DIN 51405-2004 Testing of mineral oil hydrocarbons similar liquids and solvents for paints and varnishes - Analysis by gas chromatography - General working principles《色漆和清漆用石油烃类、类似.pdf

1、DEUTSCHE NORM51405Translation by DIN-Sprachendienst.In case of doubt, the German-language original should be consulted as the authoritative text. No part of this translation may be reproduced without the prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Ber

2、lin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).January 2004General principles governing the gas chromatographic analysis of petroleum products and related liquids and solvents used in paints and varnishesDocument comprises 12 pages.ICS 75.080; 87.060.30 Supersedes May

3、 1987 edition.Prfung von Minerall-Kohlenwasserstoffen, verwandten Flssigkeiten und Lsemitteln fr Lacke und Anstrichstoffe Gaschromatographische Analyse Allgemeine ArbeitsgrundlagenEnglish price group 11 www.din.de www.beuth.de06.05 9632088!,b7“In keeping with current practice in standards published

4、by the International Organization for Standardization (ISO), a comma has been used throughout as the decimal marker.ForewordThis standard has been prepared by Technical Committee Prfung von ssigen Kraftstoffen und Heizlen of the Fachausschuss Minerall- und Brennstoffnormung of the Normenausschuss Ma

5、terialprfung (Mate-rials Testing Standards Committee).AmendmentsThis standard differs from the May 1987 edition in that the terminology has been amended, details of the detector have been included, the evaluation method has been described in more detail and the standard has been editorially revised.

6、Previous editionsDIN 51504: 1972-03, 1987-05.1 ScopeThe method specied in this standard serves to analyse petroleum products, related organic substances, gases and solvents as used for paints, varnishes and similar coatings, and their volatile components by gas chromatography. The standard also dene

7、s a number of relevant concepts.Gas chromatography provides information about the components of a sample and their concentration, thus making it possible to determine its composition or to characterize its purity.2 Normative referencesThis standard incorporates, by dated or undated reference, provis

8、ions from other publications. These normative references are cited at the appropriate places in the text, and the titles of the publications are listed below. For dated references, subsequent amendments to or revisions of any of these publications apply to this standard only when incorporated in it

9、by amendment or revision. For undated references, the latest edition of the publication referred to applies.DIN 1310 Concepts and symbols relating to the composition of gaseous, liquid and solid mix-turesDIN 32645 Establishing the limit of detection and quantication under repeatability conditions in

10、 chemical analysis Terminology, methods and evaluationDIN EN ISO 4259 Petroleum products Determination and application of precision data in relation to methods of test (ISO 4259 : 1992 + Corr 1 : 1993)ASTM E 355-96 Standard practice for gas chromatography terms and relationships 1)1) Obtainable from

11、 Beuth Verlag GmbH, 10772 Berlin, Germany.Page 2 DIN 51405 : 2004-011 Kovats, E. Gaschromatographische Charakterisierung organischer Verbindungen (Gas chromatographic characterization of organic compounds), Helv. Chim. Acta, 1958: 41, 1915-1932; and Wehrli, A., and Kovats, E. Gaschromatographische C

12、harakterisierung organischer Verbindungen (Gas chro-matographic characterization of organic compounds), Helv. Chim. Acta, 1959: 42, 2709-2736.2 Rohrschneider, L. Grundlagen chromatographischer Trennverfahren (Principles of chromatographic separa-tion methods), Ullmann, 1980: Verlag Chemie, vol. 5, 1

13、05.3 Deans, D.R., Chromatographia, 1968: 1, 18.3 Principles3.1 Gas chromatographyThe term gas chromatography (GC) refers to chromatographic methods in which the mobile phase is gaseous and the stationary phase is contained in the column (see subclause 4.1.3). In gas-liquid chromatography (GLC), the

14、stationary phase may consist of a liquid lm on the surface of a carrier material or on the internal wall of a capillary tube, while, in gas-solid chromatography (GSC), it is the surface of an adsorbent.After the sample has been injected at the column inlet, its components are swept through or eluted

15、 from the column by the mobile phase. The sample components are analysed by a detector at the outlet of the column.3.2 Gas chromatogram3.2.1 GeneralA gas chromatogram is a plot of the detector signal against time. The concepts given in subclauses 3.2.2 to 3.2.7 are used when referring to differentia

16、l gas chromatograms (see gure 1). Integral gas chromatograms are plotted, for example, in the volumetric determination of gases.Page 3 DIN 51405 : 2004-01a) Differential gas chromatogramb) Comparison of differential and integral chromatogramsFigure 1: Gas chromatograms3.2.2 Zero lineThe line recorde

