1、December 2015 English price group 10No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 65.160!%Il“2385973www.din.deDIN
2、 ISO 16632Tobacco and tobacco products Determination of water content Gas-chromatographic method (ISO 16632:2013),English translation of DIN ISO 16632:2015-12Tabak und Tabakerzeugnisse Bestimmung des Wassergehalts Gaschromatographisches Verfahren (ISO 16632:2013),Englische bersetzung von DIN ISO 166
3、32:2015-12Tabac et produits du tabac Dtermination de la teneur en eau Mthode par chromatographie en phase gazeuse (ISO 16632:2013),Traduction anglaise de DIN ISO 16632:2015-12SupersedesDIN ISO 16632:2004-05www.beuth.deDocument comprises pagesDTranslation by DIN-Sprachendienst.In case of doubt, the G
4、erman-language original shall be considered authoritative.1411.15 Contents PageIntroduction 1 Scope .2 Normative references 3 Terms and definitions .4 Principle 5 Reagents 6 Apparatus .7 Sampling 8 Procedure.8.1 Sample handling 8.2 Test portion 8.3 Setting up the apparatus.8.4 Calibration of the gas
5、 chromatograph 9 Expression of results .10 Repeatability and reproducibility .11 Alternative gas-chromatographic procedures and analysis precautions .11.1 General 11.2 Alternative columns .12 Test report Bibliography .DIN ISO 16632:2015-12 2 National foreword . 3 National Annex NA (informative) Bibl
6、iography 4 566666788888910101212121314A comma is used as the decimal marker. National foreword This document (ISO 16632:2013) has been prepared by Technical Committee ISO/TC 126 “Tobacco and tobacco products”. The responsible German body involved in its preparation was DIN-Normenausschuss Lebensmitt
7、el und landwirtschaftliche Produkte (DIN Standards Committee Food and Agricultural Products), Working Committee NA 057-04-01 AA Tabak und Tabakerzeugnisse. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. DIN shall not be held resp
8、onsible for identifying any or all such patent rights. The DIN Standards corresponding to the International Standards referred to in this document are as follows: ISO 648 DIN EN ISO 648 ISO 1042 DIN EN ISO 1042 ISO 3534-1 DIN ISO 3534-1 ISO 3534-2 DIN ISO 3534-2 ISO 3696 DIN ISO 3696 ISO 4387 DIN IS
9、O 4387 ISO 6488 DIN ISO 6488 ISO 8243 DIN ISO 8243 ISO 15592-1 DIN ISO 15592-1 ISO/IEC 17025 DIN EN ISO/IEC 17025 Amendments This standard differs from DIN ISO 16632:2004-05 as follows: a) a warning notice has been included to point out that the use of this standard can involve hazardous materials,
10、operations and equipment. b) the definition of the term “high-moisture tobacco” has been revised (3.1). Previous editions DIN ISO 16632: 2004-05 DIN ISO 16632:2015-12 3 National Annex NA (informative) Bibliography DIN EN ISO 648, Laboratory glassware Single-volume pipettes DIN EN ISO 1042, Laborator
11、y glassware One-mark volumetric flasks DIN EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories DIN ISO 3534-1, Statistics Vocabulary and symbols Part 1: General statistical terms and terms used in probability DIN ISO 3534-2, Statistics Vocabulary and sym
12、bols Part 2: Applied statistics DIN ISO 3696, Water for analytical laboratory use Specification and test methods DIN ISO 4387, Cigarettes Determination of total and nicotine-free dry particulate matter using a routine analytical smoking machine DIN ISO 6488, Tobacco and tobacco products Determinatio
13、n of water content Karl Fischer method DIN ISO 8243, Cigarettes Sampling DIN ISO 15592-1, Fine-cut tobacco and smoking articles made from it Methods of sampling, conditioning and analysis Part 1: Sampling DIN ISO 16632:2015-12 4 IntroductionDuring the development of this International Standard, inte
14、rlaboratory tests were carried out using two different principles for the determination of the water content of raw tobacco and tobacco taken from finished products. These were the gas-chromatographic procedure, and the Karl Fischer procedure.These studies show that no differences occur between the
15、results obtained by the two different methods. The Karl Fischer method is described in ISO 6488.DIN ISO 16632:2015-12 5 Tobacco and tobacco products Determination of water content Gas-chromatographic methodWARNING The use of this standard can involve hazardous materials, operations and equipment. Th
16、is International Standard does not purport to address all the safety problems associated with its use. It is the responsibility of the user of this International Standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.1 Sco
17、peThis International Standard specifies a gas-chromatographic (GC) method for the determination of water content. It is applicable to raw tobacco as well as tobacco taken from finished products. The method is suitable for water contents ranging at least from a mass fraction of 2 % to 55 %.2 Normativ
