Spinning Up To Speed: A Profile of Nonrefrigerated Microcentrifuges

Date: January 19, 1998 Chart 1 Chart 2 Chart 3 They sometimes go by different names. Be it an "air-cooled," "ambient," "ventilated," or "nonrefrigerated" model, they are all the same thing: a microcentrifuge that gets cold only in the cold room. Useful and popular, there are plenty of nonrefrigerated microcentrifuges to choose from across a spectrum of styles, features,, and prices. LabConsumer contacted 19 manufacturers and dealers of nearly 50 nonrefrigerated microcentrifuges in compiling data for this profile. With the exception of a handful of centrifuges, the most common maximum speeds range between 12,000 and 15,000 rpm. Two machines, the MIKRO 24-48 and the EBA 12, both products of Andreas Hettich GmbH & Co KG, run at speeds up to 18,000 rpm. The MIKRO 24-48 also cranks out the highest maximum g-force seen in the profile of 27,100 xg. Otherwise, g-forces fall most often between 11,000 to 18,000 xg, with values around 16,000 xg being most common. Most of the machines are variable-speed instruments, and about half feature a pulse run function for quick spin operations. Controls run from simple on/off timer, and speed knobs to microprocessor controller button panels with digital LED displays and a host of options. These include variable speed pulse runs with timing, selectable acceleration and deceleration rates, and RCF display and run modes, to name a few. Of course, greater complexity in the control parameters results in higher prices. The majority of the microcentrifuges profiled run interchangeable rotors in fixed-angle, swing-out, horizontal, drum, and hematocrit tube configurations. Most rotors are constructed of aluminum or polypropylene, but other materials are also used. Rotor capacities run from 6 to 80 places for 1.5 to 2.0 ml tubes, and up to 160 places for 0.5 ml tubes. Rotors designed for specific tube sizes, such as those offered by Jouan and Astel Enterprises, are available, but adapters and reduction sleeves are more frequently offered accessories. Surprisingly, only about one-third of the companies mentioned aerosol containment as a feature of their centrifuges or rotors. Of those that did, most rely on sealed rotor lids for protection from contamination by radioactive and pathogenic samples. Particularly noteworthy is the Eppendorf line of centrifuges distributed by Brinkmann Instruments. Not only does Eppendorf use aerosol-tight rotors, but it also provides double aerosol protection with aerosol-tight capsules that fit inside these rotors. Two other companies, Shelton Scientific Manufacturing, Inc. and Sorvall, have designed their centrifuges with disposable plastic chamber liners to simplify decontamination efforts. The manufacturers either sell their microcentrifuges with a rotor as part of the package or offer it as a separate item. In the latter case, the additional purchase of a rotor adds $80 to $800 to the purchase price of an instrument. Generally, rotors average around $250. Most laboratory personnel probably identify with being chased out of the lab by a loud, screaming microcentrifuge. Fortunately, advances in microcentrifuge construction and the use of brushless drive motor technology have reduced noise to more comfortable levels. Those manufacturers that reveal noise level measurements report values between 54 and 64 decibels. For comparison, ordinary conversation and the background noise in a small office environment produce about 60 decibels, a vacuum cleaner generates 80, and a jet plane taking off at close range runs about 140. Because of a lack of standardized noise measurement procedures, however, some controversy surrounds the accuracy of noise level measurements and their use for comparing centrifuges. Below are profiles of 19 companies and their many different nonrefrigerated microcentrifuges. Accurate Chemical and Scientific Corporation KOALA-TY Saturn Micro24 The KOALA-TY Saturn Micro24 microcentrifuge runs at one of two preset speed settings, a unique feature in this profile, since most machines feature a variable speed setting or a single maximum speed. The rigid steel cabinet and high strength steel safety chamber offer rotor containment throughout the operating range of the instrument. Suitable for use in a cold room, the Micro24 offers one of the highest g-forces in the profile for instruments priced under $1,000; however, the 24-place rotor tacks an extra $200 onto the price when purchased with the basic unit. Adapters are available to fit 0.5-0.75 ml, 0.25 ml, 0.4 