SANS 5207-2010 Water - Iron content《水 铁含量》.pdf

1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA

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3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-24304-3 SANS 5207:2010Edition 3.2SOUTH AFRICAN NATIONAL STANDARD Water Iron content Published by SABS Standards Division 1 Dr Lategan Road

4、 Groenkloof Private Bag X191 Pretoria 0001Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS SANS 5207:2010 Edition 3.2 Table of changes Change No. Date Scope Amdt 1 2004 Amended to change the designation of SABS standards to SANS standards and to update referenced standards. Amdt 2 2010

5、Amended to update referenced standards. Foreword This South African standard was approved by National Committee SABS SC 147A, Water Water sampling and analysis, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This document was publis

6、hed in March 2010. This document supersedes SANS 5207:2004 (edition 3.1). A vertical line in the margin shows where the text has been technically modified by amendment No. 2. SANS 5207:2010 Edition 3.2 1 Water Iron content 1 Scope and field of application This standard specifies a method of determin

7、ing the iron content of water and wastewater, using an air-acetylene flame and direct flame atomic absorption. This method is applicable to the determination of iron in the concentration range 0,05 mg/L to 5,0 mg/L. 2 Normative references The following referenced documents are indispensable for the

8、application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. Information on currently valid national and international standards can be obtained from the SABS Standards Di

9、vision. Amdt 1 SANS 111/ISO 835, Laboratory glassware Graduated pipettes. Amdt 1; amdt 2 SANS 112/ISO 648, Laboratory glassware Single volume pipettes. Amdt 1 SANS 115/ISO 385, Laboratory glassware Burettes. Amdt 1; amdt 2 SANS 128/ISO 1042, Laboratory glassware One-mark volumetric flasks. Amdt 1 SA

10、NS 3696/ISO 3696, Water for analytical laboratory use Specification and test methods. SANS 6168, Water Pretreatment for metal analysis. 3 Principle The pretreated sample is aspirated into an air-acetylene flame under oxidizing conditions and the absorbance measured at 248,3 nm is compared with the a

11、bsorbances of iron standards measured under the same conditions. Interference by silica is inhibited by the addition of calcium to the sample. 4 Reagents NOTE Unless otherwise specified, only use water that complies with the requirements of SANS 3696 and reagents of analytical reagent grade. SANS 52

12、07:2010 Edition 3.2 2 4.1 Nitric acid (HNO3) Concentrated (d at 25 /25 C = 1,42). 4.2 Hydrochloric acid (HCl) Concentrated (d at 25 /25 C = 1,19). 4.3 Dilute nitric acid 1+1 HNO3. 4.4 Dilute hydrochloric acid 1+4 HCl. 4.5 Acidified water Containing 1,5 mL of HNO3(see 4.1) per litre. 4.6 Calcium carb

13、onate solution Dissolve 0,63 g of calcium carbonate (CaCO3) in 50 mL of the dilute HCl (see 4.4). If necessary, heat and boil gently to dissolve completely. Cool and dilute with water to 1 000 mL in a volumetric flask. 4.7 Iron stock solution (1 000 mg/L) 4.7.1 Obtain a commercially available stock

14、solution of iron (1 000 mg/L) of guaranteed quality, or prepare the stock solution as described in 4.7.2. 4.7.2 Dissolve 1 000 g of iron wire in 50 mL of the dilute HNO3(see 4.3) and dilute with water to 1 000 mL in a volumetric flask. 4.8 Iron working stock solution (100 mg/L) Pipette 10,0 mL of th

15、e stock solution (see 4.7) into a 100 mL volumetric flask and dilute to the mark with the acidified water (see 4.5). 4.9 Iron standard solutions (0,05 mg/L to 5,0 mg/L) 4.9.1 Prepare at least three iron standard solutions that will bracket the expected concentration of the sample by dilution of the

16、working stock solution (see 4.8), using the acidified water (see 4.5) as the diluent. 4.9.2 Add 25,0 mL of the CaCO3solution (see 4.6) per 100 mL of each standard. 5 Apparatus 5.1 Atomic absorption spectrophotometer, for use at 248,3 nm. 5.2 Air-acetylene burner, suitable for attachment to the spect

