The CFC-11 scale was updated in 2016. An update was needed because existing primary standards dated to 1992 and some were showing signs of contamination. The following equation can be used to convert from the X1993 scale to the current X2016 scale.

Y = -1.7948e-6*X3 +7.4134e-4*X2 + 0.89385*X + 6.54

Where: Y=value on X2016, and X=value on X1993 (pmol/mol, or ppt)

CFC-11 calibration standards X2016 scale
updated: July, 2016
year prepared ppt assigned ppt residual ppt
SX3585 2015 230.15 230.13 -0.02
SX3586 2015 258.93 259.07 0.14
ALMX067946 2016 171.27 171.33 0.06
ALM067687 2015 201.61 201.56 -0.05
ALM026729 2016 100.84 100.82 -0.02