ml, and 0.2 ml tubes. Astel Enterprises, Inc. ALC Micro Centrifugette 4204, 4214 The ALC Centrifugette series of compact centrifuges offered by Astel Enterprises includes two microcentrifuges: the Centrifugette Model 4204 and the Model 4214. The Centrifugette 4214 is a variable-speed machine whereas the 4204 is a fixed-speed device. Both are touted as whisper quiet and cool running and feature a 15-minute timer with a hold function for continuous spins. Both Centrifugettes run a set of four interchangeable fixed-angle rotors designed to accommodate at least ten different styles of microtubes. B. Braun Biotech Sigma 1-13, 1-15 B. Braun Biotech introduced two new nonrefrigerated microcentrifuges in December 1997. The Sigma 1-13 has a small footprint and propels a large complement of rotors with a maintenance-free brushless drive. Eight rotors designed for microfuge tubes, including both fixed-angle and swing-out models, comprise the rotor complement for the Sigma 1-13, along with an additional hematocrit rotor. The Sigma 1-15 drives a 24-place, polypropylene angle rotor with a brushless drive motor. Its advanced display allows the selection of speed, RCF, and run time. Adapters fitting the 24-place rotor accommodate 0.4/0.25 ml and 0.75/0.5 ml tubes. Beckman Instruments MicrofugeTM Lite Personal Microcentrifuge True to its name, Beckman's Microfuge Lite Personal Microcentrifuge weighs in at only 9.2 pounds (4.2 kg) and features one of the smaller footprints in the profile. Shipped complete with a versatile fixed-angle rotor, the Microfuge Lite spins up to 13,000 rpm, generating a maximum 12,054 xg. Control knobs permit the selection of variable speed and time settings up to 13,000 rpm and 15 minutes, respectively. The start/stop button also acts as a pulse button for momentary operation. Bel-Art Products Scienceware® MiniCentrifuge Billed as a personal centrifuge, the Scienceware Mini-Centrifuge from Bel-Art quietly spins an autoclavable, 8-place polypropylene rotor at 3,000 rpm and 750 xg. Fitting easily at an individual workstation, the Mini-Centrifuge's 23 cm diameter clear plastic rotor chamber also functions as a shield for protection from radiation. Useful for pelleting bacteria and cons olidating micro samples for enzyme reactions, the Mini-Centrifuge's controls consist of a single power switch/speed control knob and solid-state electronics. An optional safety lid for the chamber is available. Brinkmann Instruments Inc. Eppendorf Micro CentrifugeModel 5410, Model 5415C, Model 5417C Although available from several laboratory suppliers, the Ependorf line of microcentrifuges is most frequently associated with Brinkmann Instruments. The Eppendorf microcentrifuge Model 5410 is a fixed-speed instrument that accelerates to maximum speed in less than 10 seconds. The 5410 features a quick spin function and hold button. The rotor accepts adapters for smaller tubes and runs four of Eppendorf's aerosol-tight, autoclavable capsules that hold an individual microfuge tube for containment of hazardous materials such as TB, HIV, and 32P. The Eppendorf Micro Centrifuge Model 5415C accepts three interchangeable fixed-angle rotors with lids and runs at variable speeds with a maximum time of 30 minutes. The Model 5417C Micro Centrifuge has been built around a variable-speed, maintenance-free brushless motor. Its other features include speed setting and display in either rpm or RCF modes, an adjustable-speed pulse button for quick spins, a soft start/s top function to protect delicate samples, and an RS-232 interface. The 5417C runs a choice of four autoclavable rotors with lids: a fixed-angle rotor, an aerosol-tight fixed-angle rotor, an aerosol-tight rotor that also holds 12 aerosol-tight capsules f or double aerosol protection, and a swinging bucket rotor. Unlike the Model 5410 and 5415C instruments, however, the Model 5417C is sold without a rotor. Denver Instrument Company COMPAC Microcentrifuges: Micro 6, Micro 7, Micro 12, Micro 14 The Denver Instrument Company manufactures its COMPAC Microcentrifuges for Fisher Scientific. The COMPAC line consists of four models, distinguished by maximum operating speeds and g-forces, all sharing the same set of features and benefits. Highlights for these quiet machines include a die-cast aluminum rotor shield, internal double bolt latching mechanism, simple "snap on rotor" installation, digital display of speed in rpm or g-force values, digital display of time, an rpm feedback loop to maintai n the set speed, and electronic braking. At only 11 cm tall, the COMPAC