Excel Spreadsheet Headings

• ID (NIST Identifier)

• Specie (Analyte)

• Balance Gas

• Nominal Concentration

• Batch Size (Number of Cylinders)

• Certification Date (Year and Month)

• Certified value

• Uncertainty

• Factor (Bias between producer and NIST

results)
Company Participation by Year

Year Company Coded

Y-93 a b n=2

Y-94 a n=1

Y-95 a b c d e f n=6

Y-96 a c d e f g h n=7

Y-97 a c d e f g j k n=8

Y-98 a c d e f g h j k n=9

Y-99 a c d g j n=5

Y-00 1/2 a c d e h n=5
Companies Participating in the Gas 

Mixture NTRM Program

• AGA

• Air Products

• Airgas

• ALAC

• BOC / Airco

• Matheson

• MG

• Praxair / Liquid Carbonic

• Scott

• Spectra
Graph of Number of Gas Mixture NTRM 

Batches by Year

0

10

20

30

40

50

60

70

93 94 95 96 97 98 99 1/2

2000

NIST Fiscal Year

Number of NTRM Batches
NTRM Batches by Year

93 C3H8 0.0010

93 CH4 0.0010 0.0010

93 CO 0.1000 0.1000 0.2500

93 CO2 2.5000 7.0000 14.0000

93 NO 0.0500 0.1000 0.3000

93 SO2 0.0050 0.0100 0.0260 0.0500 0.1000 0.1500 0.3500

94 C3H8 0.0100

94 CH4 0.0010

94 CO 0.0100 0.0250

94 NO 0.0050 0.0250 0.0500 0.1000

94 SO2 0.0500
NTRM Batches by Year

95 CO 0.0010 0.0050 0.0250 0.0500 0.1000 0.2500

95 CO2 3.5000 5.0000 7.0000 14.0000 18.0000 20.0000

95 NO 0.0020 0.0020 0.0025 0.0050 0.0085 0.0100 0.0100 0.0175 0.0250 0.0250

0.0250 0.0250 0.0500 0.0500 0.0500 0.0625 0.0750 0.1000 0.1000 0.1000

0.1500 0.3000 0.3000

95 O2 2.0000 2.0000 10.0000 10.0000 21.0000 21.0000

95 SO2 0.0050 0.0050 0.0100 0.0100 0.0175 0.0260 0.0375 0.0500 0.1000 0.1000

0.1250 0.1500 0.1500 0.2500 0.3000 0.3200 0.3500 0.3500

96 CO 0.0050 0.0100 0.0100 0.0250 0.1000 0.2500 0.5000 8.0000

96 CO2 18.0000 22.0000

96 NO 0.0020 0.0050 0.0500 0.0875 0.1000 0.1000 0.1000 0.1500 0.3000

96 NO2 0.0100 0.0500

96 O2 10.0000 20.0000

96 SO2 0.0500 0.0500 0.0500 0.0875 0.1000 0.1000 0.1000 0.2000 0.2800 0.3500

0.3500
NTRM Batches by Year

97 C3H8 0.0100 0.0100 0.0500 0.0500 0.1200 0.2500

97 CH4 0.0500

97 CO 0.0025 0.0025 0.0050 0.0100 0.0250 0.0500 0.1000 0.1000 0.1000 2.0000

0.0050 0.0250 0.0500 0.1000

97 CO2 0.5000 0.5000 0.5000 1.0000 1.5000 2.0000 3.0000 4.0000 5.0000 7.0000

9.0000 11.0000 14.0000 14.0000 16.0000 18.0000 20.0000 20.0000 20.0000

97 EtOH 0.0100 0.0100 0.0120 0.0220 0.0220

97 Nat Gas Multi

97 NO 0.0020 0.0100 0.1000 0.1000

97 SO2 0.0050 0.0100 0.0100 0.0100 0.0500 0.0500 0.1000 0.1500 0.1500 0.2500

0.2500

98 C3H8 0.0050 0.0300 0.0500

98 CH4 0.0010

98 CO 0.0050 0.0050 0.0050 0.0100 0.0100 0.0100 0.0250 0.0250 0.0250 0.0500

0.0500 0.0500 0.1000 0.2500 0.5000 0.5000 7.0000

