2. Analytical Chemistry 2001 chrupn@lsu.edu Dr Kresimir Rupnik, Ph.D. LSU, Fall 2015

3. If you want special accommodations, contact Office of Disabilities Comments about the syllabus

4. The course web site : Moodle Syllabus, E-mail, Phone News updates, schedule/exams calendar Lecture notes/supplements (print important pages !!!!!!, 4 or 6 on one page). You can fill in what is needed during the lecture!!! HW, pre- Exams Check for updates and notes!!!! E-mail if you have questions, e-mail to report interesting of difficult parts from reading a night before the class

5. If you want to do more-and get some credit for it… Read additional material from the textbook Read articles in Analytical Chemistry (Science, Nature, JACS.. also may have relevant research). Check websites

6. Introduction to The Analytical Process: Analytical Chemistry in application Chapter 0 (read it !)

7. Chapter 0 contains IMPORTANT take home messages about the Analytical Chemistry: What, why, how Most answers are given in this “representative” example which deals with the analysis of chocolate. Q; What are we analyzing for? A: Analytes: caffeine and theobromine. Q: Why are we analyzing? A: We have a well defined goal related to some application such as are quality, CSI, etc……The questions asked here could be: How does the amount of caffeine compare with the quality of chocolate, say which is better white or dark chocolate? Or : Are the two chocolate samples from the same origin, say the one that a crime suspect is eating and the one that was found at the crime scene – and both have similar packing?

8. … and last but not least important question: Q : How can we (or a CSI lab) find the caffeine and its quantity in chocolate? A: Find or make the procedure. In chemical analysis that is a process that can be described in terms of 7 important steps The real life analytical chemists knows the procedure, that is knows general steps in a Chemical Analysis

9. 0-2 IMPORTANT THM: 7 General Steps in Chemical Analysis Formulating the question Selecting analytical procedures Sampling Sample preparation Analysis (Chemical or Physical) Reporting and interpretation Drawing conclusions Clicker!!

10. STEP 1: Formulating the question: I need to know what I am looking for! Only then I can select an analytical procedure

11. STEP 1: Formulating the question: I need to know what I am looking for! Only then I can select an analytical procedure

12. STEP 2, selecting analytical procedure Choices of methods, more on methods throughout the textbook. Signal analysis, more in the first 5 chapters

13. Caffeine again: HPLC p. 4 High Performance (Pressure) Liquid Chromatography Instrument, more on HPLC we will learn in “Separations”, Chapter 23 and on

14. STEP 3: SAMPLING Sampling: how many chocolate bars, which chocolates? Constructing a representative sample (Box 0-1, p.7): random, homogeneous, inhomogeneous, segregated material, composite sample STEP 4: SAMPLE PREPARATION, Sample preparation (for chemical analysis): transforming a sample into a state that is suitable for analyis. More in chapter 28

15. STEP 3, STEP 4: terminology SAMPLES: Analytical chemist takes SAMPLES (small parts) of the materials for analysis. ALIQUOT: A small portion of the sample. Aliquotes masses are measured before analysis! ANALYTE: The compound you want to measure. SAMPLE is ANALYZED for a compound or analyte. Elements, ions, molecules, compounds are identified in sample (example: penicillin in antibiotic). A sample is ANALYZED for elements, ions, molecules, compounds (example: for penicillin). If the amount of elements, ions, molecules, compounds in the sample is found, we use the word quantitation (amount of penicillin in the sample is found). An ASSAY for a compound or analyte If we intend to determine what fraction of a sample is some named material, we use the word determination or ASSAY. The named material is called the ANALYTE. We can run an assay for that material.

