A double pack for 100 samples.
iRT – indexed Retention Time – is a dimensionless value that defines chromatographic retention of a peptide for a defined resin type (e.g. C18) relative to the iRT Standard. In contrast to empirical retention time, the iRT value of a peptide is stable and enables accurate prediction of peptide retention for any chromatographic setup.
The iRT Standard contains eleven non-naturally occurring synthetic peptides in a pooled mix. Peptides have been carefully optimized for stability, sensitivity and even retention time spacing over the gradient. The iRT Kit allows straightforward determination of peptide iRT values and calibration of chromatographic systems.
By calibrating your LC system with the iRT Kit you will dramatically increase the throughput of your targeted proteomics (MRM and PRM) experiments - even up to 20 times - by bundling more transitions into one run. The benefits of iRT standards are also important in the next-generation proteomic workflows such as DIA or SWATH. iRT peptides allow high-quality spectral library generation and precise normalization of your DIA or SWATH runs.
The kit components are sufficient for approximately 500 injections (or 50 samples) depending on sample volume and injection amount.
The iRT Kit is used in time resolved mass spectrometry as a two-step process:
See the Quick Reference Card for detailed information on how to use the iRT Kit.
iRT Kit reference sheet for transitions and sequence information (excel file)
FASTA of iRT peptides for shotgun search
iRT Peptides Volume Calculator (excel file)
iRT Real Sequences lists real iRT sequences and compares them to previously used nominal sequences (excel file)
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What does iRT stand for?
iRT is stands for indexed retention time. It is a dimensionless value that allows the transferring of retention time information of a peptide to different chromatographic set ups.
What are iRT peptides?
iRT peptides are 11 non-naturally occurring chemically synthesized peptides that are used in the next generation proteomics workflows to accurately calculate the indexed retention time of peptides on a chromatographic set up.
Why is it beneficial to add the iRT peptides to all my samples?
Apart from predicting the retention time the iRT peptides are used for mass calibration and QC monitoring of the LC-MS set up. In an HRM-MS experiment the iRT or HRM peptides are further used as anchor points for the data analysis.
What is the difference between the iRT peptides and the HRM calibration peptides?
On top of the 11 peptides in the iRT kit the HRM calibration kit contains additional peptides. These are used in the older versions of Spectronaut. With the new algorithm of SN 9 the HRM peptides are no longer a requirement and can be replaced with the iRT peptides if desired. This has the advantage that only one set of peptides are required for customers using all three next-generation proteomics workflows offered by Biognosys.
Do I really need to add the iRT peptides to all my runs because they make the per sample costs higher?
As of Spectronaut 9 the iRT peptides are not required in all cases for the samples used for spectral library generation. Yet, we strongly advise using them as in seldom cases spectral library generation can fail without them. For all DIA runs the peptides are required by the software. Adding the iRT peptides to the sample increase the per sample costs by less than 1% (~30cents/sample). Further, the dilution can be optimized on the newest generation of mass spectrometers to further reduce the per run cost additions.
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