How do I determine the volume values when calibrating gravimetrically?

The measuring values of the analysis scales are multiplied by the correction factor Z (see SOP pipettes). This takes into account the density of the water at the relevant temperature and the relevant air.

What does EN ISO 8655 cover?

ISO 8655 addresses the needs of suppliers, test houses, and users and specifies the general requirements for piston-operated liquid handling devices. It is structured in seven chapters: ISO 8655-1: Terminology, general requirements, and user recommendations ISO 8655-2: Piston pipettes ISO 8655-3: Piston burettes ISO 8655-4: Dilutors ISO 8655-5: Dispensers ISO 8655-6: Gravimetric method for the determination of measurement error ISO 8655-7: Non-gravimetric methods for assessment of equipment performance (titration, photometry)

What do the terms random error and systematic error mean in a pipette calibration?

The systematic error describes the deviation of the dispensed volume from the nominal volume or from the selected volume of the piston stroke device, and is determined by establishing the mean value of (usually) 10 measurements. The random error describes the mean variation of the dispensed volumes from the mean value of the dispensed volumes, and is determined by calculating the repeat standard deviation of (usually) 10 measurements.

Why are the Z factors listed in our SOP different from factors which can be derived from density reference values (of water)?

The Z factor is included in EN ISO 8655-6 and was incorporated into our SOP. As we understand it, it was incorporated in the standard by the Physikalisch Technische Bundesanstalt in Braunschweig. The Z factor describes the density of water at a particular temperature using a 5th degree polynomial. Furthermore, the density of water is corrected by the density of air (derived from air pressure) and a fixed correction value for balances. These corrections are the key reasons for the deviation from density values in various books of tables.

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Varipette^® 4720 - 大容量移液器

Varipette® 4720 positive displacement pipette from Eppendorf

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轻松应对具有挑战性的液体处理任务！Varipette 4720大体积外置活塞式移液器，适用于粘性或挥发性液体的实验室工作。适用于从较大的瓶子或者较深的窄口容器中安全移液。

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Varipette<sup>®</sup> 4720 positive displacement pipette from Eppendorf

Varipette^® 4720

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1– 10 mL（连续体积选择）

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¥ 8,702.00

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适用于较大的瓶子或者较深的窄口容器的大体积外置活塞式移液器。
使用EppendorfVaripette 4720大容量外置活塞式移液器完成便捷的单手操作，加快移液速度。Varipette 4720移液器采用优化设计，适用于粘性或挥发性、高蒸气压液体，可连续调节。与EppendorfVaritips^® S系统配合使用，它也适用于从较大的瓶子或者较深的窄口容器移取液体，或使用Varitip P型吸头从烧杯中移取液体。

操作简单，可单手操作，大大节约工作时间：按一下Varipette操作杆吸液，再按一下操作杆放液。