IL-18 Human ProcartaPlex™ Simplex Kit

The beads used in our Luminex instrument-compatible ProcartaPlex and QuantiGene Plex assays are 6.5 micron superparamagnetic beads.

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The following is a list of general lab supplies that are required for running BioSource immunoassays on the Luminex xMAP system:
1) Sonicating water bath
2) Orbital shaker
3) Vortexer
4) Repeating and/or multi-channel pipetter (not required, but recommended)
5) Calibrated adjustable precision pipettes, with disposable plastic tips
6) Glass/plastic tubes and racks for preparing reagents
7) Graduated cylinder and container for preparing wash solution
8) Aluminum foil
9) Deionized or distilled water.

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The Luminex beads should be protected from light because they are susceptible to photobleaching. We recommend protecting the beads by keeping containers covered with aluminum foil during all incubation steps, and exercising care during handling. The beads should not be frozen, subjected to excessive heat, or exposed to organic solvents.

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(1) The user did not properly aliquot the diluted beads, such that no beads were actually added to the wells (make sure that the bead concentrates are sonicated and vortexed well, then check the pipet tip to ensure that air bubbles were not drawn up)
(2) The user missed loading diluted beads to some wells, which is likely since the small volume is clear and difficult to visualize in the clear plastic plate (we have now addressed this customer difficulty by coloring each of the Buffer Reagent Kit components)
(3) The user applied too much vacuum pressure at some point during the wash steps, or allowed the pressure to spike even once, such that the filter membrane tore in a few wells releasing the beads (make sure that the vacuum manifold pressure is kept below 5mm/in Hg, depending on their system -- a good rule of thumb is that it should take a full 3-second count to GENTLY empty the wells of 200uL)
(4) The user did not properly sonicate and vortex the beads prior to dilution, such that the percent of bead aggregation was high and the instrument was unable to find enough single beads to meet the events/bead value designated by the customer (make sure that the Bead Concentrate tube is put into the waterbath all the way to the cap, since the tube is hollow until the top third)
(5) The user lost beads by shaking the plate too aggressively or handling it improperly (make sure that the orbital shaker is set to a speed that allows for maximum vortex in the wells without spillage)
(6) The user exposed the beads to an excess of light during storage or running of the assay, such that some but not all of the beads were photobleached and therefore falling outside the acceptable range for each bead region (make sure that the plate is covered on the top/sides with foil throughout the assay, away from Windows and spotlights, and that the bead component of the kits is stored in the dark)*
(7) There was a clog in the sample needle, such that the instrument was unable to take up enough sample to meet the number of events requested per bead region (suggest that the user follow the manual instructions for dislodging a clog, which include several Back Flush steps and may require removal of the needle for sonication with probe alignment).

* Some of the older Antibody Bead Kits still have clear plastic tops instead of black ones. In cases where customers store kits in lit refrigerators, or keep them open on the lab bench, even a few hours of light exposure is enough to photobleach beads. It is important to note, in general, that higher number bead regions are more susceptible to photobleaching. In order to draw conclusions about the source of the difficulty, we would ask to see the data, specifically the Masterplex QT file, which would enable us to examine the pattern of "Sample Empty" occurrences in addition to the bead counts per well.

Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.

The beads are made of polystyrene.

Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.