Lecture 9
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Lecture 9. Volatiles. Determination Various GC techniques. Partition Coefficients of some common solvents Water / air, 40º C Cyclohexane0.08 Hexane0.14 Xylene2.4 Toluene 2.8 Benzene2.9 Dichloromethane 5.6 Ethyl acetate62 Butanone140 Butanol650 2-Propanol830

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Lecture 9

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Lecture 9

Lecture 9

Volatiles


Lecture 9

Determination

Various GC techniques


Lecture 9

Partition Coefficients of some common solvents

Water / air, 40º C

Cyclohexane0.08

Hexane0.14

Xylene2.4

Toluene 2.8

Benzene2.9

Dichloromethane 5.6

Ethyl acetate62

Butanone140

Butanol650

2-Propanol830

Ethanol1360

Dioxane1620


Lecture 9

GC/FID

In 1 min, the concentration in a headspace drop (red) is close to that in

a source aqueous solution (blue)


Lecture 9

Blood alcohol

An aliquot of blood (0.200 mL) in NaF + Na2C2O4

+ 2.00 mL of 3 M NaCl with 1 mg/mL 1-propanol

In 10 mL vial for Headspace

Calibration: 0, 0.4, 0.8 , 1.6, 3.2 mg/mL EtOH


Lecture 9

Extraction from 40% K2CO3

160 ng/mL each

Detection limit is

at 1-2 ng/mL level

In practice, carry over in column

and glassware will limit

the determination

SP-1500

100ºC 2 min

10ºC/min to 160ºC

Peak-to-Peak Noise is around 0.1


Lecture 9

Dannon

Yogurt

Grape

Juice

SP-1500

100ºC 2 min

10ºC/min to 160ºC


Lecture 9

Ethanol determination at ppmv level

Some results (in ppmv):

Light sour cream 47(2) (Standard addition 48(3))

Dannon Yogurt 195(5) (Standard addition 198(8))

Kefir 12(3)

Buttermilk 16(3)

Some Yogurt samples up to 600

Grape Juice 2900 (15 acetone, 50 methanol)

Orange Juice 600


Lecture 9

Very volatile

EtOH + HONO → EtONO + HOH

ethyl nitrite

An example of chemical use:

C6H5NHOH + C4H9ONO + NH3 → NH4[C6H5N(O)NO] + C4H9OH

Amyl nitrite

Methyl nitrite


Lecture 9

Poppers

Effects are instantaneous and brief, but intense. These effects are caused by a sudden surge of blood to the heart and brain;

Light-headedness, giddiness, heat flush or heightened sensual awareness may also result. This is known as a 'head rush';

Some users may also experience the impression of time slowing down;

The effects fade two to five minutes after use;

Users are often left with a headache.


Lecture 9

Physical and Chemical Properties


Lecture 9

isoflurane

desflurane

enflurane

halothane

methoxyflurane

sevoflurane


Lecture 9

Semivolatiles: Headspace with various trap techniques

Cooled trap and GC inlet


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