Rox FIX-A is a chromogenic assay kit for quantitative determination of human Factor IXa (FIXa) contamination in human Factor IX (FIX) concentrates.
The kit method comprises activation of human FX by sample FIXa in the presence of FVIII, thrombin, calcium ions and phospholipids. Generated FXa is directly proportional to the FIXa activity in the sample and is measured through hydrolysis of a chromogenic FXa substrate.
- Chromogenic kit based upon FXa generation.
- Quantification limit = 0.02 mIU/ml FIXa.
- Detects a preactivation level in the order of 0.002%.
- Reconstituted reagents are stable for 72 h at 2-8°C.
- Reagent 1 (2 vials)
Reagent 1 contains lyophilized Factor VIII and human FX. Reconstitute with 2.8 ml water. Allow to stand for 5 min at 20-25°C with intermittent gentle mixing for complete reconstitution.
- Reagent 2 (2 vials)
Reagent 2 contains lyophilized thrombin, calcium chloride and phospholipids. Reconstitute with 4.0 ml water. Allow to stand for 5 min at 20-25°C with intermittent gentle mixing for complete reconstitution.
- FXa Substrate, 5 ml (1 vial)
Liquid solution of chromogenic FXa substrate (Z-D-Arg-Gly-Arg-pNA), 2.5 mmol/l, containing a thrombin inhibitor. Ready to use.
- FIXa Diluent Buffer, Stock Solution, 20 ml (1 vial)
Liquid stock solution of diluent buffer. Before use, dilute 1 + 9 with water to obtain a 0.05 mol/l Tris-HCl buffer working solution, pH 7.5 with 1% bovine serum albumin.
Note: All reconstitutions and dilutions should be made with water of a quality of at least NCCLS Type II water.
FIXa activity in FIX concentrates is determined in a chromogenic method, in which human FX is activated by contaminating human FIXa in the FIX concentrate in the presence of FVIII, thrombin, calcium ions and phospholipid. The amount of generated human FXa is determined from the hydrolysis of a chromogenic FXa substrate. The sample FIXa activity is determined by the slope ratio model in which the potency of the sample is calculated vs. a FIXa standard with potency expressed in International Units (IU).