The Mixer Mill MM 400 is a true multipurpose mill designed for dry, wet and cryogenic grinding of small volumes up to 2 x 20 ml. It mixes and homogenizes powders and suspensions with a frequency of 30 Hz within seconds – unbeatably fast and easy to operate.
The compact benchtop unit is suitable for classic homogenization processes, as well as for biological cell disruption for DNA/RNA and protein extraction. Long processing times up to 99 hours make the MM 400 ideally suited for research applications, for example in mechanochemistry.
With regard to performance and flexibility of this mill, there is no equivalent technology available in the market.
You may also be interested in the mixer mill models MM 500 nano and MM 500 vario which operate with the same functional principle at a frequency of 35 Hz but provide substantially higher performance. For applications which require cooling or heating the sample, the Mixer Mill MM 500 control is the perfect choice. Each RETSCH mixer mill has a specific application focus.
"We use the MM 400 to homogenize muscle, skin, liver, whole invertebrate samples prior to stable isotope and fatty acid analysis. It's fast and does a consistently thorough job of homogenizing samples. The machine has been heavily used with no mechanical issues."
Bruno Rosenberg
Fisheries and Oceans Canada
"Great for homogenous powdering of tissue samples whilst frozen"
Kristen Cooke
University of Sydney
"Perfect for preparing soil and plant material for isotope analysis."
David Mitchem
Virginia Tech
"The world's most effective instrument in medical technology. "
Muhammad Naveed
First Global Link
"I am happy to use MM 400 for my live laboratory. It would be specified as a standard machine for XRF marketplaces. "
Gye Ryoung Lee
Gachon University
"As always, excellent machine, easy to operate and user friendly. Fast milling to desired particulate size."
Hanna Kaliada
Vivex Biologics, Inc.
"This is the best ball mill I have ever used. Very easy to operate and handle."
Xinle Li
Clark Atlanta University
"I have used this machine in IISER Kolkata, India. It's very efficient, handy and convenient. It's worth buying it."
Surojit Bhunia
Northwestern University
Reproducibility is paramount in the process chain from sampling to analysis. Lab equipment which can be calibrated guarantees reproducible results with minimum standard deviation every time. This is particularly useful when comparing results produced at different locations.
The MM 400 is the first laboratory mill which can be calibrated. RETSCH initially calibrates time and frequency of the mill and offers a regular calibration service to ensure reproducible milling processes.
This functionality is particularly suitable for
Reproducibility is a fundamental principle of scientific research and is essential for ensuring the credibility and reliability of scientific findings. The Mixer Mill MM 400 was tested regarding the reproducibility within a mechanochemical reaction, and it could be proven that it provides excellent reproducibility during several repetitions, for both clamping positions, and also between different devices. [1]
Minor variations of the frequency from 30 Hz to 29 Hz or 28 Hz have an influence on the yield of the reaction. It is of fundamental interest that the mixer mill maintains a set value, e.g. 30 Hz, and does not deviate from it. A premise which is fulfilled by the MM 400 which comes with a calibration certificate.
The mechanochemical reaction γ-Al2O3 + ZnO -> ZnAl2O4 was conducted for 30 min using 25 ml grinding jars, 2 x 15 mm grinding balls, 1 g educts, at 28 Hz, 29 Hz and 30 Hz five times in a row. The comparison between left and right clamping station showed highly reproducible results, also the comparison between the 5 trials.
XRD patterns after the mechanochemical reaction γ-Al2O3 + ZnO -> ZnAl2O4: Left: Grinding at 28 Hz, 29 Hz and 30 Hz, results after 5th reaction. Middle: Comparison left and right grinding station at 28 Hz 5th reaction each. Right: Reaction 1 to 5 at 30 Hz, right grinding station. Results presented by the group of Claudia Weidenthaler. [9]
The experiments were repeated using another MM 400 device to compare the results between the two mills. Again, the excellent reproducibility was verified for the 5 tests conducted at 30 Hz, for both, left and right grinding station.
