1、 U NITED S TATESC ONSUMER P RODUCT S AFETY C OMMISSIOND IRECTORATE FOR L ABORATORY S CIENCESD IVISION OF C HEMISTRY10901D ARNESTOWN R DG AITHERSBURG,MD20878Test Method: CPSC-CH-E1003-09Standard Operating Procedure for Determining Lead (Pb in Paint and OtherSimilar Surface Coatings*April 26, 2009This

2、 document provides information on the test method that is used by the U.S. Consumer Product Safety Commissions (CPSC testing laboratory (LSC in the analysis of paint and certain painted products. The method is used to determine the total lead content of paint, or a painted surface, on a dry paint ba

3、sis.This method supersedes all previously published standard operating procedures for lead in paint testing. Existing accreditations remain valid. The rules for accreditation for lead in paint testing for compliance to the Ban of Lead-Containing Paint and Certain Consumer Products Bearing Lead Conta

4、ining Paint, Code of Federal Regulations, Title 16, Part 1303 (16 C.F.R 1303 remain unchanged, and do not explicitly require the use of this or any earlier standard operating procedureThis method is provided to inform interested parties of the method used by LSC for assessing the total lead in paint

5、 and other surface coatings. Other laboratories making such assessments are not required to follow this method; however, other laboratories should consider using these procedures to ensure they obtain results that are consistent with CPSC staffs for purposes of compliance to 16 C.F.R. 1303.CPSC staf

6、f has concluded that this test method is sufficient to make appropriate determinations concerning lead in paint, as defined in 16 C.F.R 13031. Screening tests by x-ray fluorescence may sometimes be employed by CPSC staff to determine samples in need of such testing. Definitions:1.Sample an individua

7、l consumer product or a group of identical consumer products froma batch to be tested.* This document was prepared by CPSC staff, has not been reviewed or approved by, and may not necessarily reflect the views of, the Com mission.1 The Consumer Product Safety Improvement Act of 2008 (CPSIA requires

8、the regulatory limit for lead in paint and other similar surface coatings to be reduced from 0.06% to 0.009% on August 14, 2009. CPSC staff has concluded that this method is sufficient for either limit.2.Component Part an individual sub-unit within the total sample. Each separate paintcolor on a sam

9、ple is a component part.3.Composite Testing-like parts combining like paints from several like parts or productsto obtain sufficient sample size for analysis when there is an insufficient quantity of paint on one item to perform testing.4.Composite Testing-different parts combining different paints

10、(e.g., multiple colorsfrom one or more samples to reduce the number of digestions and instrumental leadanalyses performed.5.Instrument Detection Limit (IDL 3 times the standard deviation of 10 replicatemeasurements of reagent blank. The IDL f or Pb on the Inductively Coupled PlasmaOptical Emission S

11、pectrometer (ICP-OES used by CPSC staff is 0.01 g/ml.6.Method Detection Limit (MDL reagent blank fortified with 2-3 times the IDL. Sevenreplicate measurements are made. Calculate the MDL as f ollows: MDL = t x S, t = 3.14 (99% confidence level for 7 replicates, S = standard deviation. The MDL determ

12、ined for Pb is 0.01 g/ml.7.Laboratory Reagent Blank (LRB an aliquot of the digestion reagents that is treatedexactly as a sample including ex posure to glassware, digestion media, apparatus, andconditions used for a particular Pb test, but with no added sample. LRB data are used to assess contaminat

13、ion from the laboratory environment.8.Calibration Blank deionized water acidified with nitric acid (3 ml concentrated nitricacid diluted to 100 ml with deionized water.9.Stock Standard Solution 1000 g/ml solution of Pb purchased from reputablecommercial source, used to prepare calibration standards.

