Copyright © 2006 American Association of Textile Chemists and Colorists 174TM 112-2003AATCC Technical Manual/2007Developed in 1965 by AATCC Committee RR68; reaffirmed 1968, 1972, 1989,1998, 2003; revised 1975, 1978, 1982,1984, 1993; technical correction 1983;editorially revised 1985, 1986; editorially revised and reaffirmed (with new title)1990.1. Purpose and Scope1.1 This test method is applicable to textile fabrics that may evolve formalde-hyde, particularly fabrics finished with chemicals containing formaldehyde. It provides accelerated storage conditions and an analytical means for determining the amount of formaldehyde released un-der the conditions of accelerated storage (see Section 5 and 10.1).1.2 An optional accelerated incubation procedure is available (see 13.5).2. Principle2.1 A weighed fabric specimen is sus-pended over water in a sealed jar. The jar is placed in an oven at a controlled tem-perature for a specified length of time (see 13.5). The amount of formaldehyde absorbed by the water is then determined colorimetrically.3. Terminology 3.1 formaldehyde release, n.—that formaldehyde evolved from textiles un-der the accelerated storage conditions of this test, including that which is free (un-bound or occluded) from unreacted chemicals, or from finish degradation as a result of this test.4. Safety PrecautionsNOTE: These safety precautions are for information purposes only. The pre-cautions are ancillary to the testing proce-dures and are not intended to be all inclu-sive. It is the user’s responsibility to use safe and proper techniques in handling materials in this test method. Manufac-turers MUST be consulted for specific details such as material safety data sheets and other manufacturer’s recommenda-tions. All OSHA standards and rules must also be consulted and followed.4.1 Good laboratory practice should be followed. Wear safety glasses in all labo-ratory areas.4.2 When handling glacial acetic acid to prepare Nash reagent, use chemical goggles or face shield, impervious gloves and an impervious apron during prepara-tion. Concentrated acids should be han-dled only in an adequately ventilated lab-oratory hood. CAUTION: Always add acid to water.4.3 Formaldehyde is a sensory irritant and potential sensitizer. Its chronic toxic-ity has not been fully established. Use in an adequately ventilated laboratory hood.Avoid inhalation or skin contact. Use chemical goggles or face shield, impervi-ous gloves and an impervious apron when working with formaldehyde.4.4 An eyewash/safety shower should be located nearby and a self-contained breathing apparatus should be readily available for emergency use.4.5 Exposure to chemicals used in this procedure must be controlled at or below levels set by governmental authorities (e.g., Occupational Safety and Health Administration’s [OSHA] permissible exposure limits [PEL] as found in 29CFR 1910.1000 of January 1, 1989). In addition, the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit V alues (TLVs)comprised of time weighted averages (TLV-TWA), short term exposure limits (TLV-STEL) and ceiling limits (TLV-C)are recommended as a general guide for air contaminant exposure which should be met (see 13.7).5. Uses and Limitations 5.1 The procedure is intended for use in the range of releaseable formaldehyde on the fabric up to about 3500 µg/g. The upper limit is 500 µg/g if a 1:1 ratio of Nash reagent to sample solution is used in the analytical portion of the test and 3500 µg/g if a 10:1 ratio is used. The pro-cedure promotes formaldehyde release from odor-free, fully cured durable press fabrics that have been afterwashed (Vail,S. L. and B. A. K. Andrews, Textile Chemist and Colorist , V ol. 11, No. 1, Jan-uary 1979, p. 48). For these reasons, the procedure should not be used to estimate µg/g formaldehyde in air for compliance with any mandated or voluntary stan-dards. The procedure was originally de-veloped to measure the “propensity of a resin-treated fabric to liberate an exces-sive amount of formaldehyde under hot,humid conditions.” (Nuessle, A. C.,American Dyestuff Reporter , V ol. 55, No.17, 1966, pp. 48-50; also Reid, J. D., R.L. Arcenaux, R. M. Reinhardt and J. A.Harris, American Dyestuff Reporter , V ol.49, No. 14, 1960, pp. 29-34.)AATCC Test Method 112-2003Formaldehyde Release from Fabric, Determination of:Sealed Jar MethodFig. 