INTERNAL STANDARD Propanol is sometimes used as an internal standard when gas chromatography is used to determine blood alcohol content. This is usually undertaken using a urine sample.
GC calibration standards were prepared by adding 0.50 ml of a 1% (w/v) aqueous solution of propanol to 5.00 ml of ethanol solutions of different concentrations according to table 2. 1.0 ml of each standard was injected onto the GC and the peak areas recorded
propanol (%w/v)
Ethanol (%w/v)
Total vol ml
Peak area Ethanol
Peak Area
Propanol
1.000
0.020
5.50
114
458
1.000
0.050
5.50
278
450
1.000
0.100
5.50
561
470
1.000
0.150
5.50
845
447
1.000
0.200
5.50
1070
453
Table 2
A 5.00 mL sample from a suspect driver was spiked with 0.50mL of aqueous 1% (w/v) propanol as internal standard and 1.0 ml of this solution was injected onto the GC. The peak areas for the ethanol was 782 and that of the propanol was 455
(i) Plot the calibration data and determine by the method of least squares the response factor.
(ii) calculate the concentration of alcohol in the sample.
INTERNAL STANDARD Propanol is sometimes used as an internal standard when gas chromatography is used to determine blood alcohol content. This is usually undertaken using a urine sample.
GC calibration standards were prepared by adding 0.50 ml of a 1% (w/v) aqueous solution of propanol to 5.00 ml of ethanol solutions of different concentrations according to table 2. 1.0 ml of each standard was injected onto the GC and the peak areas recorded
| propanol (%w/v) | Ethanol (%w/v) | Total vol ml | Peak area Ethanol | Peak Area Propanol |
| 1.000 | 0.020 | 5.50 | 114 | 458 |
| 1.000 | 0.050 | 5.50 | 278 | 450 |
| 1.000 | 0.100 | 5.50 | 561 | 470 |
| 1.000 | 0.150 | 5.50 | 845 | 447 |
| 1.000 | 0.200 | 5.50 | 1070 | 453 |
Table 2
A 5.00 mL sample from a suspect driver was spiked with 0.50mL of aqueous 1% (w/v) propanol as internal standard and 1.0 ml of this solution was injected onto the GC. The peak areas for the ethanol was 782 and that of the propanol was 455
(i) Plot the calibration data and determine by the method of least squares the response factor.
(ii) calculate the concentration of alcohol in the sample.
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