Table 2.

Relative uncertainty components for the LO determination of microsphere number concentration N.

Uncertainty component
Type A relative standard uncertainty	0.3 %
Type B components
Single/multiple microsphere variation	0.5 %
Undersizing of microspheres	0.5 %
Transfer and handling	0.5 %
Pump calibration	0.04 %
Total Type B relative standard uncertainty	0.9 %
Combined relative standard uncertainty	0.9 %
Effective degrees of freedom	11
Coverage factor for 95 % confidence level	2.2
Expanded relative uncertainty (k = 2)	1.8 %
Expanded relative uncertainty (95 % confidence level)	2.0 %