Question 3 [10] 3.1. (i) Describe the differences between a linear ToF mass spectrometer and an orthogonal ToF instrument. (2) (ii) What are the advantages and limitations of these two geometries? (3) (3) 3.2. Describe three ways of introducing a sample into an ICP torch. 3.3. A chromatogram of a mixture of compound X and Y provided the following data (see Table 3.1): Table 3.1: Chromatographic data for U and V 3 Retention time (min) Mobile phase peak 0.81 Compound X 9.35 Compound Y 10.76 Peak width (at base) 0.01 1.13 1.19 (i) For compound X, calculate (correct to 3 sig figs) its retention factor. (1) (ii) Calculate (correct to 3 sig figs) the selectivity factor for compound X and Y. (1)

3 questions...

1) Study the chromatograph (below) of a mixture of Compounds A and B, run on the GCs in the teaching labs at CU Boulder. Compound A has the shorter retention time. STAAT 61 1.11 227 RT TYPE AREA XXXX XXXX XXXX AREAS 0.009 55874 44.117 ARIHT 0.61 XX XX XX 1.11 2.27 XX XX XX TOTAL AREA=XX MUL FACTOR=XX 1. What is the retention time of compound A? Compound B? 2. Which compound is present in a larger amount? 3. Which compound has the lower boiling point? 4. What would happen to the retention times of compounds A and B if the column temperature were raised? 5. You suspect that compound B is octane. What can you do to provide supporting evidence for this hypothesis?

In a chromatographic separation of two components A and B. Component A has a higher Rf value than component B. This implies that: A. Component B has a higher affinity than A for the mobile phaseB. component B elutes first in the columnC. A has a higher affinity than B for the mobile phaseD. Component A has a higher affinity than B for the stationary phase.

Kk.312.

Directions: (1) Determine the total volume of the standards by using a formula in the appropriate boxes (your instructor will help you with this). (2) Determine the concentration of Cu2+ in each standard, also using a formula in the appropriate cells. (3) Plot the absorbance as a function of Cu2+ concentration. Determine the equation for the best-fit line. 1.0 M ethylenediamine (mL) concentration Cu2+ absorbance (AU) at 550 nm 0.01 M CuSO4 5H2O H2O total volume stock Cu2+ standard (mL) (mL) (mL) (units) concentration (M) 1 0.50 0.00 9.50 0.025 0.01 2 0.50 0.50 9.00 0.031 0.01 3 0.50 1.00 8.50 0.048 0.01 4 0.50 2.00 7.50 0.153 0.01 5 0.50 3.00 6.50 0.223 0.01 0.50 4.00 5.50 0.307 0.01 7 0.50 5.00 4.50 0.384 0.01

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[1] In paper chromatography, why do some ions move only a short distance from the point of application while others move much more?

In molecular exclusion (size exclusion) chromatography, the molecules have the longest retention times. a) the larger molecules b) the smaller molecules

Question 2. (B) the DART source (direct analysis in real time) is a relatively new MS technique. What is it and how does it work? What is it useful for?