SANS 6164-2009 Determination of lead (inorganic and tetra-alkyl) in workplace air by atomic absorption spectrophotometry《以原子吸收光谱法测定工作场所空气中的铅(无机铅及四烷基铅)》.pdf

《SANS 6164-2009 Determination of lead (inorganic and tetra-alkyl) in workplace air by atomic absorption spectrophotometry《以原子吸收光谱法测定工作场所空气中的铅(无机铅及四烷基铅)》.pdf》由会员分享，可在线阅读，更多相关《SANS 6164-2009 Determination of lead (inorganic and tetra-alkyl) in workplace air by atomic absorption spectrophotometry《以原子吸收光谱法测定工作场所空气中的铅(无机铅及四烷基铅)》.pdf（14页珍藏版）》请在麦多课文档分享上搜索。

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 978-0-626-21956-7 SANS 6164:2009Edition 1.1Any reference to SABS SM 1164 is deemedto be a reference to this standard(Government Notice No. 1373 of 8

4、 November 2002)SOUTH AFRICAN NATIONAL STANDARD Determination of lead (inorganic and tetra-alkyl) in workplace air by atomic absorption spectrophotometry Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.

5、co.za SABS SANS 6164:2009 Edition 1.1 Table of changes Change No. Date Scope Amdt 1 2009 Amended to change the designation from SABS to SANS, with no technical changes. Foreword This South African standard was approved by National Committee SABS TC 146, Air Quality, in accordance with procedures of

6、the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This document was published in April 2009. This document supersedes SABS SM 1164:1990 (first edition). SANS 6164:2009 Edition 1.1 1 Determination of lead (inorganic and tetra-alkyl) in workplace air by atomic absorptio

7、n spectrophotometry 1 Scope This standard specifies a method for the determination of the lead in air samples collected by filters or impingers. The method is applicable to personal sampling as well as static sampling. 2 Principle 2.1 Filter (cellulose ester membrane) samples are wet-ashed using nit

8、ric acid and hydrogen peroxide. The ash is dissolved in dilute nitric acid and diluted to a known volume. 2.2 Impinger samples are quantitatively transferred to a volumetric flask and diluted to a known volume. 2.3 The diluted samples are aspirated into an air-acetylene flame of an atomic absorption

9、 spectrophotometer and the absorbances measured at 217,0 nm. NOTE The lead content may also be determined by means of other suitable analytical techniques, which include colorimetry, polarography, anodic stripping voltammetry, atomic absorption spectrophotometry with electrothermal atomization and i

10、nductively-coupled plasma (ICP) atomic emission spectrophotometry. 3 Personal sampling of lead, inorganic dusts and fumes 3.1 Equipment. A sampling train that includes the components given in 3.1.1-3.1.7 (inclusive). NOTE Assembly instructions are given in 3.2.3. 3.1.1 A battery-operated portable pu

11、mp, that a) is capable of delivering, for a period of 8 h, 2 L of air per minute, with a filter in the sampling train; NOTE The maximum deviation from the prescribed flow rate shall not exceed 5 %. b) is intrinsically safe; c) includes a calibrated flow meter or a mechanism for maintaining a constan

12、t flow rate; and d) has an on-off switch and flow rate control or adjustment mechanism that is tamperproof. SANS 6164:2009 Edition 1.1 2 3.1.2 Cellulose ester membrane filters, of diameter 37 mm and having a pore size of 0,8 m. 3.1.3 Filter support pads, of diameter 37 mm. 3.1.4 A closed-face filter

13、 holder, of the same size as the filters (see 3.1.2 and 3.1.3) fitted with an adaptor that provides a leakproof fit for connecting flexible tubing. 3.1.5 Flexible tubing, of sufficient length, and a) of appropriate wall thickness to prevent it collapsing when air is drawn through it; and b) of appro

14、priate inner diameter to provide a leakproof connection to the filter holder adaptor and to the inlet port adaptor of the portable pump. 3.1.6 A mercury thermometer, for ambient air temperature measurement, accurate to 1 C. 3.1.7 A barometer, for measuring atmospheric pressure, accurate to 5 mm merc

15、ury. 3.2 Procedure 3.2.1 Preparation of pumps a) Fully charge the pump battery pack in accordance with the manufacturers instructions, before use in any workshift. If the pump is used for more than one shift, substitute a fully charged battery pack for the used one. b) Calibrate flow meters or const

16、ant flow devices on the pumps at 2 L/min (using a primary standard such as a bubble meter and the procedures recommended in the manufacturers instructions, and with the filter and filter holder assembly in the line), 1) at intervals not exceeding 40 h of operation; 2) immediately after they have rec

17、eived unusually harsh or potentially damaging treatment; and 3) immediately after the pump or the sampling train has been disassembled for maintenance. 3.2.2 Preparation of filter holders a) Assemble the clean filter holders in a lead-free environment. b) Use only clean flat-tipped tweezers to handl