Microcentrifuges need only a small amount of bench space for their 19 x 18 cm footprints and weigh in between 1.0 and 1.8 kilograms. Standard accessories for the Micro 6 and 7 incl ude two rotors, two aerosol seals, and a power pack; for the Micro-12 and 14, three rotors, three aerosol seals, and a power pack. Fisher Scientific Marathon Micro H, A,16KM The star runner of the Marathon team of microcentrifuges is the Marathon 16KM, its quiet, brushless motor hustling up to maximum speed in 10 seconds. The standard rotor provides aerosol containment with a see-through plastic lid and O-ring seal. In the event of a broken tube, the entire rotor is autoclavable without being opened. Microprocessor controlled, the Marathon 16KM also features bright LED displays for speed/g-force and time and a short-spin function that displays the run time in seconds on the LED. The electronic circuitry has been waterproofed for dependable cold room performance. The Marathon Micro H and Micro A, similar in size and appearance to the 16KM, are the 16KM's slower and simpler teammates. The Micro A isequipped with the same standard rotor as the 16KM, whereas the Micro H features a horizontal rotor. On all three instruments, speed and time are set by turning knobs. A third, larger capacity 40-place rotor is also available for the Marathon microcentrifuges. Heraeus Instruments, Inc. Biofuge Pico, vito and 15 Billed as the "Smaller, Quieter, Quicker Microcentrifuge," the variable speed Biofuge Pico is capable of rapid acceleration and deceleration rates and pulse-run operations. Its ergonomic design features a beveled front panel and keypad controller with easily identifiable icons and LED displays for speed and run time. The microprocessor maintains parameter settings in the memory until new ones are entered and is equipped with a digital self-diagnostic function that displays a message if a problem is detected. The Biofuge vito is unique in that it fits under the bench in a drawer unit, offering improved access to the rotor for sample loading and additional noise reduction. The slanted keyboard features a clear arrangement of keys marked with symbols that are easy to read. At the completion of a run, one movement opens the Biofuge vito, which is accessible from both sides. The microprocessor-controlled Biofuge 15 features LED displays for speed, run time, and RCF settings. Its quick-run function makes for convenient brief spins and the soft-start/soft-brake functions allow for gentle centrifugation and controlled braking of delicate samples. A lid lock, rotor imbalance cut-off, and self-diagnostic function with an error code display ability round out the Biofuge 15's safety features. The Biofuge 15 runs a hermetically sealed aluminum angle rotor for aerosol containment of radioactive and pathogenic samples. Heraeus Instruments' Biofuge series of microcentrifuges is backed by a two-year parts and labor warranty. Hermle/National Labnet Z 180 M, Z 200 M/H, Z 233 M-2 Hermle manufactures three nonrefrigerated microcentrifuges that are distributed by National Labnet. The Z 180 M is sold complete with either an 18-place or a 24-place angle rotor. Equipped with a transparent cover, both rotors accept a variety of tubes, including those with screw caps and skirted bottoms. Analog control knobs allow the accurate selection of speed and run times. A quick-run button does not override the speed control so that quick runs can be performed at preselected speeds. The Z 180 M has been designed for safe operation in a cold room or refrigerator and features maximum acceleration and deceleration times of 12 and 13 seconds, respectively. A unique version of the Z 180 M, the Z 180 HLA, comes complete with a 12-place swing-out rotor. Featuring microprocessor control, a momentary button for short spins with time display in seconds, a continous-run function, and a rotor imbalance indication with safety cut-off, the Z 200 M/H has a quiet, brushless induction drive. The minimum speed setting is 250 rpm with increases in 250 rpm increments, and a digital display shows the set and actual speed along with remaining run time. Hermle has upgraded its Z 233 M microcentrifuge into the new Z 233 M-2 microcentrifuge while maintaining the same list price. Spinning faster and stronger, the Z 233 M-2 runs one of five angle rotors. Built around a quiet, brushless induction drive, the Z 233 M-2 also features an improved control panel with analog-style knobs and digital display of time and speed, faster acceleration and deceleration rates, and automatic