New CH3CCl3 standards were prepared in 2001-2003 from new reagent material (99.8% purity).
The 1996 scale was based on standards made from reagent now known to
contain several impurities (approx 94% pure). The interim 2002 scale was based
on these new standards, but was not well-defined at mixing ratios less than 40 ppt.
The following table defines the 2003 scale. Two equations are used to convert the 1996
scale and the interim 2002 scale to the current 2003 scale.
CH3CCl3 calibration standards
updated: October 2003
	year	prepared	assigned	residual
		(ppt)	(ppt)	(ppt)
ALM-64608B	2001	99.1	99.5	0.4
ALM-65990A	2002	124.8	125.1	0.3
ALM-33800A	2002	104.0	102.7	-1.4
ALM-38422A	2002	187.2	187.1	-0.1
SX-3506	2002	76.7	76.6	-0.1
SX-3518	2003	20.7	20.6	0.0
SX-3519	2003	40.8	40.5	-0.2
SX-3522	2003	33.8	33.9	0.1
			std dev	0.58
Convert 2002 scale to 2003 scale
Y = -2.0022e-4*X^2 + 1.0402*X - 2.68
where X = conc (ppt) from 2002 scale
convert 1996 scale to 2003 scale
Y = -1.6120e-4*X^2 + 0.9654*X + 0.2
where X = conc (ppt) from 1996 scale