Method for rapidly and accurately determining concentration of tris (3-hydroxypropyl) phosphine solution

Abstract

The invention relates to the technical field of tris (3-hydroxy propyl) phosphine detection, and discloses a method for rapidly and accurately determining the concentration of a tris (3-hydroxy propyl) phosphine solution, which comprises the following steps: 1) mixing a to-be-determined tris (3-hydroxy propyl) phosphine solution containing wool component with an N-ethylmaleimide solution containing wool component, and uniformly stirring; respectively measuring the absorbance of each solution at 300nm; (2) measuring the absorbance of an N-ethyl maleimide solution which does not contain the wool component at 300nm; (3) drawing a standard fitting curve at 300nm; (4) inquiring the absorbance of the N-ethylmaleimide solution without the wool component on the standard fitting curve, and determining the concentration of the tris (3-hydroxypropyl) phosphine solution to be detected; according to the method, wool is adopted as a disulfide bond donor, the concentration of the tris (3-hydroxypropyl) phosphine solution is measured, interference of reducing impurities in the solution to be measured is avoided, and the test accuracy is improved.

Description

Technical Field

[0001] The invention relates to the technical field of tri(3-hydroxypropyl)phosphine detection, and in particular to a method for quickly and accurately determining the concentration of a tri(3-hydroxypropyl)phosphine solution. Background Art

[0002] Tris(3-hydroxypropyl)phosphine, CAS: 4706-17-6, also known as tris(hydroxypropyl)phosphine or tris(3-hydroxypropyl)phosphine, referred to as THPP, chemical formula is C 9 H 21 O 3 P, structural formula:

[0003]

[0004] This substance has reducing properties and can be miscible with water in any proportion. Most of its products are aqueous solutions. Tri(3-hydroxypropyl)phosphine solution is mainly used in the fields of wool processing, hair softening, and DNA sequencing. This substance is mainly used to open disulfide bonds in the molecular structure. At present, in the domestic market, more than 90% of tri(3-hydroxypropyl)phosphine solution is used to treat wool products, specifically the pre-treatment, dyeing and finishing of wool fiber style and feel of wool fabrics. When tri(3-hydroxypropyl)phosphine solution is used alone or as a matching reagent, it is necessary to accurately measure the concentration of the obtained raw material solution, and it is also necessary to monitor the changes in the concentration of the treatment solution during use to avoid the solution concentration exceeding the material processing requirements, resulting in material damage or substandard processing.

[0005] The existing method for determining the concentration of tri(3-hydroxypropyl)phosphine solution is to utilize the reducing property of tri(3-hydroxypropyl)phosphine and determine its concentration by redox titration. The reducing property of its solution can only be determined by the universal redox titration method, thereby indirectly calculating its concentration. Among them, the most commonly used redox titration method is the iodine titration method. The principle of the iodine titration method is to use an excess iodine (oxidant) standard solution of known concentration to fully react with a quantitative reducing agent solution to be tested (30 minutes), and then use a sodium thiosulfate (reducing agent) standard solution of known concentration to titrate the residual iodine, use starch as an indicator, and calculate the concentration of the tri(3-hydroxypropyl)phosphine solution to be tested according to the consumption of the reducing agent standard solution.

[0006] According to the determination principle, if there are reducing impurities in the solution to be tested, it will seriously affect the accuracy of the determination. During the synthesis of tri(3-hydroxypropyl)phosphine, reducing byproducts will be generated. During the treatment of wool with tri(3-hydroxypropyl)phosphine solution, reducing amino acids or polypeptides on the wool body will fall off and dissolve in the treatment solution.

[0007] Therefore, when the concentration of tri(3-hydroxypropyl)phosphine is determined by the traditional redox titration method, the determination results are often seriously distorted.

[0008] The existing method for determining the concentration of tris(3-hydroxypropyl)phosphine solution has the following problems:

[0009] 1. Inaccurate determination. Traditional redox titration has a high accuracy when determining the concentration of high-purity tri(3-hydroxypropyl)phosphine solution without reducing impurities. However, the tri(3-hydroxypropyl)phosphine solution products used in industry contain an indefinite amount of reducing impurities. In addition, during its industrial application, reducing solute impurities will dissolve into the reaction solution. The reducing impurities will react with the oxidizing agent iodine in the iodine titration concentration determination, making the titration result high and seriously deviate from the accurate value. The greater the content of reducing impurities, the worse the accuracy of the measurement result. Therefore, it is difficult to accurately determine the concentration of tri(3-hydroxypropyl)phosphine solution products using the existing iodine titration method, and it is also difficult to accurately track and monitor the concentration of the treatment solution during its application.