98 CO2 4.0000 7.0000 14.0000 20.0000

98 NO 0.0050 0.0050 0.0100 0.0100 0.0100 0.0250 0.0500 0.0500 0.1000 0.1500

0.3000 0.3000 0.3000

98 O2 2.0000 2.0000 4.5000 5.0000 7.0000 10.0000 10.0000 10.0000 10.0000 12.0000

15.0000 16.0000 21.0000 21.0000 21.0000 21.0000 21.0000 23.0000 23.0000 24.0000

98 SO2 0.0050 0.0050 0.0100 0.0100 0.0100 0.0250 0.0250 0.0250 0.0500 0.0500

0.1000 0.1000 0.3500
NTRM Batches by Year

99 C3H8 0.0003 0.0010 0.0010 0.0100 0.0250 0.0500 0.1000 0.2500 0.2500 0.5000

99 CH4 0.0003 0.0010 0.0050 0.0050 0.0100 0.0210

99 CO 0.0018 0.0025 0.0025 0.0100 0.0100 0.0250 0.0500 0.1000 0.2500 1.0000

2.0000 8.0000

99 CO2 0.1000 3.0000 3.0000 3.5000 5.0000 5.0000 7.0000 14.0000

99 H2S 0.0025 0.0050 0.0100 0.0250

99 NO 0.0050 0.0100 0.0250 0.0500 0.0500 0.0500 0.1000 0.1000 0.2800 0.3600

99 O2 0.5000 2.0000 2.0000 12.0000 21.0000

99 SO2 0.0050 0.2500

1/2 2000 C3H8 0.0050

1/2 2000 CO 0.0025 0.1000

1/2 2000 CO2 1.0000 2.0000 7.0000 18.0000 20.0000 23.0000

1/2 2000 H2S 0.0020 0.0025 0.0300

1/2 2000 NO 0.0050 0.0100 0.0250 0.0500 0.1000 0.1000

1/2 2000 NOx 0.0100

1/2 2000 O2 2.0000 10.0000 21.0000 24.0000
NTRM Batches by Specie and Year

93 C3H8 0.0010

94 C3H8 0.0100

97 C3H8 0.0100 0.0100 0.0500 0.0500 0.1200 0.2500

98 C3H8 0.0050 0.0300 0.0500

99 C3H8 0.0003 0.0010 0.0010 0.0100 0.0250 0.0500 0.1000 0.2500 0.2500 0.5000

1/2 2000 C3H8 0.0050

93 CH4 0.0010 0.0010

94 CH4 0.0010

97 CH4 0.0500

98 CH4 0.0010

99 CH4 0.0003 0.0010 0.0050 0.0050 0.0100 0.0210

97 EtOH 0.0100 0.0100 0.0120 0.0220 0.0220

97 Nat Gas 1.0000
NTRM Batches by Specie and Year

93 CO 0.1000 0.1000 0.2500

94 CO 0.0100 0.0250

95 CO 0.0010 0.0050 0.0250 0.0500 0.1000 0.2500

96 CO 0.0050 0.0100 0.0100 0.0250 0.1000 0.2500 0.5000 8.0000

97 CO 0.0025 0.0025 0.0050 0.0100 0.0250 0.0500 0.1000 0.1000 0.1000 2.0000

0.0050 0.0250 0.0500 0.1000

98 CO 0.0050 0.0050 0.0050 0.0100 0.0100 0.0100 0.0250 0.0250 0.0250 0.0500

0.0500 0.0500 0.1000 0.2500 0.5000 0.5000 7.0000

99 CO 0.0018 0.0025 0.0025 0.0100 0.0100 0.0250 0.0500 0.1000 0.2500 1.0000

2.0000 8.0000

1/2 2000 CO 0.0025 0.1000

93 CO2 2.5000 7.0000 14.0000

95 CO2 3.5000 5.0000 7.0000 14.0000 18.0000 20.0000

96 CO2 18.0000 22.0000

97 CO2 0.5000 0.5000 0.5000 1.0000 1.5000 2.0000 3.0000 4.0000 5.0000 7.0000

9.0000 11.0000 14.0000 14.0000 16.0000 18.0000 20.0000 20.0000 20.0000

98 CO2 4.0000 7.0000 14.0000 20.0000

99 CO2 0.1000 3.0000 3.0000 3.5000 5.0000 5.0000 7.0000 14.0000

1/2 2000 CO2 1.0000 2.0000 7.0000 18.0000 20.0000 23.0000
NTRM Batches by Specie and Year