18、e the filter support pad and the filter. Place a filter support pad and then a cellulose ester filter in the base of a filter holder. c) Ensure that, if necessary, the joints of the filter holder are sealed with non-porous, shrinkable cellulose band or tape. d) Label the filter holder with an approp

19、riate sample identification. e) Use suitable plugs to seal the filter holder until it is placed in position in the field and sampling is ready to commence. SANS 6164:2009 Edition 1.1 3 3.2.3 Sampling a) Assemble the sampling train by fixing one end of the flexible tubing to the inlet port of the pum

20、p and the other end with the adaptor to the outlet port of the filter holder. b) Check for air leaks by switching on the pump. The air flow indicator on pumps equipped with a flow meter should drop to the zero flow position and oscillate slightly. If this does not occur, find and repair the leak. c)

21、 Preferably attach the pump to the workers belt, or place it in his pocket. d) Place the flexible tubing over the workers shoulder and so clip the filter holder to his clothing that the inlet port faces downwards, as near as possible to the breathing zone. e) Ensure that the equipment will not inter

22、fere with the workers movements in the area. f) Remove the plug from the filter holders inlet port and switch on the pump. Note and record the following: 1) Initial air flow rate; 2) ambient temperature; 3) atmospheric pressure; and 4) time of initiation. g) Maintain the flow rate within 5 % of the

23、nominal value throughout the sampling period. Since it is possible for a filter to become clogged by heavy particulate loading or by the presence of oil mists or other liquids in the air, check the flow indicator of the pump at least once per hour for any drop in flow rate. NOTE 1) This requirement

24、may be relaxed when a flow-stabilized pump is used. 2) Terminate sampling at any evidence of a problem. Do not re-adjust the flow rate. h) Sample for a total duration of 6-8 h, if feasible, to obtain a time-weighted average concentration. Where necessary, sequential air samples may be taken as oppos

25、ed to single air samples. The total sampling duration may or may not include lunch breaks, depending on the nature of the work exposure to be measured. The total sampling duration may be shorter than 6 h, provided that the individual air samples taken during selected periods are representative of th

26、e workers exposure over the entire work shift. i) At the end of the sampling period, note and record the following: 1) Air flow rate; 2) time of termination; 3) ambient temperature and atmospheric pressure; 4) sample identification; and 5) all relevant sampling data. SANS 6164:2009 Edition 1.1 4 Swi

27、tch off the pump, remove the filter holder from the sampling train and replace the plug to reseal the filter holder. j) Calculate the mean ambient temperature and the mean atmospheric pressure during the sampling period and correct air volumes if necessary. k) With each batch of 10 samples, submit t

28、wo filters from the same lot of filters used for sample collection. Subject these filters to exactly the same handling procedures as the samples except that no air is drawn through them. Label these filters as blanks. l) Transport the filter membrane samples in a face-up position in a container that

29、 has been designed to prevent damage in transit and that has been appropriately labelled to assure proper handling. If possible, transport the samples in the holders in which they were collected, with the plugs still in position. 4 Static sampling of lead, inorganic dusts and fumes 4.1 Use the equip

30、ment as described in 3.1. 4.2 Site the sampling heads at about head height (of the worker) and as near as possible to the actual job location or as near as possible to major sources of the airborne lead to which workers in that workplace are exposed. 4.3 Give due consideration to the direction of ai

31、r currents in the workplace in relation to sources of the lead to be sampled, as well as to job locations when siting the static samples. 4.4 Ensure that the number and location of sampling points in each workplace are such that the results as a whole will be representative of the airborne lead conc

32、entration in the workplace. 5 Sampling of tetra-alkyl lead 5.1 Equipment 5.1.1 The sampling equipment as described in 3.1.13.1.7. 5.1.2 Midget impingers, each of which a) is constructed completely from borosilicate glass and has standard ground glass joints; and b) is capable of holding up to 25 mL

33、of solution and is calibrated at 10 mL. 5.1.3 A glass tube, of appropriate size to be used as a charcoal trap. 5.1.4 Volumetric flasks, of capacity 1 000 mL. 5.2 Procedure 5.2.1 Preparation of pumps Prepare the pumps as described in 3.2.1, except that the flow meters or constant flow devices on the

34、pumps are to be calibrated at 1 L/min. 5.2.2 Preparation of filter holders (pre-filter assembly) Prepare as described in 3.2.2. SANS 6164:2009 Edition 1.1 5 5.2.3 Preparation of impingers NOTE Unless otherwise specified, use only distilled or deionized water and reagents of analytical reagent grade

