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USP particle count set: New lot comes with tighter values

The United States Pharmacopoeia (USP) has now launched a new batch for the USP particle count set (L0L142). Important: This new lot has narrower limits than the previous lot (K0H089) which remains valid until 01/2014!

While the values for the previous lot range between 2860 and 4617 counts/mL for the counts at 10µm and between 1.102 and 3.149 for the ratio of 10µm and 15µm, the values of the new lot run between 3330 and 4110 counts/mL for the counts at 10µm and between 1.78 and 2.57 for the ratio of 10µm and 15µm.

The new lot has been determined in a collaborative study with at least 10 laboratories and the specifications have been determined statistically. Determination of particulate matter

In the USP chapter “<788> Particulate Matter in Injections” two methods are described to determine the size of particles and the number of particles according to their size.

For the first method – Light Obscuration Particle Count Test – the USP particle count set can be used to show system suitability. The sections on instrument standardisation have been excluded from the harmonized chapter “<788>” and are now summarized in chapter “<1788> Methods for the Determination of Particulate Matter in Injections and Ophthalmic Solutions”.

One of the instrument standardisation tests is the “particle counting accuracy – system suitability”, where several methods are described. In method 1 for MWHC (moving window half-count) instruments and 2 for multichannel instruments, the USP particle count set is used. To meet the requirements for particle counting accuracy the user has to show that the count of particles ≥10µm and (not for the second method) the ratio of counts ≥10µm to ≥15µm meet the values of the USP particle count set.

Do you have any questions regarding the USP particle count set? We are here to help! Simply email us at askus@lgcpharma.com. picture: dreamstime

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