Analysis of Determination Standards of Formaldehyde Content in Textiles

Analysis of Determination Standards of Formaldehyde Content in Textiles

The analysis of standard for formaldehyde content in textiles

Text / Yu Yan Gao Quan Yang Suying Liang Qing

Abstract: This paper describes the extraction medium, experimental equipment, test conditions, test requirements and test report. GB/T 2912.1—2009 Determination of formaldehyde in textiles Part 1: Free and hydrolyzed formaldehyde (water extraction method) 》, GB/T 2912.2-2009 "Determination of textile formaldehyde - Part 2: Release of formaldehyde (steam absorption method)" and GB/T 2912.3-2009 "Determination of textile formaldehyde - Part 3: High performance liquid chromatography" The standards are interpreted and the differences between the three are analyzed.

Key words: textiles; determination of formaldehyde content; difference analysis

1 Introduction

Formaldehyde is a limited indicator of harmful substances in human health and safety, and is an important indicator for measuring the safety performance of textiles. Formaldehyde is a colorless, highly irritating odor. Formaldehyde ranks second in the list of priority toxic chemicals in China. Due to the direct contact of formaldehyde on the skin, it can cause allergic dermatitis, inhalation of high concentrations of formaldehyde can induce bronchial asthma, irritating effects on skin and mucous membranes, etc., has been identified by the World Health Organization as carcinogenic and teratogenic substances. Therefore, accurate detection of the content of formaldehyde in textile products is a prerequisite for maintaining consumer safety.

National Standards There are three methods for the determination of formaldehyde in textiles, namely GB/T 2912.1-2009 "Determination of formaldehyde in textiles Part 1: Free and hydrolyzed formaldehyde (water extraction method)" ^[1] , GB/T 2912.2-2009 Determination of formaldehyde in textiles - Part 2: Release of formaldehyde (vapor absorption method) ^[2] and GB/T 2912.3-2009 "Determination of textile formaldehyde - Part 3: High performance liquid chromatography" ^[3] . The first method uses more, and the second and third methods are less used due to product or condition constraints. Now combined with the actual work, we will talk about the understanding of the three methods of formaldehyde content determination in textiles.

2 main differences and analysis of the three methods

2.1 Scope of application of the standard

2.2 Extraction medium

The water extraction method and the vapor absorption method require that all reagents be of analytical grade. The requirements for distilled water or deionized water are at least three levels of water requirements in GB/T 6682; high performance liquid chromatography also requires that the reagents be analytically pure. Acetonitrile is even required to be chromatographically pure, and distilled water meets the secondary water specified in GB/T 6682. From this point of view, high performance liquid chromatography requires higher reagents and distilled water.

2.3 Equipment and instruments

Water extraction method and vapor absorption method, because of different pretreatment methods, the pretreatment equipment is a constant temperature water bath and a dryer, and the measuring equipment is a spectrophotometer; high performance liquid chromatography uses a high performance liquid chromatograph with ultraviolet Detect detector or diode array detector.

2.4 Analysis steps

2.4.1 Sample pretreatment

Both the water extraction method and the vapor absorption method require that the sample be sealed and stored before the test, and the sample is not conditioned, and both samples are taken from the sample and chopped, and 1 g is weighed to the nearest 10 mg. In order to obtain satisfactory accuracy, the mass of the sample can be increased to 2.5 g in the water extraction method, which is not the case in the vapor absorption method.

2.4.2 Preparation of sample test solution

The water extraction method requires the sample to be placed in an iodine measuring flask or an Erlenmeyer flask, 100 mL of water is added, the lid is tightly closed, shaken in a 40 ° C water bath for 60 min, and then filtered using a No. 2 glass funnel; in practice, we find The static setting of the extract is an important part. The static setting can effectively remove the extremely fine particles generated by the shearing of the cut textile. It can use the sample test solution to produce slight turbidity, which will affect the transmittance of the spectrophotometer. , thus affecting the results of the measurement; the vapor absorption method is to put the sample into the wire mesh basket or tie the sample with a double strand, and then put it into the test bottle containing 50 mL of water, as long as the standard is carefully Just operate.

2.4.3 Determination of concentration

The calibration curve and measurement method of the water extraction method and the vapor absorption method are the same, and are measured by a spectrophotometer after colorimetry by Nessler reagent. Take 5 mL of the sample solution and Nessler reagent in a (40 ± 2) ° C water bath for (30 ± 5) min, cool at room temperature (30 ± 5) min, with a 10 mm cuvette at 412 The measurement was carried out at nm wavelength; high performance liquid chromatography was derivatized with 2,4-dinitrophenylhydrazine and determined by HPLC-UVD/DAD. 1.0 mL sample solution and 2.0 mL derivatization test solution were reacted in a 60 ° C water bath for 30 min, cooled to room temperature, and filtered through a 0.45 μm filter for HPLC-UVD/DAD analysis.

By comparison, it is found that the temperature of derivatization by high performance liquid chromatography is higher than the color development temperature of water extraction method and vapor absorption method, and there is no specific requirement for cooling time. It can be seen that the sample solution after derivatization does not change greatly with time. The test solution after the color development by the water extraction method and the vapor absorption method changes depending on the passage of time. If the sample solution is a dark extract, a dimethyl ketone confirmation test can be performed according to the water extraction method to confirm whether it is the absorbance of the color development of formaldehyde in the solution.

2.5 test report representation difference

The water extraction method and the vapor absorption method require the average value of the two test results as the test result, and the calculation result is rounded to the whole number. If the result is less than 20 mg/kg, the test result is reported as “undetected”, and the result is twice. The ratio of the difference to the average value is not specified; HPLC is also the average of the two test results, but the calculation results are rounded to 0.1 mg / kg, the ratio of the difference between the two results and the average If it is greater than 20%, it needs to be re-measured. If the result is less than 5.0 mg/kg, the test result reports “<5.0 ​​mg/kg”. This article considers the requirements to be more rigorous.

3 conclusions

In this paper, the formaldehyde content test standards of water extraction, vapor absorption and high performance liquid chromatography were compared. Through comparative analysis, it was found that the detection limit of high performance liquid chromatography is better than that of water extraction and vapor absorption, which is suitable for the detection of very low formaldehyde content, and the dark sample solution is simpler to operate using this standard. The detection limits of the water extraction method and the vapor absorption method are slightly higher, and the pretreatment methods are different, but the color development and concentration determination of the sample solution are the same. In the actual inspection work, the corresponding method standards should be selected for different types of samples, and each experimental step should be strictly controlled according to the standard to ensure the data is accurate.

references:

[1] GB/T 2912.1—2009 Determination of formaldehyde in textiles Part 1: Free and hydrolyzed formaldehyde (water extraction method) [S].

[2] GB/T 2912.2-2009 "Determination of textile formaldehyde - Part 2: Release of formaldehyde (vapor absorption method)" [S].

[3] GB/T 2912.3-2009 "Determination of textile formaldehyde - Part 3: High performance liquid chromatography" [S].

(Author: Hebei Provincial Product Quality Supervision and Inspection Institute, Hebei Fiber Inspection Bureau)

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