TITRIVINs play an essential role in the validation of analytical methods.
They are used to carry out the various studies required to validate an analytical method.
In fact, as part of their accreditation under ISO 17025, testing laboratories must validate non-standardized or adapted analytical methods, but also confirm the performance of standardized methods.
This validation (or confirmation) consists in declaring the method's suitability for meeting customer requirements, and therefore for its intended use.
Two standards established in the fields of water and agri-food, are today applicable for quantitative analysis methods in oenology:
The NF T90-210 "Water quality - Protocol for initial evaluation of the performance of a method in a laboratory"
The NF V03-110 "Analysis of agricultural and food products -. Protocole de caractérisation en vue de la validation d'une méthode d'analyse quantitative par construction du profil d'exactitude"
Validation of the performance of an analytical method will include :
a study of the calibration function applied in a given calibration domain, if necessary,
a study of the method's accuracy on samples associated with a reference value
a study of the presupposed limit of quantification, if necessary,
a study of repeatability on actual laboratory samples,
an additional study of interferences and/or specificity, if necessary.
The use of TITRIVIN in these different experimental designs is possible.
Principle of the study of the calibration function
In these standards, the evaluation of the calibration function is carried out under intermediate fidelity conditions (different days and different operators). To interpret the performances obtained, we check that the biases obtained on each standard are acceptable in relation to a maximum acceptable deviation (MAD) which characterizes the required performance of the calibration function.
This maximum acceptable deviation (MAD) may be derived from a regulatory or normative requirement as appropriate, or set by the laboratory in coherence with a quality control acceptance criterion or with the uncertainty of the analysis.
Principle of the accuracy study
Both standards propose an accuracy study based on acceptability limits (the EMA) around a reference value (value taken from our TITRIVIN certificate, for example). A graphical representation of the results obtained is used to build an accuracy profile.
Principle of the study of limits of quantification(1) and detection(2).
This study concerns methods whose low values can tend towards zero.
The limit of quantification can be estimated experimentally from non-zero blank values or with background noise.
In the NF T90-210 standard, the proposed approach proposes to validate a presupposed LQ defined before the start of the study.
(1) The limit of quantification (LOQ) is the smallest concentration or content of the analyte that can be quantified, with acceptable uncertainty, under the described experimental conditions of the method.
(2) The limit of detection (LOD) is the smallest concentration or content of the analyte that can be detected, with acceptable uncertainty, but not quantified under the described experimental conditions of the method.
Principle of the repeatability study
This study is a verification of performance in terms of repeatability. The comparison is established in relation to an acceptable or admissible limit in relation to the laboratory's needs.
Principle of interference and/or specificity studies
The aim of these is to verify that the analytical method's result comes solely from the analyte or is not disturbed by the presence of other compounds.