What is the difference between class A and AS?
Class A and AS refer always to highest quality grade in accord to the respective standards and 'S' stands for swift delivery only used for volumetric instruments calibrated to deliver, pipettes and burettes (TD, Ex). For volumetric instruments calibrated to contain (TC, In) a swift delivery is not necessary and therefore not defined in the respective standards.
There is a small amount of residual liquid in the tip. Should it be blown out or not?
No. The small amount of residual liquid must not be blown out as it is already taken into account during calibration of the bulb or graduated pipettes.
How can the meniscus be read easily?
The volume of a concave meniscus has to be read at the lowest point of the liquid level. Here the lowest point of the meniscus has to touch the upper edge of the graduation mark. For parallax-free adjustment of the meniscus, the burette is held upright and the observer's eye must be at the same height as the meniscus. In this position the ring mark will appear as a line. The meniscus will appear darker and more easily readable in front of a light background if a piece of dark paper is held behind the instrument immediately beneath the ring or graduation mark.
What are BLAUBRAND® and SILBERBRAND pipettes labeled with?
Every BLAUBRAND® and SILBERBRAND bulb or graduated pipette is labeled with the nominal capacity, unit symbol (ml), error limit (± ml), calibration temperature (20 °C), calibration type (Ex), Class (AS or B), country of origin (Germany), color code, manufacturer's trademark (BLAUBRAND or SILBERBRAND) or companies name or logo (BRAND), as well as with standard referring to (ISO 648 or 835) and inscription ETERNA (if applicable).
Every BLAUBRAND® pipette is labeled with the following additional information; DE-M marking for all pipettes, waiting time in combination with calibration type in the format (Ex + 5 s), batch or serial number, and in case of USP pipettes the inscription USP.
What is the difference between the handling of bulb pipettes with one and two marks?
After aspiration of bulb pipettes with one mark the liquid has to be delivered excluding the small amount of residual liquid in the tip. After aspiration of bulb pipettes with two marks the liquid has to be delivered until the lower mark. Hence, you have to set the meniscus a second time correctly.
Can you explain the waiting time for pipettes?
The waiting time begins when the meniscus comes to rest at the lower volume mark or in the tip: During the waiting time residual liquid continues to flow down from the glass wall.
You only have to consider the waiting time of 5 s for BLAUBRAND® pipettes (cl. AS) before you remove the tip from the inner surface of the vessel. For SILBERBRAND pipettes (cl. B) no waiting is prescribed.
Are pipettes calibrated according to 'TC, In' or 'TD, Ex'?
'TD, Ex': The delivered quantity of liquid corresponds exactly to the capacity indicated on the instrument.
How is the pipette used correctly?
Handling of pipettes:
Fill pipette to approx. 5 mm above selected graduation mark
Remove any liquid remaining on the outside with a tissue
Set the meniscus
Wipe off any drops of liquid
Hold pipette vertically
Align tip at inner surface of inclined vessel
Deliver liquid and, after waiting time (necessary for cl. A or AS), draw the pipette tip upwards along the inner wall.
What kind of screening inks does BRAND use for printing the bulb or graduated pipettes?
Blue and white enamel are printed on the outer surface and provide a high contrast and an optimal combination of chemical resistance and legibility for BLAUBRAND (cl. AS) and SILBERBRAND (cl. B) pipettes.
Amber diffusion stain is used for BLAUBRAND®-ETERNA (cl. AS) and SILBERBRAND-ETERNA (cl. B) pipettes. This color diffuses into the glass surface and can therefore only be removed by abrasion or glass corrosion.
For a short overview of screening inks please look into section 'Silk-screening' of our brochure about 'Volumetric Measurement in the Laboratory'.