## Appendix A
** \\ \hline \multicolumn{9}{c}{FTIR measuring cylinder} \\
2010 & MKS MultiGGas 2030 & 3.5\% & - & - & 4000 ppm & 1 & & [95] \\
2010 & AVL Sesam & - & 1.00 & - & 4000 ppm & 14 & & [159] \\
2000 & _P.Nucled_ & - & 0.95 & 1.00 & 0-3 ppm & 5-10 & & [178] \\
2000 & _P.Nucled_ & -21\% and 1.1\% & - & - & 3 ppm & 2 & Mix (CO\({}_{2}\) H\({}_{2}\)O) & [178] \\
2000 & _P.Nucled_ & -12\% and 1.1\% & - & - & 1.10 ppm & 5 & [86] \\
2000 & _P.Nucled_ & -10\% & - & - & 1451 ppm & 1 & [110] \\
2005 & _P.T.T.Gant General CR2000_ & 0.3\% & - & - & 1451 ppm & 1 & [110] \\ \hline \multicolumn{9}{c}{Both FITR and reference connected at the dilution tunnel} \\
1990 & Nicolet Sesam & \(-\)5.2\% & - & - & 0.5-1 g/m & means & G, D\(\alpha\) & [163] \\
1990 & Mattoon Horibus & - & 0.95 & 0.94 & 0-5 ppm & 25 & G, Refs [112] \\
1991 & Bio-Rad Digh FTS-60 & - & 0.93 & 0.89 & 0.40 ppm & 20 & Many G, fuels [169] \\
1993 & Mattoon REA & \(4\%\)\(\%\)\(\%\)\(\%\)\(\%\) & 1.04 & 0.78 & 0-100 ppm & 368 & 2.5 y G, CNG & [170] \\
1993 & Nicolet REA & \(32\%\)\(\%\)\(\%\)\(\%\) & 1.36 & 0.97 & 0-100 ppm & 217 & 2.5 y G, CNG & [170] \\
1994 & Nicolet REA & \(6.6\%\)\(\%\)\(\%\)\(\%\)\(\%\)\(\%\) & 1.06 & 1.00 & +14 ppm & 12 & 6 & [146] \\
1994 & Nicolet REA & 1.0\% & - & - & 3 ppm & 1 & G, Refl M8S & [171] \\
2015 & AVL Sesam & 1.3\%\(\%\)\(\%\)\(\%\) & - & - & 40-8 ppm & 2 & D\(\alpha\) & [140] \\
2000 & _P.Nucled Perdige 460_ & 0.5\% & - & - & 0.5-3 ppm & 2 & G & [86] \\ \hline \multicolumn{9}{c}{Both FITR and reference connected at the dilution tunnel} \\
1990 & Nicolet Sesam & 8.0\% & - & - & 0.5-1 g/m & means & G, D\(\alpha\) & [163] \\
1996 & Nicolet REA & \(700\)\(\%\)\(\%\)\(\%\) & - & - & 0.400 ppm & cycle & G & [90] \\
2010 & AvL Sesam & 5\% & - & 1.00 & 8-29 k/m & 25 & G, Refs [123] \\
2010 & Nicolet Magna 560 & 5.4\% (3\%\)\(\%\)\(\%\)\(\%\) & - & - & 20-100 ppm & 4 & CNG + NO\({}_{2}\) injection & [142] \\
2016 & Not disclosed & -5\% & - & - & 300-100 ppm & steady & D & [200] \\
2018 & AVL Sesam (MKS) & - & 1.03 & 1.00 & 0-600 ppm & 600 & various & [141] \\
2018 & AVL Sesam & 4\% (\%\)\(\%\)\(\%\) & - & - & 50-1200 mg/m & 22 & D & [61] \\
2000 & _P.Nucled_ & 5\% & - & - & 0-7 ppm & cycle & G & [178] \\
2005 & _P.T.T.T.Gant General CR2000_ & 13\% & - & - & 70 ppm & 1 & engine & [110] \\
2005 & _P.T.T.Gant General CR2000_ & -30\% & - & - & 1.9 g/m & 1 & G & [110] \\
2006 & _P.T.T.Gant General CR2000_ & 1.05 & 0.94 & 0-800 ppm & cycle & G & [163] \\
2017 & _P. MIDAC1-series_ 2 & - & 1.09 & 0.99 & 0-400 ppm & cycle & D & [201] \\
2020 & _P.P. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline
**Year** & **Instrument\({}^{1}\)** & **Difference** & **Slope** & **R\({}^{2}\)** & **Range** & **Points** & **Comment** & **Ref.** \\ \hline
2015 & AVL Sesam & \(-8.8\%\)...30\% & - & - & 190-301 ppm & 4 & D & [140] \\
2018 & AVL Sesam & \(11\%\) (\(\pm\)10\%) & - & - & 50-1200 mg/km & 22 & D & [61] \\
2020 & AVL Sesam & - & 0.94 & 0.79 & 0-350 mg/km & 9 & D & [198] \\
2017 & Gasnet CR2000 & - & 0.79 & 0.99 & 10-1200 mg/km & 12 & Dx2, GZ, CNC & [197] \\
2006 & _P: Toral Gamet CR2000_ & 3.6\% (2.7\%...4\%) & - & - & 02.0-3.6\%/km & 11 & G & [163] \\
2007 & _P: Nucled_ & - & 1.02 & 0.96 & 5-40 mg/mi & 8 & G4 & [92] \\
2018 & _P: Nucled Analysis ICS_ & 32\% (\(-22\%...117\%\)) & 1.21 & 0.92 & 5-650 mg/km & 18 & D, CNG & [98] \\ \hline \multicolumn{10}{c}{\({}^{1}\)_P: portable (in italic). \({}^{2}\)_Comparison on the road with PKSs.} \\ \end{tabular}
\end{table} 
Table 4: Comparisons of FTIR with NRD analyzers (FTIR, QCL, LIDS).