User-suplied inputs: Column B Concentrations of the standards (x) Column C Instrument readings of the standards (y) Column J Instrument Readings of the unknowns (InstrumentReading) Calculated outputs: Cell B28 n=number of x,y data points Cell B27 sumx=Sx Cell C27 sumy=Sy Cell D27 sumxy=S(x*y) Cell E27 sumx2=S(x*x) Cell F27 sumx3=S(x^3) Cell G27 sumx3=S(x^4) Cell H27 sumx2y=S((x^2)*y) Cell B30 D=n*sumx2*sumx4+2*sumx*sumx2*sumx3-sumx2^3-sumx^2*sumx4-n*sumx3^2 Cell B31 a=(n*sumx2*sumx2y+sumx*sumx3*sumy+sumx*sumx2*sumxy-sumx2^2*sumy-sumx^2*sumx2y-n*sumx3*sumxy)/D Cell B32 b=(n*sumx4*sumxy+sumx*sumx2*sumx2y+sumx2*sumx3*sumy-sumx2^2*sumxy-sumx*sumx4*sumy-n*sumx3*sumx2y)/D Cell B33 c=(sumx2*sumx4*sumy+sumx2*sumx3*sumxy+sumx*sumx3*sumx2y-sumx2^2*sumx2y-sumx*sumx4*sumxy-sumx3^2*sumy)/D ypred=a*x^2+b*x+c Cell E29 ssy=S(y-meany)) Cell F29 ssr=S(y-ypred^2) Cell H29 R2=1-(ssr/ssy) Column K Calculated concentration = (-b+SQRT(b*b-4*a*(c-InstrumentReading)))/(2*a)