DIN 38406-8-2004 German standard methods for examination of water waste water and sludge - Cations (group E) - Part 8 Determination of zinc - Method by atomic absorption spectromet.pdf

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1、October 2004DEUTSCHE NORM English price group 8No 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 13.060.50!$MFF“14235

2、35www.din.deDDIN 38406-8German standard methods for examination of water, waste water andsludge Cations (group E) Part 8: Determination of zinc by atomic absorption spectrometry (AAS)using an air-ethyne flame (E 8)Deutsche Einheitsverfahren zur Wasser-, Abwasser- und Schlammuntersuchung Kationen (Gr

3、uppe E) Teil 8: Bestimmung von Zink Verfahren mittels Atomabsorptionsspektrometrie (AAS) inder Luft-Ethin-Flamme (E 8)SupersedesDIN 38406-8:1980-10www.beuth.deIn case of doubt, the German-language original should be consulted as the authoritative text.Translation by DIN-Sprachendienst.Document compr

4、ises 17 pagesDIN 38406-8:2004-10 2 Contents Page Foreword3 Introduction .3 1 Scope 3 2 Normative references 4 3 Terms and definitions .5 4 Principle5 5 Interferences 5 6 Designation 6 7 Reagents.6 8 Apparatus .7 9 Sampling.8 10 Sample pretreatment .8 11 Procedure 10 12 Evaluation 11 13 Expression of

5、 result . 12 14 Test report . 12 15 Results of interlaboratory testing . 12 Annex A (informative) Trade names of suitable materials for pressure digestion vessels as in subclause 10.2.2.1 14 Annex B (informative) Explanatory notes 15 Bibliography. 17 DIN 38406-8:2004-10 3 Foreword This standard has

6、been prepared jointly with the Wasserchemische Gesellschaft (Water Chemistry Society), a specialist group of the Gesellschaft Deutscher Chemiker (German Chemists Society) (see Annex B). Expert assistance and specialized laboratories will be required to perform the analyses specified in this standard

7、. Existing safety instructions shall be observed. When using the standard, a check shall be made on a case-by-case basis as to whether and to what extent additional boundary conditions have to be specified. See Annex B for a list of other parts of DIN 38406 and of groups A to T of the German standar

8、d methods. Annexes A and B are informative. Amendments This standard differs from DIN 38406-8:1980-10 as follows: a) The sample preparation by microwave digestion has been included. b) The hexamethylene ammonium hexamethylene dithiocarbamate (HMDC) extraction method (chelate formation) has been dele

9、ted. c) The method has been updated. Previous editions DIN 38406-8:1980-10 Introduction Zinc is widely distributed in water, both in dissolved form as zinc(II) ions and in undissolved form, e.g. as zinc sulfide, carbonate or phosphate. In drinking water that has not been contaminated with materials

10、used in domestic installations, its concentration is about 10 g/l. Zinc is an essential trace element, the human daily requirement being 2 mg to 5 mg 1. About 0,5 mg is excreted daily in urine 2. CAUTION Users of this standard should be familiar with standard laboratory practice. It is not claimed t

11、hat all the safety problems associated with the use of the standard have been dealt with exhaustively here. It is therefore the responsibility of the user to take appropriate safety precautions and to ensure that these comply with national regulations. 1 Scope This standard specifies a method of det

12、ermining zinc concentrations ranging from 0,01 mg/l to 2 mg/l in natural waters and waste water by atomic absorption spectrometry (AAS) using an air-ethyne flame. Higher DIN 38406-8:2004-10 4 concentrations can be determined by dilution. The limit of determination is often lower and can be determine

13、d in each laboratory by calibration experiments. Depending on the objective, if water contains undissolved zinc, the determination may be limited to the dissolved component by filtering the sample prior to stabilization or the sample may be subjected to suitable digestion. The content of total zinc

14、in sludges and sediments can be determined after digestion by the method specified in DIN EN 13346. 2 Normative references This standard incorporates, by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text, and th

15、e 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 by amendment or revision. For undated references, the latest edition of the publication referred to applies (inc

16、luding amendments). DIN 12691, Class AS fast delivery one-mark bulb pipettes, with a waiting time of 15 seconds, for laboratory use DIN 32645, Establishing the decision limit, detection limit and determination limit under repeatability conditions in chemical analysis Terminology, methods and evaluat

17、ion DIN 38402-11, German standard methods for the examination of water, waste water and sludge General information (group A) Sampling of waste water (A 11) DIN 38402-12, German standard methods for the examination of water, waste water and sludge General information (group A) Sampling from stagnant

18、waters (A 12) DIN 38402-13, German standard methods for the examination of water, waste water and sludge General information (group A) Sampling from aquifers (A 13) DIN 38402-14, German standard methods for the examination of water, waste water and sludge General information (group A) Sampling of un

