Solution for formaldehyde content detection in textiles

Recently, the 2016 315 party website published a number of news: "Hermes was detected over formaldehyde", "Shanghai port destroyed more than 120,000 pieces of unqualified imported clothing", "Hebei: sampling cashmere sweaters 60 batches of 32 Batch unqualified... These news items involve multiple brands of apparel and textiles, most of which have problems with excessive formaldehyde.

Formaldehyde (HCHO), commonly known as formalin, is a colorless liquid with a pungent odor. The main hazard of formaldehyde is the stimulation of the skin and mucous membranes. Long-term exposure to low concentrations of formaldehyde can cause headache, dizziness, fatigue, sensory disturbances, decreased immunity, and can cause drowsiness, memory loss or neurasthenia, depression, and can cause respiratory dysfunction and hepatotoxic lesions, manifested as hepatocytes. Injury, abnormal liver radiation, etc.

In the production process, the N-methylol compound containing formaldehyde is used as a resin finishing agent to increase the elasticity of the fabric and improve the wrinkle property, and a cationic resin containing formaldehyde is also used to improve the color fastness. These compounds gradually release formaldehyde, which poses a lasting hazard to the user's body.

The national textile product basic safety technical specification GB 18401-2010 gives clear provisions for the formaldehyde content of textiles, as shown in the following table:

The textiles for infants and young children should meet the requirements of category A. Textiles that are in direct contact with the skin should meet the requirements of category B. Textiles that are not in direct contact with the skin should meet the requirements of category C.

RephiLe According to the national standard GB2912.1 and ISO14184 of the People's Republic of China, the following textile formaldehyde content detection solutions are especially recommended. The program uses spectrophotometry to detect the detailed solution as follows:

First, the experimental principle

The textile samples were extracted in a 40 ° C water bath for a certain period of time. After the extract was developed with acetylacetone, the absorbance was measured with a spectrophotometer at a wavelength of 412 nm. The standard working curve of the formaldehyde solution was compared to calculate the free formaldehyde content in the sample.

Second, instruments and reagents

Spectrophotometer

Pure water (manufactured by Direct-Pure Genie), acetylacetone reagent (1000 mL volumetric flask is added with 150 g of ammonium acetate, dissolved in 800 mL of pure water, added with 3 mL of glacial acetic acid and 2 mL of acetylacetone, and made up to 1000 mL, brown bottle storage Note: must be stored for 12 h before use, valid for 6 weeks), formaldehyde purity standard solution (100 μg / mL), dimethyl ketone ethanol solution (1 g of dimethyl ketone dissolved in ethanol to 100 mL. Now available)

Third, the test method

1. Preparation of formaldehyde standard solution and standard curve

A standard curve was prepared by diluting the formaldehyde purity standards to a series of solutions of 0.75 μg/mL, 1.50 μg/mL, 2.25 μg/mL, 3.00 μg/mL, and 4.50 μg/mL, respectively.

2, sample preparation

Take two samples from the sample and cut them, weighing 1 g, to the nearest 10 mg.

Each sample was placed in a 250 mL iodine measuring flask, 100 mL of water was added, the stopper was tightly capped, shaken in a 40 ° C water bath for 60 min, and filtered to another iodometric flask for use.

3, testing

Pipette 5 mL of the sample solution into the tube, add 5 mL of acetylacetone solution, and shake. The color was developed in a 40 ° C water bath for 30 min, taken out at room temperature for 30 min in the dark, and 5 mL of distilled water plus 5 mL of acetylacetone solution was used as a blank. The absorbance As and Ab were measured at 412 nm in a 10 mm absorption cell.

If the calculated formaldehyde content is greater than 500 mg/kg, dilute the extract to the appropriate range.

Do two parallel tests at the same time.

4. Expression of analysis results

Calculate the absorbance according to the following formula:

A = As - Ab

In the formula:

A-corrected absorbance;

As a sample to measure absorbance;

Ab-blank detection absorbance;

Using the corrected absorbance value, the formaldehyde content was calculated from the standard curve and expressed in μg/mL.

Calculate the formaldehyde content of the sample to be tested according to the following formula;

F=c×100÷m

In the formula:

Formaldehyde content in F-sample, mg/kg;

C—the concentration of formaldehyde calculated by the calibration curve using the corrected absorbance, μg/mL;

M—the mass of the sample, g;

Take the average of the two test results as the test results.

If the result is less than 20 mg/mL, the test results are reported as “not detected”.

5, other

If the color of the sample itself has an effect, confirm with diketide ethanol solution as described in ISO 14184.   

ISO and GB requirements for pure water are grade 3 water that meets ISO3996 or GB6682 requirements. For spectroscopic detection systems, dissolved organic matter can interfere with detection, so low TOC content (<50 ppb) is very important. The tiny particles in the water scatter light passing through the test solution, thereby reducing the intensity of the transmitted light, increasing the actual absorbance, and causing the detection result to deviate. We recommend purified water for spectrophotometric detection as purified water of national standard secondary water. Secondary water has low levels of inorganic, organic and granular colloidal pollutants. Typical water quality should be resistivity > 1 MΩ-cm and filtered using a 0.22 μm filter.

RephiLe's Direct-Pure Genie Ultra Pure Water Meter is an internationally leading ultrapure water system. It uses tap water as the influent water while producing ultrapure water and EDI secondary pure water. The water quality of the produced water meets or exceeds the quality standards of the first-class water and the second-grade water of China's laboratory water standards and test methods (GB6682-2008) and ASTM, CLSI and ISO3696. Direct-Pure Genie's EDI secondary pure aquatic water resistivity is typically > 5 MΩ•cm and TOC < 30 ppb. The terminal is equipped with a 0.22 μm filter to maximize the control of particulate matter in the produced water. Direct-Pure Genie's ultrapure water provides water for most analytical instruments such as HPLC, ICP-MS, and standard and blank solutions to meet the overall water needs of analytical instrumentation laboratories.

About RephiLe :

Shanghai Lefeng is a manufacturer and supplier of water purification and laboratory separation and purification products with a deep technical background. At the beginning of development, Shanghai Lefeng has established the concept of respecting intellectual property rights and independent innovation, and actively established its own brand. At present, Shanghai Lefeng has become the most complete supplier of compatible products of Miriam Pure Water System in the world, and provides experiments. Room pure water system and laboratory sample preparation pre-treatment needle filter. Product quality and service are recognized by the market, and the products are sold to more than 80 countries and regions around the world.

For more information on RephiLe products, please visit: RephiLe official website

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RephiLe enterprise WeChat name: pure water hotline 400 690 0090

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