Patent ID: 7736904

Claim:
A method for verifying the usability of a test element provided for use with a corresponding evaluation unit for analysis of a liquid sample, the method comprising the steps of: a) determining a first standard value (W 1 ) for at least one control parameter measured from a standard reference presented to the evaluation unit, the standard reference providing a standardized reference value (W 1 ) for the at least one control parameter; b) providing a first test element comprising a first test field to the evaluation device and determining a blank-field reference value (L 1 ) for the at least one control parameter from the first test field); c) calculating a first ratio (Q 1 =L 1 /W 1 or W 1 /L 1 ) from the reference value (L 1 ) and the first standard value (W 1 ); d) providing a second test element comprising a second test field to the evaluation device and determining a blank-field control value (L 2 ) for the at least one control parameter from the second test field; e) calculating a second ratio (Q 2 =L 2 /W 1 or W 1 /L 2 ) from the control value (L 2 ) and the first standard value (W 1 ); f) determining a deviation (Δ) between the second ratio (Q 2 =L 2 /W 1 or W 1 /L 2 ) and the first ratio (Q 1 =L 1 /W 1 or W 1 /L 1 ); and g) rejecting the second test element if the deviation (Δ) is not within a pre-determined tolerance range for the deviation (Δ).