16. PROCEDURES, PROTOCOLS, TECHNIQUES: A protocol is a fixed sequence of actions (events) to be carried out (example: by US EPA). These methods commonly define: -sample handling requirements -analytical TECHNIQUES VALIDATION: We need a validation of a new method by showing that its results agree with those obtained using older (other), accepted procedures. When validated, we know that the procedure measures what the analyst says it measures on a specific type of sample.. INTERFERENTS: They are “the enemy”. Interference occurs when a species (other compounds than analyte) contribute the instrument signal intensity or amplitude, by increasing it or decreasing it. So it looks like if there is more or less of the analyte then the real concentration. Interfering species determine what is the best method and protocol. We can MASK them by other chemicals so they do not interfere. NOTE : Analytical chemistry has its own language-learn it (see the “Terms to Understand at the end of the chapter). You can more about these concepts in chapters 0, 5, 28

17. STEP 5: Chemical (or Physical) Analysis Qualitative analysis: which substance Quantitative analysis: how much of it Note: Analytical Chemistry is a Science that helps improve methods of analysis. Novel directions in analysis usually also include smaller, faster, simpler cheaper methods.

18. Our choice was HPLC –how it works? Column ~25cm long where the separation takes place

19. HPLC Chromatography, p. 4 Fig 0-4, the column

20. Results of the Caffeine Analysis: Chromatogram, it shows time on the x-axis and detector response or intensity of the signal on the y-axis. Note the three analytes in this example arrive at different (retention) times!!!

21. CHAPTER 00: Unnumbered Figure 0-3

22. CHAPTER 00: Unnumbered Figure 0-4

23. CHAPTER 00: Figure 0-7

24. CHAPTER 00: Figure 0-9

25. CHAPTER 00: Figure 0-10

26. HANDOUTS Textbook p 5 and6 Figures 0-5,0-6 and 0-7 Can you tell what is going on here?

27. CHAPTER 00: Figure 0-11

28. CHAPTER 00: Figure 0-12

29. CHAPTER 00: Figure 0-13

30. Analytical “two-step” 1 st step: Calibration with known standards. Use standards, pure compound same as analyte with known concentrations and record the reading on the instrument. Form a new diagram (Figure 0-7) to get the calibration curve – you can use Excel fitting. 2 nd step: Measurement of analyte and quantitative analysis from that known calibration curve.

31. STEP 6: Data Analysis and Reporting This is what we will do in chapters 3, 4 and 5. We will discuss the so called statistical analysis which will give us uncertainty (error) limits to our data presentation and interpretation of our results. It will provide us with the limits of confidence and consequently the limits for possible answers to our question. An example: After such analysis was done we can answer the question about caffeine in our chocolate: Table 0-2.

32. SIGNALS Total analysis technique & Concentration techniques S A (signal due to analyte) =k C A (concentration of analyte) CALIBRATIONS -Accuracy, precision, sensitivity, selectivity, detection limits, noise -Robust and rugged method -Scale of operation (analytes classification ) STEP 6: terminology

33. There are methods how to calculate the best fit: linear regression of straight-line calibration curves Calibration curve shows the response of the instruments signal to different concentrations (quantities) of the analyte. It is done by the measurement of standards before the measurement of analyte!! Standards are prepared carefully, not from sample!!

34. STEP 6:Reporting and STEP 7: Interpreting results Analysis of dark and light chocolate, grams of analyte per 100g of chocolate AnalyteDark chocolate White chocolate Theobro mine 0.392+-0.0020.010+-0.007 Caffeine0.050+-0.0030.0009+-0.0014 **uncertainties =standard deviation

35. CHAPTER 00: Table 0-1

36. CHAPTER 00: Table 0-2

37. STEP 7 : Conclusion

38. Note on the methods Not all instruments are “ BIG” lab equipment. Read about biosensors, p 1 of your textbook.

39. Note on analytical Chemistry Applications Industry (almost all need QC and analysis- food, materials, …) Bio-Medicine (the basis of diagnosis, individual susceptibilities, changes..) Environment (QC, monitoring, regulations) Law (CSI,..) Others SEE ALSO: Analytical Chemistry Division at ACS and NSF. Check the pending changes in classifications! For new instrumentation see also DOE. For new protocols and standards NIST. For medical applications see NIH.

