Droplet size analysis of pharmaceutical nasal sprays in different spatial orientations with laser diffraction from 0,25 µm to 875 µm
Together with the flexible SPRAYER adapter, the compact laser diffraction sensor HELOS/BR offers meaningful and reproducible analysis of the size distribution of droplets or solid particles in pump sprays, metered dose inhalers (MDI) and other pressurised sprays in the range from 0.25 µm to 875 µm. The adapter can be flexibly adapted for a wide range of different atomizer types and simulates the manual application of the relevant spray with a force or trajectory actuator. In combination with the ROTOR, it is possible to set up tilted application arrangements.
The formation of a spray mist depends on many different parameters, and these need to be taken into account and controlled when setting up reproducible measuring conditions. Important triggering parameters include e.g. the force and acceleration conditions when the atomizer is used. Likewise, the distance and orientation of the spray in relation to the measuring zone also have an influence on the measurement results. A suction unit ensures that laminar flow conditions are established in the measuring zone and that the spray mist is purged out. In the HELOS & SPRAYER system, the key measurement and triggering parameters and the distance between the spray nozzle and the measuring zone can be controlled with the software and saved as retrievable measuring methods (Standard Operating Procedures (SOPs)). Alternatively, the integrated control panel allows for a direct and manual control of the system.
Two actuators are optionally available for the SPRAYER for simulation of different triggering processes. The force actuator ensures that the spray is actuated with a definable, constant force by pushing the actuator piston onto the triggering mechanism. On the trajectory actuator, the atomizer can be triggered with a motion path for the actuator piston that is defined by the travel (stroke), acceleration and speed. The use of controlled triggering processes that are executed by means of the actuators helps to establish reproducible measuring methods and avoids unwanted operator bias. For spatial orientation of the spray, the complete HELOS & SPRAYER system is mounted in the traversing unit ROTOR, which lifts up the system and allows for rotation in increments of 5° to the desired tilt angle between 0° and 90°. A sensor integrated in the SPRAYER records the tilt angle.
For reliable identification of the different spray phases (formation, stable phase, dissipation), a time-resolved measurement of the generated spray mist is performed with up to 2,000 particle size distributions per second. The identification of the stable phase of spray formation forms the basis for the reproducibility of subsequent measurements in the fully developed droplet cloud. The force or acceleration, speed and stroke of the triggering process are recorded by the software and can be displayed in different diagrams. The system creates the best conditions for compliance with the requirements of regulatory authorities for pharmaceutical products, e.g. the guidelines of the US FDA (Food and Drug Administration). HELOS & SPRAYER are used accordingly both for fundamental research applications and in product development, as well as in quality control.
- Particle and droplet size distribution | FDA-compliant
- For metered dose inhalers, pump sprays and pressurised sprays
- For research, product development, quality control
- 4 high-resolution measuring ranges from 0.25 µm to 875 µm | R2 to R5T
- Time-resolved measurements for identification of the spray phases
- Software-controlled adjustment of the spray position and spatial orientation
- Fully-automatic spray triggering with predefined force or speed
- Recording of force, stroke, acceleration, speed