Surface Analysis of Blemishes on the Inner Surfaces of Aluminium Metered Dose Inhaler (MDI) Cans

The purpose of this work was to investigate the appearance of blemishes on the inner surface of aluminium MDI cans.

Surface analysis of the blemishes suggests that the stain is a water drying stain.

It was shown that the area of interest was rich in calcium, sodium and chlorine.
Analysis of a Stain on the Outer Surfaces of Aluminium Metered Dose Inhaler (MDI) Cans

The aim of this work was to analyse a stain on the outer surface of an MDI can.

XPS and ToF-SIMS were used to characterise the stain. Analysis showed the stain to be organic in nature, characterised by a series of compounds which were based on fatty acids and found in lubricating oils.
Investigation into the Molecular Weight Distribution of a Fluorocarbon Coating on Barrels of a Metered Dose Inhaler (MDI)

The aim of this work was to analyse fluorocarbon-coated MDI barrels after partial silver metallisation in order to determine the molecular weight distribution.

ToF-SIMS analysis showed:

Depositions of sub-monolayer levels of silver for silver cationisation experiments were successful. For the three-sputter deposition times, 0.5 s, 1 s and 2 s, the fluorocarbon coating was only partially covered. As expected, the silver coverage increased with the deposition time.

The coating is consistent with an oxygenated fluorocarbon material. There is also evidence for the incorporation of nitrogen-containing species on/in the fluorinated surface.

There is clear evidence for interaction between the deposited silver and the oxygenated fluorocarbon coating, there is no evidence for high mass fluorocarbon-based cations giving rise to an oligomer distribution pattern.
Analysis of Metered Dose Inhaler (MDI) Barrels

The aim of this investigation was to analyse, un-used, filled and ex DTU MDI barrels using XPS and ADXPS.

Surface analysis showed:

There was significant silicone contamination of some of the barrel surfaces. The silicone is thought to originate from the lubricant, which is applied to the barrel assembly during construction/filling.

Generally there is a clear decrease in fluorine concentration with increasing analysis depth for all the barrels. However, the size of the decreases relative to the overall concentrations are marginal but do represent a ‘thinning’ of the coating.

In general the angle dependent data shows a gradual, almost linear, transition between fluoro-carbon character and substrate character which would suggest a diffuse structure rather than a discrete layer of fluoro-carbon on the substrate

No significant trend in CF3:CF2 ratio is found for changes in sampling depth or for the different barrel conditions for any particular batch.