Silicon Carbide Well Plates Silicon carbide (SiC) is the perfect material to ensure temperature homogeneity in rectangular multiwell reactors in a microwave field. The high microwave absorbance and excellent heat conductivity of SiC allows even heating of nonpolar, hence low microwave-absorbing, solvents and reagents. Used either as reactor block for small glass vials or as reusable microtiter plate AntonPaar offers several types of SiC plates for Multiwave PRO. Introduction With the growing number of microwave instruments used in chemistry labs, performing microwavemediated reaction screening becomes of increasing interest. As many microwave-assisted reactions proceed favorably under high temperature/high pressure conditions it would be preferable to have identical conditions available already in the very first step of method development. Usually, most microwave-assisted reactions in sealed vessels are performed in a range up to 20bar and 250 C, according to the limits of the first generation of commercially available single-mode reactors. However, for reactions in a well plate format such conditions have not been applicable so far. This means parallel method optimization of valuable compounds could not be performed under identical microwave conditions as the sequential processes. Utilizing silicon carbide makes it possible for the first time to run micro-scale parallel reactions under sealed vessel conditions. It enables to employ a standard microtiter plate format in the same multimode microwave environment where compounds can be obtained up to the kg range as well. To attain effective reaction screening successfully, we utilize SiC microtiter plates with a convenient 68 matrix on a compact 8562.5mm footprint. Besides the standard plates with 400µL roundbottom wells (working volume 100-300µL) a variation with 200µL conical wells to operate smallest quantities (20-100 µl) are available. These microtiter plates are equipped with a unique, all-metal sealing mechanism to enable applications at elevated pressure (Fig. 1). A disposable PFA foil seals each well individually. This setup allows accessing reaction conditions up to 200 C and 20bar utilizing microtiter plates in a microwave environment. With the Rotor448MCWellPlate up to four of those units can be processed simultaneously resulting in a total of 192 reactions at a time. Serving Individual Needs With respect to individual requirements for combinatorial purpose as well as gram scale library generation well plates of different size and dimensions are available. The different types have been developed and optimized in close cooperation with industrial and academic partners. Fig.1 Well Plate 48MC400 with sealing assembly Page 1 of 5
Especially for small-scale reactions in forensic or biomedical applications well plates with a 54 matrix on a 8562.5 mm footprint are available. Contrary to the microtiter plates the Wellplate20MGC of Rotor4x20MGC is not meant for processing reactions directly in the SiC wells but employing standard HPLC/GC autosampler vials (1232mm), as shown in Fig.2. Utilizing such commercially available vials (reaction volume up to 1.5mL) prevents loss of sample in microscale reactions as the vials can be directly transferred to the corresponding autosampler racks of GC or HPLC analyzers. Fig.2 Wellplate 20MGC on rotor turntable Both variations, screw cap and crimp top vials, can be used in the SiC plate for reactions up to 8 bar. If higher pressures are required, an aluminum sealing mechanism identical to the one for the 68 microtiter plates can be applied to achieve tightness up to 20 bar (see Fig. 3). Fig.3 Sealed Wellplate 20MGC on rotor turntable For parallel method optimization and library generation well plates with a common 64 matrix on a standard ANSI footprint (12885mm) can be used. This Wellplate 24 utilizes standard Wheaton glass vials (1546 mm) (see Fig. 4). With a reaction volume of 0.3-3.0mL even gram amounts can be prepared in one vial. When employing four plates with Rotor 424MG5 focused libraries with up to 96 members can be prepared in a single run, being much more time effective than sequential processing in a single mode instrument. Fig.4 Wellplate 24 with screw-cap vials Originally, the Rotor 4x24MG5 is delivered with screw cap vials utilizing