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Although linked to a number of adverse health effects, studies of naphthalene are lacking in the exposure-relevant literature. This compound, a major by-product of the incomplete combustion of most organic materials (traffic vehicle exhaust, power generation, tobacco smoke, etc.), has characteristics that are in between those of volatile and semivolatile organic compounds (VOCs and SVOCs) and has consequently often been excluded from studies of both compound classes. A new, highly quantitative, rapid and spatially well-resolved micro-sampling method was developed for the sampling of naphthalene vapours in indoor, outdoor and personal air. The method is based on GC capillary columns as air samplers, solvent extraction and GC-MS analysis. For the first time, naphthalene concentrations were quantitatively determined at the surface level (around the boundary layer) and at 1 mm height intervals above an emitting surface. Minimal sampling flow rates of 5 mL min−1 were applied to reduce any geometrical or dynamical disturbance to the environmental air flow regime to a minimum. Toluene was highly efficient, precise and easy to apply in the extraction of the target compound from the GC column sampler. Method quantification was confirmed using a unique calibrated vapour generator based on an inert GC inlet. Using this source, a 13 ng L−1 limit of quantitation (LOQ) with 90% mass recovery over a linear dynamic range of five orders of magnitude in high precision and accuracy of ±13% and 35%, respectively, were determined and validated. The applicability and flexibility of the method was demonstrated by investigating the vapour concentration profiles generated “0”–20 mm above a naphthalene-emitting surface in outdoor air. The concept introduced in this research could be easily adopted for the reliable, sensitive and quantitative monitoring of other VOCs and SVOCs in different micro-spaces for various applications.

Charge states of noncovalent protein complexes in the gas phase are known to affect their propensity for unfolding and dissociation. In this work, C-reactive protein (CRP) pentamer and Concanavalin A (ConA) tetramer at different charge states were subjected to collision induced dissociation (CID) and surface induced dissociation (SID) in a modified quadrupole/ion mobility/time-of-flight mass spectrometer. Charge manipulation was achieved through solution addition of charge reducing (triethylammonium acetate) or supercharging (3-nitrobenzylalcohol) reagents. The results show that charge reduction increases the stability of the proteins to dissociation and suppresses unfolding of the precursors. While CID becomes less effective at dissociation of charge reduced CRP and ConA, SID showed better preserved subunit contacts that are useful for quaternary structure elucidation. In contrast, supercharging of CRP and ConA leads to facile dissociation into subunits even for CID. The extent of precursor unfolding also increases with greater charge. Another interesting finding is that low-charge multimer products (dimers, trimers, etc.) seem to be collapsed after being released from the complexes. Further investigation is necessary to fully understand this behavior. The data presented here suggest that charge manipulation can be used to "tune" the dissociation behavior of noncovalent protein complexes in order to obtain the most useful information desired for structural analysis.