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

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 mass spectrometry 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 seven narcotic drugs were detected in <1 min (relative standard deviation (RSD) of response <1% for each drug). Calibration curves of cocaine and streptomycin in urine were 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 more sensitive 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.

Resonance Rayleigh scattering and resonance non-linear scattering method for the determination of aminoglycoside antibiotics with water solubility CdS quantum dots as probe

In pH 6.6 Britton-Robinson buffer medium, the CdS quantum dots capped by thioglycolic acid could react with aminoglycoside (AGs) antibiotics such as neomycin sulfate (NEO) and streptomycin sulfate (STP) to form the large aggregates by virtue of electrostatic attraction and the hydrophobic force, which resulted in a great enhancement of resonance Rayleigh scattering (RRS) and resonance non-linear scattering such as second-order scattering (SOS) and frequency doubling scattering (FDS). The maximum scattering peak was located at 310 nm for RRS, 568 nm for SOS and 390 nm for FDS, respectively. The enhancements of scattering intensity (DeltaI) were directly proportional to the concentration of AGs in a certain ranges. A new method for the determination of trace NEO and STP using CdS quantum dots probe was developed. The detection limits (3 sigma) were 1.7 ng mL(-1) (NEO) and 4.4 ng mL(-1) (STP) by RRS method, were 5.2 ng mL(-1) (NEO) and 20.9 ng mL(-1) (STP) by SOS method and were 4.4 ng mL(-1) (NEO) and 25.7 ng mL(-1) (STP) by FDS method, respectively. The sensitivity of RRS method was the highest. The optimum conditions and influence factors were investigated. In addition, the reaction mechanism was discussed.

[Effect of chymotrypsin on the urinary excretion of antibiotics in rabbits]

The effect of cymotrypsin on excretion of penicillin, methicillin, oxacillin, streptomycin and gentamycin with urine including the kidney clearance was studied on rabbits. It was found that the enzyme introduced intramuscularly in a dose of 20 mg/kg increased excretion of penicillin, methicillin, oxacillin and gentamycin by 37, 24, 26 and 16 per cent respectively. The only exclusion was streptomycin. Chymotrypsin increased the kidney clearance of penicillin, methicillin, oxacillin, streptomycin and gentamycin by 1.7, 1.9, 2.2, 1.2 and 1.5 times respectively.