## EPA Protocol Gas Audit Results Tri-Blend NO/SO2/CO2 Gases - Certified According to EPA Traceability Protocol EPA Cylinder Gas Assays: April 2003 - February 2004

Tag Reported Tag Reported Value Uncert. NOUncert.95% CIRelative CIOrig TagRe-analysisNO95% CIRelative CIOrig TagRe-analysis Value Uncert. SO2Uncert.95% CIRelative CIOrig Tag (ppm NO)(+/-) (ppm)(+/- ppm)(ppm) (%) (% diff) (%

diff) (ppm)(ppm) (%) (% diff) (%

diff) (ppm SO2) (+/-) (ppm)(+/- ppm)(ppm) (%) (% diff) 1 Low 54.00.8 ppm FTIR GMIS 54.9 1.3 0.2 0.34 -1.6 53.83 0.43 0.80 0.3 47.50.8 ppm FTIR GMIS 48.36 2.88 0.37 0.76 -1.8 2 Mid 401 5 ppm FTIR GMIS 395.9 3.0 2.3 0.59 1.3 392.5 0.6 0.15 2.2 499 4 ppm FTIR GMIS 497.17 3.13 0.76 0.15 0.4 3 High 91110 ppm FTIR GMIS (b) --- --- --- --- 905 1 0.07 0.7 981 9 ppm FTIR GMIS 987.26 3.29 1.66 0.17 -0.6 1 Low 48.90 1%

### 49.89 (e) 2.0Chem NTRM 53.4 1.9 0.3 0.51 -8.4 

### -6.549.93 0.35 0.70 -2.1 

### -0.1 47.73 1%

### 47.62 -0.2NDIR NTRM 47.01 2.88 0.33 0.70 1.5 2 Mid 406.0 1% 

### 405.2 -0.2Chem NTRM 411.7 3.1 0.4 0.11 -1.4 

### -1.6406.3 1.5 0.36 -0.1 

### -0.3 496.8 1%

### 500.9 0.8NDIR NTRM 492.10 3.13 3.09 0.63 1.0 3 High 900.0 1%

### 909.8 (e) 1.1Chem NTRM (b) --- --- --- --- 

### ---925 2 0.24 -2.7 

### -1.6 994.6 1% 

### 1003 0.8NDIR NTRM 994.16 3.96 5.08 0.51 0.0 1 Low 51.4 1% 

### 52.21 1.6NDIR NTRM 53.2 1.3 0.4 0.73 -3.4 

### -1.951.50 0.34 0.66 -0.2 

### 1.4 50.4 1%

### 50.05 -0.7NDIR GMIS 49.92 2.93 0.01 0.02 1.0 2 Mid 388 1% 

### 384.6 -0.9NDIR NTRM 387.2 3.0 0.7 0.18 0.2 

### -0.7382.4 1.4 0.36 1.5 

### 0.6 500 1%

### 504.3 0.9NDIR NTRM 499.89 3.17 0.35 0.07 0.0 3 High 845 1%

### 860.9 (e) 1.9NDIR NTRM (b) --- --- --- --- 

### ---870 1 0.07 -2.9 

### -1.0 1000 1% 

### 1002 0.2NDIR NTRM1000.28 3.96 2.43 0.24 0.0 1 Low 50.05 1%

### 51.69 (e) 3.3Chem GMIS 52.7 1.3 0.2 0.45 -5.1 

### -2.051.80 0.23 0.44 -3.4 

### -0.2 50.23 1%

### 51.03 1.6NDIR NTRM 50.25 2.88 0.03 0.05 0.0 2 Mid 397.5 1% 

### 401 0.9Chem NTRM 405.7 3.0 1.2 0.30 -2.0 

### -1.2400.3 2.1 0.52 -0.7 

### 0.2 502.8 1%

### 509.2 1.3NDIR NTRM 505.89 3.14 0.39 0.08 -0.6 3 High 900.0 1% 

### 900.8 0.1Chem NTRM (b) --- --- --- --- 

### ---912 2 0.19 -1.3 

### -1.2 998.8 1% 

### 1012 1.3NDIR NTRM1003.99 4.01 1.61 0.16 -0.5 1 Low 49.8 1% FTIR SRM 51.5 1.3 0.4 0.83 -3.3 50.50 0.20 0.40 -1.4 50.9 1% FTIR SRM 50.52 2.70 0.15 0.29 0.8 2 Mid 407.8 1%