g-force conversion with the touch of a button. Unlike the Z 180 M, however, the Z 200 M/H and the Z 233M-2 are sold without rotors. Andreas Hettich GmbH & Co KG MIKRO 12-24, MIKRO 24-48, EBA 12 RevPro, Inc., serves as the North American distributor for German centrifuge manufacturer Andreas Hettich, which builds three instruments. The most economical, the MIKRO 12-24, runs either a 12- or 24-place microfuge tube rotor or a 24-place hematocrit rotor. Speed settings are selectable as a percentage of the maximum value. The most expensive machine, the MIKRO 24-48, is a microprocessor-controlled instrument with short run-up and slow-down times and a rotor detection system and is touted as being extremely quiet. The MIKRO 24-48 runs several rotors: a 12 to 48-place angle rotor and a 60-place drum rotor for 1.5/2.2 ml tubes. The 48-place rotor packs a wallop, generating over 27,000 g at 18,000 rpm. Hettich's middle-priced instrument is the EBA 12. The EBA runs a variety of rotors, features a rotor detection system, nine acceleration and deceleration settings, microprocessor control, and a maintenance-free drive. The EBA 12 and its rotors are sol d separately. International Equipment Company (IEC) Micromax Microcentrifuge IEC's aptly named Micromax Microcentrifuge is loaded with operational features. Its quiet, brushless drive accelerates in either slow or fast mode and decelerates with hard or soft braking, or simply coasts to a stop. The Micromax also includes a choice of rpm or g-force speed control, momentary spin and time hold selections, and a "glove friendly" membrane control panel with digital displays. Time settings are selectable in seconds or minutes, and an audible tone signals the completion of a run. Under maximum acceleration and deceleration rates, the standard 24-place rotor will reach maximum speed or stop completely in less than 15 seconds. Four polypropylene rotors are available for the Micromax, including a sealed, 24-place fixed-angle rotor for aerosol containment. All the rotors are autoclavable and tolerate decontamination with 5% bleach or other agents. Jouan, Inc. A12 Microcentrifuge, A14 Microcentrifuge Built for intensive use, the A12 and A14 Microcentrifuges run a group of four rotors specifically designed to accommodate all the known types of microtubes. While all four are fixed-angle rotors, they collectively run between 6 and 60 tubes at g-forces between 6,921 and 17,746 xg and at speeds ranging from 12,000 to 14,000 rpm. The drives offer acceleration and braking rates from 4 seconds for the 6 x 1.5 ml rotor at 9,000 xg to 15 seconds for the 20 x 1.5 ml rotor at 17,000 xg. Both the A12 and A14 feature an automatic, 15-minute timer with a digital display and hold option and flash an LED every second to provide visual control of short runs. The A14 also has a liquid crystal speed display and a pulse button. Sarstedt, Inc. Microcentrifuge MC 2 Recently introduced to the marketplace, Sarstedt's Microcentrifuge MC 2 boasts a maintenence-free induction drive that accelerates an autoclavable, 24-place rotor up to 13,000 rpm in under 15 seconds and brakes to a stop in under 12. The MC 2 also features microprocessor control, LED displays for speed and run time, and a soft-touch keypad. Accommodating adapters for 0.5 ml and 0.2 ml tubes, the MC 2's 24-place rotor generates 16,060 gs. Its speed control is adjustable in 100 rpm steps beginning at 2,000 rpm, and the timer has a maximum 99-minute setting. Savant Instruments, Inc. SFA 13K SpeedFuge Air-cooled Microcentrifuge SFA 13KA SpeedFuge High Capacity Air-cooled Microcentrifuge Savant's SFA 13K and SFA 13KA SpeedFuges differ primarily in their respective capacities: the SFA 13K runs a 24 x 1.5 ml tube rotor, whereas the SFA 13 KA runs a 40 x 1.5 ml tube rotor. Each instrument is sold complete with its specific rotor. In all other aspects, the machines are identical. Both feature large LED displays for setting the fully programmable run time and g-force conditions, a pulse function with elapsed-time display, a closed-loop microprocessor control that never needs calibrating, and rapid acceleration/deceleration rates. Both machines can accelerate the 24-place rotor to maximum speed, or decelerate it completely from maximum speed, in about 10 seconds. Shelton Scientific Manufacturing, Inc. VS-13, VS-15, CS-15, VSMC-13, -13/1, VSB-14 Shelton Scientific Manufacturing, Inc., manufactures five nonrefrigerated microcentrifuges. All five have a 30-minute timer and a removable, high-density polyethylene chamber liner designed for