Halogen Detection in Textiles

Textile halogen testing mainly conducts scientific testing and analysis on total halogens, extractable organic halogens, specific halogen compounds, chlorobenzenes and chlorotoluenes testing, and organotin compounds, objectively assessing the product quality grade and issuing a detailed test report, providing a basis for manufacturers' quality control and downstream users' product acceptance.

Testing Items

Total halogen (TX) testing: This is the basic item of the textile halogen testing, referring to the determination of the total content of all the halogen elements (fluorine, chlorine, bromine and iodine) in the sample. The oxygen bomb combustion-ion chromatography method or the combustion furnace-microcoulometric titration method is usually adopted, converting the halogens in the organic matter into hydrogen halides for quantification. This indicator is used for the preliminary screening, judging whether the product needs the more detailed specific halogen analysis.

Extractable organic halogen (EOX) testing: This testing item targets the organic halogen compounds in the textile that can be extracted by the specific solvents (such as hexane and toluene). These compounds (such as some flame retardants and mildew inhibitors) may migrate or release under specific conditions. The testing method usually includes the Soxhlet extraction, separation and purification, and finally the determination by the microcoulometric method or ion chromatography, evaluating their potential environmental release risks.

Specific halogen compound (such as brominated flame retardants) testing: This item carries out the precise quantification of the single or a class of halogen compounds explicitly restricted by the regulations. The common target substances include polybrominated biphenyls (PBBs), polybrominated diphenyl ethers (PBDEs) and short-chain chlorinated paraffins (SCCPs). The testing usually adopts the gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS) technology, with high selectivity and sensitivity.

Chlorobenzenes and chlorotoluenes testing: Mainly detects the chlorinated organic solvents or intermediates that may remain in the textile during the dyeing, printing or finishing processes, such as dichlorobenzene and trichlorobenzene. These substances are harmful to human health and the environment. The testing methods mostly adopt the headspace gas chromatography-mass spectrometry (HS-GC/MS) or the solvent extraction combined with GC-MS, to evaluate their residual amounts on the textile.

Organotin compounds (containing halogens) testing: Some organotin compounds (such as tributyltin (TBT) and triphenyltin (TPT)) are commonly used as the antibacterial agents of textiles, and their halide forms may be included in the testing scope. The testing needs to undergo the acid perspiration or solvent extraction, and after derivatization, the analysis is carried out with GC-MS, evaluating their compliance in the ecological textile standards.

Testing Scope

Various fibre raw materials and yarns: Including the natural fibres (cotton, flax, wool and silk) and chemical fibres (polyester, nylon, acrylic and viscose) and the yarns made of them. Attention needs to be paid to the halogen-containing finishing agents, flame retardants or oil agents introduced during the fibre production, as well as the halogen-containing impurities that may be mixed in the recycled materials.

Fabrics such as woven, knitted and nonwoven fabrics: Covering all types of fabrics. The testing focus is on the printing, dyeing and finishing processes, such as the use of chlorine-containing bleaching agents (sodium hypochlorite), halogen-containing dyes and pigments, bromine-containing or chlorine-containing flame retardant coatings, and halogen-containing waterproof and oil-repellent finishing agents.

Final products such as garments and home textiles: For the final products in direct contact with the human body, such as underwear, outerwear, bedding and curtains. The testing needs to consider all the constituent parts, including the fabrics, linings, fillings, sewing threads, printed patterns and the attached accessories (such as labels containing halogen-containing flame retardants).

Auxiliary materials and decorations: Including zippers, buttons, interlinings, laces, hot-fix rhinestones, coatings or laminated films. These parts may individually use halogen-containing polymers (such as polyvinyl chloride PVC) or have halogen flame retardants and plasticizers added, and are the parts that cannot be ignored in the testing.

Children's textiles and textiles for toys: The products in this scope are subject to the strictest regulations in the world. In addition to the conventional halogen items, special attention is paid to the halogen-containing substances possibly present in the small parts, and the migratable organic halogens extracted by saliva and perspiration, to evaluate the risks brought by the children's biting and licking.

Testing Methods

Oxygen bomb combustion-ion chromatography method (IC): This is the classic method for determining the total halogens (chlorine, bromine and iodine) and the inorganic halides. The sample is burned in a closed steel bomb filled with oxygen, the halogens are converted into hydrogen halides and absorbed by the absorption solution, and then the concentrations of the halogen ions are separated and determined with an ion chromatograph. This method has complete decomposition and is applicable to various textile matrices.

Tube furnace combustion-microcoulometric titration method: This method is also used for the total halogen determination. The sample is burned and decomposed in a high-temperature tube furnace in an oxygen flow, the generated gas is carried into the titration cell by the carrier gas, the halogens are converted into halide ions and react with the silver ions, and the total halogen content is quantified by measuring the electric quantity required for the electrolytic replenishment of the silver ions. It has a high degree of automation and a fast analysis speed.

