MISSION 3: Death Valley National Park
With the goal of examining the effects of hot and dry environments on pipette
performance and data integrity, the Expedition Team ventured to Death Valley
National Park in the summer of 2007. Located between the Amargosa and Panamint
mountain ranges in Eastern California, Death Valley is synonymous with hot and dry — indeed, it is one of the hottest and driest places in the world. Vast expanses
of thick and rough salt crusts cover dry lake and stream beds, bordered by
fields of sand dunes, and surrounded by intensely colored and dramatically
shaped rock formations of the mountain ranges. Searing heat leaves the valley
floor shimmering silently for most of the year at this lowest elevation in the
Western hemisphere, with an altitude as low as 86 meters (282 feet) below sea
level.
The Expedition Team braved dry heat with temperatures of up to 52°C (125°F), combined with 7% relative humidity, in order to evaluate the accuracy and
precision of air-displacement pipettes under these conditions.
ARTEL tested pipettes from leading manufacturers for dispensing accuracy and
precision using the ARTEL PCS® (Pipette Calibration System). A robust, portable system, PCS is unaffected by environmental conditions, thus
providing standardized, NIST-traceable results for a scientifically sound
comparison of data.
THE EXPERIMENT
The experimental protocol for this mission was designed to investigate two
different variables affecting the sample delivery with pipettes: low humidity
and high temperature. All equipment (pipettes, tips, and PCS instrument) and
test solutions were allowed to equilibrate to daytime ambient temperature in
Death Valley, usually between 44 – 45°C. Each pipette was tested at or close to its minimum specified volume setting,
and at or close to its nominal volume.
The effect of low humidity, commonly encountered in heated or air-conditioned
labs without humidity control, was evaluated by measuring the sample volumes
delivered with tips which were pre-wetted five times prior to sample delivery.
These data were compared to the volumes delivered without pre-wetting the tips.
For the latter experiment, a new tip was used for each sample delivery.
To ensure consistency in pipetting technique, the scientists performing this
work were trained and certified using the ARTEL Method™.
RESULTS