17、d by the plotter or computer during the ow of pure carrier gas.3.2.3 BaselineAn imaginary line underneath a peak or a group of superimposed peaks obtained by connecting the consecutive minima of a gas chromatographic curve. It is generally assumed to be a straight line, but it does not necessarily c

18、oincide with the zero line *).3.2.4 PeakThe portion of a chromatogram that deviates from the baseline when a single component is eluted from the column, as recorded by a plotter or computer. If there are a number of components present in a sample, peaks may be superimposed.3.2.5 Peak heightThe dista

19、nce between the peak maximum and the baseline (designated by h).*) Translators note. In ASTM E 355 dened as the portion of a chromatogram recording the detector response in the absence of solvent eluted from the column.Page 4 DIN 51405 : 2004-013.2.6 Peak width at half heightThe width of a peak meas

20、ured at half its height (designated by b0,5).3.2.7 Peak areaThe area, A, enclosed between a peak and the baseline (e.g. ABin gure 1). If peaks are superimposed, the peak area may also be enclosed between the perpendiculars at the minima. In this case, particular procedures may need to be specied for

21、 determining the peak areas when using the individual test methods, a frequently used procedure being to determine the peak areas by dropping the perpendiculars at the minima.Depending on the type of detector used, the unit to measure the peak area will be ampere-second or volt-second.3.3 Retention

22、parameters3.3.1 Retention timeThe retention time, tR, of the component to be determined is the time between the injection of a sample and the detection of the peak maximum for the component. The retention time can be resolved into the dead time, tM(see subclause 3.3.3), necessary for the elution of

23、an unretarded component, and the adjusted retention time, tqR, which is the retention time less the dead time (see subclause 3.3.2.1), and is a measure of the extent to which the sample components interact with the stationary phase.3.3.2 Relative retention parameters3.3.2.1 GeneralRelative retention

24、 parameters, such as retention ratio, ri, and the retention index, Ii, both of which relate to a particular stationary phase and a particular temperature, are largely independent of equipment parameters under isothermal conditions and are consequently suitable for characterizing the separation chara

25、cteristics of this phase.3.3.2.2 Retention ratioThe retention ratio, ri, is the ratio of the adjusted retention time of substance i, tqR,i, to the adjusted retention time of a standard (St), tqR,St, i.e.:tiR,iR,St=tt(1)NOTE: For practical reasons, the standard should be readily obtainable and elute

26、in the vicinity of the sub-stance to the determined.3.3.2.3 Retention indexThe retention index, Ii, is an n-alkanes retention parameter 1. It is determined by logarithmic interpolation between the retention times of two n-alkanes that differ by one carbon atom and is calculated using the follow-ing

27、equation:I nt tt tiR,i R(n)R(n+1) R(n)lg lglg lg= + 100(2)wheren is the number of carbon atoms in the alkane having the shorter retention time;n + 1 is the number of carbon atoms in the alkane having a retention time longer than tqR,i.NOTE: For the purposes of this standard, the Kovats retention ind

28、ex system is useful for characterizing the separation characteristics of stationary phases.3.3.3 Retention volumeThe volume of mobile phase, VR, eluted in the time between the injection of the sample and the detection of a peak maximum, tR, while the dead volume, VM, is the volume eluted at the dead

29、 time.NOTE: The dead volume can be used to calculate the ow rate of the carrier gas in the column.3.3.4 Mean linear velocity of carrier gasRatio, u, of the length of the column, L, to the dead time, i.e.:uLt=M(3)Page 5 DIN 51405 : 2004-013.4 Peak resolutionThe resolution of two adjacent peaks, R, is

30、 dened as:Rt tb b=+1180 5 0 5,( ) ( )R,B R,A, A , B(4)NOTE: In this equation, R is dened as the ratio of the peak separation, tR,B tR,A, to the mean peak width, (wA+ wB)/2. This denition of R is used in ASTM E 355-96 and elsewhere. For Gaussian peaks, w is equal to 1,699 b0,5.3.5 Separation numberTh

31、e separation number, SN, is given by:SNt tb b=+R(n+1) R(n), n , n+1( ) ( )0 5 0 51 (5)and is used to characterize the separation efciency. It indicates how many peaks of the same size, given com-plete resolution, can be accommodated between a homologous pair containing n and n + 1 carbon atoms.3.6 P

32、eak skewPeak skew, PS, is a criterion describing the quality of separation by chromatography and is shown in gure 2. It is given by:PSME MBBE=(6)whereME is the distance between points M and E;MB is the distance between points M and B;BE is the distance between points B and E.If PS is less than zero

