Methods of equilibrium concentration for the gas chromatographic determination of trace volatiles

Vitenberg, A. G.

doi:10.1016/s0021-9673(01)96211-9

Cited by 20 publications

(6 citation statements)

References 82 publications

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“…Equilibration time: the time required in reaching the static thermodynamic equilibrium between liquid and vapour phase influences the method sensitivity [18]. Several tests were performed in order to adjust the time value for the most advantageous equilibrium: time intervals ranging from 5 to 20 min, incremented by five, were used in verifying the increase in peak area of quality control samples.…”

Section: Static Headspace Parameters Optimizationmentioning

confidence: 99%

Development and validation of method for analysis of some ototoxic solvents in saliva matrix by headspace gas chromatography/mass spectrometry

Gherardi

Gordiani

Gatto

2010

Journal of Chromatography B

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Section: Static Headspace Parameters Optimizationmentioning

confidence: 99%

Development and validation of method for analysis of some ototoxic solvents in saliva matrix by headspace gas chromatography/mass spectrometry

Gherardi

Gordiani

Gatto

2010

Journal of Chromatography B

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“…15 Two types of HS sampling techniques are generally available: static and dynamic. [17][18][19][20] Although the dynamic HS technique is more sensitive than static, it is restricted to aqueous solutions containing volatile components. The static HS sampling technique is based on thermostatic partitioning of volatile compounds in a closed vial between the sample dissolution medium and the surrounding gas phase, followed by the transfer of an aliquot of the vial headspace gas containing the volatile analytes to the GC equipment.…”

Section: Introductionmentioning

confidence: 99%

Recent developments in the determination of residual solvents in pharmaceutical products by microextraction methods

2015

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“…In brief, when a dilute solution of a volatile substance is allowed to equilibrate in a closed container at constant temperature the following concentration relationship holds after reaching equilibrium: The concentration of ethanol in the airphase is proportional to the peak area response on the gas chromatogram. The partition constant (k L/V ) does not need to be known and is assumed to be the same for the aqueous ethanol calibrator and the blood sample after an appropriate dilution with internal standard (Dubowski, 1975;Vitenberg, 1991). Because the concentration of ethanol in the aqueous standard (C L ) is known and the concentration in the air-space is obtained by analysis, it becomes a simple matter to calculate the concentration of ethanol in the blood samples.…”

Section: Introductionmentioning

confidence: 99%

Blood Analysis by Headspace Gas Chromatography: Does a deficient sample volume distort ethanol concentration?

Jones¹,

Fransson²

2003

Med Sci Law

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This study was prompted by a recent judgment in the Royal Courts of Justice (Gregory v. Director of Public Prosecutions, 2002) in a case of driving a motor vehicle after consuming too much alcohol (Road Traffic Act 1988). An expert witness for the defence alleged that a deficient volume of blood in the tube sent for analysis meant an excess amount of sodium fluoride (NaF) preservative, which would increase the concentration of ethanol, determined by headspace gas chromatography (HS-GC), owing to a salting-out effect. The prosecution did not produce expert evidence to rebut this argument and the drunk driving suspect was acquitted. A small volume of blood and excess sodium fluoride might have increased the concentration of ethanol in the air-space in the tube sent for analysis but this does not mean that the result of the HS-GC analysis would be higher. This follows because prior to analysis an aliquot of blood is removed and diluted (approximately 10 times) with n-propanol as the internal standard. The dilution lowers the concentration of NaF in the blood and for quantitative analysis the ratio of the ethanol to n-propanol response is measured. The use of a ratio also helps to compensate for any salting-out effect of ethanol. Our experiments showed that a deficient volume of blood and excess NaF actually lowered the concentration of ethanol by 2-3% compared with heparinised blood. Seemingly, n-propanol (n-PrOH) a 3-carbon straight chain alcohol is salted out slightly more effectively than the 2-carbon ethanol (EtOH) causing a lower peak area ratio (EtOH/n-PrOH) and a lower apparent concentration of ethanol. In a separate study, we showed that the concentration of ethanol was lowered even more when a 4-carbon alcohol (t-butanol) was used as the internal standard.

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Methods of equilibrium concentration for the gas chromatographic determination of trace volatiles

Cited by 20 publications

References 82 publications

Development and validation of method for analysis of some ototoxic solvents in saliva matrix by headspace gas chromatography/mass spectrometry

Development and validation of method for analysis of some ototoxic solvents in saliva matrix by headspace gas chromatography/mass spectrometry

Recent developments in the determination of residual solvents in pharmaceutical products by microextraction methods

Blood Analysis by Headspace Gas Chromatography: Does a deficient sample volume distort ethanol concentration?

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