40. 1. Measurements-Basic Tools -qualitative aspects (chemistry, physics) -quantitative aspects (numbers, units, uncertainty) A SHORT REVIEW

41. Reading: Chapter 1

42. CHAPTER 01: Opener A

43. CHAPTER 01: Opener B

44. CHAPTER 01: Opener C

45. 1-1Units of Measurement SI Units (from 1960) = Metric system There are two types of units for measured physical quantities (=number and unit): (1) 7 fundamental (or base) units:IMPORTANT and (2)(many) derived units obtained from base units (example velocity).

46. Mole = unit for the number of objects 6.02 10 ^23 objects is in a mole. 6.02 10 ^23 of oranges is one mole of oranges. 6.02 10 ^23 = Avogadro’s number = 1 mole of objects Q: Who found or measured Avogadros’ number first?

47. Units of Measurement: SI Units Powers of ten and exponential (scientific) notation are used for convenience with smaller or larger units in the SI system.IMPORTANT

49. There is more….

51. Length and Mass Length and Mass: meter (m) kilogram (kg). (1 kg = 2.2046 lb.) SI Units of Measurement Temperature: Temperature: Kelvin Scale Lowest temperature possible (absolute zero) is zero Kelvin. Celsius Scale has the same temperature increment (ok. in science, but be careful !) Absolute zero: 0 K = -273.15 o C. Water freezes at 0 o C and boils at 100 o C. To convert: K = o C + 273.15. IMPORTANT

52. Examples: (1) Using two or more conversion factors: # m --------  # in. # m * 100cm/m * 1in./2.4cm = # in. (2) Conversions involving volume and density # g of 2.00in. 3 of gold if density = 19.3g/cm 3 2.54cm=1.in. and 1cm 3 = 19.3g gold 2.00in. 3 *( 2.54cm/1.in. ) 3 * 19.3g/ 1cm 3 =633g

53. Solving problems in chemistry requires careful manipulation of numbers and their associated units, a method known as dimensional analysis. dimensional analysis Given units can be multiplied and divided to give the desired units. Use known conversion factors in the form:(Desired unit / Given unit ) Desired unit = Given unit  (Desired unit / Given unit) Dimensional Analysis IMPORTANT Example: 8.50 inches in cm? Number cm = 8.50in x (2.54cm/1 in) = 21.6cm

54. CHEM2001-2 Review: Moles, concentrations etc. # moles for element “E" = # grams of “E" /atomic mass of “E" # moles for molecule “MO" = # grams of “MO"/molecular weight of MO # moles for compound “COm" = # grams of “COm"/formula weight of “COm" *YOU CAN USE CORRECT NOTATION: MOLAR MASS (MM) Example: How many moles are present in 60.0 g H2SO4 ? # moles of H2SO4 = 60.0 g H2SO4 * (1 mole H2SO4/98.0 g H2SO4) = 0.612 moles Check the numbers!!

55. 1 Molecule 6.02*10 23 Molecules..

56. Interconverting Masses, Moles, and Numbers of Particles The Mole IMPORTANT 6.02*10 23 Molecules (g/mol) Number Of molecules

57. Concentrations of solutions CONCENTRATION: the amount of solute in the dissolved in a given quantity (volume or mass) of solvent or solution. Molarity = Moles of solute / Liters of solution Molarity = (n / V) molL -1

58. What if not molecular compounds ? M and F (textbook) Formality or Formal Concentration: F The molarity of strong electrolites is called formal concentration. Formula mass (FM) The molecular mass of strong electrolyte is called FM. Note that the concept of “formal” indicates that the compound is not the compound as written, it has been dissociated or we do not know what it is exactly, that is how many are in a unit or how many ions etc. M== F, same units moles/L MM== FM (FW) same units g/mole * We will not use amu unit here.

