1、 No part of this translation may be reproduced without the 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).Ref. No. DIN 51444 : 2003-11English price group 6 Sales No. 010602
2、.05Continued on pages 2 to 4.ICS 75.080Prfung von Minerallerzeugnissen Bestimmung des gebundenen Stickstoffs Verbrennungsverfahren mit Chemolumineszenz-DetektorIn keeping with current practice in standards published by the International Organization for Standardization (ISO), a comma has been used t
3、hroughout as the decimal marker.51444Determination of bound nitrogen in petroleum products by combustion and chemiluminescenceTranslation by DIN-Sprachendienst.In case of doubt, the German-language original should be consulted as the authoritative text.DEUTSCHE NORM November 2003ForewordThis standar
4、d has been prepared by Technical Committee Prfung von ssigen Kraftstoffen und Heizlen of the Fachausschuss Minerall- und Brennstoffnormung of the Normenausschuss Materialprfung (Mate-rials Testing Standards Committee).1 ScopeThe method specied in this standard serves to determine bound nitrogen in c
5、oncentrations ranging from about 0,3 mg/kg to about 300 mg/kg in petroleum products having a boiling range of 50 C to 400 C and viscosities between 0,2 mm2/s and 10 mm2/s at ambient temperature. Samples having a higher nitrogen content shall be diluted as appropriate prior to the analysis.2 Normativ
6、e referencesThis standard incorporates, by dated or undated reference, provisions 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 a
7、ny of these publications apply to this standard only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication referred to applies.DIN EN ISO 4259 Petroleum products Determination and application of precision data in relation to methods of test (
8、ISO 4259 : 1992 + Corr 1 : 1993)3 PrincipleA sample is injected into a stream of carrier gas composed of an inert gas or a mixture of an inert gas and oxygen, evaporated and conveyed into a high-temperature zone where the bound nitrogen reacts with oxy-gen to form nitrogen monoxide (NO). Reaction wi
9、th ozone converts the latter into excited nitrogen dioxide (NO2), which emits light that can be detected by a photomultiplier. The resultant signal is a measure of the nitrogen content of the sample.4 DesignationDesignation of the method of determining bound nitrogen by chemiluminescence:Test DIN 51
10、444Page 2DIN 51444 : 2003-115 Apparatus5.1 Test assemblyThe test assembly shall be as shown schematically in gure 1. It is to be made up of the following.5.1.1 Furnace, capable of maintaining a temperature sufcient to evaporate the entire sample material and oxidize the bound nitrogen to form nitrog
11、en monoxide. The furnace temperature is to be specied by the manufacturer.5.1.2 Quartz combustion tube, for evaporating or pyrolysing the sample in a carrier gas and burning it with oxygen in a zone large enough to completely oxidize the sample. The tube inlet shall be sealed (e.g. with a septum). O
12、ther combustion tubes may be used if this does not adversely affect the precision of the method.Figure 1: Test assembly (schematic)5.1.3 Dryer, for drying the reaction products prior to the analysis using a chemical desiccant, permeation drying or a combination of both, since water vapour damages th
13、e detector.5.1.4 Chemiluminescence detector, capable of measuring the light emitted by the reaction of nitrogen monoxide and ozone.5.1.5 Evaluation unit with integrator.5.1.6 Microlitre syringes, having a nominal capacity of 5 l to 250 l and a needle long enough for its tip to extend into the hottes
14、t part of the evaporator zone during injection.5.1.7 Automatic sample injection system (optional), having reproducible injection speeds and consequently resulting in optimum combustion.5.1.8 Combustion boat for sample application (optional), for use with samples that may react with the needle, the p
15、yrolysis tube being designed in this case to allow the boat to be introduced into the combustion zone completely.5.1.9 Outlet unit of combustion tube (optional), capable of accommodating a removable quartz insert tube.5.1.10 Quartz insert tube (optional), lled with copper oxide, CuO, to promote comp
16、lete oxidation of sample.6 ReagentsUnless otherwise specied, analytical grade reagents shall be used.6.1 Chemically inert desiccant (e.g. magnesium perchlorate, MgClO4), if a permeation dryer is not used.6.2 Nitrogen-free solvent (e.g. toluene, isooctane or cetane), that produces a signal in the cas
17、e of a sample composed of pure solvent that is less than the signal for a sample containing 0,3 mg/kg total nitrogen by a factor of 3.6.3 Carbazole, C12H9N, with a nitrogen content of 8,377 g/100 g or pyridine, C5H5N, with a nitrogen content of 17,708 g/100 g, for preparing calibration solutions.Che
