Teflon-PFA vessels

MultiPREP rotors (Fig. 3.7) For high-throughput synthesis, Milestone offers a series of different parallel rotors for 36, 50 or 80 glass or Teflon-PFA vessels (35/50 mL) to perform reactions at atmospheric pressure up to 230 °C. 

Figure 3.9. In the oven cavity is a carousel (turntable or rotor) that can hold multiple extraction vessels. The carousel rotates 360° during extraction so that multiple samples can be processed simultaneously. The vessels and the caps are constructed of chemically inert and microwave transparent materials such as TFM (tetrafluoromethoxyl polymer) or polyetherimide. The inner liners and cover are made of Teflon PFA (perfluoroalkoxy). The vessels can hold at least 200 psi of pressure. Under elevated pressures, the temperature in the vessel is higher than the solvent s boiling point (see Table 3.11), and this enhances extraction efficiency. However, the high pressure and temperature may pose safety hazards. Moreover, the vessels need to be cooled down and depressurized after extraction.

Komarneni and coworkers [175] conducted a polyol reaction for the preparation of Pt and Ag nanopartides. The synthesis of the metal nanopartides [175] was conducted in a double-walled digestion vessel which has an inner liner and a cover made of Teflon PFA and an outer high-strength shell of Ultem polyetherimide. 

However, several articles in the area of microwave-assisted parallel synthesis have described irradiation of 96-well filter-bottom polypropylene plates in conventional household microwave ovens for high-throughput synthesis [16-19]. While some authors have not reported any difficulties associated with the use of such equipment [19], others have experienced problems in connection with the thermal instability of the polypropylene material itself [17] and with respect to the creation of temperature gradients between individual wells upon microwave heating [17, 18]. While Teflon (or similar materials such as PFA) can eliminate the problem of thermal stability, the issue of bottom-filtration reaction vessels has not yet been adequately addressed. 

Moderate to high temperature reactions can be carried out in vessels fabricated from inert materials such as PFA Teflon, PTFE or quartz. 

A system for the sampling and filtering of large quantities of surface seawater that is suitable for trace metal analysis is described in Ref. [35]. The water is brought aboard the ship via an all-Teflon pump and PFA tubing from a buoy deployed away from the vessel. The sample is delivered directly into a polycarbonate pressure reservoir and is subsequently filtered through a polycarbonate filter and in-line holder. 

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