[0010] 2. The titration operation is complicated. In the iodine titration redox titration process, a variety of solutions need to be prepared, including iodine standard solution, sodium thiosulfate standard solution, starch solution, hydrochloric acid solution, etc., and the titration process is complicated.

[0011] 3. The determination process is time-consuming. In traditional redox titration, the reducing solution of the test sample and the oxidant solution need to react for a long time (30 minutes) before the titration test can be carried out, which is time-consuming. In the downstream industrial application process, tri(3-hydroxypropyl)phosphine solution is usually used for continuous industrial production. As the reaction proceeds, the concentration of tri(3-hydroxypropyl)phosphine in the treatment liquid will decrease. It is necessary to monitor the concentration of tri(3-hydroxypropyl)phosphine treatment liquid in real time and add it in time according to the concentration test results to maintain the concentration of tri(3-hydroxypropyl)phosphine treatment liquid within the specified range. The traditional iodine titration concentration determination takes about 1 hour, which makes the concentration determination and addition of tri(3-hydroxypropyl)phosphine seriously delayed, and cannot meet the requirements of downstream application companies.

[0012] In order to solve the above problems, a method for quickly and accurately determining the concentration of tris(3-hydroxypropyl)phosphine solution is needed. Summary of the invention

[0013] The purpose of the present invention is to provide a method for quickly and accurately determining the concentration of a tri(3-hydroxypropyl)phosphine solution, so as to solve the problems of inaccurate determination, complicated operation and long time consumption in the prior art.

[0014] The scheme of the present invention is:

[0015] A method for quickly and accurately determining the concentration of tris(3-hydroxypropyl)phosphine solution comprises the following steps:

[0016] S1. The tri(3-hydroxypropyl)phosphine solution containing wool components and the N-ethylmaleimide solution containing wool components are measured for absorbance at 300 nm respectively;

[0017] S2, measuring the absorbance of the N-ethylmaleimide solution without wool component at 300 nm;

[0018] S3, draw a standard fitting curve at 300nm;

[0019] S4. Query the absorbance of the N-ethylmaleimide solution that does not contain wool components on the standard fitting curve to determine the concentration of the tris(3-hydroxypropyl)phosphine solution to be tested.

[0020] As a preferred technical solution, the method for preparing the tri(3-hydroxypropyl)phosphine test solution containing wool components in step S1 is as follows: the tri(3-hydroxypropyl)phosphine test solution is immersed in contact with a standard wool fabric to obtain a solution.

[0021] As a preferred technical solution, the preparation method of the N-ethylmaleimide solution containing wool components in step S1 is:

[0022] The N-ethylmaleimide solution is immersed in contact with the treated standard wool fabric to obtain;

[0023] The treated standard wool fabric is obtained by being immersed in the tri(3-hydroxypropyl)phosphine test solution and then washed.

[0024] As a preferred technical solution, the immersion treatment of the tri(3-hydroxypropyl)phosphine test solution and the standard wool fabric is to immerse the wet standard wool fabric in the tri(3-hydroxypropyl)phosphine test solution, adjust the pH value of the immersion system to 2.0-9.0, and immerse for 0.1-5 minutes at 20-70°C;

[0025] The mass ratio of the standard wool fabric to the tri(3-hydroxypropyl)phosphine solution to be tested is 1:1 to 1:100.

[0026] As a preferred technical solution, a wet standard wool fabric is immersed in a tri(3-hydroxypropyl)phosphine test solution, the pH value of the immersion system is adjusted to 7.0, and the immersion is carried out at 40° C. for 1 minute;

[0027] The mass ratio of the standard wool fabric used to the tri(3-hydroxypropyl)phosphine test solution was 1:20.

[0028] As a preferred technical solution, the concentration of N-ethylmaleimide solution is 0.1-10.0 g / L; the solvent in the N-ethylmaleimide solution is one of water, ethanol and methanol.

