1. Quantitative Chemical Analysis Seventh Edition Quantitative Chemical Analysis Seventh Edition Chapter 0 The Analytical Process Copyright © 2007 by W. H. Freeman and Company Daniel C. Harris

2. How to make a biosensorB 1.Find a biological receptor for your analyte. 2.Couple the binding of the analyte to some chemical or optical response. 3.Calibrate. 4.Validate…

3. Live, genetically engineered bacteria on on test strip:

4. Specimen Sample

5. Analyte 1 Theobromine Analyte 2 Caffeine

6. Sample Preparation 1: Grinding

7. Sample Preparation 2: First Extraction Interferants Analytes + simpler matrix Analytes + complex matrix with interferants

8. Sample Preparation 3: Second Extraction

9. Separation and Analysis by Chromatography 1.Small volume (20  L) of prepared sample solution is injected into chromatographic column. 2.Components are separated. 3.Individual components are detected at column outlet by absorption of ultraviolet light.

10. Chromatography: 1.Mixture of compounds in sample solution enters top of column. 2.Different compounds are attracted more or less strongly to the particles in the column (the stationary phase or packing). 3.Solvent flow causes different compounds to travel through column at different rates.

11. Detector output versus time: chromatogram. 1.As different compounds elute, peaks in detector signal appear. This plot is called a chromatogram. 2.Peak area is proportional to concentration. 3.Retention time is characteristic of the compound.

12. Analyte peaks from sample areas are compared to analyte peaks from calibration standards. 1.Standards have known concentration of analyte. 2.For example, the standard that resulted in this chromatogram may have contained 10 ppm caffeine and 10 ppm theobromine. 3.The unit ‘ppm’ stands for ‘parts per million’. So, 10 ppm means that every million grams of solution contains 10 grams of solute.

13. Standard Calibration Plot is Prepared: 1.Analyte Standard Signals are plotted versus their concentrations. 2.Linearity of these plots validates the calibration method. 3.Sample Signals are intersected with Standard Calibration Lines to compute Sample Concentrations. 4.Amounts of Analyte in Sample are determined by auditing sample preparation process.

14. Results and Error Estimates in Informative Units:

15. Information by Comparisons to Related Samples

16. Sampling Strategies to Accurately Represent Specimen

17. Sampling in Segregated Material

18. Steps in Analysis Process: 1.Formulate Question: Translate ‘is it safe’ into something measurable. 2.Select Procedure: Usually Find Existing Standard Methods of Analysis – Validated and Interferants Known 3.Sample Representatively 4.Prepare Sample: Dissolve, Digest, Extract, Filter 5.Analyze Sample: Standards and Samples, Replicates, Independent Measurements, Methods, Speciments. 6.Report and Interpret 7.Draw Conclusions Possible/Appropriate