17、rophotometer (see 5.1). SANS 5207:2010 Edition 3.2 3 5.3 Iron hollow-cathode lamp. 5.4 Oxidant, air, dried and filtered. 5.5 Fuel, acetylene, standard commercial grade. (Replace the cylinder when the cylinder pressure drops to 700 kPa.) CAUTION: Never allow the operating pressure of acetylene to exc

18、eed 105 kPa. 5.6 Pressure-reducing regulators, for the supply of fuel and oxidant to the instrument at the appropriate levels recommended by the manufacturer. 5.7 Glassware. Where applicable, only use burettes, pipettes and volumetric flasks that comply with the requirements for class A items as spe

19、cified in SANS 111, SANS 112, SANS 115 and SANS 128, as relevant. Amdt 1; amdt 2 6 Sample pretreatment 6.1 Pretreat the sample, a blank (see 4.5) and at least one standard (see 4.9.1) in accordance with SANS 6168 in order to analyse for the appropriate form of metal, i.e. soluble, insoluble or total

20、 metal. NOTE For the purposes of legislation or specifications relating to this method, pretreat the sample for recovery of total iron, unless specifically indicated otherwise. 6.2 Add 25,0 mL of the CaCO3solution (see 4.6) per 100 mL of each sample, standard(s) and blank after pretreatment as in 6.

21、1, and mix well. 7 Procedure 7.1 Instrument operation NOTE The differences between makes and models of atomic absorption spectrophotometers make it impracticable to formulate detailed operating instructions. Follow the manufacturers operating instructions for the specific instrument but, in general,

22、 proceed in accordance with the instructions given in 7.1.1 to 7.1.10. 7.1.1 Turn on the instrument, install the iron hollow-cathode lamp (see 5.3) and apply the current recommended by the manufacturer. 7.1.2 Set the wavelength at 248,3 nm and set the slit width in accordance with the manufacturers

23、instructions. 7.1.3 Allow the lamp to stabilize for approximately 10 min and then align it to obtain optimum transmission. 7.1.4 Adjust the fine control of the wavelength setting of the monochromator in order to ensure maximum response. 7.1.5 Install the air-acetylene burner (see 5.2). 7.1.6 Check a

24、nd, if necessary, adjust the gas flow rates to ensure that they are at the levels specified for the instrument. SANS 5207:2010 Edition 3.2 4 7.1.7 Turn on the air supply and then the acetylene flow, and ignite the mixture. 7.1.8 Ensure that the flame is oxidizing (non-luminous with a hazy blue inner

25、 core), and then zero the instrument in the absorbance mode. 7.1.9 Aspirate a standard that will give an absorbance exceeding 0,2, and optimize the burner position until the maximum absorbance value is recorded. The instrument is now ready for calibration and analysis. 7.1.10 After analysis, extingu

26、ish the flame by turning off the acetylene flow first. When the flame is extinguished, turn off the air supply. 7.2 Instrument calibration 7.2.1 Aspirate the analyte blank (see 4.5) and zero the instrument. 7.2.2 Aspirate each of the standard solutions (see 4.9.2), using the acidified water (see 4.5

27、) to flush the nebulizer between aspirations, and record their respective absorbances. 7.2.3 Construct a calibration curve, using the standard concentrations and their respective absorbances. 7.3 Sample analysis 7.3.1 Aspirate the pretreated blank, standard(s) and sample (see 6.2) using the acidifie

28、d water (see 4.5) to flush the nebulizer between aspirations. 7.3.2 Record the absorbances and determine the concentrations by referring to the calibration curve as constructed in 7.2.3, or record the concentrations directly if an instrument with concentration mode is used. 7.3.3 Correct the results

29、 for the sample and the control standard(s) by subtracting the result for the pretreated blank, if applicable, and verify the absence of interference due to the pretreatment method by confirmation of the true concentration(s) of the control standard(s). 8 Expression of results So express the result

30、as to indicate the form of metal analysed and the concentration units used, e.g. Total iron as Fe in mg/L. SABS SABS Standards Division The objective of the SABS Standards Division is to develop, promote and maintain South African National Standards. This objective is incorporated in the Standards A

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