### 406.0 (f) -0.4FTIR SRM 399.5 3.0 0.6 0.16 2.1 

### 1.6397.4 1.1 0.27 2.6 

### 2.2 500.4 1% FTIR NTRM 499.80 3.13 0.71 0.14 0.1 3 High 900 1%

### 896 (f) -0.4FTIR SRM (b) --- --- --- --- 

### ---880 5 0.51 2.3 

### 1.8 1000 1% FTIR NTRM1001.47 3.96 0.31 0.03 -0.1 1 Low 50.40.5 ppm Chem GMIS 51.0 1.3 0.1 0.13 -1.1 50.50 0.11 0.22 -0.2 48.70.5 ppm NDIR GMIS 48.67 2.70 0.13 0.28 0.1 2 Mid 396 4 ppm Chem GMIS 390.2 2.4 0.2 0.06 1.5 388.3 2.4 0.61 2.0 466 5 ppm NDIR GMIS 461.75 3.04 5.57 1.21 0.9 3 High 904 9 ppm Chem GMIS (b) --- --- --- --- 903 2 0.19 0.1 95610 ppm NDIR GMIS 955.83 3.87 2.25 0.24 0.0 1 Low 48.90.4 ppm

### 50.4 (g) 3.1 FTIR SRM 51.5 1.3 0.1 0.15 -5.0 

### -2.150.57 0.07 0.14 -3.3 

### -0.3 49.50.4 ppm FTIR SRM 48.33 2.76 0.22 0.45 2.4 2 Mid 410 1 ppm

### 405.1 (g) -1.2FTIR SRM 401.6 3.0 1.6 0.41 2.1 

### 0.9397.7 0.7 0.16 3.1 

### 1.9 504 5 ppm FTIR SRM 502.79 3.04 1.70 0.34 0.2 3 High 904 9 ppm FTIR SRM (b) --- --- --- --- 907 2 0.25 -0.3 988 9 ppm FTIR SRM 994.28 5.30 7.08 0.71 -0.6 1 Low 50.00.128 ppm Chem GMIS 50.4 1.3 0.1 0.20 -0.9 50.00 0.20 0.40 0.0 50.10.507 ppm NDIR GMIS 48.89 2.70 0.23 0.46 2.5 2 Mid 3981.28 ppm Chem GMIS 396.9 3.0 0.2 0.06 0.3 391.3 1.7 0.43 1.7 5011.82 ppm NDIR GMIS 506.49 3.09 0.43 0.09 -1.1 3 High 8882.99 ppm Chem GMIS (b) --- --- --- --- 887 5 0.52 0.1 10043.1 ppm NDIR GMIS 1018.01 5.36 2.19 0.21 -1.4 1 Low 50.00.131 ppm Chem GMIS 50.8 1.3 0.3 0.58 -1.5 50.47 0.13 0.26 -0.9 49.30.506 ppm NDIR GMIS 48.16 2.70 0.66 1.38 2.4 2 Mid 4031.28 ppm Chem GMIS 399.3 2.5 0.9 0.22 0.9 396.0 2.4 0.62 1.8 4961.82 ppm NDIR GMIS 502.94 3.04 0.66 0.13 -1.4 3 High 8942.99 ppm Chem GMIS (b) --- --- --- --- 904 5 0.58 -1.1 10043.1 ppm NDIR GMIS 1018.22 5.40 1.92 0.19 -1.4 1 Low 46.2 1%

### 47.3 (h) 2.4FTIR GMIS 48.1 1.3 0.4 0.92 -4.0 

### -1.848.27 0.33 0.68 -4.3 

### -2.0 51.8 1%

### 51.5 (h) -0.6FTIR GMIS 50.49 2.75 0.22 0.44 2.6 2 Mid 398 1% FTIR GMIS 401.3 2.5 0.6 0.14 -0.8 397.3 1.9 0.48 0.2 500 1% FTIR GMIS 499.12 3.04 3.39 0.68 0.2 3 High 930 1% 

