The pipette is now set for delivery with that liquid for single or repeated deliveries.
NOTE: The circular scale on the pipette bonnet (lettered A through L) is a reference scale that
may be used to record the rotational position of the pipette plunger. (See Figure 1). This
provides a general position for the plunger. The final volume setting is determined by
rotating the plunger to raise the liquid meniscus to the appropriate incremental
graduation on the MLA Macro Graduated Pipette Tips. After adjusting the pipette to the
desired volume, observe this scale and record the letter opposite the numeric volume.
i. Remove the pipette tip from the solution and touch the tip against the side of the vessel to
remove any solution that may have adhered to the outside of the tip.
j. Place the tip against the side of the receiving vessel as close to the bottom as possible or, if the
vessel contains liquid, as close to the liquid as possible. Smoothly depress the plunger until all
liquid is dispensed.
k. While holding the plunger depressed, slowly withdraw the tip keeping it against the wall of the
container.
l. Release the plunger and remove the tip.
Hints
a. When pipetting solvents or viscous fluids, a liquid film may be retained in the tip that may change
the pipette volume. Pre-wetting the tip with the liquid to be pipetted can reduce this effect.
b. Smoothly depress and release the plunger maintaining the same speed of action for all samples.
Do not let the plunger snap back.
c. More viscous liquids and solvents require slower plunger movement.
d. Fully depress the plunger before inserting the pipette tip into a solution. This will prevent an air
bubble from forming in the solution.
e. Hold the pipette as vertically as possible at all times. Insert the tip to the same depth into the
sample each time.
f. If an air bubble forms in the tip during aspiration, return the sample, discard the tip, and apply a
fresh tip.
g. Ensure that the nose is always tightly screwed into the pipette body.
Maintenance
During factory assembly, the internal parts of the pipette are lubricated with specific grease.
Routine cleaning and lubrication should only be necessary at 6-month intervals. If the pipette is
used with acids, corrosive chemicals or solvents, lubricate and clean the pipette more often.
Lubrication is necessary if the plunger does not move smoothly or return to the “up” position.
(Regular piston lubrication is recommended if the pipette is used frequently with corrosive
chemicals or solvents.)
The nozzle should be cleaned regularly. In case of accidental sample aspiration, especially corrosive
chemicals or solvents, the nozzle should be cleaned immediately.
Should the pipette leak, fail to aspirate or dispense, or plunger settings change for known volumes,
then the metering seal should be checked for wear and replaced if necessary.
Lubricating the Piston
a. Set plunger at 5mL.
b. Hold pipette with the nozzle down.
c. Grasp nose and unscrew it from the body.
d. Remove metering seal housing with metering seal, and wave spring washer from the end of the
piston or housing recess. See Macro Adjustable Assembly diagram. Remove metering seal from
housing. DO NOT discard metering seal housing, seal or the wave spring washer.
e. With a soft tissue, remove old grease from metering seal housing and seal.
f. Use finger tip to apply a small amount of the supplied grease to the inner surface of the seal
and housing.
g. Rotate plunger clockwise until it stops.
h. Lightly grease the protruding piston.
DO NOT scratch the surface of the piston or block air inlet hole
.
i. Reinstall, or replace, metering seal in its housing and install housing in the housing recess.
j. Install wave spring washer on top of metering seal housing.
k. Carefully insert the body into the nose and screw together to a firm stop.
l. Depress plunger several times.
Cleaning the Nose and Piston
a. Follow steps a-d of Lubricating the Piston.
b. With a gentle stream of distilled or deionized water, flush the inside of the nose, metering seal
housing, seal and wave spring washer.
c. Rotate plunger clockwise until it stops.
d. Hold pipette with the piston down and flush the piston with a gentle stream of distilled or
deionized water.
e. With a soft tissue, remove excess water from piston, nose, seal housing, seal and washer.
f. Allow all components to dry.
g. Lubricate and reassemble as in steps f- l above.
Figure 1
Incremental Volume Lines and Circular Scale
Figure 2
Macro Adjustable Pipette Tip
