Test method for formaldehyde content released from fabrics

1. Test purpose:

Determine the amount of formaldehyde released from fabrics treated with formaldehyde-containing resin under accelerated storage conditions.

2. Preparation and confirmation items before testing:

1. Equipment and materials:

1.1. Wide-mouth bottle (500ML)

1.2. Constant temperature oven (49±1°C)

1.3. Formaldehyde solution (concentration about 37%)

1.4. Volumetric flask (50, 500, 1000ML)

1.5. Pipette (1, 5, 10, 25ML)

1.6. Spectrophotometer

2. Sample preparation:

2.1. Preparation of NASH REAGENT: Dissolve 150G ammonium acetate in 800ML distilled water, then add 3ML glacial acetic acid and 2ML acetylacetone, pour into a 1000ML volumetric flask, add distilled water to the mark, mix well and pour into a brown reagent bottle , it can be used after 12 hours of storage. Validity period is 6-8 weeks. It is best to make a standard curve once a week.

2.2. Preparation and calibration of standard solution: Take 3.8ML of formaldehyde solution with a concentration of about 37%, dilute it to 1000ML with distilled water, shake well, and accurately calibrate its concentration (should be about 1500UG/ML). It is valid for 4 weeks.

2.2.1. Calibration: Take 50ml to 250ml of 1mol/l Na2SO3 solution into an Erlenmeyer flask, and add two drops of 0.1% phenol

Phthalate indicator, the solution is blue. Add a few drops of 0.02N H2SO4 until the blue color disappears, then add 10ml

Standard formaldehyde solution, blue appears again, titrate with 0.02N H2SO4 until blue disappears, record

The amount of 0.02N H2SO4 used.

2.2.2. Calculation: Calculate the concentration of formaldehyde standard solution according to the following formula

30030xVH2SO4xNH2SO4

C formaldehyde standard solution =

10ML

C formaldehyde standard solution – formaldehyde standard solution concentration

VH2SO4- The H2SO4 solution used in the titration (including the solution that causes the blue color of the solution to disappear after adding the phenolphthalein indicator)

H2SO4 solution)

NH2SO4-H2SO4 solution equivalent concentration

2.3. Preparation of 0.1% thymolphthalein: accurately weigh 0.05g solid phenolphthalein + 25ml absolute ethanol + 25ml distillation

Water is all you need.

2.4. Preparation of 1mol/l Na2SO3 solution: Accurately weigh 25.21 grams of solid anhydrous sodium sulfite and dissolve it in 200ml

&Nbsp; 200 ml, 1mol/L NA2SO3 solution in distilled water.

2.5. Preparation and calibration of 0.02N H2SO4 solution

2.5.1. Preparation: Dissolve 0.555ml H2SO4 in 1000 ml distilled water.

2.5.2. Calibration:

2.5.2.1. Accurately weigh 0.10g of borax and dissolve it in 100ml of freshly boiled distilled water, and cool to room temperature. add

Add 2-3 drops of methyl red indicator (usually four samples are done to increase the accuracy of the titration).

2.5.2.2. Titrate with 0.02N H2SO4 solution to rose red (titration end point) and record the amount of solution used.

2.5.2.3. The accurate concentration of H2SO4 solution can be obtained by calculating the following formula:

Borax dosage

VH2SO4(ml)x0.1907

2.6. After leaving it for 24 hours, first dilute the above standard solution 1:10 (that is, take 25ML to 250 volumetric flask to determine the volume), measure the diluted standard solution 5, 10, 15, 20, 30ML, and put it in the volumetric flask. Add distilled water to dilute to 500ML, and calculate the respective concentrations (should be around 1.5, 3.0, 4.5, 6.0, 9.0UG/ML)

2.7. Take 6 test tubes and add 5ML Nessler’s reagent respectively. Add 5 ML of distilled water to one of them as a blank sample, and add 5 ML of diluted standard solution to the other five. After mixing, place it in a water bath at 58°C for 6 minutes, take it out and cool it, use a spectrophotometer to measure the absorption value of the 412NM spectrum, and then draw a standard curve corresponding to the concentration.

3. Test steps:

1. Cut a 1G sample and weigh it accurately to 0.01G.

2. Add 50ML distilled water to the jar, suspend the sample on the water (using the hanging wire method or the screen support method), seal it and store it in an oven at 65°C±1°C for 4 hours.

2. Take out the jar and cool it for 30 MIN. Remove the sample and its holder, then close the bottle cap and shake to dissolve the agglomerates on the bottle wall to obtain the sample liquid.

3. Take two test tubes and add 5ML Nessler’s reagent respectively. Add 5ML distilled water to one of them as a blank sample, and add 5ML sample solution to the other. After mixing, put the two test tubes into a water bath at 58°C and keep the temperature for 6MIN. After taking it out and cooling it, use a spectrophotometer to measure the absorption value of the 412NM spectrum of the sample solution.

4. Result processing:

1. According to the absorption value of the sample liquid and referring to the standard curve, the formaldehyde content (UG/ML) in the sample liquid can be obtained.

2. Then use the formula to calculate the amount of formaldehyde released in the fabric:

Formaldehyde content in sample solution (UG/ML) ´50

Formaldehyde release from fabrics Amount (PPM) =

Fabric sample weight (G)

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