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Lecture 9. Volatiles. Determination Various GC techniques. Partition Coefficients of some common solvents Water / air, 40º C Cyclohexane 0.08 Hexane 0.14 Xylene 2.4 Toluene 2.8 Benzene 2.9 Dichloromethane 5.6 Ethyl acetate 62 Butanone 140 Butanol 650 2-Propanol 830

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lecture 9

Lecture 9

Volatiles

slide2

Determination

Various GC techniques

slide3

Partition Coefficients of some common solvents

Water / air, 40º C

Cyclohexane 0.08

Hexane 0.14

Xylene 2.4

Toluene 2.8

Benzene 2.9

Dichloromethane 5.6

Ethyl acetate 62

Butanone 140

Butanol 650

2-Propanol 830

Ethanol 1360

Dioxane 1620

slide4

GC/FID

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

a source aqueous solution (blue)

slide5

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

slide6

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

slide7

Dannon

Yogurt

Grape

Juice

SP-1500

100ºC 2 min

10ºC/min to 160ºC

slide8

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

slide9

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

slide10

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.

slide13

isoflurane

desflurane

enflurane

halothane

methoxyflurane

sevoflurane

ad