Powder mixing

Dual precipitating reagents-assisted deep blue-emitting borate and near-white oxide-based luminescent materials

We explored dual precipitating reagents-assisted Ce-based deep blue-emitting borate and near-white oxide-based luminescent materials. The first precipitating reagent (aqueous sodium borohydride) was used until gelation. The second precipitating reagent (ammonia solution) was employed to prepare as-synthesized powders. XRD analysis, FTIR spectroscopy, and Raman spectroscopy of calcined powders ranging from 1000 °C to 1400 °C confirmed the development of a primary borate phase (i.e., nearly polyhedral-shaped YBO3) with secondary phases of (Y,Al)BO3 and oxide. However, the preliminary oxide phase (i.e., elongated/rod-like YAG) and secondary phases of YBO3, Al2O3, and CeO2 were developed at 1500 °C with different holding times. The emission behavior and CIE coordinates confirmed that the borate (i.e., YBO3-based) sample was deep blue. However, the oxide (i.e., YAG-based) sample showed tunable color emissions from light blue to near white with increased holding time. The average lifetime of prepared samples varied between 788 ns and 891 ns, which indicated a long decay time. The quantum yield of the sample calcined at 1400-1500 °C varied between ∼61% and ∼77%. Based on the emission behavior, CIE diagram, CCT, powder color, average lifetime, and quantum yield, the developed deep blue-emitting borate and light blue/near white oxide-based luminescent materials could be used in lighting industries.

General aspects of powder rheology applied to pharmaceutical formulations

Powder flowability is crucial in the pharmaceutical industry, strongly affecting solid dosage processing. Classical experimental techniques offer straightforward results for the rapid screening of formulations during development. However, they fail to describe powder properties under consolidation. Complex techniques, such as shear cell, accurately assess fundamental properties of particulate samples under realistic conditions, enabling prediction of their flow. Ideally, a combination of experimental methods should be used to comprehensively assess powder flowability, ensuring consistent product performance. Moreover, researchers and analytical scientists must have a solid understanding of powder rheology to effectively interpret acquired data. In this review, common techniques, experimental protocols, and typical results observed in a pharmaceutical context are described.

Reviewing the Impact of Powder Cohesion on Continuous Direct Compression (CDC) Performance

The pharmaceutical industry is undergoing a paradigm shift towards continuous processing from batch, where continuous direct compression (CDC) is considered to offer the most straightforward implementation amongst powder processes due to the relatively low number of unit operations or handling steps. Due to the nature of continuous processing, the bulk properties of the formulation will require sufficient flowability and tabletability in order to be processed and transported effectively to and from each unit operation. Powder cohesion presents one of the greatest obstacles to the CDC process as it inhibits powder flow. As a result, there have been many studies investigating potential manners in which to overcome the effects of cohesion with, to date, little consideration of how these controls may affect downstream unit operations. The aim of this literature review is to explore and consolidate this literature, considering the impact of powder cohesion and cohesion control measures on the three-unit operations of the CDC process (feeding, mixing, and tabletting). This review will also cover the consequences of implementing such control measures whilst highlighting subject matter which could be of value for future research to better understand how to manage cohesive powders for CDC manufacture.

Reduced Fine API Agglomeration After Dry Coating for Enhanced Blend Uniformity and Processability of Low Drug Loaded Blends

PURPOSE

The impact of dry coating on reduced API agglomeration remains underexplored. Therefore, this work quantified fine cohesive API agglomeration reduction through dry coating and its impact on enhanced blend uniformity and processability, i.e., flowability and bulk density of multi-component blends API loading as low as 1 wt%.

METHODS

The impact of dry coating with two different types and amounts of silica was assessed on cohesion, agglomeration, flowability, bulk density, wettability, and surface energy of fine milled ibuprofen (~ 10 µm). API agglomeration, measured using Gradis/QicPic employing gentler gravity-based dispersion, resulted in excellent size resolution. Multi-component blends with fine-sized excipients, selected for reduced segregation potential, were tested for bulk density, cohesion, flowability, and blend content uniformity. Tablets formed using these blends were tested for tensile strength and dissolution.

