Reliable Representative Samples in a Very Short Time

This is an interview with Holger Brecht about how to get representative samples in short time using the Fritsch Knife Mill PULVERISETTE 11.

For the benefit of our readers can you explain the importance of correct sample preparation?

At the beginning of every sample analysis there must be a correct sample preparation of the corresponding materials. This becomes necessary for bringing the heterogeneously distributed quality characteristics into an almost ideal order and then to subsequently feed them into downstream analytical instruments such as AAS, ICP -MS or XRD and XRF.

This becomes all the more essential, because today's analytical systems only allow grams or milligrams of sample weights to describe basic populations of several tons both qualitatively and quantitatively.

Fig 1. Homogenous sample “cereal bars“ before and after comminution

How do you ensure that you have the correct method of sample preparation? ​

We offer every potential customer the opportunity to contact our application laboratory directly or via our worldwide sales partners. As part of a product recommendation, we offer our customers a free test comminution, after which these processed samples are sent back to the customer together with a detailed grinding report for a qualitative evaluation. This practice ensures that the correct method for sample preparation is used.

Fig 2. Fast and easy sample preparation for analysis - see several applications examples

What tools are available to help with this?

We have many years of worldwide cooperation with our mostly exclusive distribution partners. These partners have acquired significant expertise in sample preparation. Through them and by utilising an online application-oriented questionnaire that automatically enters into a laboratory information management system (LIMS), we offer the highest level of correspondence to our customers.

These are all tools that ensure a 100 percent customer satisfaction prior to a product purchase. For our instruments we also offer a variety of accessories which are used for very different and specific applications, such as the different grinding vessels for the Knife Mill PULVERISETTE 11.

Fig 3. Knife Mill PULVERISETTE 11 in standard configuration

Which industries and applications is this suited for? ​

The PULVERISETTE 11 as a Knife Mill is used for comminution and homogenisation of foodstuffs and animal feed. It has a grinding chamber volume of maximum 1400 ml, enabling fast and reproducible preparation of samples from the food and feed industry.

Due to the powerful 1250-watt motor and the available blade geometries, the mill processes substances with a high water, oil or fat content just as reliably as dry, soft, medium-hard and fibrous materials. The recipe management is unique due to the help of a maximum of 20 SOP´s (Standard Operation Procedures).

Fig 4. 20 different SOP’s can be saved and edited with up to 15 grinding sequences

What does FRITSCH offer for this sample preparation? ​

For the Knife Mill PULVERISETTE 11, FRITSCH offers grinding vessels made of glass, steel and 2 different types of plastic. One of the two plastic versions is made of Tritan Copolyester and is particularly suitable for the preparation of oily samples. The other plastic grinding vessels is made of polycarbonate and is included as a standard container with the Knife Mill.

Fig 5. 1.4 litre grinding vessels in different materials

Additionally, different knife geometries are available which can be used for different applications. For example, in addition to the standard knife the customer can also buy a serrated knife or even a specially developed knife for the sample preparation of meat.

Fig 6. Different knives with 4 blades

How does the Knife Mill PULVERISETTE 11 help the end user to get optimally homogenised samples?

The knife geometries essentially influence the energy input of the sample matrix, as well as the rheological behaviour of the entire sample. The influence of temperature on the sample and the associated dwell time of the sample inside the grinding vessel are equally associated with this.

It is important to note that samples that are analysed with immunoserological methods such as ELISA or PCR do not warm up as much.

The special features of the FRITSCH Knife Mill PULVERISETTE 11 and how it works – please have a look:

Fig 7. Have a look how the Knife Mill PULVERISETTE 11 works

How do you help your users to stand out? ​

The quietly operating Knife Mill PULVERISETTE 11 is the ideal industrial laboratory mixer for fast and gentle comminution and homogenisation - including cryogenic comminution - of various samples. These include moist, oily and fatty samples as well as of dry, soft, medium-hard and fibrous samples.

This makes it a perfect all-rounder advantageous for sample preparation in the fields of foodstuffs or animal feed testing, pharmaceuticals and chemistry and many other applications. The simple cleaning procedure makes it especially convenient for use in daily laboratory routines.

What other support do you offer alongside the Knife Mill PULVERISETTE 11? ​

For difficult samples such as gummy bears, chocolate or sweets with a liquid filling, and baked goods, we offer a special solution: grinding with liquid nitrogen. For this process the 316L grinding vessel is made of stainless steel and a special lid with an easily exchangeable single-use insert is utilised..

Further information on the Knife Mill PULVERISETTE 11 can be found at www.fritsch-international.com/P-11. Please also have a look at the lecture Foodstuff Production - A culture of contradictions?

About Holger Brecht

Holger studied process technology and graduated with a Diploma in 2003. He started his career at KHS AG as a technologist.

In 2006 he joined FRITSCH GmbH as a Sales Manager for all instruments from FRITSCH Milling and Sizing.