[0029] As a preferred technical solution, the method of contacting the N-ethylmaleimide solution with the treated standard wool fabric by impregnation is:

[0030] Take a wet standard wool fabric that has been immersed in the tri(3-hydroxypropyl)phosphine solution to be tested and washed as a treated standard wool fabric, and immerse it in an N-ethylmaleimide solution at 20 to 70° C. for 0.1 to 5 minutes;

[0031] The mass ratio of the treated standard wool fabric to the N-ethylmaleimide solution is 1:1 to 1:100.

[0032] As a preferred technical solution, the method of contacting the N-ethylmaleimide solution with the treated standard wool fabric by impregnation is:

[0033] Take the wet standard wool fabric that has been immersed in the tri(3-hydroxypropyl)phosphine solution to be tested and washed as the treated standard wool fabric, and immerse it in the N-ethylmaleimide solution at 40°C for 1 minute;

[0034] The mass ratio of the treated standard wool fabric to the N-ethylmaleimide solution is 1:20.

[0035] The beneficial technical effects produced by the present invention are as follows:

[0036] 1) The method provided by the present invention uses wool as a disulfide bond donor, utilizes the efficient, rapid and specific reaction characteristics of tri(3-hydroxypropyl)phosphine and the disulfide bond of wool, and uses wool as a disulfide bond donor to measure the concentration of tri(3-hydroxypropyl)phosphine solution, thereby avoiding the interference of reducing impurities in the solution to be tested and improving the test accuracy.

[0037] 2) The method provided by the present invention for rapidly and accurately determining the concentration of tri(3-hydroxypropyl)phosphine solution uses the specific reactivity of NEM solution to thiol to determine the amount of lanolin disulfide bonds opened by tri(3-hydroxypropyl)phosphine solution, and then calculates the concentration of the solution to be tested. The rapid determination parameters used in the method improve the test efficiency and establish a corresponding relationship between the absorbance attenuation value of the NEM solution and the concentration of the tri(3-hydroxypropyl)phosphine solution.

[0038] 3) The method for quickly and accurately determining the concentration of tri(3-hydroxypropyl)phosphine solution provided by the present invention solves the problem of interference from reducing impurities in the solution to be tested. In order to solve the problem that the concentration measurement result caused by reducing impurities in the liquid to be tested is seriously high and inaccurate during the existing iodine titration method for determining tri(3-hydroxypropyl)phosphine solution or treatment liquid. By the detection method of the present invention. Utilizing the characteristics that tri(3-hydroxypropyl)phosphine has specific reducing properties for cystine disulfide bonds in wool, while reducing impurities in its products and application processes have no reducing effect on wool disulfide bonds, wool is used as a disulfide bond donor, and the tri(3-hydroxypropyl)phosphine solution to be tested treats wool under certain conditions, and then the amount of thiol groups generated by opening the wool disulfide bonds is measured, thereby calculating the concentration of the tri(3-hydroxypropyl)phosphine solution to be tested. Among them, the thiol content generated after the wool disulfide bonds are opened is determined by the thiol blocking reagent N-ethylmaleimide. This method avoids the interference of reducing impurities in the titration method and solves the problem of inaccurate determination.

[0039] 4) The present invention solves the problem of complicated operation. The present invention is simple to operate, only needs to prepare one reaction reagent, reduces the test steps, and is easy to operate.

[0040] 5) The present invention solves the problem that the prior art has a long test time and cannot meet the requirements of real-time concentration monitoring during the application process of downstream enterprises. The present invention utilizes the property of tri(3-hydroxypropyl)phosphine solution to quickly reduce disulfide bonds in wool to sulfhydryl groups under certain temperature and pH conditions to measure the concentration of tri(3-hydroxypropyl)phosphine solution. The operation method is simple, and the concentration measurement can be completed within 5 minutes. The measurement process is convenient and fast, and the time consumption is short. It can meet the needs of downstream product users for rapid real-time monitoring of product concentration, and provides a guarantee for the controllability of the use of tri(3-hydroxypropyl)phosphine solution products. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a graph showing the relationship between the absorbance attenuation and the standard tris(3-hydroxypropyl)phosphine concentration in Example 1 of the present invention. DETAILED DESCRIPTION

[0042] The present invention provides a method for quickly and accurately determining the concentration of tris(3-hydroxypropyl)phosphine solution.

