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FLORISIL [Trade Mark Registered: U.S. Silica Company. Produced under US Patent No. 2.393.625.]

FLORISIL is a Brand Name of synthetic magnesium silicate. FLORISIL, including specific grades and preparations, has been widely accepted in the separation and isolation of a variety of compounds, and is cited in many analytical methods, including those of the US CDC, US EPA, US FDA, JAP MHLW (ENV), AOAC, etc [add ref]. The reference to these grades, as used in analytical methods, is *not* an indication that the specific grade is made or analyzed as directed by the original manufacturer, U.S. Silica. Many suppliers have prepared or purchased magnesium silicate from other sources, and they continue to cite the grades as preferred by the analytical methods. This is used to shortcut the substitution within analytical methods that may cite the name FLORISIL, while they actually utilize an 'equivalent' or 'similarly performing' product [pers exp, refs]. FLORISIL A grade [U.S. Silica] FLORIDIL PR grade [U.S. Silica] FLORISIL TLC grade [U.S. Silica] FLORISIL 'Reagent' grade [ ] FLORISIL 'Analytical' grade [ ] FLORISIL 'Standard' grade [ ] FLORISIL 'Residue Analysis' grade [ ]

Typical Chemical Composition [On a volatile free basis]: MgO 15.5 +/- 0.5% SiO2 84.0 +/- 0.5% Na2SO4 0.5 avg (1.0% max) [ref U.S. Silica Co] Typical Physical Properties: Color White pH 8.5 Surface Area m2/g (BET) 298 Specific Gravity 2.51 Surface Acidity, pKa ~ 1.5 Voids, % 26 Pores, % 56 Bulk Density 29 Lb/ft3

Activation Temperatures: Normal 650 deg C Less Active  260 deg C

FLORISIL PR grade: 60/100 mesh activated per Mills, P.A., Jour Assoc Official Anal Chem, 51:29-32 (1968, Jan) "Variation of FLORISIL activity: Simple Method for Measuring Adsorbent Capacity and its use in standardizing FLORISIL columns."

FLORISIL TLC grade: 16/30 mesh contains 4% gypsum binder, no indicator.