Chapter 5: Chapter 5: Organic AnalysisOrganic Analysis

A common dose estimate for acute toxicity is A common dose estimate for acute toxicity is the LD50 (Lethal Dose 50%). This is a the LD50 (Lethal Dose 50%). This is a statistically derived dose at which 50% of the statistically derived dose at which 50% of the individuals will be expected to die. individuals will be expected to die.

Acute toxicity (LD50 mg/kg) Acute toxicity (LD50 mg/kg) of acetaminophenof acetaminophen

SpeciesOral

Rat 2680-3100

Mouse 338

Hamster 630-770

Rabbit 2640-2800

Dog 1180-1450

mg/Kg

Acetaminophen metabolites found in urineAcetaminophen metabolites found in urine

Figure 2.19 A molecular mimicFigure 2.19 A molecular mimic

Objective:Objective: You will be able to You will be able to explain the basic properties and explain the basic properties and functions of carbohydratesfunctions of carbohydrates

Organic vs. InorganicOrganic vs. Inorganic•CarbohydratCarbohydrateses•LipidsLipids•ProteinsProteins•Nucleic AcidsNucleic Acids

•WaterWater•Carbon Carbon dioxidedioxide•OxygenOxygen•MethaneMethane

CarbohydratesCarbohydrates

Readily available source Readily available source of energyof energy

Serve as raw material for Serve as raw material for synthesis of other synthesis of other moleculesmolecules

Used as a structural Used as a structural componentcomponent

Three major types is Three major types is called: called: monosaccharide, monosaccharide, disaccharidesdisaccharides

polysaccharides polysaccharides

What do all Monosaccharide's have in common?What do all Monosaccharide's have in common?

Paired ActivityPaired Activity• Create a unique Create a unique

monosaccharide based on monosaccharide based on the criteria discussed.the criteria discussed.

• After you have built your After you have built your molecule, write down molecule, write down what YOU think makes it what YOU think makes it unique.unique.

Figure 5.4 Linear and ring forms of glucoseFigure 5.4 Linear and ring forms of glucose

Figure 5.7b,c Starch and cellulose structures Figure 5.7b,c Starch and cellulose structures 

(a)

O

CH2OH

OHH

H OH

H

NH

C

CH3

O

H

H

OH

Figure 5.10 A–C

The structure of the chitin monomer.The structure of the chitin monomer.

What popular drug is created from carbohydrates?

Objective:Objective: You will be able to You will be able to state the properties of lipids and state the properties of lipids and proteinsproteins

LipidsLipids

Fats, oils and waxesFats, oils and waxes All are hydrophobicAll are hydrophobic

Three types:Three types: TriacylglycerolsTriacylglycerols PhospholipidsPhospholipids SteroidsSteroids

FATSFATS Triacylglycerol or fat is made up of 3 Triacylglycerol or fat is made up of 3

fatty acids and one glycerol fatty acids and one glycerol

Are significant to forensics because Are significant to forensics because many substances are stored in fatsmany substances are stored in fats PCB’sPCB’s Marijuana, Cocaine, etc…Marijuana, Cocaine, etc… Because they are stored, there affect may Because they are stored, there affect may

be long lastingbe long lasting

3D lipids

ProteinsProteins• Made up of a specific

sequence of amino acids– Each protein has its own

specific number of amino acids and in its own unique order

• This sequence will lead to a specific shape that will give the protein its function– Ex. Enzymes, hormones

ProteinsProteins• Proteins have many

functions in the body• A key function is that they

act as chemical messengers– Many of the illegal drugs

cause their affect because they act as messengers

EXTRACELLULARFLUID

Receptor

Signal molecule

Relay molecules in a signal transduction pathway

Plasma membraneCYTOPLASM

Activationof cellularresponse

Figure 11.5

Overview of cell signalingOverview of cell signaling

Reception1 Transduction2 Response3

Drugs that act as messengersDrugs that act as messengers• Opiates

– Morphine– Heroin

• These chemicals help reduce pain

Opiate ReceptorsOpiate Receptors

Three neurons engage in opiate action. When opiates bind to opiate receptors, a signal goes to the dopamine terminal (shown here as part of another neuron) to release dopamine. Dopamine binds to dopamine receptors, stimulating the post-synaptic cell and a positive emotional feeling

Nucleic AcidsNucleic AcidsDNADNA

Stores genetic informationStores genetic information Double strandedDouble stranded Is transcribed to synthesize proteinsIs transcribed to synthesize proteins

____________________________________________________________________________________

RNARNA Translates DNA and carries out protein synthesisTranslates DNA and carries out protein synthesis Single strandedSingle stranded

Objective:Objective: You will be able to describe the theory of You will be able to describe the theory of chromatography.chromatography.

Analyzing Organic Analyzing Organic CompoundsCompounds

• Quality versus quantity– Quality identifies exactly what it is– Quantity may be important because

larger amounts of illegal substances may carry longer jail time

• Many times substances are in fact mixtures– Drug dealers may “cut” the drugs– This requires a different technique to

identify the substance

ChromatographyChromatography

• This technique has the ability to purify substances– It rips each component from

mixture and separates it single components

• Theory of chromatography– Chemical substances

partially escape into surroundings when:

• Dissolved in a liquid• Absorbed into a solid

Dissolved in liquid Dissolved on a solidDissolved on a solid

Gas chromatography TLC

Thin Layer Chromatography Thin Layer Chromatography (TLC)(TLC)

• Separation of mixture is done by using a stationary solid phase (paper) and moving liquid phase

• Still based on solubility of each substance in the liquid

• Substances that are highly soluble move faster

Analyzing the TLC sampleAnalyzing the TLC sample• A measurement of how far

each component of a substance would then be taken– This will determine the RF value of

a substance– A substances RF value can be

used to HELP determine what it is– Not unique and other substances

may have same RF value

• A direct comparison can also be made by running a known sample versus and unknown

Activity:Activity:We need to find out who We need to find out who

wrote that note!!!wrote that note!!!• Work with your group to Work with your group to

develop a method to develop a method to determine whose pen was determine whose pen was used.used.