1—The wire mesh basket detailed on the left is suspended in a sealed jar with one fabric specimen as shown on the right.Copyright The American Association of Textile Chemists and Colorists Provided by IHS under license with AATCC Licensee=Hong Kong Polytechnic Univ/9976803100 Not for Resale, 03/24/2007 04:07:53 MDT No reproduction or networking permitted without license from IHSCopyright © 2006 American Association of Textile Chemists and Colorists AATCC Technical Manual/2007TM 112-20031756. Apparatus and Materials6.1 Mason or equivalent canning jars,0.95 L (1 qt) and gas sealing caps.6.2 Small wire mesh baskets (or other suitable means for suspending fabric above the water level inside the jars; see 13.1). As an alternative to the wire mesh baskets, a double strand of sewing thread may be used to make a loop in the fabric that has been folded in half twice, sus-pended above the water level. The two double-thread ends are draped over the top of the jar and held securely by the jar cap.6.3 Thermostatically controlled oven,49 ± 1°C (120 ± 2°F) (see 13.5).6.4 Nash reagent prepared from ammo-nium acetate, acetic acid and acetylace-tone and water (see7.1).6.5 Formaldehyde solution, approxi-mately 37%.6.6 V olumetric flasks, 50, 500 and 1000 mL.6.7 Mohr pipettes, graduated in tenths of a mL; and 5, 10, 15, 20, 25, 30 and 50mL volumetric pipettes, all calibrated “to deliver” and meeting Class B volume ac-curacy and flow time requirements (see 13.2).6.8 Graduated cylinders, 10 and 50mL, graduated in mL, calibrated “to de-liver” and meeting Class A volume accu-racy requirements (see 13.2).6.9 Photoelectric colorimeter or spec-trophotometer (see 10.2).6.10 Test tubes or colorimeter tubes (see 13.2).7.Preparation of Nash Reagent7.1 In a 1000 mL volumetric flask, dis-solve 150 g of ammonium acetate in about 800 mL of distilled water; add 3mL of glacial acetic acid and 2 mL of acetylacetone. Make up to the mark with distilled water and mix. Store in a brown bottle.7.2 The reagent darkens in color slightly on standing over the first 12 h.For this reason the reagent should be held 12 h before use. Otherwise, the reagent is usable over a considerable period of time,at least 6-8 weeks. However, since the sensitivity may change slightly over a long period of time, it is good practice to run a calibration curve weekly to correct for slight changes in the standard curve.8.Preparation of Standard Solution andCalibration (Caution)8.1 Prepare an approximately 1500 µg/mL stock solution of formaldehyde by di-luting 3.8 mL of reagent grade formalde-hyde solution (approximately 37%) to one liter with distilled water. Equilibrate the stock solution for at least 24 h before standardization. Determine the concen-tration of formaldehyde in the stock solu-tion by a standard method (see 13.6 or any other suitable procedure such as so-dium sulfite titration using 0.1 N HCl.Reference: J. Frederick Walker, Formal-dehyde , 3rd Ed. Reinhold Publ. Co., New York, 1964, p. 486). Record the actual concentration of this standardized stock solution. This stock solution will keep for at least four weeks and is used to prepare standard dilutions. A 1:10 dilution of the standardized formaldehyde stock solution is prepared by pipetting 25 mL of the standardized stock solution into a 250 mL volumetric flash and diluting to the mark with distilled water. If the stock solution is titrated and found to be different than 1500 µg/mL, three methods that can be used for preparing the calibration curves are:8.1.1 Calculate new volumes of stock solution aliquots to pipette to achieve ex-actly 1.5, 3.0, 4.5, 6.0 and 9.0 µg/mL, re-spectively. (For example, if the formalde-hyde stock solution were found to be 1470 µg/mL by titration, not 1500 µg/mL, pipette 5.1 mL, 10.2 mL, 15.3 mL,20.4 mL and 30.6 mL of the 147 µg/mL dilution into a 500 mL volumetric flask and dilute to mark with distilled water.)