What sets Cayman Chemical kits apart?
The comprehensive collection of immuno- assay kits, cell-based assay kits and enzyme activity assay kits from Cayman Chemical are available in a variety of formats. These kits enable researchers to monitor biomarkers, assess cellular health and measure enzyme activity/inhibition with reliable and reproducible data.
Measure with confidence
Acetylcholinesterase (AChE) is used as the enzymatic label. With the fastest turnover rate of any enzymatic label, AChE assay kits are developed with Ellman's Reagent (containing acetylthiocholine as the substrate). The final product of the enzymatic reaction, 5-thio-2-nitrobenzoic acid, is bright yellow and can be read at 405-420 nm.
Advantages of using AChE over other labels in ELISAs
• Wider dynamic range and greater sensitivity - hydrolysis of acetylthiocholine by AChE shows true first-order kinetics with a turnover of 64,000 sec-1
• Low background - nonenzymatic hydrolysis of acetylthiocholine in buffer is absent so AChE has a low background and an increased signal/noise ratio compared to TMB
• High sensitivity and precision – average 10 percent CVs
• Completely stable enzyme unlike peroxidase - plate can be redeveloped if accidently splashed or dropped during development
• Long shelf life - unlike alkaline phosphatase tracers, AChE can be lyophilised allowing tracers prepared with unstable molecules such as LTE4 or LTC4 to be stored for over one year without activity loss
Each of Cayman’s assay kits undergoes rigorous quality testing to certify high precision and accuracy to deliver the sensitivity and specificity needed to detect biologically significant analyte levels. Cayman Chemical use an alternative approach to determine the sensitivity of their assay kits.
Competitive ELISA standard curve quantitation
Cayman provides researchers with both the 80 percent B/B0 value and the LLOD along with the assay’s high-low range and 50 percent B/B0 mid-point (the direct centre of the most reliable portion of the curve) to further qualify the ELISA’s robustness. 80 percent binding is the minimum level where reliable, reproducible data can be obtained and represents the minimal functional sensitivity outside of the range of statistical bias.
Competitors typically define by the Lower Limit of Detection (LLOD), usually considered the mean zero plus two standard deviations. While this is the lowest level of analyte detected by the kit, this range is typically not reliable nor reproducible and may reside at a concentration below the linear range of the assay. This value typically lies below an assay’s functional sensitivity range.
Sample competitive ELISA standard curve
Please note above data is example data only and does not represent a specific kit.
- Assay range - the range between the highest standard and the lowest standard.
- Sensitivity - the lowest level of reliable quantification. For competitive ELISAs, this is defined as the 80 percent B/B0. 80 percent binding is the minimum level where reliable, reproducible data can be obtained.
- Mid-point - The middle point (50 percent B/B0) of the standard curve.
- Lower limit of detection - The smallest measure that can be detected with reasonable certainty for a given analytical procedure. The LLOD is defined as a point two standard deviations greater than the mean zero value.
Immunometric (sandwich) ELISA standard curve quantitation
Cayman provides both the Lower Limit Of Quantification (LLOQ) value and the LLOD along with the assay’s high-low range to further qualify the ELISA’s sensitivity. LLOQ is the minimum level where reliable, reproducible data can be obtained. It is demarcated by a set goal for bias and precision: the lowest standard concentration in which optical density (O.D.) of the sample minus (1.64 x S.D.) is higher than the blank value of O.D. plus (1.64 x S.D.).
Many other immunoassay suppliers define the sensitivity of their assays with the LLOD, the lowest level of analyte detected by the assay. Typically, LLOQ will be found at a higher concentration than LLOD, but how much higher is dependent on the LLOQ-defined specifications for bias and imprecision.
Sample sandwich ELISA standard curve
- Assay range - range between highest standard and lowest standard.
- Sensitivity (LLOQ): lowest level of reliable quantitation defined as the lower limit of quantification (LLOQ). LLOQ is the lowest standard concentration in which O.D. - (1.64 x S.D.) is higher than the blank value of O.D. + (1.64 x S.D.).
- Lower limit of detection (LLOD) - smallest measure that can be detected with reasonable certainty for a given analytical procedure. Defined as a point two standard deviations greater than the mean zero value.
A small selection of the Cayman Chemical assay kits available are shown below. To see the full range, search our website or speak to our Cayman Chemical specialists.
Note: product availability depends on country - see product detail page.
|Cat number & supplier
|ROS Detection Cell-Based Assay Kit (DHE) CAY601290-96 wells · Cayman Chemical
CAY601290-96 wellsCayman Chemical
|Steatosis Colorimetric Assay Kit CAY10012643-1 ea · Cayman Chemical
CAY10012643-1 eaCayman Chemical
|Testosterone ELISA Kit CAY582701-96 strip wells · Cayman Chemical
CAY582701-96 strip wellsCayman Chemical
|96 strip wells
96 strip wellsview