With real-time PCR (qPCR), target-gene expression levels are often normalized to the expression of a reference gene to obtain relativequantificationof expression. This normalization strategy corrects for differences in the amount of input RNA and variation in reaction efficiency. A housekeeping gene that is stably expressed in all the samples being tested is commonly used as the reference. However, in some experimental systems, it may be difficult to identify a gene with stable expression. In such cases, an external standard RNA can be added to the reaction to serve as a reference.

External Standard Kit (Lambda PolyA) for qPCR provides an external reference for qPCR normalization. The kit contains the reference RNA (λpolyA⁺ RNA-A) and primers for real-time PCR detection. A fixed amount of theλpolyA RNA can be directly added to RNA samples before cDNA synthesis with oligo-dT. Subsequently, intercalating green dye-based qPCR detection can be used to quantify the amount ofλpolyA RNA in each sample.