93 NO 0.0500 0.1000 0.3000

94 NO 0.0050 0.0250 0.0500 0.1000

95 NO 0.0020 0.0020 0.0025 0.0050 0.0085 0.0100 0.0100 0.0175 0.0250 0.0250

0.0250 0.0250 0.0500 0.0500 0.0500 0.0625 0.0750 0.1000 0.1000 0.1000

0.1500 0.3000 0.3000

96 NO 0.0020 0.0050 0.0500 0.0875 0.1000 0.1000 0.1000 0.1500 0.3000

97 NO 0.0020 0.0100 0.1000 0.1000

98 NO 0.0050 0.0050 0.0100 0.0100 0.0100 0.0250 0.0500 0.0500 0.1000 0.1500

0.3000 0.3000 0.3000

99 NO 0.0050 0.0100 0.0250 0.0500 0.0500 0.0500 0.1000 0.1000 0.2800 0.3600

1/2 2000 NO 0.0050 0.0100 0.0250 0.0500 0.1000 0.1000

96 NOx 0.0100 0.0500

1/2 2000 NOx 0.0100

95 O2 2.0000 2.0000 10.0000 10.0000 21.0000 21.0000

96 O2 10.0000 20.0000

98 O2 2.0000 2.0000 4.5000 5.0000 7.0000 10.0000 10.0000 10.0000 10.0000 12.0000

15.0000 16.0000 21.0000 21.0000 21.0000 21.0000 21.0000 23.0000 23.0000 24.0000

99 O2 0.5000 2.0000 2.0000 12.0000 21.0000

1/2 2000 O2 2.0000 10.0000 21.0000 24.0000
NTRM Batches by Specie and Year

99 H2S 0.0025 0.0050 0.0100 0.0250

1/2 2000 H2S 0.0020 0.0025 0.0300

93 SO2 0.0050 0.0100 0.0260 0.0500 0.1000 0.1500 0.3500

94 SO2 0.0500

95 SO2 0.0050 0.0050 0.0100 0.0100 0.0175 0.0260 0.0375 0.0500 0.1000 0.1000 0.1250

0.1500 0.1500 0.2500 0.3000 0.3200 0.3500 0.3500

96 SO2 0.0500 0.0500 0.0500 0.0875 0.1000 0.1000 0.1000 0.2000 0.2800 0.3500 0.3500

97 SO2 0.0050 0.0100 0.0100 0.0100 0.0500 0.0500 0.1000 0.1500 0.1500 0.2500 0.2500

98 SO2 0.0050 0.0050 0.0100 0.0100 0.0100 0.0250 0.0250 0.0250 0.0500 0.0500 0.1000

0.1000 0.3500

99 SO2 0.0050 0.2500
Measurement of Bias

NTRM Mutiplication Factors

0

10

20

30

40

50

60

70

80

1% + 0.5-1% 0.2-0.5% 0.0-0.2%

Factor Distribution

Percent of Batches

93-95

96-97

98

99
Continuing Problems

• Straight thread valves

• NO mixtures for NO2

• Low NO mixtures

• NOx mixtures

• H2S mixtures

• Hydrocarbon mixtures

– Analyze BS using GC then homogeneity by GC or THCA

– Other hydrocarbons 

• NIST Primary Standards

• Sufficient standards for producer work
Standards for Producer Analysis

• SRMs

• In certification NTRMs

• PRMs from NMi

• GMIS

If standards other than SRMs or NTRMs are used then information 

detailing their preparation and verification will have to be 

supplied
NIST Gripes

• Analyses by Producers

– Many seem to be done in production facility rather than laboratory

– Some data resolution done to 1 part in 50 which is 2% whereas we would 

like to see work done to 0.2%

– Data reduction does not seem to be sufficiently reviewed 

– Reports are boiler plate rather than specific

– Report contents could be improved

• Producer Scheduling; planning ahead and sticking to plan 
Producer Gripes

• Turnaround time

• Scheduling and sticking to schedule

• Cylinder return

• Conflict resolution
Conflict Resolution

• Most of this results from disagreement between NIST and the producer 

on the analytical value of batch ie Factor “f” too large

• Past approach

– NIST would redo the analysis to double check their result

– This was frequently done at a later time because of slowness of NIST data 

evaluation

– NIST would inform Producer of problem only after 2nd analysis which 

could have been months after 1st analysis

• Current approach

– NIST reviews NIST data in real time

– Any re-analysis is done while instrumentation is still set up

– Producer is informed shortly after QA on NIST results

– If Producer works to resolve the problem then continues to work with them

– If Producer does not respond promptly then a report will be issued stating 

that the batch is not certified “at this time” but giving the Producer the option 

to resolve conflict and have the batch certified

– The cost of certification is charged by NIST regardless of outcome
Some Rejected Batches

• NO at 100ppm for high NO2

• NO at 50ppm for degradation with high NO2

• SO2at 50ppm for inhomogeneity

• NO at 20ppm and below for degradation

– To date the only batches of NTRMs that have not passed the recertification tests have been low level NO

• CO at 10ppm

– Producer said 0.3% spread in batch 

– NIST determined 3% spread

• NO submitted at 100ppm analyzed to be 500ppm

– Producer could not definitively explain
Uncertainties

• What are the requirements for U’s for NTRMs and SRMs?

• Are there regulations?

• Are there EPA requirements?

• Are U’s at 0.5% relative needed?

• Are U’s at 1% relative sufficiently good?

• Where are U’s incorporated in calculations?