quick and easy chamber decontamination. Three similar app earing models, the VS-13, VS-15, and CS-15, feature a stainless steel housing and cover, electronic braking for rapid stops or free coast down, and quiet, cool, vibrationless operation. Shelton's VSMC-13 is a variable-speed instrument that features electronic braking for full stops in less than 15 seconds, a cast aluminum housing, and an isolated tripod suspension system that reduces noise and vibration. A modified version of the VSMC-13, the VSMC-13/I, includes a zero-speed interlock that prevents the lid from being opened until the rotor has stopped spinning. The variable-speed VSB-14 is the only Shelton microcentrifuge built around a brushless motor and sold complete with a rotor and transparent cover. The VSB-14 also features an interlocking lid that does not open until the rotor speed falls below 200 rpm. Sorvall, Inc. MC12 Microcentrifuge Equipped with a removable polyethylene chamber liner for easy cleaning and decontamination, Sorvall's MC12 Microcentrifuge quietly propels a complement of five rotors. This variable-speed instrument accelerates in 12 seconds and comes to a halt in 20. Other features include a see-through chamber lid, a pulse button, and a door that will not open when rotor speeds exceed 230 rpm during deceleration. The five autoclavable aluminum rotors include the 18-place F-12/M.18 for 1.5 ml tubes and four rotors i n the FA-Micro series. These rotors run up to 24 tubes in various sizes and configurations. All rotors are backed by a seven-year warranty. Stratagene ProFugeTM 10K Microcentrifuge Microcentrifuge 2400 The ProFugeTM 10K Microcentrifuge from Stratagene has one of the smallest footprints of the microfuges profiled, and is also one of the lightest. This unit spins at a single rotational speed of 10,000 rpm and cranks out 5,600 xg, powerful enough to pellet single-and double-stranded DNA. The ProFuge 10K features three operation modes: pulse, timed and continuous, with run times of up to 10 minutes. Safety-wise, a magnetic lock keeps the lid tightly during spinning; if the lid opens during spinning, an a utomatic braking system stops the rotor within 5 seconds. An audible tone indicates when a timed run is complete. The new Microcentrifuge 2400 is a variable speed bench top centrifuge ideal for DNA isolation and purification protocols Users can adjust the speed between 4,000 and 13,000 rpm. This quiet model has a built-in timer for runs up to 30 minutes and a puls e switch for quick runs. The 2400 is also one of the most compact centrifuges profiled. The rotor acts as an airfoil during operations so the airflow within the centrifuge continuously keeps samples cool, even during long spin cycles. The Microcentrifuge 2400 features an interlocking lid that automatically prevents the lid from being opened while the rotor is spinning. Stratagene offers a 120-volt and a 230-volt model to meet the power needs of laboratories. TOMY TECH USA, INC. HF-120 Mini Micro Centrifuge Capsulefuge MC-140 High-Speed Micro Centrifuge MC-150 High-Speed Micro Centrifuge Bearing a strong resemblance to the top half of a giant time-release cold capsule, the simple yet surprisingly useful HF-120 Capsulefuge is just begging for a spot on a lab bench. Weighing in at only one pound, this little device is as easy to transpor t around the lab as it is to load and run. Spinning six 1.5 ml tubes at 6,400 rpm and 2,000 xg, the Capsulefuge is started by simply closing its clear plastic dome lid and stopped by pressing the tab to open it. Featuring an easily accessible, high-mounted rotor, the MC-140 High-Speed Micro Centrifuge runs at a fixed rpm with a twist of the 30-minute timer knob or a push of the "Flash" pulse-run button. Its black-anodized fixed-angle aluminum rotor holds eighteen 1.5 ml tubes and produces 15,700 xg. Elevated above the chamber, the rotor is protected by a steel-reinforced chamber lid and dual interlock system. TOMY TECH's MC-150 High-Speed Tabletop Micro Centrifuge has the most features of the three TOMY instruments. The MC-150 runs a choice of three interchangeable rotors consisting of fixed-angle, horizontal, and swing-out versions. The simple and precise analog controls allow the selection of speed settings from 0 to 15,000 rpm and run times from 0 to 20 minutes with an additional continuous-run setting. Chart 1 Chart 2 Chart 3 The author can be reached online at MDBrush@compuserve.com

Spinning Up To Speed: A Profile of Nonrefrigerated Microcentrifuges

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