### 930 0.0FTIR GMIS (b) --- --- --- --- 948 9 0.99 -1.9 991 1% 

### 992 0.1 FTIR GMIS 995.74 5.30 2.35 0.24 -0.5 1 Low 51.2 1% Chem GMIS 51.9 1.3 0.3 0.59 -1.3 51.50 0.49 0.95 -0.6 50.0 1% UV GMIS 49.59 2.75 0.19 0.38 0.8 2 Mid 406 1% NDIR GMIS 405.1 2.5 0.4 0.11 0.2 400.6 1.00 0.25 1.3 509 1% NDIR GMIS 506.59 2.83 3.11 0.61 0.5 3 High 914 1% NDIR GMIS (b) --- --- --- --- 933 1 0.07 -2.0 999 1% NDIR GMIS 1000.59 5.31 6.58 0.66 -0.2 1 Low 50.0 1% FTIR NTRM 51.0 1.3 0.3 0.63 -1.9 50.30 0.45 0.89 -0.6 50.4 1% FTIR NTRM 49.10 2.81 0.18 0.38 2.7 2 Mid 402 1% FTIR NTRM 401.7 2.5 2.2 0.55 0.1 397.2 3.7 0.94 1.2 503 1% FTIR NTRM 497.63 2.83 2.63 0.53 1.1 3 High 911 1% FTIR NTRM (b) --- --- --- --- 918 3 0.28 -0.8 1011 1% FTIR NTRM1000.65 3.83 4.28 0.43 1.0 1 Low 50.80.3 ppm Chem GMIS 51.7 1.3 0.1 0.14 -1.8 51.77 0.24 0.46 -1.9 50.90.6 ppm UV GMIS 51.07 2.75 0.12 0.23 -0.3 2 Mid 397 2 ppm Chem GMIS 399.9 2.5 0.9 0.22 -0.7 395.5 0.7 0.16 0.4 504 5 ppm UV GMIS 502.94 2.87 0.88 0.17 0.2 3 High 886 5 ppm Chem GMIS (b) --- --- --- --- 899 4 0.48 -1.4 99710 ppm UV GMIS 992.93 3.81 3.28 0.33 0.4 1 Low 50.1 1% Chem NTRM 51.1 1.3 0.3 0.65 -2.0 50.80 0.00 0.00 -1.4 50.2 1% NDIR NTRM 49.19 2.75 0.18 0.37 2.1 2 Mid 405 1% FTIR NTRM 404.2 2.5 0.8 0.21 0.2 400.8 1.7 0.43 1.0 495 1% NDIR GMIS 493.05 2.83 0.85 0.17 0.4 3 High 923 1% FTIR NTRM (b) --- --- --- --- 934 4 0.39 -1.2 988 1% NDIR GMIS 987.60 3.85 1.15 0.12 0.0 

### (a) AMETEK Model 922 UV measurements of NO were adjusted for SO2 interference (b) The high-level NO evaluations were based solely on the FTIR results because the AMETEK UV NOx monitor setup performed by the manufacturer was not optimum for the 1000 ppm range. (c) High-range gas cylinder was returned to Air Liquide for CO2 reanalysis. Vendor reported a new CO2 value (on May 6, 2004) of 17.9%, which differs by less than 2.0% from the EPA-determined value. Reanalyzed value is also within +/- 2.0% of original tag value. No corrective action taken by the vendor. (d) The high-level CO2 evaluations were based solely on the NDIR results because there was not enough high-level CO2 SRM or NTRM to provide reference spectra for the FTIR. (e) Gas cylinders were returned to Airgas for NO reanalyses. Vendor reported new NO values on April 26, 2004, which differ by less than 2.0% from the corresponding EPA-determined values. In all but one case, the reanalyzed value was within +/- 2.0% of original tag value. No corrective action taken by the vendor. (f) Mid- and high-level gas cylinders were returned to BOC Gases for NO reanalyses. Vendor reported new values on June 9, 2004, which differ by less than 2.0% from the corresponding EPA-determined UV or FTIR values. The two reanalyzed NO values also differ by less than 2.0% of original tag value. No corrective action was taken. (g) Gas cylinders were returned to Matheson for NO and CO2 reanalyses. Vendor reported new values on May 10, 2004, which differ by less than 2.0% from the corresponding EPA-determined values. Two of the three reanalyzed values differed by more than 2.0% of original tag value. The corrected concentrations for NO were done by a shift to a wavenumber within a spectral region where CO2 interference is minimized. Matheson found an operator calculation error for the CO2 concentration in this sample from early 2003, and implemented data acquisition and calculation software for their FTIRs in early 2004 to preclude the potential for operator errors. (h) Gas cylinders were returned to National Specialty Gases for NO, SO2, and CO2 reanalyses. Vendor reported new values on May 10, 2004, which differ by less than 2.0% from the corresponding EPA-determined values. Two of the three reanalyzed values differed by more than 2.0% of original tag value. As a result of the audit, National Specialty Gases recalibrated their FTIR and obtained a more experienced, analyst. (i) High-range gas cylinder was returned to Praxair for CO2 reanalysis based on an initial EPA finding of 18.07% CO2. Vendor reported a new CO2 value (on May 27, 2004) of 17.82%. Vendor had independent 3rd party (Scott Marin) analyze the cylinder, resulting in 17.77% CO2. Vendor had the National Institute of Standards and Technology (NIST) analyze cylinder, resulting in 17.85% CO2. All of the reanalyzed values differ by less than 2.0% from the EPA-determined value. The original tag value is within +/- 2.0% of each of the reanalyzed values. The original tag value and the vendor reanalyzed value are within +/- 2.0% of the NIST-generated "true" value. Therefore no corrective action is required.