Almost identical results (weight % of educts and product) and reproducibility are obtained with a different MM 400 device. Results presented by the group of Claudia Weidenthaler. [1]
Mixer mills are frequently used for homogenizing biological samples. The so-called bead beating with small glass beads is an established method for cell disruption of yeasts, microalgae or bacteria. The sample is only moderately warmed in the process which can be reduced to a minimum by pre-cooling.
The MM 400 allows for efficient cell disruption of up to 240 ml cell suspension for DNA/RNA and protein extraction. For accurate diagnosis of infections, it is possible to isolate intact bacteria from tissue in 8 x 30 ml bottles or 10 x 5 ml vials by using adapters.
The MM 400 can be operated with a range of adapters for single-use vials with the following capacities:
20 x 0.2 ml / 20 x 1.5 or 2 ml / 10 x 5 ml / 8 x 30 ml / 8 x 50 ml
For the pulverization of 25 to 30 g plant material, such as cannabis flower, conical centrifuge tubes are best suited. Up to 8 tissue samples, like fresh liver in buffer solution, can also be homogenized in these 50 ml tubes using steel or zirconium oxide balls. To keep the mechanical stress on the vials as low as possible, a reduced frequency and a high filling level, e. g. with buffer and sample, are recommended.
Mixer Mill MM 400 - Yeast Cell Disruption*
*The video shows the previous model with identical functional principle.
Mixer Mill MM 400 - Homogenization of cannabis*
The CryoKit is a cost-effective solution for cryogenic sample processing with the Mixer Mill MM 400. The set consists of two insulated containers, two tongs and safety glasses.
The sample to be embrittled and the grinding ball are filled into the stainless-steel grinding jar which is tightly screwed. Indirect embrittlement is effected by pre-cooling the jar in a liquid nitrogen bath. After approximately 2 minutes, the sample is sufficiently cooled for cryogenic processing.
If direct contact with liquid nitrogen is to be avoided, the CryoMill or Mixer Mill MM 500 control are suitable options. Both mills can be operated with jars made of other materials than steel for cryogenic grinding.
Mixer Mill MM 400 - Cryogenic Grinding*
Mechanochemistry enables fast reactions of substances in a solvent-free environment. Some chemical reactions require the frictional forces of a planetary ball mill, while other reaction types need energy input through impact – that is where the Mixer Mill MM 400 comes into play.
The sample volumes available for research applications are often very low. This makes small grinding jar sizes of up to 50 ml, like they are available for the MM 400, beneficial. Due to the frequently long reaction times, the possibility to program process times of several hours is another important aspect.
Mixer mills offer a unique advantage over planetary ball mills in mechanochemical applications: the use of transparent jars in combination with the typical horizontal jar movement enables in-situ RAMAN spectroscopy. This permits real-time monitoring of the reaction process to identify the optimal time for maximum yield and avoid prolonged processing.
The MM 400 offers many advantages for mechanochemical applications:
Time course of the Knoevenagel reaction between vanillin and barbituric acid under mechanochemical conditions using 2x10mm zirconium oxide grinding balls in 19 ml PMMA grinding jar at 30 Hz. Reaction running over 30 minutes with visible progress indicated by color change.
Courtesy of Dr. Sven Grätz, Ruhr-University Bochum, Faculty of Chemistry and Biochemistry, AG Prof. Borchardt.
In-situ Raman spectroscopy is a powerful analytical technique that allows for the monitoring and analysis of materials in their natural or process environment. This method utilizes Raman scattering, a phenomenon where light interacts with molecular vibrations, leading to shifts in the wavelength of the scattered light. These shifts provide a unique spectral fingerprint for the material being analyzed, offering insights into its chemical composition or molecular structure.
The "in-situ" aspect refers to the ability to observe and measure these characteristics directly during an ongoing process. This can include observing changes in the presence of various chemical reactions, also the so called mechanochemistry. Mechanochemistry involves the use of impact, shearing, or friction actions to induce chemical changes in solids. This approach is increasingly popular for its ability to bypass the need for solvents, potentially offering a more environmentally friendly and energy-efficient pathway for chemical synthesis. The Raman spectroscopy can provide invaluable insights into the reaction mechanism, phase transformations, reaction kinetics or for optimization of reaction conditions.
