbic acid, the resulting indicator smear is moistened with the test solution and, in the event of a rust-brown color, make the conclusion b in the presence of ascorbic acid.

In a semi-quantitative determination, the obtained stains are compared with the stains formed by solutions with a known content of ascorbic acid.

To sample the analyzed solution, it is desirable to use capillaries with a thin tip with a diameter of 0.5 mm. For a semi-quantitative determination, it is convenient to use a spot with a diameter of 4-5 mm. Coloring. Dried spots are well preserved; 3 for a long time.

To prepare the comparison scale, standard solutions of corbic acid with a concentration of 0 are used; 0.03; 0.1; 0.3 and 1.0%.

In tab. 1 shows the initial solutions that are used to prepare a chemical reagent,

100 ml of homogeneous formulations is enough to apply 0.3-0.5 m of average raft filter paper. nosti.

Indicator paper retains its properties for more than 2 years. Example 1. A homogeneous ammonium composition for the manufacture of indicator paper for ascorbic acid.

1. To a solution of 2.5 g of copper sulfate (CuSO) or an equivalent amount of another copper salt in 100 ml of water, add 7 ml of concentrated ammonia (mp 0.90 6.3 g). To the resulting blue solution is added a solution of 3.0 g nitropruss-. yes sodium (Na, Fe (CN) N0 2HjO) in

100 ml of water. The resulting dirty green solution is impregnated with filter paper. The specified quantities of ingredients give well preserved paper.

Ii. They work according to variant 1, but they use solutions of 2.3 g of copper sulfate and 2.9 g of sodium ntrogfusside, each in 100 ml of water and 6.5 ml of ammonia (5.9 g). The quality of the indicator paper obtained with this composition does not practically differ from the quality given by the composition of variant I.

Iii. Use the products of option 1 with the difference that using solutions of 2.7 g of copper sulfate in

100 ml of water, 3.1 g of sodium nitroprusside in 100 ml of water and 7.5 ml of ammonia (6.8 g). The sensitivity of the paper is the same as with the compositions of variants G and II. If the ratio of nitroprussy sodium sulfate decreases further, the sensitivity of the paper falls, although its preservation is good.

EXAMPLE 2: A homogeneous citrate formulation for the preparation of test paper for ascorbic acid.

I. A solution of 12 tons of trisodium citrate (CgH OsNa-j 5) in 40 ml was added to a solution of copper sulphate or another copper salt according to the variants of example 1; water and then nitroprusside solutions. sodium according to the variants of example 1. The resulting homogeneous brownish solutions absorb filter paper strips. Keeping paper is good.

II. Work on option 1, but use a solution of 8 g of trisodium citrate in 40 kls of water. The persistence and properties of the indicator paper, as in option 1. A further decrease in the amount of trisodium citrate gives

3, 1

suspensions with which it is difficult to ensure uniform impregnation of the filter paper.

Iii. Work on option I, but using a solution of 16 g of trisodium citrate in 40 ml of water. The quality of the indicator paper and its preservation are almost the same as the paper obtained using the G and II examples of the example.

In tab. 2 shows examples of solutions for filtering the filter paper. The results of the analysis for the content of ascorbic acid are presented in Table. 3

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Formula

the invention

A method of preparing indicator paper for ascorbic acid by treating filter paper with a chemical reagent and drying it, characterized in that, in order to increase the storage time of indicator paper, a mixture obtained by treating a sulfate or copper chloride solution sequentially with ammonia or trisodium citrate solutions is used as chemical reagent nitroprusside sodium.

Table

Copper sulphate solution (A)

Cuso

SHgO

Water

Copper (B) chloride solution

1.7

98.3

27.3 72.7 23

2.2

2.6 97.6 97.6

1.6

1.8 98.3 98.3

28 77

17 77 Sod Solution. The optimal solution of nitro roprous sodium (D) NajFex "(CNVNOt 2H202.9 Water97.1 Example} Mixable initial solutions

I.A or BV

D

II.A or BV

D

I.A or BG

D

II.A or G

D

III.A or G

D

49.0

48

3.0

3.0

48.5

48.5

48.5

48.5

3.0

3.0

49.0

48.0

39.0

40.0

21.0

21.0

39.5

39.5

39.5

39.5

20.0

23.0

39.5

39.5

39.5

39.5 21.0

21.0 40.0

39.5 Continuation of the table. 1, wt.% Maximum-Minimum 3,02,8 97,197,1 Table 2 Content j wt.% Optimal-Maximum-Minimum maximum 0.71

0.31 0.20 0.16 0.109 0.046

Table3

Claims (1)

Claim A method of preparing indicator paper for ascorbic acid by treating filter paper with a chemical reagent and drying it, characterized in that, in order to increase the shelf life of the indicator paper _? 10 as a chemical reagent, use the mixture obtained by processing a solution of copper sulfate or chloride sequentially with solutions of ammonia or trisodium citrate and nit15 sodium roprusside. Table! Solution Content, wt.% Optimal Maximum Minimum new new new Copper Sulfate Solution (A) 4 CuSO ^ x "5H ₂ 0 2,4 2.6 2.2 Water 97.6 97.6 97.6 Copper Chloride Solution (B) CuCl 1 _g * * 2H _g 0 1.7 1.8 1,6 Water 98.3 98.3 98.3 Ammonia water solution specific weight 0.90 (V) Ammonia 27.3 - - Water 72.7 - - Trisodium citrate solution (G) c _{b )} o ₅ o ₃ · * «5.5Hf.O 23 28 17 Water 77 . 77 77 5 1269 007 6 Continuation of table 1 Solution Content, wt. X . Optimal. new Maximum Minimum new A solution of sodium nitroprusside (D) Na ₂ Fex "(CN) _S 'NO * * 2H _g 0 2.9 3.0 2.8 Water 97.1 97.1 97.1 T a b l and a 2 Example Mixed source Contents j May L solutions Optimal Maxi- Minimum new little new 1 I. A or B 48.5 49.0 48 IN 3.0 3.0 3.0 D 48.5 48.5 48.5 II. A or b 48.5 48.5 48.5 IN s oh s oh 3.0 D 48.5 49.0 48.0 2 I. A or B 39.5 40,0 39.0 G 21.0 21.0 21.0 D 39.5 39.5 39.5 II. A or B. 39.5 39.5 39.5 G 21.0 23.0 20,0 d 39.5 39.5 39.5 III. A or b 39.5 39.5 39.5 G 21.0 21.0 21.0 d 39.5 40,0 39.5 Table 3 Taken 0.70 0.29 0.18 0.14 0.125 0,062 Found (visual definitions) 0.71 0.31 0.20 0.16 0.109 0,046