18、e referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) appl
19、ies.ISO 3696, Water for analytical laboratory use Specification and test methodsISO 4874, Tobacco Sampling of batches of raw material General principlesISO 8243, Cigarettes SamplingISO 15592-1, Fine-cut tobacco and smoking articles made from it Methods of sampling, conditioning and analysis Part 1:
20、Sampling3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1high-moisture tobaccoany tobacco sample containing volatile matter over 20 % as determined by drying at between 100 C and 105 C4 PrincipleThe water content of a sample of tobacco or a tobac
21、co product is determined by methanolic extraction, followed by capillary GC analysis with thermal conductivity detection, using isopropanol as internal standard. The method is applicable to any type of tobacco sample provided that the particle size reduction is less than 4 mm.NOTE If a size reductio
22、n (grinding or cutting) is applied, it can create a decrease in the original water content. Cryogenic techniques may be used to prevent such moisture losses.5 ReagentsUse only reagents of recognized analytical grade.5.1 Carrier gas: helium.DIN ISO 16632:2015-12 N1)N1)National footnote: In the German
23、 version of this standard, the term “particle size reduction” has, for a better understanding, been translated as “Teilchengre” (see 8.1). 6 5.2 Methanol, with a maximum water content of 1,0 mg/ml.This is hygroscopic so it is recommended to cap the bottle with an automatic delivery pipette equipped
24、with a drying tube.5.3 Internal standard: isopropanol, of at least 99 % purity.5.4 Water, complying with grade 2 of ISO 3696, or better.5.5 Extraction solvent: methanol (5.2) containing 2,0 ml of internal standard (5.3) per litre.5.6 Desiccant: silica gel, freshly activated.5.7 Calibration solutions
25、Prepare a series of at least four calibration solutions whose concentrations of added water cover the range expected to be found in the test portion by adding weighed amounts of water (5.4) to the solvent (5.5). One of these calibration solutions shall be the extraction solvent with no added water (
26、solvent blank).To prevent water being absorbed, the bulk solvent container shall be fitted with a water trap and all solutions shall be kept sealed. The solvent shall be stirred continuously to ensure the homogeneity of the water concentration in the solvent. The calibration solutions shall be made
27、up using an extraction solvent from the same batch used in 8.1. Transfer them to injection vials and cap immediately.It is recommended that the calibration solutions be made up at least each week.NOTE For example, calibration solutions may be prepared as follows. Create a stock standard solution by
28、accurately weighing (to the nearest 0,1 mg) 25,000 g of water into a dry 500 ml volumetric flask. Dilute the water with extraction solvent (5.5) to the 500 ml mark. Pipette 0 ml, 5 ml, 10 ml, 20 ml, 30 ml, 40 ml, 50 ml and 60 ml of the stock standard water solution into each of eight dry 100 ml volu
29、metric flasks. Dilute to volume with extraction solvent (5.5). The standard calibration solutions contain 0,0 mg, 2,5 mg, 5,0 mg, 10,0 mg, 15,0 mg, 20,0 mg, 25,0 mg, and 30,0 mg of water per millilitre of extraction solvent.6 ApparatusUsual laboratory apparatus and, in particular, the following item
30、s.All glassware used in the preparation and in the water determination shall be heated at (105 5) C for at least 1 h after visible water has evaporated. The glassware shall then be cooled and stored in a desiccator over desiccant (5.6) until used.6.1 Extraction vessels, dry serum bottles with crimp
31、caps, or conical flasks with ground glass lids, of capacity 125 ml.It is especially important to have excellent seals to prevent water absorption from air exposure.6.2 Shaker, preferably horizontal, but wrist-action acceptable.6.3 Disposable syringes, of capacity 10 ml, equipped with 25 mm diameter
32、membrane filters with 0,45 m pore size, or equivalent.6.4 Volumetric flasks, of capacities 100 ml, 250 ml and 500 ml.6.5 Gas chromatograph, equipped with a thermal conductivity detector and recorder or integrator.DIN ISO 16632:2015-12 7 6.6 Column, of internal diameter 0,53 mm, and of length 25 m.Th
33、e column is preferably made of PLOT fused silica.NOTE PoraPLOT U1), 20 m film thickness, has been found to be satisfactory as the stationary phase (see also Clause 11).7 SamplingSample raw tobacco in accordance with ISO 4874 and cigarettes in accordance with ISO 8243. Sample fine-cut tobacco in acco
34、rdance with ISO 15592-1.Each time a sample is collected and stored, it should be placed in an airtight container having a size just sufficient to contain the sample.If samples are stored at 4 C, allow the closed container to equilibrate at room temperature before opening.8 Procedure8.1 Sample handli
