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Frequently Asked Questions

Q-Plex™ Technology offers quality imaging and data analysis

for every application and budget

Multiplexed ELISA Kits

What is Q-Plex?

Q-Plex technology is a multiplex ELISA, an assay platform that can simultaneously quantify the concentrations of multiple analytes by utilizing enzymes and adsorbed antibodies and/or antigens. Each fully-quantitative Q-Plex kit consists of arrays of up to 20 distinct capture antibody nano spots deposited into each well of a microtitre plate, meaning that in a 96-well plate, you can obtain up to 96 X 20 = 1920 data points. This is different from a traditional ELISA, where an entire well is devoted to a single type of antibody population, such that only 96 data points are acquired in one plate. Q-Plex kits can be imaged and analyzed using our high-quality, low-cost Q-View imager, or other imagers, and our Q-View Software.

Can you build a custom assay for me?
Yes, Quansys specializes in assay development. Customizing with us is easy and fast. We can help you measure specific analytes or biomarker panels. Please call or email for details and pricing. Read more on the customization webpage.
What is the shelf life of a Q-Plex kit?
Q-Plex plates are stable for at least two years when stored unopened at 4°C (unless stated otherwise on the kit). The SHRP and Substrate are only stable for 1 year and 18 months, respectively. Contact us if your unused kits are more than a year old, and we can arrange to send replacement reagents to you.

Assay Performance

How do your multiplex ELISA kits work?

The Q-Plex kits consist of a printed array of capture antibodies for a variety of biological markers. The user adds a calibrator and samples to individual wells of a 96-well plate. After incubation and washing, a mixture of biotinylated antibodies is added to the plate. This is followed by incubating with streptavidin-HRP or IR dye and is completed by capturing the light produced from adding chemiluminescent substrate with an imaging system. Pixel intensity values from the images are used to construct a standard curve and calculate the concentrations of the unknown sample for each system. 

Are the results quantitative?
Yes, the array uses a standard curve to accurately quantify samples and the curve has been designed to encompass the biological ranges for individual proteins.
How much variance should I expect in a Quansys multiplex ELISA?
The Quansys Multiplex ELISA assay has <15% CV between kit lots. Samples are usually linear out to a 1 to 64 dilution.

Test Protocol

What kind of samples can be run in the Quansys multiplex ELISA array?
The Q-Plex Array has been tested with serum, plasma, urine, and cell and tissue lysate. We have experienced no interference from FBS, 1% NP-40, 1% Tween, 1% Triton X-100, heparin (30 mg/ml), 1M urea, 20 mM EDTA, 20% citrate. SDS has been shown to interfere with the assay. Human samples containing human antibodies must be diluted 1:2 in the provided sample dilution buffer to remove potential false postives. If tissue homogenates or cell lysates are used, centrifuging is recommended to clarify samples prior to using in the assay. When using tissue homogenates, we recommend preparation in a protein-free buffer so that samples can be tested for total protein to normalize cytokine responses.
How much sample is required for the Quansys multiplex ELISA array?
Most Q-Plex kits work best with 30 µl—50 µl (total volume per well, sample plus diluent). Smaller sample volumes may be used when high levels of detectable proteins are anticipated. Samples containing antibodies MUST be diluted 1:2 in sample dilution buffer prior to running the assay.
How long does it take to complete the Quansys multiplex ELISA protocol?
Most protocols require as little as two and a half hours for completion including analysis with the Q-View Software.
Can I stop the assay once I start it?
No, for best results it is recommended that the assay be completed once started. After reading the results with a camera, the user has the option to delay data analysis to a convenient time. The IR plate may be read at any time after completion of the assay.
Do I have to use the entire 96 well plate in one assay?
Once the lyophilized reagents are reconstituted they should be used immediately. If the user desires to run several assays using the 96 well plate, we recommend the user purchase the Q-Plex Stripwell kits. These kits come with additional reagents for multiple testing periods. Customers can purchase additional reagents as needed.
How should I dilute my sample if I expect a high response for one biomarker and a low response for another?
We recommend testing each sample in step dilutions. For example, when testing cell culture supernatant for unknown cytokine concentrations; a 1:2, a 1:10, and a 1:50 dilution are typically used.

Software and Analysis

Does the standard curve encompass the lower limit of detection (LLD) for each cytokine?

The LLD is the lowest concentration of an analyte where its signal is distinguishable from the background (2 times the standard deviation of the mean of the background). This is different than the lower limit of quantification (LLOQ) which is the lowest concentration of an analyte that can be accurately measured. In many cases, the typical standard curve does not reach the LLD nor the LLOQ for a given protein. The user has an option of using additional dilutions of the calibrator mix to achieve the lower limit of quantification (LLOQ) for a given protein. A quick determination of LLOQ is to examine the backfit of your regression analysis and determine where the model no longer predicts within 80-120% of the actual standard value. I.E. the LLOQ is the lowest point where the backfit is within 80-120% of its corresponding value on the standard curve.

How is the data gathered from the CCD imager analyzed?

Q-View Software allows the user to open the plate image, mark the spots, input well assignments and select the product type. The software then automatically analyzes the pixel intensity of individual spots on the plate and processes the data. All customers can download a free trial of the software and have full access for 60 days. After 60 days, the software will still process images and calculate raw data but will no longer perform regression analysis. Visit our Q-View Software page to learn more about the software and how to start your free trial.

How long does it take to complete the Quansys multiplex ELISA protocol?
Most protocols require as little as two and a half hours for completion including analysis with the Q-View Software.
Can I stop the assay once I start it?
No, for best results it is recommended that the assay be completed once started. After reading the results with a camera, the user has the option to delay data analysis to a convenient time. The IR plate may be read at any time after completion of the assay.

Imaging and Equipment

What additional equipment (not provided in the kit) is required to run this assay?

 The user will need to provide a pipette and imager. For convenient processing, we also recommend an automatic plate washer and multichannel pipette for best results.

Will different CCD and CMOS Cameras give different pixel intensities and how will this affect my assay?

Yes, different CCD and CMOS cameras give different pixel intensities based on the sensitivity of the camera. However, this will not affect assay performance or standard curve generation as the pixel intensities are relative values.

I don't have access to a CCD camera system. Is there a testing service?

Yes, your samples can be mailed to Quansys where they will be tested using the Quansys Multiplex ELISA platform. Data, along with statistical analyses will be provided to the user within two weeks. Please contact us for details and pricing.

As researchers and problem solvers ourselves, we understand the value of sound data. We are proud to be a part of research that can better the world. We value the relationships, partnerships, and friendships that we have built with the people who trust and use our technology. We are committed to building these relationships. You can count on us to answer the phone and take time to thoroughly address questions or concerns about any of our products. In an industry that is reputed for grandiose claims, we trust that our quality standards and our customer service set us apart from the competition. If you’re happy with our products or if you think we can do something better, we hope you will let us know.