35、or (when such a grade is unobtainable) of the purest grade available. a) Reagents 1) Sodium hydroxide, pellets. 2) Hydrochloric acid, concentrated (d at 25 /25 C = 1,19) 3) Iodine monochloride solution, approximately 0,1 mol/L. Dissolve, with care, 16,24 g of iodine monochloride (ICI) in 50 mL of co

36、ncentrated hydrochloric acid and add to approximately 500 mL of water in a 1 000 mL volumetric flask. Dilute to volume and mix thoroughly. 4) Sodium thiosulfate solution, 125 g/L. Dissolve 125 g of sodium thiosulfate pentahydrate (Na2S2O3.5H2O) and 40 g of sodium hydroxide (NaOH) pellets in water, a

37、llow to cool and dilute to volume in a 1 000 mL volumetric flask. 5) Charcoal, activated. 6) Glass wool, lead-free. b) Prepare the impingers in a lead-free environment. c) To two clean impingers, add 10 mL of the freshly prepared iodine monochloride solution. d) To a third impinger, add 10 mL. of th

38、e sodium thiosulfate solution. Assemble the base and the top of the impinger and plug the inlet and outlet ports. e) Pack a sufficient quantity of activated charcoal in the glass tube (see 5.1.3) and seal both ends with glass wool and stoppers. 5.2.4 Sampling a) Assemble the sampling train on a trip

39、od or other suitable support, in the following sequence: 1) Pre-filter assembly; 2) two impingers containing the iodine monochloride absorbing solution; 3) impinger containing sodium thiosulfate solution; 4) charcoal trap; and 5) pump. b) Label both impingers containing the iodine monochloride solut

40、ion with an appropriate sample identification. c) Ensure that the sampling assembly will not interfere with the workers movements in the area. Also give due consideration to the provisions described in 4.3 and 4.4. d) Check for air leaks in the sampling train, as described in 3.2.3(b). SANS 6164:200

41、9 Edition 1.1 6 e) Remove the plug from the filter holders inlet port and switch on the pump. Note and record the following: 1) Initial air flow rate; 2) ambient temperature; 3) atmospheric pressure; and 4) time of initiation. f) Ensure that sampling is carried out for at least 2 h to ensure the col

42、lection of sufficient sample for analysis. g) During sampling, check the sampling train periodically to ensure that it is functioning properly. If the air flow rate changes significantly, terminate sampling and take another sample. Do not re-adjust the flow rate. h) During sampling, record the ambie

43、nt temperature and atmospheric pressure in the sampling area at least once and correct the final air volume where necessary. i) Prepare two blank impingers with absorbing solutions in the same manner as the sample impingers (see 5.2.3(c). Keep these blanks sealed during sampling, i.e. no air is to b

44、e drawn through these impingers. j) At the end of the sampling period, note the following: 1) Air flow rate; 2) time of termination; 3) sample identification; and 4) all relevant sampling data. k) Switch off the pump. Disconnect the various components of the train. Remove each impinger stem from the

45、 absorbing solution and tap gently against the inside wall to recover as much of the trapped solution as possible. l) Using 1-2 mL of water, rinse the absorbing solution adhering to the inside of the inlet and stem directly into the impinger flask. m) Plug the impingers tightly or transfer their con

46、tents into small clean glass bottles provided with polytetra fluoroethylene screw-caps. n) Transport the samples to the laboratory in a protective container. Ensure that the samples can not be overturned during transportation. 6 Analysis conditions 6.1 Work area Carry out the analysis in a lead-free

47、 environment. SANS 6164:2009 Edition 1.1 7 6.2 Test samples Use only clean flat-tipped tweezers to handle the filters containing the collected dust. 6.3 Glass apparatus 6.3.1 Before use, clean all glassware by soaking it in detergent solution to remove any residual grease or chemicals. 6.3.2 After i

48、nitial cleaning (see 6.3.1), soak all glassware overnight in dilute (1 + 5) nitric acid, and then rinse thoroughly with water (see 6.4). 6.4 Reagents Unless otherwise specified, use only lead-free distilled or deionized water, and reagents of analytical reagent grade or (when such a grade is unobtai

49、nable) of the purest grade available. 7 Determination of lead, inorganic dust and fumes as lead 7.1 Apparatus 7.1.1 Atomic absorption spectrophotometer, equipped with an air-acetylene burner head. 7.1.2 Hot plate, thermostatically controlled and capable of maintaining a surface temperature of 140 5 C. 7.1.3 Beakers, of capacity 50 mL. 7.1.4 Watch-glasses, to fit the beakers. 7.1.5 Volumetric flasks, of capacity 1 000 mL, 500 mL, 100 mL and 25 mL. 7.2 Reagents 7.2.1 Nitric acid, concentrated (d at 25 /25 C = 1,42). 7.2.2 Nitric acid, 10 %(V/V). Add 50 mL of co