33、(negative), the peak is fronted (see gure 2), if it is greater than zero, the peak is tailed, and if it equals zero, the peak is symmetrical.Since peak skew is always referred to in connection with particular separation problems, the above denition gives an adequate description of a requirement for

34、the separation system on a case-by-case basis.Figure 2: Peak skewNOTE: Asymmetrical peaks occur if there is no linear relationship between the distribution of the sample com-ponents between the mobile and stationary phases, and the concentration. This may be due, for example, to the column being ove

35、rloaded with an excessively large sample quantity, or to the stationary phase or temperature in the column being inappropriate, and to an insufcient deactivation of the separation system. In such cases, quantity-dependent changes may occur in the retention parameters, the separation number and the p

36、eak resolution.3.7 UnitsAs specied in DIN 1310, all results and calibration factors shall be reported in SI units or combinations of such units (e.g. g/100 g, g/g or mg/kg for proportions by mass, v, ml/100 ml or ml/m3for proportions by volume, f, and mol/mol for mole fractions, x).Page 6 DIN 51405

37、: 2004-014 Apparatus4.1 Gas chromatograph4.1.1 GeneralThe test equipment used shall be a commercial gas chromatograph consisting essentially of the components described below (see gure 3).Key:1 Pressure regulator 7 Capillary column2 Pressure gauge 8 Oven chamber3 Injection block 9 Detector temperatu

38、re control4 Injection-block temperature control unit 10 Flame ionization detector (FID)5 Sample splitter 11 Flow resistance6 AdsorberFigure 3: Example of capillary gas chromatograph with carrier gas pressure regulator and ame ionization detectorOther gas chromatographs may be used if they conform to

39、 this standard or meet the requirements specied in the individual test standards.4.1.2 Carrier gas regulatorsTo ensure reproducibility of the column inlet pressure or the carrier gas ow, the chromatograph shall be tted with a suitable pressure or ow regulator.NOTE: A owmeter (e.g. soap-lm owmeter) s

40、hould be available for checking the carrier gas ow.4.1.3 Sample inlet systems4.1.3.1 GeneralSample inlet systems are intended to introduce gaseous or liquid samples into the carrier gas ow in a repro-ducible manner. The sample should be undecomposed and be applied to the top of the column as a narro

41、w band.4.1.3.2 Gaseous sample injectionSuitable injectors for gaseous samples are gas sampling loops or gastight injection syringes. Details are to be specied in the relevant test standards.4.1.3.3 Liquid sample injectionAn injection syringe is to be used for liquid samples.a) Direct injectionThe di

42、rect injection of unvaporized samples into the column has proved particularly suitable for sensitive sub-stances. On-column injectors are needed for the injection into capillary columns.Page 7 DIN 51405 : 2004-01b) Splitless injectionIn splitless injection, the sample is injected through a silicone

43、rubber septum into the heated evaporation cham-ber with carrier gas owing through it. The sample evaporates and is conveyed to the column by the carrier gas ow.c) Split injectionSample splitting is necessary when the quantity of sample material permitted for the column or the detector is less than c

44、an be reproducibly injected using an injection syringe (especially in the case of capillary columns). Before it enters the column, the carrier gas ow containing the sample vapour is split into two ows. The split ratio (ratio of split ow to column ow) shall be chosen to suit the particular problem.4.

45、1.3.4 Automatic injection systemsAutomatic injection systems may be used if they meet the requirements specied in the relevant test standards. Due attention shall be paid to the manufacturers instructions.NOTE: It is especially difcult to achieve discrimination-free sample injection of mixtures with

46、 a wide distillation range, especially if capillary splitters are used. Since the degree of discrimination may depend on such spe-cic experimental parameters as sample injection, split ratio, column arrangement, state of the evaporation chamber, etc., it is desirable, as far as possible, to use the

47、same experimental conditions for calibration and analysis. Calibration measurements using a homologous mixture containing known concentrations of, for example, n-alkanes may be used to detect discrimination and to check the reproducibility of the system.4.1.4 Column4.1.4.1 GeneralThe column is a met

48、al, glass or quartz tube containing the stationary phase for separating the sample compo-nents. In packed columns, the stationary phase is distributed over the cross section of the tube, while in capil-lary columns the stationary phase is on the wall of the tube and the centre of the column is unobs

49、tructed.4.1.4.2 Column switching techniquesColumn switching techniques are used, for example,a) to increase the separation efciency of the system using additional columns to separate unseparated peaks (multidimensional chromatography), orb) to shorten the analysis time by back-ushing high-boiling components and determining them jointly in a detector.Suitable devices for switching the columns may be valves that have a small switching volume compared with the peak volume and do not interact wi