Issue link: https://www.e-digitaleditions.com/i/1546206
Inhalation August 2026 21 be when evaluating those products as they mimicked young pediatric use. Inhalation: What issues did you and your EPAG colleagues help MSP solve for the first 50 to 100 NGIs? Jolyon: Many of the NGI parts, such as the lid, the seal body and the pre-separator were coated with nickel. e purpose of the nickel coating was to maintain electrically conductive surfaces to eliminate static- charge build-up. Users saw frequent tarnishing of those parts, especially the pre-separator. erefore, we encouraged users to take pictures of the parts so that MSP could review and take corrective action. It turns out there are a host of detailed issues, includ- ing part cleanliness and the specific chemistry of the nickel- containing plating baths, that affect coating nickel onto aluminum, with its troublesome nat- ural oxide surface layer. ese issues were eventu- ally ironed out with regular feedback to MSP from industrial users. Inhalation: Did you encounter any difficulties transitioning to the NGI from the Andersen Cascade Impactor? Jolyon: Not really. In fact, I noticed an immediate improvement in productivity in terms of the number of APSD characterizations that could be done each day, largely due to the NGI's simpler single-body design that avoided placing stages in the wrong order. e Andersen Cascade Impactor (ACI) requires complete disassembly after each run to recover the collected fractions of the active pharmaceutical ingre- dient on the stages. In this respect, another important feature of the NGI was the introduction of the frame, which requires only a single action to assemble all the collection cups for insertion into the body of the NGI. Inhalation: Were there problems with particle/droplet bounce on the collection cups? Daryl: e collection surfaces of the cups in the first 25 or so NGIs were smooth at the micron size scale, just like native sheets of stainless steel. is surface caused aqueous solutions to "bead up" periodically and made it difficult to apply coatings to minimize particle bounce. Coating with a surfactant was not entirely sat- isfactory either because when the air flow started, this material tended to move away from the cup surface immediately underneath each of the nozzles of some stages. MSP solved this coating problem by purposely roughening the surface with glass beads, achieving a surface roughness in the range of 0.5 micron to 2.0 micron, as described in the second republished article in this issue. e problem was resolved satisfactorily and customers continued to successfully coat using a ments to check for small burrs or other flaws on the parts they made for us. ose inspections helped sub- stantially in perfecting the nozzles. We also learned a lot about electropolishing. One day I received an e-mail with photos of an NGI (with a serial number greater than 500), that had been relayed from an irritated customer who was complaining about the nozzle on stage one being "out of round." While we found a mistake that was occur- ring at one of our machine shops, surprisingly our investigation revealed that testing a nozzle with a go/ no-go pin gauge is insufficient to determine whether it has the correct diameter. We then launched into a study of nozzle roundness on all stages and imple- mented a quantitative specification of roundness for all future nozzles. Another surprise was in receiving a returned NGI that had substantial corrosion all over the unit. We traced the problem to residual acid from the anod- ization of the aluminum bottom frame. e situa- tion reminded us that when selling hundreds of a single system, it's not possible to be 100% perfect. Still, we strived for perfection as we continued to make and sell NGIs. Inhalation: Jolyon, what was your role in the manufacturing of the NGI? Jolyon Mitchell: I was a member of the Executive Committee of the consortium of pharmaceutical companies that established the performance speci- fications for the NGI, funded its development and guided the design through to the final product. I was also the consortium representative who supervised the two archival calibrations of the NGI. In early 2001, as the industry began to purchase NGIs from MSP, it became evident there would be a need to ensure its quality and to communicate its desir- able design attributes to pharma members who were not part of the NGI Consortium. In that context, I helped launch the European Pharmaceutical Aero- sol Group (EPAG), along with the group's leader, Dr. Steve Nichols. We and others were a small team of knowledgeable professionals who purposely followed the successes and problems of the NGI as it started to proliferate into the inhaler testing community. EPAG's work included the writing of several arti- cles to demonstrate how the NGI performed with the different inhaler device types. At that time, I was Scientific Director at Trudell Medical International and involved in the evaluation of the NGI when test- ing pressurized metered dose inhalers in combination with valved holding chambers, and when testing a novel breath-actuated jet nebulizer. For each inhaler type, issues came to the foreground. Examples included how to interface a valved holding chamber or nebulizer with the NGI and breathing simulator and how low the flow rate through the NGI could