3D-printed pipette-tip device for the efficient extraction of opioids from oral fluids using particulate-coated...

Integrating planar sorptive phases into pipette tips enables easier sample handling with disposable units, which is especially relevant in bioanalysis. However, the flat shape of these phases does not fit well with the tip's geometry. Consequently, the majority of the sample does not come into contact with the sorbent, thus reducing the extraction efficiency. In such conditions, the samples need to be aspirated several times to accomplish an acceptable extraction efficiency of the target compounds. This shortcoming makes the extraction tedious and slow.

In this article, a new 3D-printed pipette tip was developed to enable full exposure of the planar sorptive phase to the sample. To prove the potential of this approach, the determination of opioids in oral fluids was selected as a case of study. With the new platform, the extraction of the analytes is enhanced by a factor ranging from 3.3 to 5.1 compared to using a commercial pipette tip. The analytical performance showed competitive sensitivity, permitting the determination of the drugs in saliva. The intra-day and inter-day precision at the limit of quantification, expressed as relative standard deviation, were always better than 10.8 % and 24.7 %, respectively. In addition, the trueness (relative recovery) ranged from 87 % to 115 % for all target compounds. Notably, the use of isotopically labeled surrogates as internal standards for each compound significantly improved the analytical results.

This study deepens the potential of 3D printing for designing functional extraction devices. In this case, the extraction kinetics are positively affected by changing the geometry of the planar sorptive phase holder. The new design allows proper exposure of the sorptive material, a particle-coated adhesive tape, to the bulk sample.