14、 Replace before expiration date.10.Calibration Standards solutions containing 0 to 25 g/ml of Pb in 3% nitric acid matrixare used. A minimum of 4 calibration standards are used. Calibration standards shouldbe prepared weekly.11.Quality Control Sample (QCS a solution containing Pb that is used to eva

15、luate theperformance of the instrument system. QCS is obtained from a source external to thelaboratory and Stock Standard Solution.12.Certified Reference Material (CR M CRMs are materials with similar matri ces as testsamples with known lead levels. The CRMs are used to verify digestion and analysis

16、methods. For example, standard reference materials (SRMs are CRMs that are available from the National Institute of Standards and Technology (NIST, such as those listed inthe Equipment and Supplies section below.Equipment and Supplies: The materials used for sampling and analysis are as follows:1.Ni

17、tric acid, trace metal grade2.Disposable plastic digestion vessels, 50 ml, or glass test tubes3.Hot block digester or hot plate with test tube block4.Disposable razor blade or scalpel5.Methylene chloride (optional6.Distilled water7.Microwave digestion apparatus8.CRMs such as NIST SRMs2 2581 and 2582

18、 lead in powdered paint9.Internal Standard (such as yttrium, from a stock standard solution of that elementappropriate to the instrument parameters of the ICP used for the analysisNote on composite testing: Composite testing-like parts (as defined above is appropriate and may be necessary to obtain

19、valid analytical results. Composite testing-different parts (as defined above must be done with adequate care, planning, and understanding of the limitations and propagations of error in measurements or the test may fail to detect excessive lead in one individual paint because of dilution. If compos

20、ite testing-different parts is used, great care must be taken to accurately weigh each component paint and account for the propagation of errors due to weighing and measuring, and the analyst must ensure the compositing will not result in a Pb measurement being below the detection limit for a paint

21、component that would exceed 0.009% Pb.Each individual paint must be weighed individually with sufficient precision and sufficient safety factors to assure that no false negatives are reported.Sufficient paint must be used for each of the paints giving proper consideration for the weighing capabiliti

22、es of the balance used and the detection limits and necessary dilution for the subsequent instrumental analysis. The combined paints can then be digested according to the procedure given below for a single paint, before analysis by Inductively Coupled Plasma (ICP spectroscopy. Appropriate weights fo

23、r each of the individual paints which are composited depend on final dilution volumes, weighing accuracy, and detection limits. All of the lead found in the digestate for the combined composite can be attributed to the weight of each of the individual paints as though all of the lead came from any o

24、ne of the individual paints. The measured lead should be treated in calculations as if it originated solely from one part of the composite; the lead concentration calculation should be carried out for each part unless identical weights of each sample are used in the analysis.An example is given at t

25、he end of this document.In considering results from such a composite sample, it is imperative that a sufficient “safety factor” be applied to account for weighing inaccuracy and propagation of errors from each stepin the analytical procedure to ensure no violative paints are misrepresented as n on-v

26、iolative. It has been suggested, for example for a composite of 3 samples, that any sample possibly having greater than 80% of the limit for lead in paint in any of the composited paints should be retested3. CPSC staff considers this a reasonable practice.Method: The digestion method is based on the

27、 Association of Official Analytical Chemists (AOAC standard AOAC 974.024 (Lead in Paint. Alternate microwave digestion based on ASTM E16455may be used as well. Analysis by Inductively Coupled Plasma (ICP spectroscopy is based on ASTM E16136.3 Toy Industry Association Inc. Laboratory Testing Technica

28、l Work Group, that includes (but is not limited to representatives of the following laboratories: Specialized Technology Resources(STR, SGS consumer Testing Services; EMC Inc., Bureau Veritas,(BV, CMA Testing NSF International, Intertek (ITS and Toy Safety and Quality, Inc.Compositing Acceptance Met

29、hod for Lead in Surface Coatings, Comment submitted to CPSC, March 18, 2009.4 AOAC Official Method 974.02 Lead in Paint1. For testing of wet paint, apply a thin coating to a glass slide, and dry completely prior to testing by heating in an oven at nominally 105 C (105 C 2 C until the weight is stabl

30、efor at least two successive readings; the readings should be separated by 30 minutes of heating in the oven.2. For products coated with paint or a similar surface coating, remove and digest the coating, separately from the substrate material. Care should be taken to remove as little of the substrat

31、e as possible. It may be necessary to add a few drops of solvent, such as methylene chloride, to soften the paint and aid in its removal from the substrate. If used, such solvent must be evaporated away prior to analysis. The scraped paint should be finely divided to help in digesting.3. Scrape appr

32、oximately 5-100 mg of paint from the product. If it is not possible to collect this much paint, it may be necessary to combine more than one unit of the product to collect sufficient paint.4. Prepare a LRB and digest and test a standard reference paint material, such as National Institute of Standar