19、treated water and drinking water (A 14) DIN 38402-15, German standard methods for the examination of water, waste water and sludge General information (group A) Sampling from flowing waters (A 15) DIN 38402-51, German standard methods for the examination of water, waste water and sludge General info

20、rmation (group A) Calibration of analytical methods, evaluation of analytical results and linear calibration functions used to determine the performance characteristics of analytical methods (A 51) DIN 51401-1, Atomic absorption spectrometry (AAS) Terminology Supplement 1 to DIN 51401-1, Atomic abso

21、rption spectrometry (AAS) Terminology, explanatory notes DIN EN 13346, Characterization of sludges Determination of trace elements and phosphorus Aqua regia extraction methods (EN 13346:2000) DIN EN ISO 1042, Laboratory glassware One-mark volumetric flasks (ISO 1042:1998) DIN EN ISO 5667-3, Water qu

22、ality Sampling Part 3: Guidelines on preserving and handling water samples (ISO 5667-3:2003) DIN 38406-8:2004-10 5 DIN EN ISO 5667-13, Water quality Sampling of water Part 13: Guidance on sampling of sludges from sewage and water treatment works (ISO 5667-13:1997) DIN ISO 3696, Water for analytical

23、laboratory use Specification and test methods (ISO 3696:1987) DIN ISO 8466-2, Water quality Calibration and evaluation of analytical methods and estimation of performance characteristics Part 2: Calibration strategy for non-linear second order calibration functions (ISO 8466-2:2001) ISO 8466-1, Wate

24、r quality Calibration and evaluation of analytical methods and estimation of performance characteristics Part 1: Statistical evaluation of the linear calibration function 3 Terms and definitions See DIN 51401-1 and Supplement 1 to DIN 51401-1 for concepts associated with atomic absorption spectromet

25、ry. 4 Principle The test solution is converted into an aerosol using a pneumatic atomizer fitted with an impact ball and mixing vane or a pneumatic atomizer fitted with a mixing vane. The aerosol is injected into the air-ethyne flame of an atomic absorption spectrometer that employs a zinc hollow ca

26、thode lamp (HCL) or an electrodeless discharge lamp (EDL) as the radiation source. A background correction is used to perform the measurement, a continuum source normally being used. The absorbance is determined at 213,8 nm, the main detection line of zinc, with a spectral slit width of less than 1

27、nm. 5 Interferences Provided their concentrations by mass do not exceed those listed below in Table 1, the following ions do not interfere with the determination. The data in the table apply to atomizers having a mixing vane with or without impact ball. Table 1 Maximum concentrations by mass of ions

28、 that do not cause significant interferences Ion Concentration mg/l Ion Concentration mg/l Sulfate 10 000 Iron 1 000 Chloride 10 000 Nickel 1 000 Sodium 10 000 Copper 1 000 Potassium 10 000 Cobalt 1 000 Magnesium 10 000 Chromium 100 Calcium 10 000 The total salt content and electrical conductivity o

29、f the test solution shall not exceed 15 g/l and 2 000 mS/m, respectively. If the matrix effect of a water sample is not known a check shall be made and, if necessary, compensated for either by dilution or by using the standard addition method described in subclause 11.2.3. DIN 38406-8:2004-10 6 6 De

30、signation Designation of the method of determining zinc by atomic absorption spectrometry (AAS) using an air-ethyne flame (E 8): Method DIN 38406 E 8 7 Reagents 7.1 General Only analytical grade reagents and grade 1 water as in DIN ISO 3696 shall be used for preparing the samples and the solutions.

31、The zinc content of the reagents and the zinc content of the boiling stones (8.9) that is soluble under the test conditions shall be negligible compared with the lowest concentration to be determined. The following reagents shall be used. 7.2 Nitric acid, HNO3, of density 1,40 g/ml. 7.3 2 mol/l nitr

32、ic acid, HNO3. 7.4 30 % (m/m) hydrogen peroxide, H2O2. 7.5 Zinc stock solution, of density 1 000 mg/ l, prepared by quantitatively transferring the contents of an ampoule of commercial zinc standard containing (1,000 0,002) g of zinc to a 1 000 ml volumetric flask, adding 10 ml of nitric acid (7.2)

33、and making up to the mark with water (7.1). Store the solution in a polyethylene or borosilicate bottle. This solution will be stable for at least one year. Commercial ready-to-use zinc standards containing (1,000 0,002) g/l of zinc may also be used. In both cases the manufacturers information on th

34、e shelf life of the solutions shall be taken into account. The zinc stock solution may also be prepared using metallic zinc of suitably high purity by transferring (1,000 0,002) g of zinc to a 1 000 ml volumetric flask, adding 10 ml of nitric acid (7.2), dissolving in water and making up to the mark

35、 with water (7.1). Store the solution in a polyethylene or borosilicate bottle. This solution will be stable for at least one year. 7.6 Standard zinc solution, of density 10 mg/l, prepared by pipetting 1 ml of the zinc stock solution (7.5) into a 100 ml volumetric flask, adding 1 ml of nitric acid (

