The oral fluid (OF) became a widely used sample for drugs of abuse preliminary screening, particularly in on-site (roadside) testing. However, confirmatory analysis must be performed in most cases when the initial test is based on immunoassay. The dry OF spot as an analogue to dry blood spot can be applied as a suitable technique for sampling, storage and transportation of the sample as well as fast sample-prep procedure.

Dry OF spot were prepared from devices used in roadside OF tests (Drager Drug Test 5000 cartridges) or from collected OF samples. Sample (100-200μL) was placed on 3-th layers paper filter and dried on air at room temperature. Acetonitrile extraction (3mL) was performed in the presence of 100μL 1M NaOH. After sonication (3min) the extract was separated and concentrated under nitrogen up to 50μL and analyzed by GC-MS.

Using the procedure described above it is possible to detect the presence of different psychoactive drugs as methadone, codeine, heroine, acetylcodeine, cocaine, amphetamine, metamphetamine in saliva. The presence of each compound found in dry OF spot was confirmed by liquid-liquid extraction of the native OF. A comparative study of 71 cases, preliminary tested using Drager Drug Test 5000 was performed. The highest number of discrepancies was found for amphetamine, metamphetamine and MDMA – 5/11 were false positive. An increased number of combined drug usage was detected, which was named THC- based (13/38) and methadone-based (5/38). In all cases a blood sample was analyzed also.

The analytical procedure presents a direct analysis of dry OF samples. The advantages of spot analysis are stable sample, pre-concentration (on spot), and fast and simple sample treatment with decreased matrix contamination. The dry spot can be successfully used as confirmation sample for DRUID-analyses.