• You need to: You need to: – Give the names of the Give the names of the

suspectssuspects– State which method you are State which method you are

going to usegoing to use– Describe the “science” Describe the “science”

behind the methodbehind the method– Provide an outline of steps Provide an outline of steps

you are going to useyou are going to use

Gas ChromatographyGas Chromatography• Can separate substances because of

differences in solubility in a liquid– Force air to continuously move in one direction– Gas phase is moving phase, liquid phase is

stationary phase

• The chemical race– High solubility means it wants to stay in liquid– This makes the highly soluble substance move

slower

Objective:Objective:You will be able to explain how GC You will be able to explain how GC can be used for the quantitative and qualitative can be used for the quantitative and qualitative analysis of compounds.analysis of compounds.

Do Now:Do Now:• Read “Gas Chromatography” on p. 123 and Read “Gas Chromatography” on p. 123 and

only first paragraph on 124only first paragraph on 124• Differentiate between the two types of Differentiate between the two types of

columns used in GCcolumns used in GC

ActivityActivity

• Work in pairs to create a parts list Work in pairs to create a parts list for the gas chromatography for the gas chromatography machinemachine

• Make sure you draw each part and Make sure you draw each part and give its functiongive its function

• Use the diagram on p. 136 to help Use the diagram on p. 136 to help youyou

Gas ChromatographyGas Chromatography• Uses a stationary liquid phase and a

moving gas phase • Can separate substances because of

differences in solubility in a liquid– High solubility means it wants to stay in

liquid

• The chemical race– Force air to continuously move in one

direction– Gas phase is moving phase, liquid phase is

stationary phase• Need large enough area so that the molecules can

be fully separated

The GC MachineThe GC Machine• Sample is placed into the injector and

travels through the column• Carrier gas is typically nitrogen or

helium• Column is heated to keep substance

being tested in a gaseous state• As each substance in the sample

emerges from the column, it enters a detector

• Here it is ionized by a flame that creates an electric signal

• This signal creates a chart called a chromatogram

Components of a Gas Chromatograph

Inert gas

Sample injected here

This is heated to keep sample in gas state

Creates a chromatogram

ChromatogramsChromatograms• Chromatograms are plotted based on

retention time• Usually has a series of peaks which

represents each substance from a mixture

• Qualitative analysis done by comparing retention time with known samples– Not 100% reliable because two

substances may have same retention time

• Quantitative analysis is done by viewing how high the peak is

Each peak represents a different substance from the mixture

Which substance had the highest solubility?

A

B

C

D

E

Mixture of material in marijuana

chromatograms may also be able to identify substances by comparing to known standards.

Material must be a gas to Material must be a gas to enter GCenter GC

• Some material like paint, fibers and plastics cannot be readily dissolved into a liquid to go into the GC machine

• A technique called pyrolysis heats these materials so they decompose into gaseous materials– These materials are then injected into

the GC machine

Objective:Objective: You will be able to explain how the mass You will be able to explain how the mass spectrometer can be used to specifically identify a spectrometer can be used to specifically identify a substance.substance.

Do Now:Do Now:• Read the chapter Read the chapter

summary on p. 142-143summary on p. 142-143• Give three things that you Give three things that you

learned the best in this learned the best in this chapterchapter

Mass SpectrometerMass Spectrometer• As the gas leaves the GC, it enters As the gas leaves the GC, it enters

the MSthe MS• Within the MS, a beam of Within the MS, a beam of

electrons is shot at the substance electrons is shot at the substance breaking it down into fragmentsbreaking it down into fragments

• These fragments pass through an These fragments pass through an electric field which separates electric field which separates them by their massesthem by their masses

• The fragment masses are then The fragment masses are then recorded on a graphrecorded on a graph

• Each substance breaks down into Each substance breaks down into its own characteristic patternits own characteristic pattern

MASS

MS of CaffeineMS of Caffeine

Objective:Objective: You will be able to discuss the various You will be able to discuss the various properties of lightproperties of light

Do Now:Do Now:• Read “Electrophoresis” on Read “Electrophoresis” on

p. 131-132p. 131-132• How are the processes of How are the processes of

electrophoresis and TLC electrophoresis and TLC similar? Different?similar? Different?

• What is electrophoresis What is electrophoresis used for?used for?

Pair WorkPair WorkRead page 136-137 (The Read page 136-137 (The

Spectrophotometer)Spectrophotometer)

Explain how a spectrophotometer Explain how a spectrophotometer works byworks by

giving the function of the:giving the function of the:

Radiation sourceRadiation source

MonochromatorMonochromator

Sample cellSample cell

Detector and Detector and RecorderRecorder

Explain how samples are preparedExplain how samples are prepared

                                                  

       

                                                  

       

Objective:Objective: You will be able to explain how the You will be able to explain how the ultraviolet, visible and infrared spectrophotometer can ultraviolet, visible and infrared spectrophotometer can be used in qualitative analysis.be used in qualitative analysis.

Do Now:Do Now:• Read “Absorption of Read “Absorption of

electromagnetic radiation” on electromagnetic radiation” on p. 135-136p. 135-136

• How does spectrophotometry How does spectrophotometry work?work?

• Relate energy requirement to Relate energy requirement to absorptionabsorption