59. When one mole NaCl is dissolved in H2O, Na+ & Cl- ions are present and no intact NaCl molecules! Term from freshman chemistry "formula weight" ( salts of strong acids and strong bases should dissolve completely). WHEN one mole CH3COOH acetic acid is placed into water not only does it dissociates into CH3COO- & H+3O ions, but also some CH3COOH remains not dissociated. Thus; all three are present in the aqueous solution. Formality again can be used to describe the solution. However, one mole of sucrose in one liter of water would be a one molar solution and not a formal one. Note: Chemists sometimes use formality to describe the initial concentrations of substances that ionize in solution, whereas their equilibrium concentrations are described in terms of molarity. Molarity describes both the initial and equilibrium concentrations of non-ionic substances.

60. .250L of 1.00M solution of CuSO 4 39.9g of CuSO 4 (FW= 159.6amu) Molarity: Moles of solute per liter of solution: How to do it??

61. Important:

62. Example: molarity of a solution 23.4 g Na 2 SO 4 * (1 mol/142gNa 2 SO 4 ) =.165 mol Na 2 SO 4 V=125mL solution (In H 2 O)= 0.125L Molarity =.165 mol Na 2 SO 4 / 0.125L = 1.32M

63. Molarity: Expressing the concentration of electrolytes What are the molar concentrations of each of the ions present in a dissolved electrolyte? Example: given: 0.025M of calcium nitrate Ca(NO 3 ) 2  0.025M in Ca 2+ what is ion concentration of (NO 3 ) - ( 2 per molecule !!) 2*0.025M = 0.050M in (NO 3 ) -

64. Molarity: Interconverting Molarity, Moles and Volume M = n/V n= V*M =.400 mol = 2.0 L * 0.200M V=n/M Molarity (.200M of HNO 3 for example ) is a conversion factor between volume of solution (2.L, for example) and moles of solute (0.400mol HNO 3, for example).

65. Molarity: Dilution, from initial concentration to the final with the SAME number of molecules (moles) only the volume changes n(initial) = n(final) Example: M initial (= 3.0M H 2 SO 4 ) * Vinitial( ? ) = Mfinal (=0.10M H 2 SO 4 ) * Vfinal (=0.450L H 2 SO 4 )

66. More Ways of Expressing Concentration All methods involve quantifying amount of solute per amount of solvent (or solution). Generally amounts are measures are masses, moles or liters. Qualitatively solutions are dilute or concentrated. Definitions:

67. Ways of Expressing Concentration Parts per million (ppm) can be expressed as 1 mg of solute per kilogram of solution. –If the density of the solution is 1g/mL, then 1 ppm = 1 mg solute per liter of solution. Parts per billion (ppb) are 1  g of solute per kilogram of solution.

68. More Ways of Expressing Concentration Mole Fraction Recall mass can be converted to moles using the molar mass. l Molality Molality = (moles of solute / kilograms of solvent) molkg -1 »Converting between molarity (M) and molality (m) requires density.

69. Ways of Expressing Concentration Mole Fraction, Molarity, and Molality

70. FYI: Normality (old unit) = (# equivalents / Liters of solution)= " N " An equivalent =“the amount of one chemical species reacting stoichiometrically with other chemical species DEPENDS ON CHEMICAL REACTION!!! An equivalent = (# g compound /MW compound) * (# H+ions, if acid) (# OH-ions, if base) (# e- lost or gained if oxidized or reduced species) So that : EW = FW/n So that: N= n x M Examples: a 1M HCl soln. would be ---> 1N HCl soln. and a 1M H2SO4 would be ---> 2N H2SO4 1M FeCl3 soln where iron is +3, would be ----> 3N Fe+3 soln

71. pH=-log[H+], What is pCl - ?

72. 1-4 Real chemical reaction: the chemical change is a transformation where atoms (physical objects) are conserved: mass, charge, protons, atoms, electrons

73. Reactants and products: 2H 2 + O 2  2H 2 O Stoichiometric coefficients in front of chemical formulas give the number of reactants and number of products. Chemical Equations: Description of Chemical Reactions in terms of Atoms and their quantities IMPORTANT

74. Quantitative Information from Balanced Equations (A  B)

75. Titration (textbook example)

79. HW and practice Complete Problem Set 1, HW 1 and pre- exam.