of the analytical capabilities of individual producers. EPA presents this information without assigning a rating to the gas vendors, for example, who is the best, who is approved, or who is not approved. %Change in Vendor Certified Value 

### Analysis by UV (a) 

## SO2 Component Analysis by UV 

## NO Component %Change in Vendor Certified Value Vendor Analytical TechniqueReference

Standard Reanalyzed Value (ppm) Vendor Analytical TechniqueReference

Standard



### Airgas NCN Specialty Gases

Airgas South Specialty Gases

BOC Gases

AGA (Linde Gas Group)

Messer MG Industries (Spec Air Specialty Gases) Matheson Tri-Gas

Messer MG Industries Gas Vendor Cyl. No. 

### Analysis by FTIR

Scott-Marrin In. Air Liquide

Airgas Southwest Specialty Gases Gas Conc. Range Re-analyzed Value (ppm)



### National Specialty Gases

Spectra Gases Inc. Praxair

Scott Specialty Gases

If the difference between EPA’s value and a gas vendor’s value differs by ±2.0% or less, then (because of the uncertainties in the total measurement system) statistically there is no difference between the two values. Thus, a difference of 2.0% would be interpreted as being equal to one of, for example, 0.4%. Any accuracy assessment is an instantaneous snapshot of the process being measured. These results should not be regarded as a final statement concerning the accuracy of EPA Protocol Gases. They can be used as an indicator of the current status of the accuracy of EPA Protocol Gases as a whole. However, individual results should not be taken as definitive indicatorsTag Reported Re-analysisSO295% CIRelative CIOrig TagRe-analysisValue Uncert. CO2 Uncert. 95% CIRelative CIOrig TagRe-analysisCO295% CIRelative CIOrig TagRe-analysis (% diff) (ppm)(ppm) (%) (% diff) (%

diff) (%

CO2) (+/-) (%)(+/- % CO2)(%

CO2) (%) (% diff) (%

diff) (%)(% CO2) (%) (% diff) (%

diff) 47.93 0.09 0.19 -0.9 4.970.06% CO2 FTIR GMIS 5.02 0.07 0.01 0.12 -1.0 4.991 0.027 0.54 -0.4 Yes 498.5 2.3 0.45 0.1 12.1 0.1% CO2 FTIR GMIS 12.09 0.11 0.02 0.18 0.1 11.98 0.08 0.63 1.0 Yes 1004.5 1.5 0.15 -2.3 17.7 0.2% CO2

