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
2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any
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 978-0-626-24303-6 SANS 5208:2010Edition 3.2SOUTH AFRICAN NATIONAL STANDARD Water Lead 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 5208:2010 Edition 3.2 Table of changes Change No. Date Scope Amdt 1 2004 Amended to change the designation of SABS standards to SANS standards, to update referenced standards, and to delete r
5、eference to specific clauses in SANS 6168. Amdt 2 2010 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 ann
6、ex 3 of the WTO/TBT agreement. This document was published in March 2010. This document supersedes SANS 5208:2004 (edition 3.1). A vertical line in the margin shows where the text has been technically modified by amendment No. 2. SANS 5208:2010 Edition 3.2 1 Water Lead content 1 Scope and field of a
7、pplication This standard specifies a method of determining the lead content of water and wastewater, using an air-acetylene flame and direct flame atomic absorption. The method is applicable to the determination of lead in the concentration range 0,1 mg/L to 5 mg/L, but the detection limit can be re
8、duced to less than 0,05 mg/L by concentration of the sample through evaporation. When the sample has a high dissolved solid content, background correction may be required to eliminate non-specific or continuous absorption. 2 Normative references The following referenced documents are indispensable f
9、or the 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 Stand
10、ards Division. 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. Am
11、dt 1 SANS 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 217,0 nm is compared wit
12、h the absorbances of lead standards measured under the same conditions. 4 Reagents NOTE Unless otherwise specified, only use water that complies with the requirements of SANS 3696 and reagents of analytical reagent grade. SANS 5208:2010 Edition 3.2 2 4.1 Nitric acid (HNO3) Concentrated (d at 25 /25
13、C = 1,42). 4.2 Acidified water Containing 1,5 mL of HNO3(see 4.1) per litre. 4.3 Lead stock solution (1 000 mg/L) 4.3.1 Obtain a commercially available stock solution of lead (1 000 mg/L) of guaranteed quality, or prepare the stock solution as described in 4.3.2. 4.3.2 Dissolve 1,599 g of lead nitra
14、te (Pb(NO3)2), previously dried at 105 C for 1 h and cooled in a desiccator, in 200 mL of water. Add 1,5 mL of HNO3(see 4.1) and dilute with water to 1 000 mL in a volumetric flask. 4.4 Lead working stock solution (100 mg/L) Pipette 10,0 mL of the stock solution (see 4.3) into a 100 mL volumetric fl
15、ask and dilute to the mark with the acidified water (see 4.2). 4.5 Lead standard solutions (0,1 mg/L to 5,0 mg/L) Prepare at least three lead standard solutions that will bracket the expected concentration of the sample by dilution of the working stock solution (see 4.4), using the acidified water (
16、see 4.2) as the diluent. 5 Apparatus 5.1 Atomic absorption spectrophotometer, for use at 217,0 nm. 5.2 Air-acetylene burner, suitable for attachment to the spectrophotometer (see 5.1). 5.3 Lead hollow-cathode lamp. 5.4 Oxidant, air, dried and filtered. 5.5 Fuel, acetylene, standard commercial grade.
17、 (Replace the cylinder when the cylinder pressure drops to 700 kPa.) CAUTION: Never allow the operating pressure of acetylene to exceed 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 Glass
18、ware. Where applicable, only use burettes, pipettes and volumetric flasks that comply with the requirements for class A items as specified in SANS 111, SANS 112, SANS 115 and SANS 128, as relevant. Amdt 1; amdt 2 SANS 5208:2010 Edition 3.2 3 6 Sample preparation 6.1 Sample concentration Where it is
19、required to extend the working range below 0,1 mg/L, concentrate the sample, using the appropriate technique for the relevant form of metal required, as follows: a) total metal recovery: evaporate a sample aliquot on a hotplate and reconstitute to a volume that will result in the required degree of
20、concentration; b) suspended metal recovery: so filter a sufficient volume of sample in accordance with SANS 6168, that the required degree of concentration is achieved when the residue is reconstituted to 100 mL; Amdt 1 c) dissolved metal recovery: evaporate the acidified filtrate in accordance with
21、 SANS 6168, and reconstitute the filtrate to a volume that will result in the required degree of concentration. Amdt 1 Determine the concentration factor as follows: =VfV10where f is the concentration factor; V0is the initial sample aliquot, in millilitres; V1is the concentrate volume, in millilitre
22、s. 6.2 Sample pretreatment Pretreat the sample or concentrated sample (see 6.1), a blank (see 4.2) and at least one standard in accordance with SANS 6168 in order to analyse for the appropriate form of metal, i.e. soluble, insoluble or total metal. NOTE For the purposes of legislation or specificati
23、ons relating to this method, pretreat the sample for recovery of total lead, unless specifically indicated otherwise. 7 Procedure 7.1 Instrument operation NOTE The differences between makes and models of atomic absorption spectrophotometers make it impracticable to formulate detailed operating instr
24、uctions. Follow the manufacturers operating instructions for the specific instrument but, in general, proceed in accordance with the instructions given in 7.1.1 to 7.1.11. 7.1.1 Turn on the instrument, install the lead hollow-cathode lamp (see 5.3) and apply the current recommended by the manufactur
25、er. 7.1.2 Set the wavelength at 217,0 nm and set the slit width in accordance with the manufacturers instructions. 7.1.3 Allow the lamp to stabilize for approximately 10 min and then align it to obtain optimum transmission. SANS 5208:2010 Edition 3.2 4 7.1.4 Adjust the fine control of the wavelength
26、 setting of the monochromator in order to ensure maximum response. 7.1.5 Apply and optimize the background correction facility installed on the instrument, to correct for background absorption. NOTE If the instrument is not fitted with a background correction facility, verify (for each sample) the p
27、resence or absence of continuous absorption by measuring the absorption in the immediate vicinity of the resonance wavelength at which the lead absorption is determined. The absorbance of the continuum should then be subtracted from the observed absorbance at the lead resonance wavelength in order t
28、o determine the true lead absorbance. 7.1.6 Install the air-acetylene burner (see 5.2). 7.1.7 Check and, if necessary, adjust the gas flow rates to ensure that they are at the levels specified for the instrument. 7.1.8 Turn on the air supply and then the acetylene flow, and ignite the mixture. 7.1.9
29、 Ensure that the flame is oxidizing (non-luminous with a hazy blue inner core), and then zero the instrument in the absorbance mode. 7.1.10 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
30、is now ready for calibration and analysis. 7.1.11 After analysis, extinguish 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 4.2) and zero the instrument. 7.2.2 Aspirate each
31、of the standard solutions (see 4.5), using the acidified water (see 4.2) 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 th
32、e pretreated blank, standard(s) and sample (see 6.2), using the acidified water (see 4.2) 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
33、an instrument with concentration mode is used. 7.3.3 Correct the results 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
34、 the control standard(s). 7.3.4 In the case where the sample is preconcentrated, determine the true sample concentration as a product of the concentration factor (see 6.1) and the sample result determined in 7.3.3. SANS 5208:2010 Edition 3.2 5 8 Expression of results So express the result as to indi
35、cate the form of metal analysed and the concentration units used, e.g. Total lead as Pb in mg/L. SABS This page has been left blank intentionally SABS Standards Division The objective of the SABS Standards Division is to develop, promote and maintain South African National Standards. This objective
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