Sample Preparation & Processing
Table 3. Summary of fi ve determinations of 10 mL c(NaOH) = 0.1 mol/L with c(HCl) = 0.1 mol/L. All titrations were performed with the same solutions and pipets.
The time during each analysis can then be used to either prepare the next sample or work on another system in parallel. In this way the throughput is increased and the cost per analysis is decreased.
Summary
This white paper explains the advantages of automated titration over manual methods. Besides signifi cant improvements in productivity, accuracy, and precision, the human infl uence on the analysis is reduced to a minimum. All these points make automated titration easier to use than manual titration, as well as results being more comparable and reproducible.
References
1. Szabadváry, F. History of Analytical Chemistry, 1st edition; Belcher, R., Gordon, L. Eds.; Pergamon, 1966.
2. Becker, P. History and progress in the accurate determination of the Avogadro constant. Rep. Prog. Phys. 2001, 64, 1945–2008.
3. Achinstein, P. Evidence, Explanation, & Realism; Oxford University Press, 2010.
about 1 min 33 s per analysis. Compared to the manual titration where the lab analyst is needed during the entire titration, this accounts for a signifi cant amount of time saved.
4. Jander, G.; Jahr, K. F. Massanalyse, 15th edition; Schulze, G., Simon, J. Eds.; de Gruyter: Berlin, New York, 1989.
Read, Share and Comment on this Article, visit:
www.labmate-online.com/article Knife Mill Delivers Fast Representative Samples for Reliable Analysis
The Knife Mill PULVERISETTE 11 from Fritsch provides a homogeneous sample in a very short time and is ideal for a wide range of different materials, regardless of whether the sample is dry, moist, soft, medium-hard, fibrous or oily. It is the perfect instrument for sample preparation in the fields of foodstuffs or animal feed testing, agriculture and forestry, biology, pharmaceuticals and chemistry.
The standard knife made of stainless steel can be used for comminution of nearly all materials due to its four blades and a well-conceived geometry. For comminution of brittle, hard samples the stainless steel sickle knife is recommended.
In addition to the grinding vessel made of scratch-resistant Polycarbonate, a stainless steel 316L grinding vessel for cryogenic comminution and for grinding harder sample materials is available. Alternatively, a glass grinding vessel for food-safe analysis and for verification of polymers is available. For grinding oily samples and for BPA-free sample preparation, the Eastman Tritan Copolyester grinding vessel is recommended.
The freely adjustable Vario-Lid system can be used to reduce the grinding chamber volume down to 0.54 litre and to manually compress and loosen up the sample material at the beginning and at any time during comminution. The grinding vessel, lid and knife of the PULVERISETTE 11 can be cleaned in a dishwasher. Depending on the version, all parts which come into contact with the sample materials such as grinding vessel, lid and knife are autoclavable.
Difficult to grind samples such as gummi bears, chocolate or plastic toys can be embrittled with liquid nitrogen for comminution directly in the stainless steel 316L grinding vessel. The sample material remains 100% cold. Just select the special lid with the easily exchangeable single-use sieve insert. The PULVERISETTE 11 allows users to program and save up to 20 Standard Operating Procedures (SOPs). In each SOP you can save up to 15 grinding sequences.
All saved SOPs can be uploaded, exchanged and saved with the free SOP editor by laptop via the integrated USB interface. Simply download the SOP Editor at
www.fritsch.de/p-11/sop.
With the software P-11Control, the mill can be controlled via the integrated USB port. SOPs can be edited, saved and managed directly on the connected laptop via drag & drop. Reversion-proof grinding reports can be created, archived quickly and easily with the integrated report generator. More information online:
ilmt.co/PL/dDAX
49418pr@reply-direct.com
Next Generation High-Torque and High Speed Stirrers Introduced
Wiggens introduces the new generation of high-torque and high speed overhead stirrers with the WB-3000, WB-1800, and WB-6000 series. These units are specifically designed for high torque applications and / or high speed applications where conventional stirrers reach their limit with regard to sample viscosity or speed requirements. The Wiggens high-torque and high speed stirrers feature a high resolution TFT display which can show not only the current speed and torque, but also the set speed, gear stage, controlling mode and timer settings. All stirrers come with a BLDC motor, which is highly beneficial to the durability of the product. In comparison to AC motors, BLDC motors are quieter, more robust and maintenance free. In addition, all stirrers employ a two stage gear transmission box for optimal processing of high torque at low speeds or lower torque at higher speeds. A special feature is the smart torque adjustment that enables the stirrer to maintain the set speed even if the viscosity of the sample changes during the stirring process. The latest chuck design makes impeller changes easy and guarantees that the impeller sits perfectly. The housing is made of die-cast aluminium and features heat reduction fins, which contribute to keeping the unit cool in long-term applications.
An RS-232 and RS-485 input as well as analogue control make all stirrers highly versatile and adoptable for different applications. Thus, they can be used as a stand-alone unit or, for instance, integrated in chemical reaction systems. The Wiggens high-torque and high speed series are also available as remotely controllable units, with the stirring and controlling box separated. This makes them an even better fit for integration in reaction systems where the controller is required to be in an easily reachable position.
More information online:
ilmt.co/PL/PDOe 50538pr@reply-direct.com
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