[0043] Here’s how it works:

[0044] The wool scale layer contains a large number of disulfide bonds. Under certain temperature and pH conditions, tri(3-hydroxypropyl)phosphine solution can effectively reduce the disulfide bonds in the wool structure, breaking the disulfide bonds to generate thiol groups. The reaction principle is as follows:

[0045]

[0046] N-ethylmaleimide (NEM, hereinafter referred to as NEM) can react specifically with the thiol groups generated on wool fibers to form a stable covalent thioether bond. The reaction formula is as follows:

[0047]

[0048] The concentration of NEM solution is reduced. NEM has a characteristic absorption peak at 300nm, and its peak value is proportional to the concentration. After the wool is reduced by the tri(3-hydroxypropyl)phosphine solution to be tested, it reacts with an excess of NEM solution. The absorbance attenuation of the NEM solution at 300nm before and after the reaction is measured. The concentration of the tri(3-hydroxypropyl)phosphine solution to be tested is proportional to the attenuation of the NEM absorbance, and the concentration of the tri(3-hydroxypropyl)phosphine solution to be tested can be calculated from this.

[0049] Kit materials used in the following tests:

[0050] 1. Test material: white wool fabric (the best is Australian wool fabric with fiber fineness of 80s)

[0051] 2. Test chemicals: tri(3-hydroxypropyl)phosphine standard solution, N-ethylmaleimide

[0052] 3. Test instrument: UV-visible spectrophotometer

[0053] 4. Process steps:

[0054] The process steps include: drawing a standard curve and determining the concentration of tri(3-hydroxypropyl)phosphine in the sample to be tested. (Before determining the concentration of a tri(3-hydroxypropyl)phosphine solution of unknown concentration, its standard curve must be drawn first)

[0055] Part I: Plotting the Standard Curve

[0056] (1) Wetting treatment. Standard wool fabric is rinsed with 0.1-2.0 g / L of penetrant at 20-70°C (preferably 40°C) for 0.1-2 min (preferably 1 min), with a bath ratio of 1:1-1:100 (preferably 1:20), and then washed with distilled water;

[0057] (2) Standard concentration tri(3-hydroxypropyl)phosphine reacts with wool fabrics respectively. The wool treated in step (1) is treated in a series of tri(3-hydroxypropyl)phosphine (0.1-15 g / L) solutions of different concentrations for 0.1-5 min (preferably 1 min), at a temperature of 20-70°C (preferably 40°C), a pH value of 2.0-9.0 (preferably 7.0), and a bath ratio of the wool fabric to the tri(3-hydroxypropyl)phosphine solution of 1:1-1:100 (preferably 1:20). After the reaction is completed, the wool fabric is washed with distilled water; in this application, the bath ratio is a mass ratio, for example, the bath ratio of 1 g wool fabric: 20 g solution is 1:20.

[0058] (3) Reaction with NEM solution and absorbance measurement. The wool fabric treated in step (2) is immersed in 0.1-10.0 g / L NEM solution (preferably 8.0 g / L), the solvent can be water, ethanol, methanol (preferably ethanol), the treatment time is 0.1-5 min (preferably 1 min), the temperature is 20-70° C. (preferably 40° C.), the bath ratio of wool to NEM solution is 1:1-1:100 (preferably 1:20), the absorbance of the NEM solution before and after treatment is measured, and the absorbance attenuation value is recorded.

[0059] (4) Drawing a standard curve: Using the concentration of standard tri(3-hydroxypropyl)phosphine in step (3) as the horizontal axis and the absorbance decay value as the vertical axis, a standard curve is drawn, and the standard curve equation is fitted to establish a functional relationship between the absorbance decay value of the NEM solution and the concentration of standard tri(3-hydroxypropyl)phosphine.