### 17.9 (c) 1.1 FTIR NTRM 18.15 0.17 0.01 0.08 -2.5 

### -1.4 (d) --- --- --- 

### --- Yes 

### 1.347.52 0.40 0.84 0.4 

### 0.2 5.011 1% 

### 5.045 0.7NDIR NTRM 4.97 0.07 0.01 0.26 0.8 

### 1.54.984 0.039 0.78 0.5 

### 1.2 Yes 

### 1.8501.3 0.5 0.09 -0.9 

### -0.1 12.0 1% 

### 11.95 -0.4NDIR NTRM 12.07 0.11 0.01 0.11 -0.6 

### -1.012.06 0.07 0.56 -0.5 

### -0.9 Yes 

### 0.91008.2 2.0 0.20 -1.3 

### -0.5 17.99 1% 

### 17.97 -0.1 NDIR NTRM 18.09 0.17 0.01 0.04 -0.6 

### -0.7 (d) --- --- --- 

### --- Yes 

### 0.349.79 0.08 0.16 1.2 

### 0.5 5.01 1% 

### 5.064 1.1 NDIR NTRM 5.00 0.07 0.01 0.10 0.2 

### 1.34.970 0.020 0.40 0.8 

### 1.9 Yes 

### 0.9504.2 0.3 0.05 -0.8 

### 0.0 12.0 1% 

### 11.94 -0.5NDIR NTRM 12.07 0.11 0.01 0.09 -0.6 

### -1.112.04 0.10 0.84 -0.3 

### -0.8 Yes 

### 0.21006.8 2.3 0.23 -0.7 

### -0.5 18.0 1% 

### 18.06 0.3NDIR NTRM 18.15 0.17 0.00 0.01 -0.8 

### -0.5 (d) --- --- --- 

### --- Yes 

### 1.650.58 0.08 0.16 -0.7 

### 0.9 5.041 1% 

### 5.057 0.3NDIR NTRM 5.01 0.07 0.01 0.22 0.7 

### 1.04.9980.008 0.16 0.9 

### 1.2 Yes 

### 0.7507.9 0.8 0.16 -1.0 

### 0.3 12.0 1% 

### 11.88 -1.0NDIR NTRM 12.05 0.11 0.01 0.09 -0.4 

### -1.412.17 0.04 0.30 -1.4 

### -2.4 Yes 

### 0.81016.1 2.7 0.27 -1.7 

### -0.4 18.07 1% 

### 18.15 0.4NDIR NTRM 18.18 0.17 0.02 0.11 -0.6 

### -0.2 (d) --- --- --- 

### --- Yes 50.83 0.32 0.63 0.1 5.0 1% FTIR NTRM 4.98 0.07 0.01 0.22 0.5 4.9730.031 0.62 0.5 Yes 499.8 2.6 0.51 0.1 11.98 1% FTIR NTRM 12.05 0.11 0.01 0.06 -0.6 11.94 0.05 0.44 0.3 Yes 1015.6 1.9 0.18 -1.5 18.02 1% FTIR NTRM 18.14 0.17 0.01 0.06 -0.7 (d) --- --- --- Yes 49.54 0.12 0.24 -1.7 5.2 0.5% CO2 NDIR NTRM/GMIS5.22 0.07 0.01 0.17 -0.5 5.1460.004 0.08 1.0 Yes 464.2 2.0 0.43 0.4 12.5 0.1% CO2 NDIR NTRM/GMIS12.68 0.12 0.01 0.04 -1.4 12.45 0.05 0.38 0.4 Yes 967.3 0.7 0.07 -1.2 18.3 0.2% CO2 NDIR NTRM/GMIS18.53 0.17 0.02 0.08 -1.2 (d) --- --- --- Yes 48.95 0.12 0.25 1.1 5.230.05% CO2

### 4.94 (g) -5.5FTIR SRM 4.99 0.07 0.01 0.28 4.8 

### -1.04.9790.006 0.12 5.0 

### -0.8 Yes 503.6 1.0 0.20 0.1 12.2 0.1% CO2 FTIR SRM 12.06 0.11 0.01 0.11 1.2 11.93 0.04 0.30 2.3 Yes 1006.5 1.7 0.17 -1.8 17.9 0.1% CO2 FTIR SRM 18.07 0.17 0.00 0.02 -0.9 (d) --- --- --- Yes 49.26 0.36 0.73 1.7 5.050.0444% CO2 NDIR GMIS 5.08 0.07 0.01 0.23 -0.5 5.0230.007 0.14 0.5 Yes 508.5 0.6 0.11 -1.5 12.10.0501% CO2 NDIR GMIS 12.22 0.11 0.02 0.13 -1.0 12.18 0.06 0.49 -0.7 Yes 1029.3 1.5 0.14 -2.5 18.20.0501% CO2 NDIR GMIS 18.27 0.17 0.00 0.02 -0.4 (d) --- --- --- Yes 49.12 0.27 0.55 0.4 5.070.04444% CO2 NDIR GMIS 5.09 0.07 0.01 0.12 -0.5 5.0530.010 0.20 0.3 Yes 504.0 1.7 0.34 -1.6 12.10.0501% CO2 NDIR GMIS 12.22 0.11 0.01 0.10 -1.0 12.18 0.04 0.30 -0.7 Yes 1029.8 3.3 0.32 -2.5 18.30.0501% CO2 NDIR GMIS 18.31 0.17 0.00 0.01 -0.1 (d) --- --- --- Yes 

