A 10.00 g sample containing an analyte was transferred to a 250 mL volumetric flask and diluted to volume. When a 10.00 mL aliquot of the resulting solution was diluted to 25.00 mL it was found to give a signal of 0.235 (arbitrary units). A second 10.00 mL aliquot was spiked with 10.00 mL of a 1.00 ppm standard solution of the analyte and diluted to 25.00 mL. The signal for the spiked sample was found to be 0.502. Calculate the weight percent of analyte in the original sample.

A 10.00 mL of natural water sample containing Ni2+ was pipetted into a volumetric flask and diluted to 50.00 mL with pure water. In the second 10.00 mL of natural water sample transferred into a volumetric flask, exactly 4.00 mL of a Ni2+ solution with a concentration of 5.99 mg/L was added and then diluted to 50.00 mL with pure water. The measured absorbance is A1= 0.436 and A2 = 0.663. What is the Ni2+ concentration in unit of mg/L in the natural water sample?

You are developing a procedure for determining traces of copper in biological materials using a wet digestion followed by measurements by atomic absorption spectrophotometry. In order to test the validity of the method, you obtain a NIST orchard leaves standard reference material and analyze this material with your procedure five times and obtain a mean of 12.27 ppm with a standard deviation of 0.097 ppm. The NIST sample is listed as 11.7 ppm. Does your method give a statistically valid value at the 95% confidence level?

The concentration of acetylsalicylic acid in an antipyretic tablet was determined by HPLC using a normal calibration curve. Standard solutions of acetylsalicylic acid were prepared and analysed using a 10µL loop. The results obtained for the standards are tabulated below: Conc. of Acetylsalicylic Acid (ppm); Signal (arbitrary units) 50; 6352 100; 12869 150; 19175 200; 25536 250; 31936 To determine the concentration of acetylsalicylic acid in an antipyretic tablet, 10 tablets were weighed (6.500 g total) and crushed to a fine powder using a mortar and pestle. A quantity of powder equal the mass of one tablet was added to a 100 mL volumetric flask. The tablet powder was dissolved with 20 mL of methanol and the flask was made to volume using water. The solution was filtered. A 1.000 ml aliquot was transferred to a 10 ml volumetric flask, which was then made to volume with water. Analysis was conducted using a Bio Sil HL C18, 250mm x 4.6mm column; 5um, with a mobile phase of acetonitrile:…

Tooth enamel consists mainly of the mineral calcium hydroxyapatite, Can(PO)(OH). Trace elements in teeth of archeological specimens provide anthropologists with clues about diet and disease of ancient people. Students at Hamline University measured the trace element strontium in cnamel from extract wisdom teeth by atomic absorption spectroscopy. Solutions were prepared with a constant total volume of 10.0mL. containing 0.750mg dissolved tooth enamel plus variable concentration of added Sr. \table[[Added Sr (ng/mL- ppb), Signal (arbitrary units)], [0, 28.0], [2.50, 34.3], [5.00, 42.8], [7.50, 51.5], [10.00, 58.6]] a) Prepare a graph to find the concentration of Sr in the 10mL sample solution in part per billion = n m L. (2%) b) Find the concentration of Sr in tooth enamel in part per million = μ (3%) 5. Tooth enamel consists mainly of the mineral calcium hydroxyapatite, Ca(PO)(OH). Trace elements in teeth of archeological specimens provide anthropologists with clues about diet and…