33、ds and Technology (NIST SRM 2581 - PowderedPaint Nominal 0.5% Lead or NIST SRM 2582 - Powdered Paint Nominal 0.02% Lead,with each batch of samples tested.5. Digest appropriately according to AOAC 974.02 or ASTM E1645 in either a disposable glass test tube with a heating block, a disposable plastic d

34、igestion vessel in a hot block digester, or in a suitable digestion vessel and digestion microwave oven system.6. Dilute samples so that Pb results are within the calibration range of the instrument. Be careful not to dilute a sample that could have 0.009% Pb to a level below the method detection li

35、mit.7. Analyze diluted samples for Pb concentration using an ICP spectrometer (or Atomic Absorption spectrometer. Analysis procedures for ICP-OES, flame atomic absorption spectrometry (FLAA, and graphite furnace atomic absorption spectrometry (GFAA are based on the methodology in ASTM E1613-04. Indu

36、ctively coupled plasma mass spectrometry (ICP-MS may also be employed with appropriate procedures, such as EPA 6020A7.ICP Analysis Operating Procedures and Quality Control Measures:1.Ignite plasma. Perform wavelength calibration or torch alignments per instrumentmanufacturer recommendations.2.Allow

37、the instrument to become thermally stable before continuing.3.Ensure the following element and wavelength are selected in analytical method:One other Pb line such as Pb 217.00 should be used to ensure spectral interferences arenot occurring during analysis.4.An internal standard such as 2 g/ml yttri

38、um should be used.5.Perform calibration using calibration blank and at least 3 standards. Calibration shouldbe performed a minimum of once a day when used for analysis, or each time the5 ASTM E1645 Standard Practice for Preparation of Dried Paint Samples by Hotplate or Microwave Digestion for Subseq

39、uent Lead Analysis6 ASTM E1613 Standard Test Method for Determination of Lead by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES7 EPA 6020A Inductively Coupled Plasma-Mass Spectrometryinstrument is set up. Results for each standard should be within 5% of the true value. If the value

40、s do not fall within this range, recalibration is necessary.6.Analyze the QCS immediately after the calibration. The analyzed value of Pb should bewithin 10% of the expected value. If the Pb value is outside the 10% limit,recalibration is required.a.At least one LRB must be analyzed with each sample

41、 set. If the Pb value exceeds3 times the MDL, laboratory or reagent contamination should be expected. Thesource of the contamination should be identified and resolved before continuinganalyses. The LRBs should be at the same acid concentration as that of thesample and should be taken through the sam

42、e digestion procedure as that of asample.7.At least one certified reference material (CRM should be analyzed with each batch ofsamples. The CRM should have a known amount of Pb and be of a material similar to a test specimen. Analyte recoveries should be within 15% of expected values. Ifrecoveries a

43、re outside this limit, the source of the problem should be identified andresolved before continuing analyses.8.Dilute any samples that have Pb values exceeding 1.5 times the high calibration standard,and reanalyze.Calculations and Results Reported: Results for the Pb test methods are calculated and

44、reported as follows: 1. Total Pb concentration:8 % Pb (wt/wt = 0.10 cd/w a. c = concentration of Pb detected (g/ml b. d = dilution volume (ml c. w = weight of aliquot digested (mg Example 1: Single Paint Tested An aliquot of 10 mg of yellow paint scrapings is digested in acid and diluted to a final

45、volume of 50 ml. When analyzed on the ICP-OES, the analytical result is 0.080 g/ml lead in the acid. The paint therefore contained 0.10 x 0.080 g/ml x 50 ml /10 mg = 0.04% (400 ppm. Table 1: Total Pb Analysis Item (c Analytical result Pb (g/ml 0.080 (d Dilution volume (ml 50 Total Pb (g 4 (w Sample

46、wt (mg 10 Pb (% Yellow Paint 0.04 Example 2: Composite Testing Different Parts One example of composite testing of different paints would be as follows, and considers the case of weighing to the nearest 0.01 mg, digesting in acid, diluting to a final volume of 10 ml, and testing on an ICP-OES with an MDL of 0.01 g/ml. A sample bears red, green, and orange paint. The paints are removed from the sample and 4.90 mg of red paint is combined with 5.00 mg of