The alcoholic beverages were rinsed by the assessors in their mouths for 30 sec and then spit out similar to a wine tasting (no ingestion or swallowing was allowed). Saliva was sampled prior to rinsing, as well as 30 sec, 2 min, 5 min and 10 min after spitting-out. Sampling was conducted using the saliva collection system salivette® (Sarstedt, Nümbrecht, Germany). The system consists of cotton swabs that are gently chewed Defactinib concentration by the assessors. Afterwards, the swab is replaced in the suspended insert of the salivette®, which is firmly closed using a stopper. The saliva is recovered by centrifugation of the salivette® at

1,000 g for 2 min. The clear saliva supernatant was used for selleck screening library acetaldehyde analysis. Analytical procedure The determination of acetaldehyde in saliva samples was conducted using either enzymatic analysis or gas chromatography. The enzymatic analysis was conducted with aldehyde dehydrogenase according to the method of Lundquist

[37, 38], which is available as commercial test-kit (acetaldehyde UV-method, Cat. No. 0668613, R-Biopharm, Darmstadt, Germany). The detection limit of the assay is 0.25 mg/l (5.6 μmol/l). For further details about the method see Beutler [39]. The test-kit instructions of the manufacturer were followed without modification. 0.2 ml of saliva supernatant were Src inhibitor used as sample solution. The enzymatic measurement was conducted immediately (within 1 hour) after saliva sampling to exclude losses of acetaldehyde due to evaporation or oxidation. The spectrophotometric measurements were performed on a Perkin Elmer Lambda 12 dual beam spectrometer equipped with automatic cell changer, which allows the software-controlled measurement of a sample series (n = 13) without manual intervention. The procedure for the gas chromatographic (GC) analysis was previously described in Org 27569 detail for the determination

of acetaldehyde in saliva after alcohol-containing mouthwash use [40]. Both the enzymatic and the GC procedure were validated for the use to determine saliva after alcoholic beverage use, which leads to higher concentrations than used in our previous validation after mouthwash use [40]. Artefactual acetaldehyde formation was excluded by analyzing blank samples (i.e. saliva before alcohol use) with addition of 50 μl of pure ethanol. All samples were below the detection limit of both the enzymatic and GC method, no artefactual acetaldehyde was formed. The method was further validated using authentic saliva samples after alcohol use (2 min). Saliva samples of five samplings were pooled and homogenized as quality control sample. The quality control sample (250 μM) was then analyzed for five times with each method. The precision of the method expressed as coefficient of variation (CV) was 9.7% (GC) and 10.3% (enzymatic method). The recovery of the method was determined by spiking blank saliva samples with acetaldehyde (n = 6). The recovery was 102.2 ± 2.9% for GC and 103.3 ± 5.9% (enzymatic method).