PT  - JOURNAL ARTICLE
AU  - Robert Caldow
AU  - James Blesener
TI  - A Procedure to Verify the Lower Counting Limit of Optical Particle Counters
DP  - 1989 Jul 01
TA  - PDA Journal of Pharmaceutical Science and Technology
PG  - 174--179
VI  - 43
IP  - 4
4099  - http://journal.pda.org/content/43/4/174.short
4100  - http://journal.pda.org/content/43/4/174.full
SO  - PDA J Pharm Sci Technol1989 Jul 01; 43
AB  - A procedure has been developed to verify the particle counter lower counting limit (LCL) specified by the manufacturer for a laser particle counter (LPC). The procedure uses existing commercially available products to confirm an LPC lower size counting limit. The procedure involves the use of NBS traceable polystyrene latex (PSL) particles and an electrostatic classifier to generate highly monodisperse (single size) particles near the lower size limit of the LPC. A condensation nucleus counter (CNC) is used as a standard for particle concentration, since its lower size limit is far below the LPC’s. By comparing the LPC concentration with that of the CNC, the lower counting limit of the LPC can be verified. This is especially well suited for certifying that pharmaceutical and electronics clean room counters are operating according to manufacturer specifications. The method is unique in that it specifies the LCL as an efficiency curve rather than as a single efficiency point.