Phosphatidylethanol (PEth) detected in blood for 3 to 12 days after single consumption of alcohol—a drinking study with 16 volunteers

In most studies, the alcohol marker phosphatidylethanol (PEth) was used to differentiate social drinking from alcohol abuse. This study investigates PEth’s potential in abstinence monitoring by performing a drinking study to assess the detection window of PEth after ingesting a defined amount of alcohol. After 2 weeks of abstinence, 16 volunteers ingested a single dose of alcohol, leading to an estimated blood alcohol concentration (BAC) of 1 g/kg. In the week after drinking, blood and urine samples were taken daily; in the second week, samples were taken every other day. PEth 16:0/18:1 and 16:0/18:2 were analyzed in blood by online-SPE-LC-MS/MS. Ethyl glucuronide and ethyl sulfate were determined in urine for abstinence monitoring. Prior to start of drinking, PEth 16:0/18:1 exceeded 30 ng/mL in blood samples of five volunteers despite the requested abstinence period. Positive PEth values resulted from drinking events prior to this abstinence period. After the start of drinking, maximum BACs were reached after 2 h with a mean of 0.80 ± 0.13 g/kg (range: 0.61–1.11 g/kg). PEth 16:0/18:1 increased within 8 h to maximum concentrations (mean: 88.8 ± 47.0 ng/mL, range: 37.2–208 ng/mL). After this event, PEth was detectable for 3 to 12 days with a mean half-life time of approximately 3 days. PEth has a potential in abstinence monitoring, since PEth could be detected for up to 12 days after a single drinking event. Further investigations are necessary, to establish cut-off levels for PEth as diagnostic marker for the determination of drinking habits like abstinence, social drinking, or risky alcohol consumption.