Li-Cor Dyes IRD700/800
Biolegio is officially licensed by Li-Cor to synthesize IRDye labeled primers for use with the Li-Cor sequencers.
These near-infrared fluorescent labels consist of IRDye700(685 nm) and IRDye800(795 nm). See fig 1.
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Fig 1: Structures of IRDye700 and IRDye800
Standardly these IRD-labeled primers are spin-column purified which results in loss of uncoupled label and byproducts of the synthesis. However, unlabeled -full-length- products are not lost with this kind of purification. See fig 2.
Despite the presence of unlabeled primers in this sample, these samples are well used for different purposes.
Fig 2: HPLC results from unpurified IRD700-labeled primer ( - = abs 260 nm, - = abs 685 nm)
Alternatively, you can choose to have these primers HPLC-purified to eliminate the presence of unlabeled primers in your sample. The resulting product is >95% pure IRD-labeled primer. However do consider that HPLC purification results in a loss of yield. See fig 3
Fig 3: HPLC results from purified IRD700-labeled primer (- = abs 260 nm, - = abs 685 nm)
Quantification of IRD-labeled primers
The quantification of IRD-labeled primers is based on the presence of IRDlabel. The quantity of the primers is determined with the OD measurement at 685 nm (IRD700) or 795 nm (IRD800).
So even there is some unlabeled primers in the sample, these are not taken into account for the actual quantification.
The IRD-labeled primers are standard delivered in solution (water, TE or LoTE), They are packed in dark vials to prevent any damage by light during use, and are colorcoded; green (IRD800) and blue (IRD700).