Malvern 2000

The average particle size of the co-processed excipients was determined by laser diffraction (Malvern 2000, Malvern Instruments Ltd., England) based on Fraunhofer’s approach. The powders were dispersed in water, and measurements were made in triplicate for all batches prepared.

Particle surface charges were measured in ultrapure water (18 MΩ) using a Malvern 2000 Zetasizer, Malvern, UK following appropriate dilution and sonication within a DTS 1060C cuvette (Malvern, UK).

The mastersizer (Malvern-2000) with the optical bench was used to retrieve a scattering pattern from a field of particles and to calculate particle dimensions [52 ]. The set-up consisted of a water tank with an overhead mixer which provided a feed to a cell where the laser beam impacted the sample solution. Initially, the water tank was cleaned thoroughly with repeated flashes of 5% solution of DECON, a surfactant specifically made for Malvern instruments and large amounts of de-ionized water. When the software showed a small amount of background noise from the cell, the model system emulsion was diluted in the water tank with overhead blade stirring at standard rotational speed. The laser refractive index and laser absorption values for petrolatum were provided before commencing the measurements.

The mean particle size (MPS) and distribution of the emulsion were measured by a laser particle analyzer (Malvern 2000, Malvern Instruments Ltd., Worcestershire, UK). The surface mean diameter (d3,2) was selected.
The emulsion yield was determined according to the method of Teng et al. [17 (link)] with mirror modifications. Then, 3.0 mL n-hexane was added into 1.0 mL emulsion and was mixed under vortex for 30 s. Then, the mixture was centrifuged for 5 min under 10,000× g (H1850R, Xiangyi, Changsha, China). The supernatant was collected in a 10 mL volumetric flask, and the volume was filled with n-hexane. The absorption value of β-carotene was measured at 450 nm using a UV spectrometer (UV-2600, Shimadzu Co., Kyoto, Japan). The content of unwrapped β-carotene in the supernatant was calculated according to a standard curve. The emulsion yield (EY) was then calculated using the following equation
$$EY(\%)=\frac{\beta -\mathrm{carotene} \mathrm{content} \mathrm{in} \mathrm{emulsion}}{\mathrm{Total} \beta -\mathrm{carotene} \mathrm{content}}\times 100$$

A laser diffraction technique using a Malvern 2000 (Malvern Instruments Co., Ltd., Malvern, UK) was applied to characterize the granule size (d₅₀) of three samples for each granulation run. One bar of dispersive air pressure, 1.6 g feed quantity, and obscuration were adjusted at approximately 1%.

Particle size analysis was conducted employing a protocol adapted marginally [36 (link)]. In this method, a 1.5 mL aliquot was subjected to centrifugation at 8819 g for 10 min. Subsequently, the particle size distribution pertinent to the MPs within the specimen was determined using a nanoparticle size analyzer (Malvern 2000, Malvern City, UK) operating under a controlled temperature of 25 °C. It is imperative to underscore the meticulous rigor of the analysis, with each individual sample being analyzed in triplicate to ensure reliability and statistical significance.