**6.5 Limit of quantification**

The lower limit of quantification is the amount equal to or greater than the lowest concentration point on the calibration curve that can be measured with an acceptable level of accuracy and precision [29].

It can be calculated by the equation:

$$\mathbf{10SB/b} \tag{5}$$

**39**

1989. p. 12

*Drug Analysis*

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Where SB = Sy/x (calculated from the regression analysis data), b is slope.

#### **6.6 Method comparison**

The comparison of two methods should be carried out using a suitable statistical procedure to test if there are significant differences between them. The *t*-test provides a simple check on accuracy and the *F*-test on precision. These tests require the knowledge of what is known as the number of degrees of freedom.
