Polymer‐spray mass spectrometric detection and quantitation of hydrophilic compounds and some narcotics

Abstract

RATIONALE High throughput screening of biofluids is essential in monitoring concentration of a variety of drugs to determine their efficacy and toxicity. Organosiloxane polymers prepared by sol-gel chemistry as sample supports and electrospray-ionization emitters in a single material and as an alternative to paper substrates, is described in this study. METHODS Hydrophobic drugs and hydrophilic streptomycin were analyzed by polymer-spray MS with an LTQ-Orbitrap mass spectrometer. Drug samples in urine (1–2 μL) were deposited on an OSX polymer, allowed to dry, then electrosprayed from the polymer tip into the mass spectrometer without sample pretreatment. The OSX polymers, whose polarity and porosity can be controlled, were prepared by sol-gel chemistry where methyl-substituted alkoxysilanes were hydrolyzed in the presence of a pore template and an acid catalyst. RESULTS Five nanograms each of 7 narcotic drugs were detected in <1 min (RSD of response <1% for each drug). Calibration curves of cocaine and streptomycin in urine was used to establish the performance of the polymer. For sample 1 (n=2), the mean recovery for cocaine was 81% with paper and 90% with polymer. Streptomycin is detected with polymer, not with paper; for samples 1 and 2 (n=3), mean recovery was 97% and 95%, respectively. CONCLUSIONS Organosiloxane polymers achieve better sensitivity analysis than paper, allowing for more accurate quantitation of both hydrophobic and hydrophilic drug compounds. The ability to tailor the polymer polarity and porosity allows for the synthesis of a wide range of polymers, and thus opens many possibilities for further development and applications.

Emerging trends in paper spray mass spectrometry: Microsampling, storage, direct analysis, and applications

“…Replacing paper substrate with an organic‐inorganic hybrid organosiloxane, polyester, and polyethylene materials is the logical next step in the field. The polymeric substrates cut to a triangle performs similarly to modified PS, in that the lack of hydroxyl groups results in a higher response of deposited analytes, increasing sensitivity (Dulay and Zare, ). The use of a conductive polymer, carbon NTs in poly(methyl methacrylate), eliminates the difficulty of extracting analyte from pores and showed a 2–25 times increase in sensitivity for organic molecules in the plasma (Song, Chen, & Zare, ).…”

Fiber spray ionization mass spectrometry in forensic chemistry: A screening of drugs of abuse and direct determination of cocaine in urine

“…28 In this way, the emergence of novel substrates to overcome substrate/analyte interactions affecting the evaluation of biological matrices by PSI-MS is notable, e.g. the use of a wooden tip was very efficient in the analysis of drugs from urine 29,30 and oral fluids 29,31 ; a synthetic hydrophobic organosiloxane polymer allowed the determination of new psychoactive substances in urine with RSD lower than 1% 32 ; and a carbon fiber was used in the detection of MA from human urine without any sample pretreatment. 33 Thus substrates with greater hydrophobicity have the ability to decrease or eliminate the hydrogen bonding interaction between cellulosic paper and polar analytes and to allow a more effective elution process while improving the analyte ionization.…”

“…33 Thus substrates with greater hydrophobicity have the ability to decrease or eliminate the hydrogen bonding interaction between cellulosic paper and polar analytes and to allow a more effective elution process while improving the analyte ionization. 32 Therefore, the use of a low-polarity polymeric fiber has provided high sensitivity in the analysis of biological samples due to its hydrophobicity, morphology, and porosity. 32,34,35 The methodologies using polymeric fibers as substrates are currently known as fiber spray ionization mass spectrometry (FSI-MS) techniques, 36,37 which are based on an electrospray generation process from porous materials through capillary flow patented by Fenn, 38 as well as on nanoelectrospray production from a mesoporous polymer discussed by Tepper and Kessick.…”

“…32 Therefore, the use of a low-polarity polymeric fiber has provided high sensitivity in the analysis of biological samples due to its hydrophobicity, morphology, and porosity. 32,34,35 The methodologies using polymeric fibers as substrates are currently known as fiber spray ionization mass spectrometry (FSI-MS) techniques, 36,37 which are based on an electrospray generation process from porous materials through capillary flow patented by Fenn, 38 as well as on nanoelectrospray production from a mesoporous polymer discussed by Tepper and Kessick. 39 Wang and co-workers showed the use of polystyrene (PS) microspheres in a hot-polymerization process to cover the surface of chromatographic paper, producing a PS-coated paper impregnated with microspheres used in the determination of therapeutic drugs, e.g.…”

High‐throughput polymer tip‐electrospray ionization mass spectrometry for enhanced detection of neopterin and biopterin in clinical urine samples

“…Therefore, there is an expectation to seek hydrophobic materials for enhanced detection hydrophilic analytes from complex samples . More recently, Dulay and Zare developed a novel polymer tip‐ESI‐MS for enhanced detection of hydrophilic analytes.…”