Development and Validation of Seven Phosphatidylethanol Homologues in Dried Blood Spots Including Preliminary Results after Excessive Use of an Ethanol-Based Hand Sanitizer

Monitoring of phosphatidylethanol in dried blood spots and of ethyl glucuronide in hair over 6 months of alcohol consumption

The aim of this study was to monitor seven phosphatidylethanol (PEth) homologues in dried blood spots (DBS) and ethyl glucuronide in hair (EtGH) over a 6-month period of drinking while documenting the daily drinks (amount and type) of alcohol via app. A total of 23 volunteers (12 males and 11 females) aged 19-54 years were enrolled. At four-weekly intervals, capillary blood to create DBS and after 3 and 6 months, respectively, a strand of hair (proximal, 3 cm) was collected. Analyses of EtGH and PEth homologues were performed using liquid chromatography-tandem mass spectrometry. All participants consumed alcohol during the 6 months. Only one participant tested negative for both PEth and EtGH. Eight participants had PEth 16:0/18:1 concentrations between 20 and <210 ng/mL (mean: 45.6 ng/mL) but EtGH concentrations below 5 pg/mg. PEth 16:0/18:1 concentrations between 20 and <210 ng/mL and EtGH concentrations between 5 and <30 pg/mg were assigned to eight subjects, uniformly matching them in the category of socially accepted drinking behavior. Four test subjects exceeded the cutoff for social drinking behavior in both PEth 16:0/18:1 (mean: 528 ng/mL) and EtGH (mean: 84.5 pg/mg). Two participants exceeded the threshold for PEth 16:0/18:1 of 210 ng/mL in blood but remained below 30 pg EtG/mg hair. PEth showed a higher detection rate for alcohol consumption than EtGH did. Moreover, PEth concentrations reacted quickly to changes in drinking behavior, whereas EtGH concentrations remained similar over time.

Storage stability of phosphatidylethanol homologues in whole blood and dried blood spots of nonalcoholics at different temperatures over 60 days

Phosphatidylethanol (PEth) has recently become a popular direct alcohol marker for evaluating drinking behavior. This study aimed at gaining further information on the long-term stability of five PEth homologues (16:0/18:1, 16:0/18:2, 16:0/20:4, 18:0/18:1, 18:0/18:2) in whole blood (WB) and dried blood spots (DBS) stored at -80°C, 4°C, and room temperature (18°C) over a period of 60 days. Venous blood was taken from 10 volunteers (five females and five males, aged 21-40 years) with a moderate drinking behavior and a negative breath alcohol test at the time of collection. 100 μL aliquots of WB were prepared in addition to 20 μL DBS samples. The initial PEth concentrations were determined on the day of the blood collection. On days 1, 3, 5, 7, 11, 17, 40, and 60, DBS were analyzed in triplicate by means of LC-MS/MS. On these days, WB aliquots having been stored until that time were used to create further DBS in triplicate, which were subsequently stored at 18°C and analyzed in a single batch after day 60. All homologues, except PEth 16:0/20:4, were stable at -80°C in DBS and WB for 60 days. The initial PEth 16:0/18:1 concentrations remained stable in both DBS and WB in all but one volunteer's specimen at 4 and 18°C. Apart from this exception, simultaneously detected PEth homologues 16:0/18:2, 18:0/18:1, and 18:0/18:2 remained stable over at least 40 days in DBS. Nevertheless, the storage time between sample collection and analysis should be kept as short as possible if an ethanol-free sample cannot be ensured.

Formation of phosphatidylethanol and ethylglucuronide after low to moderate alcohol consumption in volunteers with a previous three-week alcohol abstinence

AIMS

Phosphatidylethanol (PEth) is only formed when ethanol is present in blood. This direct alcohol marker has been widely discussed, including the minimum amount of ethanol being necessary to form as much PEth as to exceed the threshold of 20 ng/mL in previously PEth negative subjects. In order to corroborate hitherto existing results, a drinking study including 18 participants after a 3-week alcohol abstinence was performed.

METHODS

They consumed a pre-calculated amount of ethanol to reach a blood alcohol concentration (BAC) of at least 0.6 g/kg. Blood was drawn before and periodically seven times after alcohol administration on day 1. Blood and urine were also collected the next morning. Dried blood spots (DBS) were prepared immediately from collected venous blood. BAC was determined by head space gas chromatography and the concentrations of both PEth (16:0/18:1, 16:0/18:2 and five additional homologues) and ethyl glucuronide (EtG) were analysed using liquid chromatography-tandem mass spectrometry.

RESULTS

Out of 18, 5 participants had concentrations of PEth 16:0/18:1 above the threshold of 20 ng/mL, and 11 out of the 18 subjects had concentrations between 10 and 20 ng/mL. In addition, four persons had PEth 16:0/18:2 concentrations above 20 ng/mL the following morning. All test subjects tested positive for EtG in DBS (≥ 3 ng/mL) and urine (≥100 ng/mL) upon 20-21 h after alcohol administration.

CONCLUSION

By combining both a lower cutoff of 10 ng/mL and the homologue PEth 16:0/18:2, the sensitivity to detect a single alcohol intake after a 3-week abstinence increases to 72.2%.