UIBC - Unsaturated Iron-Binding Capacity - Infrared Laboratory Systems

The chromatic interference suppression of the Synermed® UIBC method is based upon the higher sensitivity of the chromogen used and the detection at a red wavelength, thus optimizing the signal to noise ratio.

- - - - Liquid-Stable Ready-to-Use Reagents
      - Minimal Interference from Serum Bilirubin and Lipemia
      - Extended "On-Board" Stability
      - Proven Automated Methods
      - Usable with Dialysis Patients

Principles of the Reaction

Albumin binds with bromcresol green to form a colored complex. The absorbance of the complex is quantitated at 660 nm and is directly proportional to the albumin concentration in the sample.

In the Synermed UIBC reagent system, a known amount of ferrous iron is added, in excess, to the serum at an alkaline pH to enable saturation of the unoccupied iron binding sites on the transferrin molecule.

OH-
transferrin + Fe+2 -> transferrin-Fe complex + excess Fe +2

The ferrous ion that remains unbound to transferrin is then quantitated by complexing with the chromogen 3-(2-Pyridyl)-5,6-bis(2-[5-furylsulfonic Acid]-1,2,4-triazine to form a blue chromophore which absorbs in the near-infrared region of the spectrum. The absorbance of the blue iron-dye complex is proportional to UIBC concentration and is read spectrophotometrically at 600 nm.

excess Fe+2 + chromogen -> Fe+2-chromogen complex
(yellow) (blue)

Then by subtracting the amount of unbound iron thus measured from the total amount of iron originally added to the sample, the unsaturated iron-binding capacity may be determined.

To calculate the TIBC, perform a serum iron assay on the sample. Take the result obtained for the iron assay and add the UIBC result to obtain a value for TIBC.

Special Performance Characteristics

The Synermed UIBC methodology was correlated to a widely accepted UIBC method. The calculated linear regression on 74 samples ranging from approximately 10 to 75 µmol/L (55 to 400 µg/dL) with Synermed results on the Y-axis is: Y = 0.97X - 0.7 with a correlation coefficient of 0.995.
The sensitivity of the procedure is such that an absorbance change of 0.001 will detect as little as 1.1 µmol/L (6 µg/dL) UIBC.
The average within run precision of the method was determined by assaying 30 samples of quality control material at two levels of UIBC concentration which provided the following results:

Mean SD CV

9.9 µmol/L (55 µg/dL) 0.39 (2.2) 4.0%

41.1 µmol/L (229 µg/dL) 0.33 (2.6) 1.1%
The run to run reproducibility of the method as applied to an automated analyzer was determined from the values obtained by 5 replicate analyses of quality control material assayed over a 22 batch period. The following results were obtained:

Mean SD CV

10.3 µmol/L (57 µg/dL) 0.46 (2.6) 4.5%

43.0 µmol/L (240 µg/dL) 1.20 (6.7) 2.8%

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Cat No.	Product Name	Packaging	Package Volume (mL)	Storage
IR150-X	UIBC	1x245 mL + 1x80 mL + 1x5 mL	990	0-4° C
IR150	UIBC	3x245 mL + 3x80 mL + 3x5 mL	990	0-4° C
IR151-L	UIBC Binding Buffer	6x490 mL + 6x10 mL	3,000	0-4° C
IR152-L	UIBC Chromogen	6x250 mL	1,500	0-4° C
IR150-WK	UIBC	1x25mL + 1x7.2mL	32.2	0-4° C