Analytical chemistry

Question 1

Soft ionization methods:

Answer 1

Large molecules, create molecular ions, ESI, CI, FAB, MALDI, API

Question 2

Hard ionization methods:

Answer 2

Create fragment ions, EI,

Question 3

Mass spec that can be used with HPLC:

Answer 3

ESI, APPI, APCL

Question 4

Mass spec for GC:

Answer 4

EI, CI

Question 5

When to use positve vs negative mode:

Answer 5

Acids-Negative
Base-Positive

Question 6

Quadropole:

Answer 6

4 metal rods applied with voltage, selected mz will reach detector the rest will collide with the metal rods and be filtered. Used for quantative and qualative analysis.

Question 7

TOF, time of flight:

Answer 7

All ions are accelerated with the same energy, small iopns reach detector first, longer flight gives better resolution

Question 8

Tandem mass spectormetry:

Answer 8

Q1 is product ion scan, Q2 collision gas and Q3 presectutor ion scan which detects and analyzes product ion.

Product ion scan, used to determine shape of molecules

SIM/MRM single reaction monitoring / multiple reaciton monitoring, used for qualative metho in complex mixtures

Prececusor ion scan, used ot identify compounds in mixtures (such as drug detection)

Question 9

Flourescent:

Answer 9

Light source(laser), monocrhomator grater, sample holder cuvette, filter, detector photomultiplier, data analyzer. More sensitive and can detect low concentrations since it reads from a black background. Can analyze drugs, biological samples such as proteins and nucleotides, pollutions, certain metals etc.

Question 10

Atomic:

Answer 10

Hollow cathode, flame and analyte sample under, monocrhomator, detector, amplifier and computer. Has a single peak in the abspbtion spectra.Used to analyze concentraiton of specific atom.

Question 11

Molecular:

Answer 11

Light source, monochromator, cuvette, photoresistor, amplifier, detector

Can use either a poly or mono chromator/ single or double beam monochromator. Has a curve and a top of the curve wich is the lambda max. Used to analyze concentration of molecules.

Question 12

Beer lamberts law

Answer 12

A=lce

It only works when the solution is dilute, monocrhomatic light source, homogenous, can’t udnergo reactions under the light

Question 13

Electrophoresis:

Answer 13

2 samples of buffer, cations and anions, voltage and a detector. Neutral ions do not migrate, small highly charged molecules migrate faster. Electrophoretic velocity depend on voltage and electophoretic mobility which is dependant on the ion.

EOF is a flow of the buffer solution caused by the interaction between the electric field and the charged walls of the capillary. The charged walls attract counterions and repel coions in the solution, leading to a net flow of the buffer solution in the direction of the cathode.

One can change the electoosmotic flow by chaing buffer, pH and voltage.

Electrokinetic injection uses an electric field to inject the sample, while hydrodynamic injection uses pressure-driven flow.

Proteins, nuelcotide acids, ions, carbohydrates and small molcules can be analyzed

Question 14

WCOT

Answer 14

Wall-coated open tubular columns (WCOT), liquid stationary phase. Used in GC

Question 15

Porous-layer open tubular column (PLOT)

Answer 15

Adsorption chromatography
 Porous stationary phase, solid particles less common. Used in GC

Question 16

How do you calculate retention factor?

Answer 16

tr-tm/tm

Question 17

How do you calculate seperation factor?

Answer 17

k2/k1

Question 18

How do you calculate plate number

Answer 18

5.54 x(tr/0.5waev)^2

Question 19

How do you calculate resolution?

Answer 19

tr2-tr1/0.5(waev1+2)

Question 20

What is god quality for plate number and plate height?

Answer 20

High plate number low plate hieght

Question 21

How do we calculate plate height with van deemter equation?

Answer 21

H=A+B/u+Cu

A is eddy diffusion

B is longtidudinal diffusion

Cu is mass transfer