1. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Subgroup Additional Pollutants Validation of N 2 O measurement

2. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP 4.1.4.9.1. A gas chromatograph with an electron-capture detector (GC–ECD) may be used to measure N 2 O concentrations of diluted exhaust by batch sampling from exhaust and ambient bags. Refer to §7.2. in this Annex. 4.1.4.10. Nitrous oxide (N 2 O) analysis with IR-absorption spectrometry (where applicable) The analyser shall be a laser infrared spectrometer defined as modulated high resolution narrow band infrared analyser. An NDIR or FTIR may also be used but water, CO and CO 2 interference must be taken into consideration. Methods for Measurement of N2O in GTR draft GC-ECD Laser infrared spectrometer NDIR FTIR

3. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Instrument availability and availability of data for evaluation Instrument manufacturers Data for validation GC-ECDseveralVP2/industry laser infrared spectrometer QCL Lasar Cavity ring down several 1 industry none NDIRseveralindustry FTIRseveralnone

4. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Performance criteria for N2O measurement 4.1.4.10.1. If the analyser shows interference to compounds present in the sample, this interference can be corrected. Analysers must have combined interference that is within 0.0 ± 0.1 ppm. Established by AP working group, not contained in GTR Interference correction contained in GTR

5. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP N2O vehicle emission results from VP2 Analyser: GC-ECD Lab: AECC Source: WLTP VP2

6. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP GC-ECD

7. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP main column pre column sample loop valve 2 valve 1 total flow backflu sh flow make up gas flow carrier gas filtration sampl e pump bachflush valve ECD Argon/Methan (95/5) N2 O2-doting Flow schematic of GC-ECD

8. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP LOD and LOQ of GC-ECD-Measurement Assuming background is constant the LOD can be estimated as equal or better 3 * STD and LOQ as 10 * STD STD = 0,00164 ppm LOD = 0,0049 ppm LOQ = 0,0164 ppm LOD and LOQ meet the requirements Source: Daimler

9. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Conclusions GC-ECD Systems are commercially available With proper application method is free of interferences (base line separation of N2O peak LOD and LOQ meet the requirements GC-ECD has proven to be a reliable method Results from VP2 Results from industry Chemistry lab and well trained personal required Complicated and time consuming sampling and analysis

10. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP laser infrared spectrometer (QCL)

11. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Correlation of GC-ECD and QCL GC-ECD and QCL show perfect correlation QCL measures approx. 3 % less Source: Daimler

12. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP LOD and LOQ exceed the requirements by far Measurement of pure N2 for 30 s LOD and LOQ derived from standard deviation Determination of LOD and LOQ for QCL Source: Daimler

13. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Interference QCL there is no interference from CO but a slight interference from CO2 (or water) can be observed no interference correction is applied the maximum interference requirement of +/- 0,1 ppm is met in all cases Source: Daimler

14. WLTP-DTP-AP Validation of N 2 O measurement Scatter of mass emission results (NEDC) results from all 6 correlation vehicles where within +/- 0,8 mg/km data pool: 128 emission test (NEDC) performed on 6 different vehicles (Euro 3/4/5) results from 3 different test cells test period: 6 month -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 Korr02Korr03Korr04Korr05Korr06Korr07Korr08 deviation to mean N2O [mg/km ] vehicle N2OGes. [mg/km] Source: Volkswagen

15. WLTP-DTP-AP Validation of N 2 O measurement ambient N2O concentration ambient N 2 O concentration is about 0,330 ppm on average all analysers are in excellent agreement (± 0,003 ppm) All mesrements are within +/- 0,015 ppm Source: Volkswagen

16. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Conclusions QCL Systems are commercially available Perfect correlation to GC-ECD LOD and LOQ exceed the requirements Slight interference from CO2/water but well within limits QCL has proven to be a reliable method various installations running without major problems stable operation over more than one year

17. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP laser infrared spectrometer (LASAR)

18. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Linearisation results LASAR The instrument is highly linear Source: SEMTECH

19. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Accuracy, repeatability and noise testing results LASAR Source: SEMTECH

20. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Interference LASAR Source: SEMTECH no interference from CO2, CO or water no inteference correction applied

21. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Conclusions LASAR System commercially available Perfect correlation to calibration gas LOD and LOQ exceed the requirements No interference from CO2/water or CO

22. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP NDIR

23. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Correlation not entirely satisfactory Deviation of NDIR to GC of up to 25 % Interference correction has large influence on NDIR results Correlation of GC-ECD and NDIR Source: Daimler

24. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Even with interference correction in place the maximum interference requirement of +/- 0,1 ppm is not met in all cases Interference correction NDIR Source: Daimler

25. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Conclusions NDIR Systems are commercially available correlation to GC-ECD not entirely satisfactory Pronounced interferences from CO2/water and CO require interference correction. For the NDIR investigated the combined interference did not fulfill the requirements, even when interference correction was applied with great care. NDIR is a comparatively inexpensive analyser. For the analysis of N2O it has to be operated at its limits.

26. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP FTIR

27. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Linearity FTIR Linearity requirements are met Source: BMW

28. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP Conclusions FTIR Systems are commercially available LOQ ~ 300ppb ambient air level with typically 30 sec integration time Cross interference CO within LOD 100ppb (optimized spectral method) Cross interference CO2/H2O (optimized spectral method): N2O in 3 rd bag FTP diluted exhaust typically at ambient air level for petrol vehicles with CO2 ~ 1Vol% and H2O ~1Vol%  cross interference below LOD Linearity requirements comparable to other analyzers are met  Analyzer capable to meet legal requirements with increased integration time

29. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP The California ARB has published a procedure for N2O emission measurement with FTIR

30. WLTP-DTP-AP Validation of N 2 O measurement WLTP-DTP-AP The methods to measure N2O as described in GTR draft have proven to be sufficiently accurate and robust Systems are commercially available from several instrument manufacturers General conclusions