[0060] Part II: Determination of the concentration of tri(3-hydroxypropyl)phosphine sample to be tested

[0061] (1) Wetting treatment: Standard wool fabric is rinsed with 0.1-2.0 g / L of penetrant at 20-70°C (optimal 40°C) for 0.1-2 min, with a bath ratio of 1:1-1:100 (preferably 1:20), and then washed with distilled water;

[0062] (2) The tri(3-hydroxypropyl)phosphine solution to be tested reacts with wool fabric (the reaction conditions are the same as those in the step of drawing the standard curve). The wool treated in step (1) is immersed in the tri(3-hydroxypropyl)phosphine (0.1-15 g / L) solution to be tested for 0.1-5 min (preferably 1 min), at a temperature of 20-70° C. (preferably 40° C.), a pH value of 2.0-9.0 (preferably 7.0), and a bath ratio of the wool fabric to the tri(3-hydroxypropyl)phosphine solution of 1:1-1:100 (preferably 1:20). After the reaction is completed, the wool fabric is washed with distilled water;

[0063] (3) Reaction with NEM solution and absorbance measurement (reaction conditions are the same as those in the standard curve drawing step). The wool fabric treated in step (2) is immersed in 0.1-10.0 g / L NEM solution (preferably 8.0 g / L), the solvent can be water, ethanol, methanol (preferably ethanol), the treatment time is 0.1-5 min (preferably 1 min), the temperature is 20-70°C (optimally 40°C), the bath ratio of wool to NEM solution is 1:1-1:100 (preferably 1:20), the absorbance of the NEM solution before and after treatment is measured, and its absorbance attenuation value is recorded.

[0064] (4) Calculating the content of tri(3-hydroxypropyl)phosphine in the sample to be tested. The color data measured in step (3) is compared with the standard curve and fitting equation drawn in the first part to calculate the content of tri(3-hydroxypropyl)phosphine in the sample to be tested.

[0065] Embodiment 1:

[0066] The concentration of the unknown tris(3-hydroxypropyl)phosphine solution was determined.

[0067] Selected standard wool fabric: 100% Australian wool white fabric, warp and weft yarn count 70 / 2*50 / 2 (2 refers to double strands), 250g / m 2 , wool fiber fineness 80s.

[0068] Testing instrument: UV-visible spectrophotometer

[0069] Test chemicals: Tris(3-hydroxypropyl)phosphine standard solution, N-ethylmaleimide

[0070] Part I. Drawing of the Standard Curve

[0071] (1) Wetting treatment: The standard wool fabric was rinsed with 0.5 g / L penetrant at 40 °C for 1 min, with a bath ratio of 1:20, and then washed with distilled water;

[0072] (2) A series of tri(3-hydroxypropyl)phosphine solutions of standard concentrations are reacted with wool fabrics respectively. The wool treated in step (1) is treated in a series of tri(3-hydroxypropyl)phosphine solutions of different concentrations (0 g / L, 2.0 g / L, 4.0 g / L, 6.0 g / L, 8.0 g / L, 10.0 g / L) for 1 min at a temperature of 40°C, a pH value of 7.0, and a bath ratio of 1:20. After the reaction is completed, the wool fabric is washed with distilled water; in this embodiment, the bath ratio is a mass ratio, such as a bath ratio of 1 g wool fabric: 20 g solution is 1:20;

[0073] (3) Reaction with NEM solution and absorbance measurement. The wool fabrics treated in step (2) were immersed in 8.0 g / L NEM solution, the solvent was ethanol, the treatment time was 1 min, the temperature was 40°C, the bath ratio of wool to NEM solution was 1:20, the absorbance of the NEM solution before and after treatment was measured, and the absorbance attenuation value of each sample was recorded.

[0074] (4) Plotting a standard curve. Using the concentration of standard tri(3-hydroxypropyl)phosphine in step (3) as the horizontal axis and the absorbance decay value as the vertical axis, a standard curve is plotted, and the standard curve equation is fitted to establish a functional relationship between the absorbance decay value of the NEM solution and the concentration of standard tri(3-hydroxypropyl)phosphine, such as Figure 1 shown.