special manufactured PEEK screw caps (12 mm thread) with lip type seals for reactions up to 20 bar. Optional the SiC plates may be used with commercially available standard crimp top vials (13 mm crimp) for reactions up to 8 bar. Higher pressure is not applicable with those vials since the employed septa pop up at about 8 bar. Note: not any crimp top vials for Rotor4x20MGC or Rotor 4x24MG5 are supplied by Anton Paar, but have to be purchased from local sources. If required, even just single vials can be processed in both, Rotor 4x20MGC and Rotor4x24MG5. Since excessive microwave energy is absorbed by the silicon carbide there is no need to provide sufficient reagent load. Thus, identical methods like with monomode reactors can be applied, with the additional benefit to move on to parallel processing on demand. To perform a single reaction takes the same time as 20, 24, 80 or 96 reactions showing clearly the efficiency of such parallel systems. Benefits Inert and stable well plate material for unlimited reuse Utmost heat uniformity for a well plate format in the microwave field Efficient application of non-polar solvents under microwave irradiation Effective processing of smallest quantities in a multimode equipment Applying sealed plate systems at elevated pressure Various designs for different requirements available Page 2 of 5
Fields of Applications Parallel method development & optimization Catalyst screening Combinatorial chemistry Library generation Derivatizations in forensic investigations Proteomics Liquid phase protein hydrolysis The 68 well plates allow effective initial microwavemediated screening reactions in microtiter plate format under reaction conditions similar to other microwave equipment. This enables consecutive processing from micro-scale reactions up to molar amounts in one microwave system without changing of parameters. The 54 well plates can be applied with various kinds of HPLC/GC vials to process volumes from maximum 1.5mL down to 10µL per vial. This provides effective procedures for life science applications like derivatizations for forensic investigations within Rotor 4x20MGC. On the other hand the somewhat higher capacity of the Wheaton vials make Rotor 4x24MG5 with its 64 well plates a perfect tool for parallel method development and optimization in pharmaceutical and biomedical research. As silicon carbide interacts extremely well with microwaves even non-polar solvents and reagents can be applied effectively with all the different rotor types. Those materials will be heated not directly by microwave irradiation but by thermal convection from the hot SiC plate. Due to its high conductivity and excellent heat capacity the small volumes are uniformly heated as fast as by pure microwave heating itself. Thus, completely new pathways for performing microwave-mediated reactions can be investigated since a variety of solvents can be employed in one run under enhanced microwave conditions. As an additional benefit, all three configurations are based on the same rotor body. With the corresponding holders and sealing mechanisms the modular system allows upgrading and switching within the rotor types with ease. Scope and Limitations The used plate material is a sintered silicon carbide ceramic, which is extremely stable and inert over a wide temperature range. It can be heated by microwave irradiation to several hundred C easily. However, to avoid any deformation or melting of other materials used within the corresponding rotors the operation limit of all SiC rotor systems is 200 C. Employed in this temperature range, silicon carbide remains absolutely inert and does not interfere with the applied reagents. No cross contamination between the individual wells can be observed and the products are achieved in satisfactory purity. Since no active pressure sensing is present in any of the systems, the resulting pressure has to be calculated approximately according to the vapor pressure diagrams of the employed solvents. The rotor systems are tested up to 20bar and 200 C, up to these values the microtiter plates and glass vials remain tight and are safe to use Note: An applied temperature of 200 C would lead to pressures significantly higher than 20bar for some low boiling solvents like methanol or ethanol. When such