(NOTE: It is easy to make errors using a graduated pipette!)8.1.2 Pipette 5, 10, 15, 20 and 30 mL of the 1:10 dilution into a 500 mL volu-metric flask and dilute to mark with dis-tilled water. (If, for example, the stan-dardized stock solution were found to be 1470 µg/mL by titration, calculate new values for the calibration curve abscissa;i.e., 1.47, 2.94, 4.41, 5.88, 8.82 µg/mL.)This is the preferred method for those with a microprocessor spectrophotometer or computer. However, it is harder to plot manually.8.1.3 Calculate a concentration correc-tion factor for each sample. Correct the concentration for the dilution value using this factor. Plot the curve as if each of the dilutions were exactly 1.5, 3.0, 4.5, 6.0and 9.0 µg/mL. Calculate the correct con-centration for each of these values using the factor. For example, if the standard-ized stock solution were found to be 1470µg/mL by titration, then the correction factor (CF ) is:8.2 When 5, 10, 15, 20 and 30 mL ali-quots of the 1:10 dilution of the standard-ized stock solution from 8.1 are diluted with distilled water in 500 mL volumetric flasks, formaldehyde solutions contain-ing approximately 1.5, 3.0, 4.5, 6.0 and 9.0 µg/mL formaldehyde respectively will be obtained. Record accurately the concentration of solutions. The equiva-lent concentrations of the formaldehyde in the test fabric based on the weight of CF Actual Nominal --------------------14701500-----------0.980===1g of the test fabric and 50 mL of water in the test jars, will be 50 times the accu-rate concentrations of these standard so-lutions.8.3 Use 5 mL aliquots of each of the standard solutions and the procedure de-scribed in 10.4-10.7 to prepare a calibra-tion chart in which µg/mL formaldehyde are plotted against absorbance.9. Test Specimens 9.1 Cut approximately 1 g specimens;weigh each one to ± 0.01 g.10. Procedures 10.1 Place 50 mL of distilled water in the bottom of each jar. Suspend one fab-ric specimen above the water in each jar,using a wire mesh basket or other means (see Fig. 1). Seal the jars and place them in the oven at 49 ± 1°C (120 ± 2°F) for 20h (see 13.5).10.2 Remove and cool the jars for at least 30 min.10.3 Remove the fabric and baskets, or other support, from the jars. Recap the jars and shake them to mix any condensa-tion formed on the jar sides.10.4 Pipette 5 mL of Nash reagent into a suitable number of test tubes, small (50mL) Erlenmeyer flasks, or other suitable flasks (colorimeter or spectrophotometer tubes can be used directly, see 13.2) and pipette 5 mL of the reagent into at least one additional tube for a reagent blank.Add 5 mL aliquots from each of the sam-ple incubation jars to the tubes and 5 mL of distilled water to the tube which is used as a reagent blank.10.5 Mix and place the tubes in a 58 ±1°C water bath for 6 min. Remove and cool.10.6 Read the absorbance in the colo-rimeter or spectrophotometer against the reagent blank using a blue filter or a wavelength of 412 nm. Caution: Expo-sure of the developed yellow color to di-rect sunlight for a period of time will cause some fading. If there is appreciable delay in reading the tubes after color de-velopment and strong sunlight is present,care should be exercised to protect the tubes such as by covering them with a cardboard box or by similar means. Oth-erwise the color is stable for considerable time (at least overnight) and reading may be delayed.10.7 Determine the µg/mL formalde-hyde (HCHO) in the sample solutions us-ing the prepared calibration curve (see 8.3 and 13.3).11. Calculation 11.1 Calculate the amount of formalde-hyde released for each specimen to the nearest µg/g using the following equation:F = (C ) (50)/WCopyright The American Association of Textile Chemists and ColoristsProvided by IHS under license with AATCCLicensee=Hong Kong Polytechnic Univ/9976803100 Not for Resale, 03/24/2007 04:07:53 MDT No reproduction or networking permitted without license from IHSCopyright © 2006 American Association of Textile Chemists and Colorists 176TM 112-2003AATCC Technical Manual/2007where:F concentration of formaldehyde (µg/g),C =concentration of formaldehyde in solution as read from the calibra-tion curve, and W =weight of the test specimen, g.12. Precision and Bias 12.1 Precision.12.1.1 Interlaboratory tests. Two inter-laboratory studies (ILS) of AATCC Method 112 were conducted in 1990 and 1991, with a 20 h incubation at 49°C and a 5/5 sample to Nash solution ratio. Sin-gle operators in each participating labora-tory ran triplicate determinations on each fabric. In the first ILS, results from nine laboratories testing one fabric each at three low formaldehyde levels in the range of 100-400 µg/g were analyzed by analysis of variance (ANOV A). In the second ILS, results from eight laborato-ries testing ten fabrics of nominal 0 µg/g were analyzed by ANOV A. The analyses have been deposited for reference in the RA68 committee files.12.1.2 Critical differences were calcu-lated for zero-formaldehyde fabrics,shown in Table I, and for low level-form-aldehyde fabrics shown in Table II.12.1.3 When two or more laboratories wish to compare test results, it is recom-mended that laboratory level be estab-lished between them prior to beginning test comparisons.12.1.4 If comparisons are made be-tween laboratories on a single fabric level of formaldehyde release, the critical dif-ferences in the column, single level, in Table II should be used.12.1.5 If comparisons are made be-tween laboratories on a series of fabrics of a range of formaldehyde levels, the critical differences in the column, multi-ple levels, in Table II should be used.12.1.6 The number of determinations per laboratory average (det/avg) also de-termines the critical difference.12.2 Bias.12.2.1 The formaldehyde release of a fabric can be defined only in terms of a test method. There is no independent method for determining the true value. As a means of estimating formaldehyde re-leased from a fabric under the conditions of accelerated storage in AATCC Method 112, the method has no known bias.12.2.2 AATCC Method 112 generallyis accepted by the textile and apparel in-dustries as a referee method.13. Notes 13.1 A simple cloth support for insertion in the mason jars can be constructed as follows:A piece of aluminum wire screening 15.2 ×14.0 cm (6.0 × 5.5 in.) is bent around a length of wood 3.8 cm (1.5 in.) square and fastened together to form a rectangular, open-endedcage. One side is cut at the corners about half-way up the side and the cut section folded in-ward and fastened. This folded piece forms the bottom of the wire basket while the other three sides form the support legs. Fastening can be accomplished by twisting short lengths of wire through or around the appropriate part.13.2 The ratio of reagent to sample solu-tions can be adjusted, within limits, to suit the individual absorbance range and optical pathlength of the sampling tubes or cuvettes of the particular photometric instrument being used.For example, although 5 mL reagent to 5 mLsample solution has been found convenient for several types of instruments, other 1:1 ratios,such as a ratio of 2 mL reagent to 2 mL sam-ple may be more suitable for others. The same ratio should be used with the standards as with the sample. The use of colorimeter or spectro-photometer tubes directly for color develop-ments avoids the transfer step, test tubes to spectrophotometer cells, and may save consid-erable time when many determinations are to be made. Repipettes or similar devices can be used for reagent dispensing, and Oxford or Eppendorf disposable tip automatic pipettes can be used for the sample solutions.13.3 The procedure in Section 10 has been set up to cover the range from about 0 µg/g on the weight of the fabric to about 500 µg/g. In fabrics containing releasable formaldehyde in the range from 500 µg/g on the weight of the fabric to about 3500 µg/g, it is recommended that a ratio of 10 mL Nash reagent to 1 mL sample be used. If this is done, it is necessary to prepare an additional calibration chart with 10:1 ratios of standard solutions to Nash re-agent by diluting 5, 10, 15 and 20 µg/mL, re-spectively, of the approximately 1500 µg/mL standardized stock solution of