Air: 1
Con 2-5

for ppm = a*ratio^b:

Gas    | a       | b
Methane_1| 1.1086  | -0.0448
Methane_2| 0.9867  | -0.0105
Methane_3| 1.097   | -0.0335
Methane_4| 1.0513  | -0.0261
Methane_5| 1.1424  | -0.0381
Methane_6| 2.2563  | -0.1231
IsoButane_1| 1.0725  | -0.0786
IsoButane_2| 1.5342  | -0.1838
IsoButane_3| 1.8529  | -0.2248
IsoButane_4| 3.1315  | -0.3168
IsoButane_5| 4.8725  | -0.3808
IsoButane_6| 4.0796  | -0.3586
CO_1   | 1.4117  | -0.2244
CO_2   | 2.2176  | -0.3572
CO_3   | 2.7757  | -0.406 
CO_4   | 5.0696  | -0.5116
CO_5   | 5.2111  | -0.5156
CO_6   | 3.0264  | -0.4477
Ethanol_1| 1.6105  | -0.3138
Ethanol_2| 3.0468  | -0.5012
Ethanol_3| 6.1074  | -0.6522
Ethanol_4| 6.3217  | -0.6583
Ethanol_5| 1.2629  | -0.4251
Ethanol_6| 1.0192  | -0.3983
Hydrogen_1| 1.5579  | -0.3691
Hydrogen_2| 2.6156  | -0.5214
Hydrogen_3| 2.2189  | -0.4857
Hydrogen_4| 3.5841  | -0.5698
Hydrogen_5| 0.5806  | -0.3063
Hydrogen_6| 0.2205  | -0.1853

for ppm = 10^[(log10(ratio)-b)/m]:

Gas    | m       | b
Methane_1| -0.0448 | 0.0448 
Methane_2| -0.0105 | -0.0058
Methane_3| -0.0335 | 0.0402 
Methane_4| -0.0261 | 0.0217 
Methane_5| -0.0381 | 0.0578 
Methane_6| -0.1231 | 0.3534 
IsoButane_1| -0.0786 | 0.0304 
IsoButane_2| -0.1838 | 0.1859 
IsoButane_3| -0.2248 | 0.2679 
IsoButane_4| -0.3168 | 0.4958 
IsoButane_5| -0.3808 | 0.6878 
IsoButane_6| -0.3586 | 0.6106 
CO_1   | -0.2244 | 0.1498 
CO_2   | -0.3572 | 0.3459 
CO_3   | -0.406  | 0.4434 
CO_4   | -0.5116 | 0.705  
CO_5   | -0.5156 | 0.7169 
CO_6   | -0.4477 | 0.4809 
Ethanol_1| -0.3138 | 0.207  
Ethanol_2| -0.5012 | 0.4838 
Ethanol_3| -0.6522 | 0.7859 
Ethanol_4| -0.6583 | 0.8008 
Ethanol_5| -0.4251 | 0.1014 
Ethanol_6| -0.3983 | 0.0083 
Hydrogen_1| -0.3691 | 0.1925 
Hydrogen_2| -0.5214 | 0.4176 
Hydrogen_3| -0.4857 | 0.3461 
Hydrogen_4| -0.5698 | 0.5544 
Hydrogen_5| -0.3063 | -0.2361
Hydrogen_6| -0.1853 | -0.6566

Methane
10, 1
30, 0.952
100, 0.94
300, 0,906
1000, 0.878
3000, 0.842
10000, 0.726

[(10, 1), (30, 0.952), (100, 0.94), (300, 0.906), (1000, 0.878), (3000, 0.842), (10000, 0.726)]

Methane_1: [(10, 1), (30, 0.952)]
Methane_2: [(30, 0.952), (100, 0.94)]
Methane_3: [(100, 0.94), (300, 0.906)]
Methane_4: [(300, 0.906), (1000, 0.878)]
Methane_5: [(1000, 0.878), (3000, 0.842)]
Methane_6: [(3000, 0.842), (10000, 0.726)]

IsoButane
10, 0.895
30, 0.821
100, 0.658
300, 0.514
1000, 0.351
3000, 0.231
10000, 0.15

[(10, 0.895), (30, 0.821), (100, 0.658), (300, 0.514), (1000, 0.351), (3000, 0.231), (10000, 0.15)]

IsoButane_1: [(10, 0.895), (30, 0.821)]
IsoButane_2: [(30, 0.821), (100, 0.658)]
IsoButane_3: [(100, 0.658), (300, 0.514)]
IsoButane_4: [(300, 0.514), (1000, 0.351)]
IsoButane_5: [(1000, 0.351), (3000, 0.231)]
IsoButane_6: [(3000, 0.231), (10000, 0.15)]

CO
10, 0.842
30, 0.658
100, 0.428
300, 0.274
1000, 0.148
3000, 0.084
10000, 0.049

[(10, 0.842), (30, 0.658), (100, 0.428), (300, 0.274), (1000, 0.148), (3000, 0.084), (10000, 0.049)]

CO_1: [(10, 0.842), (30, 0.658)]
CO_2: [(30, 0.658), (100, 0.428)]
CO_3: [(100, 0.428), (300, 0.274)]
CO_4: [(300, 0.274), (1000, 0.148)]
CO_5: [(1000, 0.148), (3000, 0.084)]
CO_6: [(3000, 0.084), (10000, 0.049)]

Ethanol
10, 0.782
30, 0.554
100 0.303
300, 0.148
1000, 0.067
3000, 0.042
10000, 0.026

[(10, 0.782), (30, 0.554), (100, 0.303), (300, 0.148), (1000, 0.067), (3000, 0.042), (10000, 0.026)]

Ethanol_1: [(10, 0.782), (30, 0.554)]
Ethanol_2: [(30, 0.554), (100, 0.303)]
Ethanol_3: [(100, 0.303), (300, 0.148)]
Ethanol_4: [(300, 0.148), (1000, 0.067)]
Ethanol_5: [(1000, 0.067), (3000, 0.042)]
Ethanol_6: [(3000, 0.042), (10000, 0.026)]

Hydrogen
10, 0.666
30, 0.444
100, 0.237
300, 0.139
1000, 0.07
3000, 0.05
10000, 0.04

[(10, 0.666), (30, 0.444), (100, 0.237), (300, 0.139), (1000, 0.07), (3000, 0.05), (10000, 0.04)]

Hydrogen_1: [(10, 0.666), (30, 0.444)]
Hydrogen_2: [(30, 0.444), (100, 0.237)]
Hydrogen_3: [(100, 0.237), (300, 0.139)]
Hydrogen_4: [(300, 0.139), (1000, 0.07)]
Hydrogen_5: [(1000, 0.07), (3000, 0.05)]
Hydrogen_6: [(3000, 0.05), (10000, 0.04)]