solvents are used care has to be taken not to exceed the recommended limits (for details see D19IE019EN). Due to the excellent heat capacity of silicon carbide the temperature is identical within the whole plate (see Fig. 5). However, since the surface temperature is somewhat lower (approximately 10%) than the inside temperature this has to be considered upon method development. Thus, the maximum applicable IR limit is 180 C, corresponding nicely to a desired reaction temperature of 200 C. Fig.5 Uniform heat distribution in a SiC plate For a comprehensive discussion regarding application limits of various solvents and details on the estimation of an exact correlation factor C for the individual well plates refer to the corresponding product information D19IE019EN. Page 3 of 5
Summary of SiC Plate Specifications WP48 200 µl WP48 400 µl WP 20 WP 24 Size 8562.5mm 8562.5mm 8562.5mm 12885 mm Weight 258 g 218 g 258 g 592 g Well Matrix 68 68 54 64 Well Shape conical round bottom flat bottom flat bottom Vial a - - - - - - 1232 mm 1546 mm Volume min. 20 µl 100 µl 100 µl 300 µl Volume max. 100 µl 300 µl 1.5 ml 3.0 ml Temperature 200 C 200 C 200 C 200 C max. b Sealing Mechanism Pressure max. mandatory mandatory optional - - - 20 bar 20 bar 20 bar (8 bar) c 20 bar (8 bar) d Major application Combinatorial chemistry Reaction screening Forensics, Proteomics Parallel optimizations a Anton Paar only provides screw cap vials for Wellplate 20 and 24. Crimp top vials can be used, but have to be purchased from local suppliers. No warranty can be issued for vials from other sources than Anton Paar. b software-tolerated IR limit of 180 C corresponds to approx. 200 C internal temperature (see D19IE019EN) c 20 bar achievable with the all-aluminum sealing mechanism only d 20 bar achievable with the supplied Anton Paar screw caps only. Commercially available vial caps are tight just up to 8 bar Page 4 of 5
Ordering Information 41217 Wellplate 48MC assembled Complete well plate unit, comprising the aluminum sealing assembly, a 400 µl SiC well plate (41021) and one package of PFA sealing foils (41020). 41021 Well Plate 48MC Microtiter plate made of silicon carbide (SiC) with round bottom 400 µl wells in a 68 matrix. 81925 Wellplate 48MC200 Microtiter plate made of silicon carbide (SiC) with conical 200 µl wells in a 68 matrix. Note: no particular Mat.No. is applicable if a well plate assembly or a fully equipped Rotor448MC with Wellplate 48MC200 is required. In such a case, please denote on your order that Wellplate48MC200 (81925) should be delivered instead of Wellplate48MC (41021). 79110 Wellplate 24 SiC plate for vials MG5 (41214) with standard ANSI footprint (128x85mm) comprising appropriate wells in a 64 matrix. Fully equipped rotor systems: 40421 Rotor 448MC Wellplate Fully equipped rotor (baseplate and lid), comprising four sealable SiC microtiter well plates (41217), 40 PFA sealing foils (41020) and an Allen key for fixing the aluminum sealing assembly. 79114 Rotor 424MG5 Fully equipped rotor (baseplate and lid) with four Wellplate24 (79110), its corresponding holders (79112), a package of 200 disposable Wheaton glass vials (41214), 96 PEEK screw caps (41188) and 200 disposable PTFE seals (41186). 92283 Rotor 420MGC Fully equipped rotor (baseplate and lid) with four assembled Wellplate20MGC (92282), a package of 100 disposable 1.5mL HPLC/GC autosampler glass vials (1232mm) (92685) with PP screw cap and PTFE coated silicone seals (92734) and an Allen key for fixing the aluminum sealing assembly. 79112 Holder for Well Plate 24 Holder to place the SiC plate (79110) on the rotor baseplate. Four PEEK screws for proper adjustment on the turntable are included. 91160 Wellplate 20MGC SiC plate with compact footprint (8562.5mm) comprising appropriate wells in a 54 matrix for carrying standard HPLC/GC autosampler glass vials (1232mm). 92282 Wellplate 20MGC assembled Complete well plate unit, comprising an aluminum sealing assembly, and a Wellplate20MGC for standard HPLC/GC autosampler glass vials (1232mm). 41216 Rotor 448 (without Wellplate) Rotor turntable with corresponding protection lid, no other accessories included. Spare part for 40421, 79114, and 92283. Fig.6 Fully equipped systems: Rotor4x20MGC, Rotor4x24MG5, Rotor448MCWellPlate (left to right) Page 5 of 5