formaldehyde to the mark with distilled water in 500 mL vol-umetric flasks. Formaldehyde solutions con-taining approximately 15, 30, 45 and 60 µg/mL respectively will be obtained (see 8.3).13.4 The chromotropic acid colorimetricmethod can be used as an alternate to the Nash reagent for the determination of the formalde-hyde content of the sample jars after oven in-cubation. It should be noted that the Precision and Bias Statement was not developed usingthe chromotropic acid method. A suitable pro-cedure is given in J. Frederick Walker, Form-aldehyde, 3rd Edition, Reinhold Publishing Co., NY, 1964, p470. When using this methoda change may be necessary in the size of both the aliquots taken from the sample jars (see10.2) and the standard formaldehyde solutions used in preparing the calibration curve (see 8.3).Caution! Since concentrated sulfuric acid is used with the chromotropic acid method, adequate care should be exercised to protect operating personnel and spectrophoto-metric equipment.13.5 Incubation conditions of 65 ± 1°C (149 ± 4°F) for 4 h can be used as an alternate to the incubation conditions of 49 ± 1°C (120± 2°F) for 20 h (see 5.3 and 10.1). The incuba-tion conditions of time and temperature mustbe reported. Upon completion of the 4-h incu-bation period, remove and cool the jars for at least 30 min and remove the fabric from the jars. Recap the jars and shake them to mix any condensation formed on the jar sides. Proce-dures for sample preparation and color devel-opment following the incubation period are performed as outlined in 10.4-10.7.13.6 Standardization of Formaldehyde Stock Solution. General: The stock solution containing approximately 1500 µg/mL of formaldehyde must be accurately standardized in order to make precise calculations from the calibration curve used in colorimetric analysis.An aliquot of the stock solution is reacted with an excess of sodium sulfite followed by a back-titration with standard acid solution in the presence of thymolphthalein as indicator.Apparatus: 10-mL volumetric pipette, 50-mL volumetric pipette, 50-mL burette, 150-mL Erlenmeyer flask.Reagents: 1 M sodium sulfite (126 g Anhy-drous Na 2SO 3/L), 0.1% Thymolphthalein Indi-cator in ethanol, 0.02 N sulfuric acid (can bepurchased in standardized form from chemical supply companies or must be standardizedfrom standard NaOH solution). Do not usecommercial standardized sulfuric acid that has been stabilized with formaldehyde. If there isa doubt, check with the chemical supplier.Procedure: A. Pipette 50 mL of 1 M Na 2SO 3 into the Erlenmeyer flask. B. Add 2drops of thymolphthalein indicator. C. Add a few drops of standard acid until blue color dis-appears (if necessary). D. Pipette 10 mL of thestock formaldehyde solution to the flask.(Blue color will reappear.) E. Titrate the solu-tion with the standard 0.02N H 2SO 4 until theblue color is discharged. Record the volume of acid used. (The volume of acid should be in the range of 25 mL for 0.02N acid.)Calculations:C = (30,030) (A ) (N )/10where:C =Wt/Vol concentration of formalde-hyde (µg/mL)A =V ol of acid used (mL)N =Normality of acid Perform the standardization in duplicates.Average the results and use the accurate con-centration in preparing the calibration curve for the colorimetric analysis.13.7 Available from Publications Office,ACGIH, Kemper Woods Center, 1330Kemper Meadow Dr., Cincinnati OH 45240;tel: 513/742-2020.Table I—Critical Differences for Zero Formaldehyde Det/Avg Critical Differences for Averages 95% Probability, µg/g Within Lab Single Fabric Between Labs Multiple Fabric Between Labs 17.712.013.82 5.510.612.73 4.510.212.3Table II—Critical Differences for Low Level Formaldehyde Det/Avg Critical Differences for Averages 95% Probability, µg/g Within Lab Single Fabric Between Labs Multiple Fabric Between Labs 121.680.3116.0215.278.9115.0312.478.4114.7Copyright The American Association of Textile Chemists and ColoristsProvided by IHS under license with AATCC Licensee=Hong Kong Polytechnic Univ/9976803100Not for Resale, 03/24/2007 04:07:53 MDT No reproduction or networking permitted without license from IHS。
