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Lecture 9

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

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  1. Lecture 9 Volatiles

  2. Determination Various GC techniques

  3. 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

  4. GC/FID In 1 min, the concentration in a headspace drop (red) is close to that in a source aqueous solution (blue)

  5. 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

  6. 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

  7. Dannon Yogurt Grape Juice SP-1500 100ºC 2 min 10ºC/min to 160ºC

  8. 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

  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

  10. 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.

  11. Physical and Chemical Properties

  12. isoflurane desflurane enflurane halothane methoxyflurane sevoflurane

  13. Semivolatiles: Headspace with various trap techniques Cooled trap and GC inlet

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