874 USB Oven Sample Processor Automatic thermal sample preparation for Karl Fischer titration Principle of the oven method 02 The oven method is suitable for samples that release their water only at high temperatures, are difficult to dissolve or react with the KF reagent. Sample preparation is very simple. The substance to be analyzed is weighed out into a sample vial, which is her-metically sealed with a septum and placed on the rack. The sample vial is heated in an oven to release the water from the sample. A double hollow needle pierces the septum and a stream of carrier gas transports the moisture to the titration cell for subsequent determination. The advantage of the oven method is that the sample itself does not get in contact with the KF reagent. This prevents contamination of the oven and the titration cell, which means that there is no risk of carryover or memory effects. Possible contamination is confined to the sample container alone. Diagram of oven method Advantages of the 874 USB Oven Sample Processor • The 874 USB Oven Sample Processor is simply connected to the USB port of a computer and is automatically recognized. • Use your own sample vessels. The oven and the rack can be adjusted to different sample vials. • An 800 Dosino can be connected directly to the MSB port of the 874 USB Oven Sample Processor and used with a Dosing Unit for automatic replacement of the reagent. • The optimum oven temperature for every sample can be determined with the temperature gradient. • A heated transfer tube ensures that the moisture is completely transferred to the titration cell. 03 High flexibility You want to work with your own sample vessels? 04 No problem at all. The oven and rack can be adjusted to fit your sample vessels. Automatic reagent change – safe handling of toxic reagents The 874 USB Oven Sample Processor has three MSB vented. This means that the conditioning time of the ports. In addition to the stirrer, Dosinos and Dosing Units fresh reagent is very short and you save valuable time can be connected to the Sample Processor. This allows and also avoid direct contact with toxic reagents. spent reagent to be removed automatically from the Reagent change can be triggered by limits related to the titration cell and the cell to be filled with fresh titration number of analyses, the age of the reagent, its water medium. Because the titration cell is not opened, mois-capacity or the drift value. ture absorption from the atmosphere is reliably pre- Optimum heating temperature with temperature gradient The optimum heating temperature is always a question falsify the results. With the 874 USB Oven Sample 05 with unknown samples. The temperature should always Processor you can record the heating curve of an un - be high enough to ensure that the water enters the titra-known sample. This curve can be used to determine the tion cell as quickly as possible. However, the sample must optimum temperature for the analysis. not decompose, because decomposition products may Example of a heating curve Coulometry or Volumetry? 06 Once the moisture from the sample has been transferred to the titration cell, the water content is determined. This can be done by coulometric or volumetric Karl Fischer titration. Coulometric titration – 874 USB Oven Sample Processor with 831 KF Coulometer Volumetric titration – 874 USB Oven Sample Processor with 841 Titrando Order Information 2.874.0010 874 USB Oven Sample Processor for 6-mL sample vessels incl. tiamo TM full 07 2.874.0020 874 USB Oven Sample Processor for special sample vessels incl. tiamo TM full Optional Accessories 2.756.0110 756 KF Coulometer 2.831.0110 831 KF Coulometer 2.841.0010 841 Titrando 2.851.0110 851 Titrando 2.852.0150 852 Titrando 2.890.0210 890 Titrando with tiamo TM light 6.1448.050 Aluminum septum seal, 1000 units 6.2419.000 Sample vessel 6 mL, 1000 units www.metrohm.com G, CH-9101 Herisau ohm A , gedruckt in der Schweiz bei Metr SW Änderungen vorbehalten Gestaltung Ecknauer+Schoch A 8.874.5001EN – 2009-05