### 2.050.64 0.19 0.38 2.3 

### 1.7 4.9 1% 

### 4.9 0.0FTIR GMIS 4.87 0.06 0.01 0.11 0.5 4.8850.032 0.66 0.3 Yes 502.2 3.2 0.64 -0.4 12.0 1% FTIR GMIS 11.97 0.11 0.01 0.08 0.3 12.09 0.06 0.48 -0.7 Yes 1011.0 3.8 0.37 -2.0 17.8 1%

### 18.23 (h) 2.4FTIR GMIS 18.30 0.17 0.01 0.04 -2.8 

### -0.4 (d) --- --- --- --- Yes 50.36 0.34 0.68 -0.7 5.00 1% NDIR GMIS 5.03 0.06 0.00 0.05 -0.6 4.9860.014 0.28 0.3 Yes 511.6 0.9 0.17 -0.5 12.18 1% NDIR GMIS 12.17 0.11 0.02 0.16 0.1 12.23 0.02 0.12 -0.4 Yes 1008.7 1.6 0.16 -1.0 17.59 1%

### 17.82 (i) 1.3NDIR GMIS 17.85 0.13 0.01 0.06 -1.5 -0.2 (d) --- --- --- --- Yes 50.38 0.08 0.16 0.0 5.04 1% FTIR NTRM 5.01 0.06 0.00 0.03 0.6 4.9870.020 0.40 1.1 Yes 503.0 1.9 0.37 0.0 12.10 1% FTIR NTRM 12.04 0.11 0.01 0.07 0.5 12.18 0.03 0.25 -0.7 Yes 1021.3 0.8 0.08 -1.0 17.97 1% FTIR NTRM 18.03 0.17 0.01 0.07 -0.3 (d) --- --- --- Yes 51.17 0.13 0.26 -0.5 5.110.05% CO2 GC GMIS 5.09 0.06 0.00 0.03 0.4 5.0460.032 0.63 1.3 Yes 507.9 0.4 0.08 -0.8 12.020.02% CO2 GC GMIS 12.11 0.11 0.01 0.07 -0.7 12.07 0.07 0.55 -0.4 Yes 995.9 1.2 0.12 0.1 17.920.05% CO2 GC GMIS 18.13 0.17 0.02 0.12 -1.2 (d) --- --- --- Yes 49.82 0.18 0.36 0.8 5.02 1% NDIR GMIS 5.01 0.06 0.01 0.13 0.1 5.0030.015 0.30 0.3 Yes 493.1 1.0 0.21 0.4 12.03 1% NDIR NTRM 12.10 0.11 0.01 0.07 -0.5 12.24 0.01 0.10 -1.7 Yes 998.5 5.7 0.57 -1.1 18.07 1% NDIR NTRM 18.08 0.17 0.01 0.05 0.0 (d) --- --- --- Yes



### (g) Gas cylinders were returned to Matheson for NO and CO2 reanalyses. Vendor reported new values on May 10, 2004, which differ by less than 2.0% from the corresponding EPA-determined values. Two of the three reanalyzed values differed by more than 2.0% of original tag value. The corrected concentrations for NO were done by a shift to a wavenumber within a spectral region where CO2 interference is minimized. Matheson found an operator calculation error for the CO2 concentration in this sample from early 2003, and implemented data acquisition and calculation software for their FTIRs in early 2004 to preclude the potential for operator errors. (h) Gas cylinders were returned to National Specialty Gases for NO, SO2, and CO2 reanalyses. Vendor reported new values on May 10, 2004, which differ by less than 2.0% from the corresponding EPA-determined values. Two of the three reanalyzed values differed by more than 2.0% of original tag value. As a result of the audit, National Specialty Gases recalibrated their FTIR and obtained a more experienced, analyst. (i) High-range gas cylinder was returned to Praxair for CO2 reanalysis based on an initial EPA finding of 18.07% CO2. Vendor reported a new CO2 value (on May 27, 2004) of 17.82%. Vendor had independent 3rd party (Scott Marin) analyze the cylinder, resulting in 17.77% CO2. Vendor had the National Institute of Standards and Technology (NIST) analyze cylinder, resulting in 17.85% CO2. All of the reanalyzed values differ by less than 2.0% from the EPA-determined value. The original tag value is within +/- 2.0% of each of the reanalyzed values. The original tag value and the vendor reanalyzed value are within +/- 2.0% of the NIST-generated "true" value. Therefore no corrective action is required. 

## CO2 Component Analysis by FTIR Re-analyzed Value (%)%Change in

Vendor Certified Value Supplied Complete Documentation Vendor Analytical TechniqueReference

Standard 

### Analysis by NDIR Analysis by FTIR