A novel LC-MS approach for the detection of metabolites in DMPK studies.

BACKGROUND: The profiling and quantification of drug metabolites in discovery and development bioanalysis studies is playing an increasingly important role in early candidate selection. Using a conventional tandem quadrupole mass spectrometer this activity normally requires several analytical runs to acquire the necessary analytical data. RESULTS: In this article we present the use of a new tandem quadrupole mass spectrometer equipped with a novel collision cell design, which allows the rapid switching between multiple reaction monitoring and full-scan MS mode. This approach allowed for the collection of multiple reaction monitoring data and full-scan data with no loss in sensitivity, with analysis times in the 1-2 min range. CONCLUSION: A modified approach of using the multiple reaction monitoring data to trigger the acquisition of full scan MS/MS data is described, where the data is collected on the trailing edge of the LC-MS peak, thus improving data quality and throughput.

Rapid detection and identification of counterfeit and [corrected] adulterated products of synthetic phosphodiesterase type-5 inhibitors with an atmospheric solids analysis probe.

The market success of the three approved synthetic phosphodiesterase type-5 (PDE-5) inhibitors for the treatment of erectile dysfunction has led to an explosion in counterfeit versions of these drugs. In parallel a large market has developed for herbal products claimed to be natural alternatives to these synthetic drugs. The herbal products are heavily advertised on the internet and are freely available to purchase without prescription. Furthermore, adulteration of these supposed natural medicines is a very common and serious phenomenon. Recent reports have shown that the adulteration has extended to the analogues of the three approved synthetic PDE-5 inhibitors. An Atmospheric Solids Analysis Probe (ASAP) was used for the direct analysis of the counterfeit pharmaceuticals and herbal products. Using the ASAP combined with time-of-flight mass spectrometry (TOF MS) it was possible to detect fraudulent counterfeit tablets. The physical appearance of the pills resembled the pills from the original manufacturer but contained the wrong active pharmaceutical ingredient (API). Detecting adulteration for five herbal supplements marketed as natural alternatives to PDE-5 inhibitors was also possible using the ASAP. Three types of adulteration were found in the five samples: adulteration with tadalafil or sildenafil, mixed adulteration (tadalafil and sildenafil), and adulteration with analogues of these drugs.

Use of an atmospheric solids analysis probe (ASAP) for high throughput screening of biological fluids: preliminary applications on urine and bile.

A hybrid quadrupole orthogonal time-of-flight mass spectrometer (QToF) equipped with a solids analysis probe (atmospheric solids analysis probe-mass spectrometry (ASAP-MS)) has been applied to the high throughput qualitative analysis of bile (rat and dog) and urine (rat) samples. The metabolic profiles generated by ASAP-MS was less comprehensive than that provided by liquid chromatography (LC) or gas chromatography-mass spectrometry (GC-MS) metabonomic profiling, though simple types of sample preparation were found to increase the range of ions detected for bile (a complex, multicompartment sample type). While unsuited to biomarker discovery, ASAP-MS of these biofluids generated sufficiently complex metabolic fingerprints to enable them to be distinguished from each other using multivariate statistical methods such as principal components analysis (PCA). This ability to provide an effective means of sample classification suggests possible diagnostic applications.

Comparison of different fluorimetric HPLC methods for analysis of acidic polyether toxins in marine phytoplankton.

The human toxic syndrome, diarrhetic shellfish poisoning (DSP), is caused by polyether toxins that are present in bivalve molluscs but originate from some species of marine phytoplankton. During the last few years different HPLC methods with fluorescence detection (FLD) have been proposed for analysis of marine toxins, including polyether toxins, in shellfish and phytoplankton. Several derivatization reagents have been proposed in the literature, with the aim of converting the acidic DSP toxins into their corresponding fluorescent derivatives. In this work we report results obtained from HPLC-FLD analysis of extracts from phytoplankton, including Dinophysis spp.,harvested off the south-west coast of Ireland. Three different reagents were used for fluorescent derivatization: 3-bromomethyl-6,7-dimethoxy-1-methyl-2(1H)-quinoxalinone (BrDMEQ), 9-chloromethylanthracene (CA), and "in situ" 9-anthracenyldiazomethane (ADAM). Derivatization was performed under conditions previously optimised. The DSP derivatives were cleaned using different SPE procedures then analysed by HPLC-FLD. In this study, the use of BrDMEQ, CA, and "in situ" ADAM was compared in terms of sensitivity and selectivity. Evaluation of HPLC methods for analysis of DSP toxin derivatives was also conducted; the presence of okadaic acid (OA), dinophysistoxin-2 (DTX-2), and pectenotoxin-2 seco acids (PTX1SAs) was detected in the sample extracts studied.