Bio-Rad Human Metabolic and Hormone Assays User Manual

Page 29

Possible Causes

High Intra-Assay CV

Improper pipetting technique

Reagents and assay components
not equilibrated to room
temperature prior to pipetting

Contamination with buffer
during wash steps

Slow pipetting of samples and
reagents across the plate

Low Bead Count

Beads clumped in multiplex
bead stock tube

Possible Solutions

Pipet carefully when adding
standards, samples, detection
antibodies, and streptavidin-PE,
especially when using a multichannel
pipet. Use a calibrated pipet. Change
pipet tip after every volume transfer.

All reagents and assay components
should be equilibrated to room
temperature prior to pipetting.

During the wash steps, be careful
not to splash buffer from one well
to another. Be sure that the wells
are filtered completely and that no
residual volume remains. Ensure
that the microplate shaker setting is
not too high. Reduce the microplate
shaker speed to minimize splashing.

Sample pipetting across the entire
plate should take less than 4 min.
Reagent pipetting across the entire
plate should take less than 1 min.

Vortex for 30 sec at medium speed
before aliquoting beads.