GeneChip® Eukaryotic Poly-A RNA Control Kit

index | previous question | next question

The concentrations of the poly-A RNA controls in the stock solution are as follows:

lys - 7.6 nM
phe - 15.2 nM
thr - 30.4 nM
dap - 114.0 nM

A complexity ratio is the ratio of the number of copies of poly-A control transcript to the total number of mRNA transcripts in the sample. Complexity can also be expressed as a ratio of molar amounts (since 1 mole contains 6.02 x 10^23 molecules).

Here are the calculations for the 1:100,000 concentration in terms of complexity ratio for lys when spiked into 5 µg of starting total RNA:

Calculations for lys:
Stock concentration of lys: 7.6 nM (7.6 nmoles/L)
Total dilution in final input (from Product Insert): 1:10,000 (or (1:20) * (1:50) * (1:10))
Amount of diluted poly-A spike-in volume (from Product Insert): 2 µL
(7.6 nmoles/L)*(1/10,000)*(1 L/1x10^6 µL)*(2 µL) = 1.52 x 10^-9 nmoles

Calculations for starting RNA:

Starting total RNA: 5 µg
% of mRNA in total RNA: 2%
Starting mRNA: (5 µg)*(0.02) = 0.1 µg
Average transcript length: 2,000 bases
Average MW of single base: 330 g/mole
Average MW of transcript: (2,000 bases)*((330 g/mole)/base) = 660,000 g/mole
(660,000 g/mole)*(1 x 10^6 µg/g)*(1 mole/1 x 10^9 nmoles) = 660 µg/nmole
(0.1 µg)*(1 nmole/660 µg) = 0.000152 nmole = 1.52 x 10-4 nmoles

Concentration in Terms of Complexity Ratio Calculation:

Complexity ratio, lys = (1.52 x 10^-9 nmoles)/(1.52 x 10^-4 nmoles) = 1 x 10^-5

1 x 10^-5 = 1/100,000