S-PLEX Sample-Testing Services

DISCOVER True Sensitivity


S-PLEX Sample-Testing Services


S-PLEX assays achieve femtogram/mL sensitivity with the precision and reliability you have come to expect from MSD. S-PLEX sample-testing services are available to clients who need sensitivity even higher than currently available from MSD assays. Now you can detect and quantitate very low abundance proteins in your samples with the confidence that you are specifically measuring your protein of interest. Our experts will work with you to understand your sample-testing needs and develop a plan that is right for you.

For Research Use Only. Not for use in diagnostic procedures.


Currently we have the following assays available for sample-testing services.

Target Analyte Limit of Detection (LOD)
Lower Limit of Quantitation (LLOQ)
Upper Limit of Quantitation (ULOQ)
Cardiac Troponin I 25 125 480,000
IFN-γ 2.5 14 56,000
IL-2 0.8 1.9 22,000
IL-4 0.7 3.6 10,000
IL-6 0.7 3.1 12,000
IL-10 0.7 2.3 25,000
IL-17A 12 42 160,000
PSA (free) 141 480 240,000
TNF-& 6.7 18 120,000
Tau 6.2 21 160,000
TSLP 1.5 60 20,000
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Sensitivity You Can Trust

S-PLEX technology utilizes a novel process to generate sensitivity that is typically 100-1,000 times greater than ELISAs. The assays detect low abundance proteins with extremely high specificity. IL-17A data are shown below.

IL-17A Calibration Curve

(A) Limit of detection (LOD) is a calculated concentration corresponding to the average signal 2.5 standard deviations above the background (zero calibrator). Lower limit of quantitation (LLOQ) and upper limit of quantitation (ULOQ) are established for the plate lot by measuring multiple levels of calibrator near the expected LLOQ and ULOQ. LLOQ and ULOQ are, respectively, the lowest and highest concentration of calibrator tested that have a %CV of 20% or less, with recovered concentration within 70-130%.

IL-17A Concentrations in Serum and Plasma
IL-17A Concentrations in Serum and Plasma

IL-17A levels were measured in 42 serum, 42 EDTA plasma, and 12 heparin plasma samples from apparently normal individuals.

IL-17A Depletion Data
Depletion Data

Six unique IL-17A specific antibodies were selected to deplete IL-17A from six normal samples (three serum and three plasma samples). Depletion antibodies were conjugated to magnetic beads and then incubated with the samples for 2 hours at room temperature, followed by testing in the S-PLEX IL-17A assay. Data are presented relative to the un-depleted control samples. All the antibodies used resulted in IL-17A depletion by 95% or more in the six samples.

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For details on performance of some of the S-PLEX assays in detecting low abundance proteins, you can download these posters:

S-PLEX Posters and Publications


Assays in Development

We are expanding our S-PLEX offering with the following assays in development; please submit an inquiry for more information on these assays.

In Development:
HIVp24 IL-21
IL-1β IL-25
IL-5 Phospho-Tau
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