36、7.2) and making the solution up to the mark with water (7.1). Store the solution in a polyethylene or borosilicate bottle. The solution will be stable for at least one month. 7.7 Zinc reference solutions At least 10 ml of the reference solutions will be needed for every run. Add 0,1 ml of nitric aci

37、d (7.2) to every 10 ml of the reference solution to stabilize it. Prepare the reference solutions to meet the expected concentration range directly from the standard zinc solution (7.6) or further intermediate dilutions of the latter, proceeding as follows. DIN 38406-8:2004-10 7 a) For a concentrati

38、on range of 0,02 mg/l to 0,1 mg/l of zinc, for example, pipette 0,20 ml, 0,40 ml, 0,60 ml, 0,80 ml and 1,0 ml, respectively, of the standard zinc solution (7.6) into a series of 100 ml volumetric flasks, or b) for a concentration range of 0,4 mg/l to 2,0 mg/l of zinc, for example, pipette 4,0 ml, 8,

39、0 ml, 12,0 ml, 16,0 ml and 20,0 ml, respectively, of the standard zinc solution (7.6) into a series of 100 ml volumetric flasks. Add 1 ml of nitric acid (7.2) to each solution, make up to the mark with water (7.1) and mix. In case a) the reference solutions contain 0,02 mg/l, 0,04 mg/l, 0,06 mg/l, 0

40、,08 mg/l and 0,1 mg/l of zinc, respectively, and in case b) they contain 0,4 mg/l, 0,8 mg/l, 1,2, mg/l 1,6 mg/l and 2,0 mg/l of zinc, respectively. Make up fresh solutions for every working day. 7.8 Blank solution Prepare the blank solution in the same way as the reference solutions by pipetting 1 m

41、l of nitric acid (7.2) into a 100 ml volumetric flask, making up to the mark with water (7.1) and mixing. If the sample is digested, subject it to the same pretreatment as the blank solution (see clause 10). 7.9 Zero member compensation solution Use water (7.1) as the zero member compensation soluti

42、on, or the blank solution (7.8) if its zinc content is negligible. 8 Apparatus 8.1 General Before use, glassware shall be cleaned with hot dilute nitric acid (7.3) and then rinsed thoroughly with water (7.1). Batches of pipette tips and disposable plastic containers shall be examined for contaminati

43、on with zinc. The following equipment shall be used. 8.2 Atomic absorption spectrometer, with background correction and radiation source for determining zinc (e.g. HCL, EDL). 8.3 Atomizer, with mixing vane and burner head for air-ethyne flames having an irradiated path length of 10 cm, operated in a

44、ccordance with the manufacturers instructions. 8.4 Ethyne bottles, with a residual gas pressure of not less than 5 105Pa. 8.5 Volumetric flasks, of nominal capacities 10 ml, 100 ml and 1 000 ml 8.6 One-mark bulb pipettes, of nominal capacities 1 ml, 2 ml, 3 ml, 4 ml, 5 ml, 10 ml, 20 ml and 50 ml (e.

45、g. DIN 12691 VPAS 1 pipettes). 8.7 Microlitre pipettes or diluters, for a volume range of 100 l to 10 ml. 8.8 Reaction vessels suitable for open or closed digestion, made of an inert material (e.g. fluoropolymers such as FEP or PFA), of nominal capacity 100 ml or 250 ml, suitable for safe use in the

46、 temperature range. (e.g. DIN EN ISO 1042 A 100 C volumetric flasks). DIN 38406-8:2004-10 8 8.9 Magnetic followers, PTFE-coated (PTFE = polytetrafluoroethylene) or boiling stones. 8.10 Heat source (e.g. electric hotplate or sand bath). 8.11 Microwave-assisted heating system as an alternative to the

47、above, either temperature- or power-controlled, equipped with a pressure gauge. The pressure and temperature measurements shall be precise enough for the system to be used reliably in the specified range. This shall also include traceability of the measurement values to national or international sta

48、ndards for pressure or temperature. The microwave unit shall ensure a uniform energy distribution throughout the samples. The microwave unit shall be well ventilated and protected against corrosion. Additionally, the air circulation in pressure-controlled systems shall be high enough for ambient tem

49、perature to be maintained in the unit. 8.12 Membrane filtration apparatus with membrane filters, of effective pore size 0,45 m, carefully cleaned with dilute nitric acid (7.3) and water (7.1). 9 Sampling Follow the instructions given in DIN 38402-11 to DIN 38402-15 and in DIN EN ISO 5667-3 and collect water samples in glass or quartz containers or containers made of suitable fluoropolymers (e.g. polytetrafluoro-ethylene copolymers (FEP), perfluoroalkoxyalkanes (PFA). NOTE Polyethylene and polypropyle