The MM 400 is “Raman-ready”, allowing easy removal of the bottom plate inlay. The bottom plate has openings for the Raman probe to consistently measure at the bottom of the jars by placing the Raman probe underneath the mill and thus underneath the jars, where particle interaction is most intense, ensuring accurate data. The Retsch PMMA grinding jars, with their transparency and chemical resistance, enhance spectral data without contamination. The plane outer shapes of the jars further enhance the spectroscopic data. These design adjustments streamline the experimental workflow. Researchers can now perform in-situ Raman spectroscopy with greater ease and precision, opening new possibilities for in-depth material analysis.
The nominal volume of the screw-top grinding jars ranges from 1.5 ml to 50 ml; available materials include hardened steel, stainless steel, agate, tungsten carbide, zirconium oxide and PTFE, ensuring contamination-free sample preparation.
Transparent PMMA grinding jars are used for in-situ RAMAN spectroscopy but also enable applications with photochemical reactions. Moreover, these are resistant to a variety of chemicals. The jars can be used with the predecessor of the MM 400 just like older jar models are compatible with the latest mixer mill model.
Adapters for 0.5 / 1.5 / 2 / 5 ml single-use vials can be used in the MM 400. For larger sample amounts, e. g. for protein extraction, adapters for 50 ml conical centrifugation tubes or 30 ml wide-mouth bottles are available.
The MM 400 can be equipped with adapters that accommodate four 5 ml stainless-steel grinding jars, allowing for simultaneous pulverization of a maximum of 8 samples. This increased throughput is particularly beneficial for mechanochemical applications.
1.5 or 2 ml
Safe-lock
single-use vials
2 x 10 vials max.
5 ml
Safe-lock
single-use vials
2 x 5 vials max.
30 ml
disposable wide
mouth bottles
2 x 4 bottles max.
50 ml
disposable conical
centrifugation tubes
2 x 4 tubes max.
The jar size should be adapted to the sample volume to ensure optimum results. Ideally, the grinding balls are 3 times the size of the largest sample piece. The numbers and sizes of balls given in the table below follow this rule of thumb. To pulverize, for example, 20 ml of a sample consisting of 8-mm sized particles, the use of a 50 ml jar and 25 mm balls is recommended. According to the table, one grinding ball is required. 20 ml of a sample with 5-mm particles, however, can be homogenized with four 15 mm balls.
| Grinding jar nominal volume |
Sample amount | Max. feed size | Recommended ball charge (pieces) | ||||||
| Ø 5 mm | Ø 7 mm | Ø 10 mm | Ø 12 mm | Ø 15 mm | Ø 20 mm | Ø 25 mm | |||
| 1.5 ml | 0.2 - 0.5 ml | 1 mm | 1 - 2 | - | - | - | - | - | - |
| 5 ml | 0.5 - 2 ml | 2 mm | - | 1 - 2 | - | - | - | - | - |
| 10 ml | 2 – 4 ml | 4 mm | - | 5 - 7 | 1 - 2 | 1 - 2 | - | - | - |
| 25 ml | 4 – 10 ml | 6 mm | - | - | 5 - 6 | 2 - 4 | 1 - 2 | - | - |
| 35 ml | 6 – 15 ml | 6 mm | - | - | 6 - 9 | 4 - 6 | 2 - 3 | 1 | - |
| 50 ml | 8 – 20 ml | 8 mm | - | - | 12 - 14 | 6 - 8 | 3 - 4 | 1 | 1 |
The table shows the recommended charges (in pieces) of differently sized grinding balls in relation to the grinding jar volume, sample amount and maximum feed size.
RETSCH mixer mills are true allrounders. They homogenize, for example, alloys, animal feed, bones, ceramics, cereals, chemical products, coal, coke, drugs, electronic scrap, glass, grains, hair, minerals, oil seeds, ores, paper, plant materials, plastics, sewage sludge, soils, straw, tablets, textiles, tissue, tobacco, waste samples, wood, wool, etc.
