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ISO 17226-1 Chemical determination of formaldehyde content in leather (high-performance liquid chromatography)
Category:
Formaldehyde Emission
ISO 17226-1 Standard Description
ISO 17226-1 Leather - Chemical determination of formaldehyde content - Part 1 ： Method using high-performance liquid chromatography
ISO 17226-1 Standard Introduction
Formaldehyde is a potentially harmful chemical that may be generated during leather processing. The presence of this compound in leather products should be carefully monitored, particularly because it may cause allergic reactions and environmental impacts. ISO 17226-1 uses the HPLC-DAD method to determine the levels of free and released formaldehyde in leather. These tests are essential for ensuring that products comply with safety requirements and for enhancing competitiveness in the international market.
ISO 17226-1 Scope of Application
This standard applies to all types of leather products, including but not limited to:
◎ Unprocessed raw hides and leather
◎ Leather after various treatments (such as tanning, dyeing, and finishing)
◎ Leather materials used for manufacturing finished products such as footwear, apparel, furniture, and luggage
ISO 17226-1 Test Method
Ⅰ Reagent Preparation
1. Reagents Related to Formaldehyde Stock Solution
◎ Approximately 37% (mass fraction) formaldehyde solution
◎ 0.05 mol/L iodine solution (12.68 g iodine/L)
◎ 2.0 mol/L sodium hydroxide solution
◎ 2.0 mol/L sulfuric acid solution
◎ 0.1 mol/L sodium thiosulfate solution
◎ 1% starch solution (1 g starch/100 ml water)
2. HPLC Method-Related Reagents
◎ 0.1% sodium dodecyl sulfate or sodium lauryl sulfate (detergent solution, 1 g/1000 ml water)
◎ DNPH solution: 0.3 g DNPH dissolved in 10 ml concentrated phosphoric acid (85% mass fraction)
◎ HPLC-grade acetonitrile
Ⅱ Sample pretreatment
1. Sampling and Sample Preparation
◎ Sampling shall be conducted according to ISO 2418. If sampling cannot be performed in accordance with this standard (such as for finished leather products including shoes and apparel), the sampling details shall be specified in the test report.
◎ Leather samples shall be cut according to ISO 4044.
If the results are to be expressed on a dry matter basis, the moisture content of the same sample shall be determined according to ISO 4684 for conversion.
2. Extract
◎ Weigh approximately (2 ± 0.1) g of leather fragments, accurate to 0.01 g, and place them into a 100 ml glass conical flask.
◎ Add 50 ml of preheated detergent solution at 40 °C, and shake in a constant-temperature water bath at (40 ± 1) °C (frequency: 50 ± 10 times/min). Then filter using a glass fiber filter.
◎ Cool the filtrate to room temperature (18 °C–26 °C). Maintain a constant leather/solution ratio. Extraction and analysis shall be completed within the same working day.
3. Reaction with DNPH
◎ Take 5 ml of the filtered extract, add 4 ml of acetonitrile and 0.5 ml of DNPH solution, adjust the final volume to 10 ml, shake to mix, and allow to stand for 60–180 minutes.
◎ If the formaldehyde content is greater than 100 mg/kg, reduce the volume of the extract and dilute with water accordingly. (For example, for 500 mg/kg, take 0.5 ml of extract solution + 4.5 ml of water), then proceed with the above steps.
◎ Filter through a 0.45 μm polyamide membrane and perform HPLC analysis.
Ⅲ HPLC Analysis
1. Calibration
◎ Calibration using formaldehyde stock solution: Dilute a formaldehyde stock solution with a known concentration to approximately 2 μg/ml standard solution. Prepare a series of concentrations ranging from 0.1–2.0 μg/ml, react with DNPH, and establish a calibration curve based on the DNPH-formaldehyde peak area.
◎ Calibration using derivatized DNPH-formaldehyde: Add 4 ml of acetonitrile into six 10 ml volumetric flasks, add 1.0 μg, 4.0 μg, 8.0 μg, 12.0 μg, 16.0 μg, and 20.0 μg formaldehyde respectively, adjust the volume, analyze, and establish a calibration curve.
2. Sample Determination
Inject the prepared sample solution into the HPLC system. Use acetonitrile/water (60:40) as the mobile phase, with a flow rate of 1.0 ml/min. Use a C18 reversed-phase column (with a 1 cm RP18 pre-column), an injection volume of 20 μl, and detect at a wavelength of (355 ± 5) nm.
ISO 17226-1 Determination Basis
Calculate the formaldehyde concentration in the sample (mg/kg).
Among them:
WF: Formaldehyde concentration in the sample (mg/kg)
ρS: Formaldehyde concentration obtained from the calibration curve (μg/10 ml)
F: Dilution factor (ml)
M: Mass of leather sample (g)
SATISFY provides one-stop formaldehyde emission testing services, including preliminary assessment, preparation and submission of relevant documentation, complete test monitoring, report interpretation, data analysis, and corrective action recommendations. For more information, please contact SATISFY customer service.
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