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The DIAsource 25OH Vitamin D Total RIA is a competitive RIA assay, based on patented monoclonal antibodies, with a novel pre-treatment step performed inside the RIA coated tubes.

The novel pre-treatment step of the 25OH Vitamin D Total RIA takes place directly in the coated tubes. It uses a unique displacement reagent that displaces the 25OH Vit D from the binding proteins. The advantage of the technique is that it works at neutral pH so it can be used in the presence of the antibodies, which is not the case for the other known methods, most of them using acidic or alkaline pH.

Furthermore, this novel pre-treatment step, which eliminates the use of organic solvent precipitation and centrifugation, highly facilitates the automation on e.g. RIAMAT, Tecan or BioTek pipetting systems. The assay uses small sample volume (25 µL) which makes it particularly suitable for pediatric samples. The incubation steps are performed at room temperature without need for dedicated equipment.

The assay is calibrated to the ID-LC-MS/MS reference method developed by Prof. Dr. Linda THIENPONT from the Ghent University in Belgium, as encompassed in the Vitamin D Standardization Program initiative. It shows a high correlation with other commercially available LC-MS/MS and RIA assays.

At first calibrators, controls and samples (serum or heparin plasma) are pre-treated to release 25OH Vitamin D2 and 25OH Vitamin D3 from Vitamin D Binding Protein (DBP). A fixed amount of 125I labelled 25OH Vitamin D competes with the 25OH Vitamin D2 and 25OH Vitamin D3 from treated samples, controls or calibrators, for a fixed amount of a specific monoclonal antibody sites immobilized to the lower and inner surface of plastic tubes. After 2 hours incubation at room temperature on a tube shaker, an aspiration step terminates the competition reaction. The tubes are then washed twice and aspirated again. A calibration curve is plotted and the total 25 OH Vitamin D (D2 and D3) concentrations of the samples are determined by dose interpolation from the calibration curve.

Catalog #: KIP1971
Format: RIA CT
Label: I125
Size: 96 tests
Sample Type: Serum
Sample Volume: 25 µL
Controls: 2 levels
Range: 10-100 ng/mL
Sensitivity: 1,63 ng/mL
Pretreatment: direct pretreatment
Incubation: 3 hours at room temperature
Shelf Life (weeks): 8