Reference Material (RM) 8785 Air Particulate Matter on Fil-ter Media is intended primarily for use in the evaluation of analytical methods used to characterize the carbon composition of atmospheric fine particulate matter (PM) for national air quality monitoring programs. This RM consists of a fine fraction (nominally <2.5 µm aerodynamic diameter) of standard reference material (SRM) 1649a Urban Dust resuspended in air and filtered onto quartz-fiber filters. RM 8785 will also provide the atmosphericchemistry and ocean-sciences communities with a means to intercompare methods and laboratories for the measurement of elemental (black) carbon. RM 8785 has values assigned for total carbon, elemental carbon, and organic carbon mass fractions measured according to two thermal-optical methods: the Interagency Monitoring of Protected Visual Environments (IMPROVE) and Speciation Trends Network-National Institute of Occupational Safety and Health (STN-NIOSH) protocols. Each filter is uniquely identified by its air particulate matter (APM) number and its gravimetrically determined mass of fine SRM 1649a. We will discuss the method used to produce RM 8785 and the results of an intermethod and interlaboratory comparison that provided assigned values for the above analytes.

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Abstract. For a drug with low bioavailability, a matrix tablet with liquid permeation enhancer (Labrasol®) was formulated. Factorial design was used to evaluate the effect of three formulation factors: drug percentage, polymer type (Methocel® K100M or Eudragit® L 100-55), and tablet binder percentage (Plasdone® S-630) on tablet characteristics. Tablets were prepared by direct compression and characterized. Compressibility index values ranged between 15.90% and 29.87% and tablet hardness values from 7.8 to 29.78 Kp. Eudragit®-containing formulations had better compressibility index values with higher tablet hardness. Time for 75% of drug release (T 75 ) was calculated, and formulations containing Eudragit® L 100-55 had faster release rates than tablet formulations with Methocel® K100M. Formulations with Methocel® K100M fit well in the Higuchi model as indicated by their R 2 values (>0.98). Among all the formulation factors studied, polymer type displayed the highest and statistically significant effect on compressibility index, tablet hardness, and dissolution rate. Statistical design helped in better understanding the effect of formulation factors on tablet characteristics important for designing formulations with desired characteristics.