CIR 2021/808 written as

"the CCα shall be calculated as follows:

Method 1: by the calibration curve procedure according to ISO 11843-1:1997 ( 14) (here referred to as critical value of the net state variable). In this case, blank material shall be used, which is fortified at and above the RPA or LCL in equidistant steps. Analyse the samples. After identification, plot the signal where possible, or the recalculated concentration against the added concentration. The corresponding concentration at the y-intercept plus 2,33 times the standard deviation of the within-laboratory reproducibility at the intercept equals the decision limit. This method is applicable to quantitative assays only. Decision limits obtained with this approach shall be verified by analysing blank matrix fortified at the calculated decision limit."

I think the formula to calculate CCα will be CCα=|(-b)/a|+2.33x SD(b) as shown below. But I'm not so sure.Does anyone know for sure what it will be like?

I saw another document and it said:CCα=(2.33 xSD(b))/a. I think it is not in accordance with the guidance of CIR 2021/808

If you have more detailed instructions, please share with me

Best regards!