30 ml sample
50 ml stainless steel jar
1 x 25 mm stainless steel ball
2 min at 30 Hz
30 ml cell suspension
8 x 50 ml conical centrifuge tubes (adapter)
with 25 ml glass beads each; 0,5-0,75 mm
30 s at 30 Hz
15 ml sample
50 ml stainless steel jar
1 x 25 mm stainless steel ball
embrittlement in LN2 for 3 min
4 x 2 min at 30 Hz with intermediate cooling
20 ml sample
50 ml stainless steel jar
1 x 25 mm stainless steel ball
1 min at 30 Hz
5 ml sample
10 ml zirconium oxide jar
2 x 12 mm zirconium oxide balls
3 min at 30 Hz
20 ml sample
50 ml stainless steel jar
1 x 25 mm stainless steel ball
embrittlement in LN2 for 3 min
4 x 2 min at 30 Hz with intermediate cooling
3 g sample
50 ml stainless steel jar
1 x 25 mm stainless steel ball
embrittlement with LN2 for 2 min
90 s at 30 Hz
10 ml sample
25 ml zirconium oxide jar
2 x 15 mm zirconium oxide balls
2 min at 30 Hz
To find the best solution for your sample preparation task, visit our application database.
Our instruments are recognized as the benchmark tools for a wide range of application fields in science and research. This is reflected by the extensive citations in scientific publications. Feel free to download and share the articles provided below.
| Applications | size reduction, mixing, homogenization, cell disruption, cryogenic grinding, mechanochemistry |
| Field of application | agriculture, biology, chemistry / plastics, construction materials, engineering / electronics, environment / recycling, food, geology / metallurgy, glass / ceramics, medicine / pharmaceuticals |
| Feed material | hard, medium-hard, soft, brittle, elastic, fibrous |
| Size reduction principle | impact, friction |
| Material feed size* | <= 8 mm |
| Final fineness* | ~ 5 µm |
| Batch size / feed quantity* | max. 2 x 20 ml |
| No. of grinding stations | 2 |
| Vibrational frequency | 3 - 30 Hz (180 - 1800 min-1) |
| Typical mean grinding time | 30 s - 2 min |
| Max. grindig time | 99 h |
| Dry grinding | Yes |
| Wet grinding | Yes |
| Cryogenic grinding | Yes |
| Cell disruption with reaction vials | yes, up to 20 x 2.0 ml |
| Self-centering clamping device | Yes |
| Type of grinding jars | screw top design |
| Material of grinding tools | hardened steel, stainless steel, tungsten carbide, agate, zirconium oxide, PTFE, PMMA |
| Grinding jar sizes | 1.5 ml / 5 ml / 10 ml / 25 ml / 35 ml / 50ml |
| Setting of grinding time | digital, 10 s - 8 h |
| Storable SOPs | 12 |
| Storable cycle programs | 6 |
| Electrical supply data | 100-240 V, 50/60 Hz |
| Power connection | 1-phase |
| Protection code | IP 30 |
| Power consumption | 165W |
| W x H x D closed | 385 x 350 x 470 mm |
| Net weight | ~ 27,5 kg |
| Standards | CE |
The grinding jars of the mixer mill MM 400 perform radial oscillations in a horizontal position. The inertia of the grinding balls causes them to impact with high energy on the sample material at the rounded ends of the jars and pulverize it. Also, the movement of the jars combined with the movement of the balls result in the intensive mixing of the sample.
The degree of mixing can be increased even further by using several smaller balls. If several small balls are used (e.g. glass beads) then, for example, biological cells can be disrupted. The large frictional impact effects between the beads ensure effective cell disruption.
[1] Reaction scheme and performance of the experiments: Prof. Dr. Claudia Weidenthaler, Research Group Leader Heterogeneous Catalysis Powder Diffraction and Surface Spectroscopy, Max-Planck Institut für Kohleforschung, Mülheim an der Ruhr.
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