[0075] Part II: Determination of concentration of test samples

[0076] (1) Wetting treatment: The standard wool fabric was rinsed with 0.5 g / L penetrant at 40 °C for 1 min, with a bath ratio of 1:20, and then washed with distilled water;

[0077] (2) The tri(3-hydroxypropyl)phosphine to be tested reacts with wool fabric. The wool treated in step (1) is immersed in the tri(3-hydroxypropyl)phosphine solution to be tested for 1 min at a temperature of 40° C., a pH value of 7.0, and a bath ratio of 1:20. After the reaction is completed, the wool fabric is washed with distilled water;

[0078] (3) Reaction with NEM solution and absorbance measurement. The wool fabric treated in step (2) was immersed in 8.0 g / L NEM solution, the solvent was ethanol, the treatment time was 1 min, the temperature was 40°C, the bath ratio of wool to NEM solution was 1:20, and the absorbance of the NEM solution before and after treatment was measured, and its absorbance attenuation value was 0.536.

[0079] (4) Calculation of sample concentration. Figure 1 The functional relationship between the absorbance attenuation value of the NEM solution and the concentration of the standard tri(3-hydroxypropyl)phosphine was used to calculate the concentration of the tri(3-hydroxypropyl)phosphine solution to be tested to be 3.53 g / L.

[0080] Taking the sample concentration measured by liquid chromatography as a reference standard, the following samples were tested at different pH values ​​and temperatures using the method in the above embodiment, and the test results shown in the following table were obtained.

[0081] Table 1

[0082]

[0083] According to the data in the table, it can be seen that under the different test conditions selected, the test results of this method are close to those of the chromatography method, which also shows that the test accuracy of this method is high.

[0084] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for quickly and accurately determining the concentration of tris(3-hydroxypropyl)phosphine solution, characterized in that: The following steps are involved: S1. The tri(3-hydroxypropyl)phosphine solution containing wool components and the N-ethylmaleimide solution containing wool components are measured for absorbance at 300 nm respectively; S2, measuring the absorbance of the N-ethylmaleimide solution without wool component at 300 nm; S3, draw a standard fitting curve at 300nm; S4. Query the absorbance of the N-ethylmaleimide solution that does not contain wool components on the standard fitting curve to determine the concentration of the tris(3-hydroxypropyl)phosphine solution to be tested.

2. A method for quickly and accurately determining the concentration of tris(3-hydroxypropyl)phosphine solution as claimed in claim 1, characterized in that The preparation method of the tri(3-hydroxypropyl)phosphine test solution containing wool components in step S1 is as follows: the tri(3-hydroxypropyl)phosphine test solution is immersed in contact with a standard wool fabric to obtain the obtained solution.

3. A method for quickly and accurately determining the concentration of tris(3-hydroxypropyl)phosphine solution as claimed in claim 2, characterized in that: The preparation method of the N-ethylmaleimide solution containing wool components in step S1 is as follows: The N-ethylmaleimide solution is immersed in contact with the treated standard wool fabric to obtain; The treated standard wool fabric is obtained by being immersed in the tri(3-hydroxypropyl)phosphine test solution and then washed.

4. A method for quickly and accurately determining the concentration of tris(3-hydroxypropyl)phosphine solution as claimed in claim 2, characterized in that: The immersion treatment of the tri(3-hydroxypropyl)phosphine test solution and the standard wool fabric is as follows: taking the wet standard wool fabric and immersing it in the tri(3-hydroxypropyl)phosphine test solution, adjusting the pH value of the immersion system to 2.0-9.0, and immersing it at 20-70° C. for 0.1-5 minutes; The mass ratio of the standard wool fabric to the tri(3-hydroxypropyl)phosphine solution to be tested is 1:1 to 1:

100.

5. A method for quickly and accurately determining the concentration of tris(3-hydroxypropyl)phosphine solution as claimed in claim 1 or 3, characterized in that: The concentration of the N-ethylmaleimide solution is 0.1-10.0 g / L; the solvent in the N-ethylmaleimide solution is one of water, ethanol and methanol.

6. The preparation method of a method for quickly and accurately determining the concentration of tris(3-hydroxypropyl)phosphine solution as claimed in claim 3, characterized in that: The method of immersing the N-ethylmaleimide solution in contact with the treated standard wool fabric is as follows: Take a wet standard wool fabric that has been immersed in the tri(3-hydroxypropyl)phosphine solution to be tested and washed as a treated standard wool fabric, and immerse it in an N-ethylmaleimide solution at 20 to 70° C. for 0.1 to 5 minutes; The mass ratio of the treated standard wool fabric to the N-ethylmaleimide solution is 1:1 to 1:100.

Images