Silica dioxide, inert

Silica dioxide, inert, 107-108 Simplex optimization, 83-86,87 Sisomicin, 438-461... 

Silicas (mostly silicon dioxides) are low cost, inert, and very hard. 

Other metal carbonates behave similarly (i.e., the oxides are formed during the ashing procedure). The stable mineral quartz (silicon dioxide, silica, Si02) is the only major mineral found in coal that is inert during high-temperature ashing. 

In order to improve the separating performance of HPTLC pre-coated plates silica gel 60 even at larger applied volumes, as may be necessary at low sample concentrations, and with a rapid and simple technique of application, HPTLC pre-coated plates silica gel 60 with so-called "concentrating zones" were developed (10, 11, 12). This type of plate consists of two distinct layer sections, namely the separating layer proper consisting of silica gel 60 and a concentrating zone composed of an inert, porous silicon dioxide. These two sorbent materials pass into one another at a clearly defined boundary-line in such a way that the eluant is offered no resistance as it passes through. 

Among the transition metals, Pd, Pt, Ir, and Rh in various forms have been reported active in methanol synthesis (32-34), as noted in Section II. Palladium, platinum, and iridium metals were supported on silica, and it has recently been suggested that palladium is present in its valence state Pd(II) which is the active form of the catalyst (70). Under the synthesis conditions the Pd(II) ions could not survive the highly reducing atmosphere of the CO/H2 synthesis gas, and so this valence state would have to be induced by the presence of silicon dioxide. Should this be a general case, silica would not act merely as an inert support, and the silica-supported transition metals would have to be considered binary catalysts whose active state is formed by a support-metal interaction. ... 

All manipulations were carried out in Kel-F, Teflon FEP, or fused silica reaction vessels attached to a stainless steel or Monel fluorine-type vacuum system and/or in a Vacuum Atmospheres inert atmosphere Dri lab. Hexafluorobenzme, oclafluorotoluene, octafluoronaphthalene (PCR Inc., Gainesville, FL), sulfur dioxide, anhydrous hydrogen fluoride (Matheson, E. Rutherford, NJ), cesium fluoride (ROC/RIC, Sun Valley, CA), trifluoroacetic acid (Aldrich, Milwaukee, Wl), and tungsten hexafluoride, arsenic pentafluoride, and antimony pentafluoride (Ozark-Mahoning, Inc., Tulsa, OK) were used as received after their purity was checked by infrared spectroscopy. Dioxygenyl salts and rhenium and... 

Practitioners broke into two camps. One pursued the use of pure carbon dioxide with apparently more inert open tubular columns, while the other experimented with more polar binary and ternary mobile phases and continued to use silica-based packed columns. 

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