1

EPA Protocol Revisions

– Traceability for Gaseous Calibration Standards

1. Include a procedure specifically for the use of Fourier Transform infrared Spectroscopy: The current document’s purpose is to provide traceability and ensure accuracy

of the anal ys i s. It is not designed to provide detailed instructions on doing the anal ys is on a specific anal yz er. If FT IR were to be added, then various GC detectors and other process analyzers would need to be added making the document cumbersome and limiting the new technology that could be used.

2. Improve statistical procedures for uncertainty calculations and revise the Excel spreadsheet: We see no real reason for changing the statistical calculations and the Excel spreadsheet. In fact, there are numerous other acc eptable methods for calculating total uncertainty that could be used.

3. Include mercury calibration standards in the protocol: There appears to be no reason to specificall y add Mercury to Table 2

- 3 or create a special section for mercury

or any other co mpound. However a footnote for Table 2

- 3 that makes it clear that the components listed are not the only ones that can be made as EPA Protocols. As long as new traceable standards exist, and the protocol can be followed, then a component can be called an E PA Protocol.

4. Eliminate (or retain) gas manufacturers intermediate standards (GMISs): The purpose of the EPA protocol is to ensure accuracy and traceability . Changes that should be considered should help improve these two aspects. GMI Ss are standards th at are unverified b y EPA or N IST and as such are suspect. In fact they are made using a similar methodology

to making EPA Protocol mixes, so if a compan y cannot accuratel y make protocols, then it is likely that they will have significant errors in their GM ISs that will carry over to samples that they anal yz e. Even using the best of techniques, the uncertaint y of the GMI S has to be greater than that of the SRMs, NTRMs, or PRMs due to the propagation of error. As a result of these two issues, using GMISs inhe rently is less accurate and invites problems. Using the verified metrology standards is the best guarantee for eliminating or minimizing the uncertainty contribution from the reference standards.

5. Lengthen the certification periods for EPA Protocol Gases: The current expiration dates are valid from the perspective of stability and use. Most users will run out of gas in about 18 months, so the 24 and 36 months expiration periods for stable components are sufficient. In regard to reactive components at low concentrations, increasing2

the expiration dates runs the risk of failure due to instability , which was not identified during the 2 required triad anal yses. The rate of reaction ty picall y slows as the concentration of the reactive component decreases, lea ding to the potential for component instability . The requirement to recertify

these mixtures after the initial 6

- month period is designed to prevent long

- term stability

problems in the field.

6. Change the cylinder pressure limitations for EPA Protocol Ga ses: We see this as a two

- part issue. We believe the limit of 150 psig, below which the Protocol cannot be used, should remain unchanged. We have seen instances where wall effects in the cy linder resulted in concentration changes at low pressure.
The sec ond part of the issue relates to the 500 psig limit for recertification of mixtures. We agree with lowering that limit, but certainly no lower than 150 psig. There are instances, where a Protocol has expired while in use, and being able to recertify it hel ps the end user with the state or federal agency that monitors that facility

.

7. Include a procedure for analyzing and certifying zero gases: There are no trace standards currently available from NI ST to analyze most of the contaminants of interest. These would have to be developed in conjunction with any specific procedure for anal yz ing and certifying these ty pes of gases. Currently , some manufacturers do not specificall y analyze the zero gases for individual impurities, and just “assume” that they are cle an, and of course, this is not alway s the case. This may be more involved than initially thought and perhaps should be an addendum to the protocol. Otherwise we are in favor of this.

8. Include gas dilution systems in the protocol: The G2 protocol includ es mention of dilution. I f the suggestion is to add specifics on what specific t ypes of s ys tems/ devices can be used and how they are to be used, we feel this would be too restrictive and bey ond the scope of the intent of the protocol.

9. Tighten documenta tion requirements: Field verification of conformance of a calibration gas mixture to the protocol is an important compliance tool. In order to facilitate calibration gas verification, a full disclosure certification should include: 1. Cylinder identificat ion number 2. Certified minor component concentration(s) 3. Balance gas 4. Cylinder pressure at time of certification 5. Assay

/ certification date3

6. Certification expiration date 7. Reference standard identification (standard number, cylinder number, minor component conce ntration, expiration date) 8. Statement that the assay / certification conforms to EPA Protocol guidelines 9. Analy

tical methodology

used for certification 10. Laboratory

identification (name, address, telephone number) 11. Record of previous EPA protocol gas certificat ion 12. Analy

tical accuracy

for each certified minor component 13. Statement that the certified concentration has been corrected for interference, if applicable. 14. Analyzer identification (make, model, serial number, measurement principle, and last multi

- point calib ration date) 15. All triad anal yz er readings used to obtain the certified minor component concentration(s) 16. Correlation coefficient and calibration curve equation used to calculate the certified minor component concentration(s). 17. Specific Total Oxides of Nitroge n reference value for all Nitric Oxide protocol gas cy linders. Having all this information will allow end users as well as auditors/ inspectors to more readil y identify where expired standards were used, falsification of the ZRT Triad anal ys is, inappropriate anal yz ers used for analy sis without addressing interference issues, as well as independent verification of the mathematics used to calculate the concentrations against a curve.

10. Develop audit participant identification number for regulatory data repo rting purposes: There is no value in regard to strengthening the purpose and intent of the existing protocol, as the manufacturer’s contact information is alread y on the Certificate of analysis.

11. Require ISO 17025 accreditation for producers of environm ental calibration gases: ISO 17025 is an extremely expensive certification and does not guarantee that a better protocol product will be manufactured. In fact, a gas manufacturer, holding certification to the I SO 17025 standard, registered at least 1 fail ure in the recent blind audit. The high cost of accreditation to the I SO 17025 standard would create an economic inequity among gas manufacturers, creating a competitive advantage favoring large manufacturers.
Technicall y, one of the core concepts of the ISO 17025 standard is the manner b y which uncertaint y is propagated. In order to assert accreditation of a laboratory to the I SO 17025 standard as a requirement, the protocol would need to be changed so the calculation of uncertaint y would match the conve ntions dictated by I SO 17025. As previously stated (see item 2), we do not view this as a valuable change to the existing protocol.4

12. Include provision for preparation and analysis of batches of EPA Protocol gases: Batch anal ys is of protocol mixes does n ot move us in the direction of making better product. It will reduce costs but expose the customer to possible problems that can and will occur since homogeneit y is not guaranteed. NIST has seen problems of homogeneity with batch preparation of SRMs, and those same problems occur when preparing Protocols. In fact, the problems will be greater since man y protocols are now multicomponent mixtures, and homogeneity

is more difficult than with a single component Protocol. As an aside, some producers anal yz e NOx in NO Protocol mixes on a batch basis, which is erroneous. Scott recommends that EPA require that NOx values that are assigned to NO protocol gas mixtures be actual values and not batch values since end users need to know the actual NOx value for each cyl inder of NO Protocol.

13. Require on
- site visits of specialty gas producers by EPA representatives: This would provide no value to the end users. A producer would do the “right” things if and when an audit would occur, and the costs would be prohibitive. B etter to spend the resources of EPA auditing end users, and if problems are found there, test those protocols that are questionable.

14. Provide for technical assistance/outreach to specialty gas producers by NIST representatives: This should not be part of the protocol. An y gas company can approach NIST with questions regarding product production, whether it is related to protocols or not. At the same time, having NI ST and/or EPA auditing gas producers opens up the possibility of the auditors passing o n technical suggestions for improvement that originate in one producer and would provide an advantage to a competitor.