PEth Half-Life Calculator – Calculate PEth Half Level
PEth Half-Life Calculator
Phosphatidylethanol (PEth) is a direct alcohol biomarker formed in blood only in the presence of ethanol. The half-life is the time it takes for the PEth concentration to decrease by 50% after alcohol consumption stops.
PEth Half-Life Chart
| Days Passed | PEth Remaining (ng/mL) | % of Initial PEth |
|---|---|---|
| 0 | 1000.00 | 100% |
| 1 | 868.12 | 86.81% |
| 2 | 753.55 | 75.36% |
| 3 | 653.27 | 65.33% |
| 4 | 566.19 | 56.62% |
| 4.5 (Half-Life) | 500.00 | 50.00% |
| 5 | 476.01 | 47.60% |
| 6 | 404.96 | 40.50% |
| 7 | 344.69 | 34.47% |
| 8 | 293.41 | 29.34% |
| 9 | 249.67 | 24.97% |
| 10 | 212.09 | 21.21% |
| 13.5 (2 Half-Lives) | 125.00 | 12.50% |
| 15 | 106.05 | 10.61% |
| 20 | 56.19 | 5.62% |
| 22.5 (3 Half-Lives) | 31.25 | 3.13% |
| 30 | 7.91 | 0.79% |
PEth Half-Life Formula
The formula for calculating PEth half-life is:
Final Concentration = Initial Concentration × (0.5)^(time/half-life)Where:
- Initial Concentration = Starting PEth level (ng/mL)
- Time = Number of days since last drink
- Half-life = Approximately 4-12 days (average 7 days)
How to Calculate PEth Half-Life
- Measure initial PEth concentration
- Record time elapsed since last alcohol consumption
- Use the half-life formula to calculate expected concentration
- Compare with actual measurements to verify abstinence
- Initial PEth: 800 ng/mL
- Days since last drink: 14
Half-life: 7 daysFinal Concentration = 800 × (0.5)^(14/7) = 800 × (0.5)^2 = 800 × 0.25 = 200 ng/mL
Heavy Drinker:
- Initial: 1200 ng/mL
- After 7 days: 600 ng/mL
- After 14 days: 300 ng/mL
Moderate Drinker:
- Initial: 500 ng/mL
- After 7 days: 250 ng/mL
- After 14 days: 125 ng/mL
Light Drinker:
- Initial: 200 ng/mL
- After 7 days: 100 ng/mL
- After 14 days: 50 ng/mL