Detection limit estimated from slope of calibration curve: an application to competitive ELISA. |
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Authors: | Yuzuru Hayashi Rieko Matsuda Katsutoshi Ito Waka Nishimura Kazuhiro Imai Masako Maeda |
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Institution: | National Institute of Health Sciences, 1-18-1 Kami-Yoga, Setagaya, Tokyo 153-8501, Japan. |
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Abstract: | This paper theoretically derives a general rule that while the slope of the semi-logarithmic plot (Y vs. log X) of a calibration curve varies depending on analyte concentration, X, the slope takes a specific value at the detection limit (L(D)). This rule holds good irrespective of the shape of the calibration curve (linear or non-linear) and in this paper, is applied to competitive ELISA (enzyme linked immunosorbent assay). The following relationship is deduced: slope of log-dose B/B0 at L(D) = relative standard deviation (RSD) of blank responses] / 0.13. The L(D) obtained from the above-mentioned slope corresponds to the dose at which the RSD of dose estimates is 0.3 (= 30%). A commercial kit for 17alpha-hydroxyprogesterone is taken as an example. |
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