35、ngCombine and mix enough retail units to constitute at least 100 g for each test subsample. If size reduction is employed, the sample should be cut sufficiently small to pass through a 4 mm screen. The sample may be frozen with liquid nitrogen before cutting if the absolute moisture level is of inte
36、rest. Cut filler from cigarettes need not be reduced further in size.If high-moisture samples (see 3.1) cannot be analysed immediately, they should be stored below 4 C for no longer than 10 days.8.2 Test portionWeigh, to the nearest 0,1 mg, 5,0 g of the sample (8.1) into the dry extraction vessel (6
37、.1). A minimum of two test portions shall be prepared and analysed for each test sample.Pipette 100,0 ml of extraction solvent (5.5) into the extraction vessel and immediately seal the vessel. Place the extraction vessel in the shaker (6.2) and shake for 3 h. Remove the extraction vessel from the sh
38、aker and set it aside overnight. The test portions should be gently swirled or mixed mechanically prior to removal of the analysis aliquot. Assemble a disposable syringe (6.3) with a 0,45 m filter (6.3). Carefully transfer about 5 ml of the supernatant liquid into the disposable filtration assembly.
39、 Purge the filter of adsorbed water by disposing of a small volume of the extract. Filter the extract into a 2 ml GC injection vial and cap the vial. Store the filtered extract in a refrigerator below 4 C until GC analysis, making certain of tight seals.If the extract is not analysed on the same day
40、, store in a refrigerator. After conditioning to room temperature, the extract should be analysed.8.3 Setting up the apparatusSet up the apparatus and operate the gas chromatograph (6.5), recorder or integrator and autosampler (if used) in accordance with the manufacturers instructions. Ensure that
41、the peaks for water, internal standard and solvent are well resolved. Condition the system just prior to use by injecting two 0,5 l aliquots of the extraction solvent as a primer.Suitable operating conditions are as follows: carrier gas: helium;1) PoraPLOT U is an example of a suitable product comme
42、rcially available. This information is given for the convenience of users of this International Standard, and does not constitute an endorsement by ISO of this product.DIN ISO 16632:2015-12 8 linear velocity: 30 cm/s at 50 C; injection temperature: 250 C; injection liner: appropriate liner packed wi
43、th glass wool; injection mode: splitless (split valve closed during injection, to be opened after about 1 min); injection volume: 0,5 l; initial temperature: 60 C; initial hold time: 0 min; temperature ramp A: 5 C/min; final temperature A: 130 C; final hold time A: 0 min; temperature ramp B: 10 C/mi
44、n; final temperature B: 170 C; final hold time B: 5 min; total analysis time: 23,00 min; detector: 250 C.Optimize the GC conditions for analyte separation and sensitivity. Once optimized, the same GC conditions shall be used for the analysis of all standards and samples, including the same injection
45、 volume of 0,5 l.8.4 Calibration of the gas chromatograph8.4.1 ProcedureInject an aliquot (0,5 l) of each of the calibration solutions (5.7) into the gas chromatograph. Record the peak areas (or heights) of the water and internal standard (5.3). Carry out the determination at least twice, with one s
46、eries preferably interspersed with the test portion injections.Calculate the ratio of the water peak to the internal standard peak (Yi= AH2O/AIS) from the peak area (or height) data for each of the calibration solutions including the solvent blanks. Plot the graph of the concentrations of added wate
47、r (X-axis) in accordance with the area ratios (Y-axis). Calculate a linear regression equation (y = a + bx) from these data, and use both the slope and the intercept of the linear regression equation.If the correlation coefficient R2is less than 0,99, the calibration should be repeated. If an indivi
48、dual calibration point differs by 10 % or more from the expected value (estimated by linear regression), it should be omitted. The signal (peak area or height) obtained for all test portions must fall within the working range of the calibration curve.Perform this full calibration procedure daily. In
49、 addition, inject an aliquot of an intermediate concentration standard after every 20 sample determinations. If the calculated concentration for this solution differs by more than 3 % from the original value, repeat the full calibration procedure.Perform the full calibration if a new extraction solvent is made. If only four calibration solutions are available, no calibration solution should be omitted from
