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Fevition tic. <br />Cate. t '� <br />faze C <br />The con fide-nci - limits about the regression limit line are given <br />by: <br />Y - Yo + bx + (Sy.x) t (-I + 1/N + (x -x) / (x -.x) ) ) <br />for the upper confidence limit and <br />Y- Y- ..A - (Sy. x)% 1 1 /N <br />for the lower confidence limit where <br />Sy.x - ( (Yz - (Y + b(xi - x))) / (N -2) ) <br />t = student's t for P 0.05 and N-2 decrees of freedom <br />N - number of target concentrations (multiply by two if <br />duplicates are run) <br />X = the average of all target concentraticns <br />y - the average of all found concentrations <br />The detection limit is the value of x corresponding to a point on <br />the lower confidence limit curve where the value of y equals the <br />value of y on the upper confidence limit curve at x - 0. <br />This procedure is referenced in the Federal Register, 40 CFR, <br />Pert 136, Volume 49, No. 209, October 26,1984. <br />