1. The following results were obtained when each of a series of standard silver solutions was analyses by flame atomic-absorption spectrometry. 25 Concentration, ng mL -1 Absorbance 5 10 15 20 30 0.003 0.127 0.251 0.390 0.498 0.625 0.763 Determine (present answers using both manual calculations and Excel generated result) the slope and intercept of the calibration plot, and their confidence limits at 95%. 2. Manual calculations: Using the data in item no. 1, estimate the confidence limits for the silver concentrations in a. a sample giving an absorbance of 0.456 in a single determination, and b. a sample giving absorbance values of 0.308, 0.314, 0.347 and 0.312 in four separate analyses. 3. Estimate the limit of detection of the silver analysis from the data in item 1.