Teemu Nissilä

Rapid screening of drug compounds in urine using a combination of microextraction by packed sorbent and rotating micropillar array electrospray ionization mass spectrometry.

RATIONALE Screening of drugs from urine samples can be non-selective or laborous, using either immunological, gas chromatography/mass spectrometry (GC/MS) or liquid chromatography (LC)/MS methods. Therefore, a rapid screening method for selected drugs in urine sample was developed in a proof-of-principle manner, utilizing simple and fast techniques for both sample treatment and sample analysis. METHODS Sample treament of spiked urine samples was performed with microextraction by packed sorbent (MEPS). Five different sorbent materials (C(2), C(8), C(18), M1 (cation exchanger), and Sil (pure silica)) were tested for the MEPS. The sample analysis was performed using a circular microchip with 60 micropillar electrospray ionization (μPESI) tips combined with a mass spectrometer (either a triple-quadrupole or ion-trap mass spectrometer) without any chromatographic step. RESULTS The sample treatment/analysis setup was tested using three drug compounds at a concentration of 1  μM. We found that the C(2), C(8) and C(18) sorbents in combination with 96% alkaline methanol as an eluent worked the best. All compounds were easily detected and identified by MS/MS in spiked urine samples. The whole qualitative analytical procedure was rapid as the sample treatment together with the MS analysis took about 5  min per sample. CONCLUSIONS A rapid screening method for selected drugs from urine samples was developed, providing adequate selectivity and sensitivity, as well as a short total analysis cycle time. This new method can provide a new alternative for screening purposes, as both the extraction and analysis steps could be totally automatized.

High Sensitivity Micropillar Electrosprayionization Chip Fabricated of Silicon

We have designed, fabricated and tested a micropillar array electrospray ionization (muPESI) chip for mass spectrometer (MS) analysis of drugs and biomolecules. The chip has a lidless microstructured channel that contains a perfectly ordered array of micropillars. The typical sample volume is 2.5 mul and the sample flow in the channel is spontaneous. The limit of detection for verapamil measured with MS/MS was 30 pmol/1. The system shows also quantitative linearity (r =0.997) with linear dynamic range of at least six orders of magnitude and good stability (standard deviation < 4%) at measurement for 60 minutes.

Microfabricated electrospray ionization platform with 60 tips for high throughput mass spectrometric analyses

This paper presents a novel multi-tip electrospray ionization (ESI) platform design, which has 60 individual ESI tips. The unique feature of the design is that the tips are located at the periphery of a circular platform. The platform is fixed in front of a mass spectrometer (MS), on a computer controlled rotating table. After each MS measurement a new tip is aligned towards the MS by rotating the table electrically. Our platform design enables high throughput analyses. Sixty MS measurements were done in less than 12 minutes. The fabrication process of silicon-made platform is described in detail. We also demonstrate that a similar microchip could be made of polycarbonate using a high-throughput, low-cost injection compression molding process.