18、mi-luminescence detectorDryerOzone generatorCombustion tube Inlet systemFurnaceOxygen Carrier gasPage 3DIN 51444 : 2003-116.4 99,996 % (V/V) carrier gas, helium or argon, supplied in compressed gas cylinders.6.5 99,995 % (V/V) oxygen, supplied in compressed gas bottles.NOTE: Depending on the type of
19、 apparatus used, a mixture of the gases specied in subclauses 6.4 and 6.5 may be used.6.6 Copper oxide wire, as recommended by the manufacturer of the equipment.6.7 Quartz wool.7 Safety aspectsSince this method involves high temperatures, particular care is to be taken in handling ammable materials
20、in the vicinity of the furnace.8 Sample handlingSamples shall be analysed as soon as possible after collection to prevent falsication due to the evaporation of volatile components or contamination due to contact with the environment.9 Preparation of apparatusGas ow rates and combustion temperatures
21、for the chosen working conditions shall be selected in accor-dance with the equipment manufacturers instructions. The temperature in the inlet zone will depend on the sample application method (see subclause 5.1.7 or 5.1.8) or on the type of furnace used (see subclause 5.1.1).10 CalibrationThe test
22、equipment shall be calibrated for a total of three measuring ranges using the following calibration solutions of known nitrogen contents and prepared by adding appropriate amounts of carbazole or pyridine:a) ve calibration solutions containing 0,3, 1, 2, 3 and 5 mg/kg of nitrogen for a range of 0,3
23、mg/kg to 5 mg/kg;b) ve calibration solutions containing 5, 7, 10, 30 and 50 mg/kg of nitrogen for a range of 5 mg/kg to 50 mg/kg;c) ve calibration solutions containing 50, 70, 150, 250 and 300 mg/kg of nitrogen for a range of 50 mg/kg to 300 mg/kg.Carry out the analysis in triplicate for each of the
24、 chosen calibration solutions using a volume equal to that of the sample, and calculate the mean. Derive the calibration equation by linear regression of the results obtained. Check the calibration daily and if the concentration ranges are altered.11 Procedure11.1 Sample volumeAlthough volumes of 3
25、l to 40 l have been found suitable, the optimum volume injected will depend on the nitrogen content of the particular sample and the equipment used. This also applies to the calibration de- scribed in clause 10. Examples providing guidance to recommended sample volumes are given in table 1.Table 1:
26、Recommended sample volumesNitrogen content, in mg/kg Sample volume, in l0,3 to 1 Up to 4010 Up to 8100 Up to 8300 Up to 4For contents greater than 300 mg/kg, dilute as appropriate.11.2 Sample injectionInject the sample using an appropriate microlitre syringe, rinsing the syringe several times with s
27、ample before-hand.Page 4DIN 51444 : 2003-1111.3 Injection speedSince the injection speed is a function of the type of equipment used, the viscosity of sample and the nitrogen concentration, choose the speed in accordance with the equipment manufacturers instructions.11.4 AnalysisAnalyse the sample a
28、s described in subclauses 11.1 to 11.3, taking the mean of three measurements.11.5 Checking the measurementCheck the measurement made as specied in subclause 11.4 using one or more reference samples for the particular measuring range. As the reference, choose a sample from the sample spectrum to be
29、analysed that has a nitrogen content, known to be stable, at the upper end of the calibration range concerned. If the result of the check differs by more than ten percent from the specied value, check the equipment and repeat the calibration.12 EvaluationDetermine the nitrogen content of the sample
30、from the measured result using the calibration graph (see clause 10), taking account of the sample volume and allowing for any prior dilution (cf. clause 1).13 Expression of resultsRefer to this standard and report the content of bound nitrogen, in mg/kg, to an accuracy of 0,1 mg/kg for a range of 0
31、,3 mg/kg to 50 mg/kg and to an accuracy of 1 mg/kg for contents greater than 50 mg/kg.EXAMPLE:Nitrogen content: 100 mg/kgTest DIN 51444 100 mg/kg14 PrecisionSee DIN EN ISO 4259.14.1 Repeatability limit(same operator, same equipment)If two results are obtained under repeatability conditions, both res
32、ults shall be considered acceptable and in conformity with this standard if they differ by no more than the values specied in table 2.14.2 Reproducibility limit(different operators, different equipment)If two separate laboratories each obtain a result under reproducibility conditions, both results s
33、hall be consid-ered acceptable and in conformity with this standard if they differ by no more than the values given in table 2.Table 2: Repeatability and reproducibility limits (values given in mg/kg)Nitrogen content Repeatability limit, r Reproducibility limit, RUp to 1 0,1 0,5Above 1 up to 10 0,3 4,7Above 10 0,030 8 * X 0,467 7 * XX is the mean of the two values to be compared; the calculated results shall be rounded as in clause 13.
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