Rationale

The burgeoning concern of N-nitrosamine (NAM) contamination found in various pharmaceutical compositions has increased the demand for rapid and reliable screening methods to better assess the breadth of the problem. These carcinogenic compounds are also found in food, water, and soil, and they have been used in poison-related homicides.

Methods

A combination of complementary, ambient ionization methods, paper spray ionization (PSI) and filter cone spray ionization-mass spectrometry (FCSI-MS), was characterized towards trace-level residue screening of select NAMs (e.g., NDMA, NDEA, NDBA) directly from complex and problematic matrices of interest, including prescription and OTC tablets, drinking water, soil, and consumable goods. Spectral data for analyte confirmation and detection limit studies were collected on a Thermo LCQ Fleet ion trap mass spectrometer.

Results

PSI-MS and FCSI-MS readily produced mass spectral data marked by its simplicity (e.g., predominantly protonated molecular ions observed) and congruence with traditional ESI-MS spectra in under 2 minutes/sample. Both methods proved robust to the complex matrices tested, yielding ion signatures for target NAMs, as well as active pharmaceutical ingredients (APIs) for analyzed tablets, flavorants inherent to food products, etc. Low part-per-million (ppm) detection limits were observed but were shown dependent on sample composition.

Conclusions

PSI-MS and FCSI-MS were successful in detecting trace-level NAMS in complex liquid- and solid-phase matrices with little to no prior preparation. This work suggests that these methodologies can provide a means for assessing problematic pharmaceutical adulterants/degradants for expedited quality control, as well as enhancing environmental stewardship efforts and forensic investigations.

RATIONALE

By combining precision satellite-tracking with blood sampling it has been possible to use seabirds to validate marine carbon and nitrogen isoscapes, but it is unclear whether a comparable approach using low precision light-level geolocators (GLS) and feather sampling can be similarly effective.

METHODS

Here we used GLS to identify wintering areas of northern gannets Morus bassanus and sampled winter grown feathers (confirmed from image analysis of non-breeding birds) to test for spatial gradients in δ¹³C and δ¹⁵N in the NE Atlantic.

RESULTS

By matching winter-grown feathers with non-breeding location of tracked birds we found latitudinal gradients in δ¹³C and δ¹⁵N in neritic waters. Moreover, isotopic patterns were best explained by sea surface temperature. Similar isotope gradients were found in fish muscle sampled at local ports.

CONCLUSIONS

Our study reveals the potential of using seabird GLS and feathers to reconstruct large scale isotopic patterns.

Rationale

Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) of tissues became popular in the last decade. Consequently, adapting sample preparation methods for different materials turned out to be a pivotal step for successful analysis due to the requirement of sample slices of 12–20 μm thickness. However, acquiring thin sections compatible with MALDI-IMS for unusual samples is challenging, as existing histological protocols may not be suitable, thus requiring new methods. Açaí (Euterpe oleracea Mart.) seed is an example of a challenging material due to its toughness and resistance to crack, therefore our goal was to develop a methodology to obtain thin (12–20 μm) and entire sections of açaí seeds for MALDI-IMS analysis.

Methods

Different strategies were evaluated for obtaining thin sections of seeds, and the combination of the following steps was found to be the most suitable option: (i) softening of seeds by water immersion for 24 h; (ii) transversal cut of seeds to obtain half-seeds using a razor blade and a hammer; (iii) half-seeds imbibition in gelatin; (iv) samples sectioning using a cryostat at −20°C to obtain samples with 12–20 μm thickness; (v) collection of samples in an indium tin oxide-coated glass slide covered by double-sided copper tape to avoid sample wrapping and ensure adhesion after unfreezing; and (vi) storage of samples in a −80°C freezer, if necessary.

Results

This adapted sample preparation method enabled the analysis of açaí seeds by MALDI-IMS, providing spatial distribution of carbohydrates in the endosperm.

Conclusions

The adaptations developed for sample preparation will help investigate the metabolic and physiological properties of açaí seeds in future studies.