Help with this question please! Breathalyzer tests are used for routine roadside

Question

Help with this question please!

Breathalyzer tests are used for routine roadside and screening and substantiation of arrests from impaired driving. This measurement is quick, portable, and non-invasive. A predetermined factor is used to convert the breath alcohol level to a blood alcohol level, but this conversion varies between people. If an accident, injury, or death has been the result of suspected impaired driving, the blood alcohol level is often determined directly by analyzing a blood sample with gas chromatography.

A 5.00 mL blood sample from a suspect is spiked with 0.500 mL of aqueous 1% propanol internal standard. A 10 ?L portion of the mixture is injected into the gas chromatograph and the peak areas are recorded. Standards are treated analogously. The table below shows the results of the calibration and the analysis of a blood sample.

Pct. Ethanol (wt/vol)

0.020
0.050
0.100
0.150
0.200 Unknown

Peak Area Ethanol 114
278
561
845
1070
782

Peak Area Isopropanol 457
449
471
453
447
455

Determine the driver’s blood alcohol (i.e. ethanol) level for the data.

(a) What is the blood alcohol level (as % wt/vol)? (b) Is the level above the legal limit in BC?

Explanation / Answer

The table is not clear in the question, but I guess it looks like this;

a) The peak area ratio for ethanol:isopropanol in 0.200 wt/vol ethanol is = 1070:447

So unknown peak is =1070*455*0.2/447*782 = 0.278 wt/vol.

b) This limit is an extreme and above legal limit.

Thank you!!!!

Pct. Ethanol (wt/vol) Peak Area Ethanol Peak Area Isopropanol 0.020 114 457 0.050 278 449 0.100 561 471 0.150 845 453 0.200 1070 447 Unknown 782 455

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