Gas chromatography-mass spectrometry method (GC-MS): This is the gold standard method for detecting the specific volatile and semi-volatile organic halogen compounds (such as brominated flame retardants, chlorobenzenes and some organochlorine pesticides). The sample is injected after the Soxhlet extraction and the purification by gel permeation chromatography (GPC) or solid phase extraction (SPE), and the qualitative and quantitative analysis is carried out by using the high selectivity of the mass spectrometry.

Liquid chromatography-mass spectrometry method (LC-MS/MS): Suitable for analysing the thermally unstable, strongly polar or high-molecular-weight organic halogen compounds, such as some new fluorine-containing and chlorine-containing surfactants (such as perfluorooctanoic acid PFOA) and some dyes. The pre-treatment of this method is relatively mild, and an extremely high sensitivity and accuracy can be obtained through the multiple reaction monitoring (MRM) mode.

Pyrolysis/thermal desorption-gas chromatography-mass spectrometry method (Py/TD-GC-MS): Used for the screening of the unknown halogen-containing polymers or additives in the textile. Through the programmed-temperature pyrolysis or thermal desorption, the polymer materials are decomposed into small-molecule volatiles, which directly enter the GC-MS for analysis, and it can be quickly judged whether the textile contains substances such as polyvinyl chloride (PVC) and halogen-containing flame retardants.

Testing Standards

Domestic Standards:

1. GB/T 42908-2023, Determination of organic halogen content in textile dyeing and finishing auxiliaries

2. GB/T 29493.1-2013, Determination of harmful substances in textile dyeing and finishing auxiliaries — Part 1: Determination of polybrominated biphenyls and polybrominated diphenyl ethers by gas chromatography-mass spectrometry

3. GB/T 29493.8-2013, Determination of harmful substances in textile dyeing and finishing auxiliaries — Part 8: Determination of perfluorooctane sulfonates and perfluorooctanoic acids

4. GB/T 20385-2006, Textiles — Determination of organotin compounds

International Standards:

1. EN 14582:2016, Characterization of waste — Determination of halogen and sulfur content — Oxygen combustion in closed systems and determination methods

2. EN 17137:2018, Textiles — Determination of the content of chlorinated paraffins

3. ISO 9562:2021, Water quality — Determination of adsorbable organically bound halogens (AOX)

4. IEC 62321-3-2, Determination of certain substances in electrotechnical products — Part 3-2: Screening — Fluorine, bromine, chlorine and iodine in polymers and electronics by combustion-ion chromatography

Note: The applicable standard can be selected according to the product use and customer trade requirements; standards agreed in the contract take precedence over general standards.

Testing Instruments and Equipment

Ion chromatograph (IC): Core for detecting the inorganic halogen ions (F⁻, Cl⁻, Br⁻ and I⁻). The key components include the high-efficiency separation column, suppressor and conductivity detector. In the textile halogen testing, it is mainly used for the separation and quantification of the halogen ions in the absorption solution after the oxygen bomb combustion or high-temperature hydrolysis, with the advantages of high sensitivity and the simultaneous determination of multiple ions.

Microcoulometric titrator: Specially used for determining the total halogens (chlorine, bromine and iodine) and the total sulfur and other elements. Its core is the coulometric titration cell. According to Faraday's law of electrolysis, the halogen content in the sample is precisely calculated by measuring the electric quantity consumed for the electrolytic generation of the titrant (such as silver ions). It is usually combined with the tube furnace combustion system for automated analysis.

Gas chromatography-mass spectrometer (GC-MS): Composed of the gas chromatography unit and the mass spectrometry detector. The GC is responsible for separating the components in the complex sample, and the MS acts as the detector to provide the molecular structure information of the compounds. In the halogen testing, an electron impact (EI) ion source is usually equipped, and the qualitative and quantitative analysis is carried out by using the characteristic ion fragments (such as the isotope cluster peaks of chlorine and bromine).

Liquid chromatography-tandem mass spectrometer (LC-MS/MS): Composed of the high-performance liquid chromatography (HPLC) and the triple quadrupole mass spectrometry. The HPLC is responsible for the separation, and the triple quadrupole mass spectrometry greatly reduces the background interference through two mass selections. This equipment is particularly suitable for detecting the trace and polar organic halogen pollutants, and is the key equipment for coping with the increasingly strict regulatory requirements (such as the restriction on PFAS).

Microwave digestion instrument/oxygen bomb combustor: Belonging to the pre-treatment equipment. The microwave digestion instrument can be used for the acid digestion of the organic matter in some samples, converting the halogens into the ionic state. The oxygen bomb combustor ignites the sample in a high-pressure pure oxygen environment, so that the organic halogens are completely converted into hydrogen halides and absorbed by the absorption solution, preparing for the subsequent ion chromatography or titration analysis, ensuring the complete decomposition of the sample without loss.