RESULT

All dry coated ibuprofen powders exhibited dramatic agglomeration reduction, corroborated by corresponding decreased cohesion, unconfined yield strength, and improved flowability, regardless of the type and amount of silica coating. Their blends exhibited profound enhancement in flowability and bulk density even at low API loadings, as well as the content uniformity for the lowest drug loading. Moreover, hydrophobic silica coating improved drug dissolution rate without appreciably reducing tablet tensile strength.

CONCLUSION

The dry coating based reduced agglomeration of fine APIs for all three low drug loadings improved overall blend properties (uniformity, flowability, API release rate) due to the synergistic impact of a minute amount of silica (0.007 wt %), potentially enabling direct compression tableting and aiding manufacturing of other forms of solid dosing.

4D study of liquid binder penetration dynamics in pharmaceutical powders using synchrotron X-ray micro computed tomography

The properties of pharmaceutical powders, and the liquid binder, directly influence the penetration behavior in the wet granulation process of the pharmaceutical industry. Conventional methods encounter challenges in understanding this fast process. In this work, an emerging synchrotron-based X-ray imaging technique (having fast imaging capability) was employed to investigate the internal process from 2D and 3D to real-time (in-situ with ms time intervals) 3D (also considered 4D) perspectives. Two commonly used excipients (lactose monohydrate (LMH) and microcrystalline cellulose (MCC)) were used to make binary mixtures with acetaminophen (APAP) as the active pharmaceutical ingredient (API). Isopropanol and water were employed as liquid binders in the single droplet impact method. Results showed that for most of the mixtures, the porosity increased at higher fractions of APAP. MCC mixtures experienced less agglomeration and more uniform pore distribution than LMH ones, resulting in a faster droplet penetration with isopropanol. Moreover, the imbibition-spreading studies showed that isopropanol penetration in MCC powders followed more unidirectional vertical movement than horizontal spreading. Our results also demonstrated that simultaneous granulation of LMH with water resulted in much slower penetration. This study revealed that synchrotron X-ray imaging can investigate 3D internal pore structures and how they affect the quantitively real-time internal penetration dynamics.

Mixing of dry powders for inhalation: A review

The process of solids mixing is applied across a considerable range of industries. Pharmaceutical science is one of those industries that utilizes solids mixing extensively. Specifically, solids mixing as a key factor in the preparation of dry powder inhalers using the ordered mixing process will be discussed here. This review opens with a history of dry powder mixing theory, continues to ordered mixing in the preparation for dry powder inhalers, details key interparticulate interactions, explains formulation components for dry powder blends, and finally discusses different types of mixers used in the production of dry powder blends for inhalation. Lastly, the authors offer some suggestions for future work on this topic.

The use of X-ray microtomography to investigate the microstructure of pharmaceutical tablets: Potentials and comparison to common physical methods

Within this study, tablets microstructure was investigated by X-ray microtomgraphy. The aim was to gain information about their microstructure, and thus, derive deeper interpretation of tablet properties (mechanical strength, component distribution) and qualified property functions. Challenges in image processing are discussed for the correct identification of solids and voids. Furthermore, XMT measurements are critically compared with complementary physical methods for characterizing active pharmaceutical ingredient (API) content and porosity and its distribution (mercury porosimetry, calculated tablet porosity, Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM)). The derived porosity by XMT is generally lower than the calculated porosity based on geometrical data due to the resolution of the XMT in relation to the pore sizes in tablets. With rising compactions stress and API concentration, deviations between the actual and the calculated API decrease. XMT showed that API clusters are present for all tablets containing >1 wt% of ibuprofen. The 3D orientation of the components is assessable by deriving cord lengths along all dimensions of the tablets. An increasing compaction stress leads to rising cord lengths, showing higher connectivity of the respective material. Its lesser extent in the z-direction illustrates the anisotropy of the compaction process. Additionally, cracks in the fabric are identified in tablets without visible macroscopic damage. Finally, the application of XMT provides valuable structural insights if its limitations are taken into account and its strengths are fostered by advanced pre- and post-processing.

In Situ Synthesis of Alumina Nanoparticles in a Binary Carbonate Salt Eutectic for Enhancing Heat Capacity

A binary carbonate salt eutectic (Li2CO3-K2CO3)-based nanofluid was in situ synthesized by mixing with a precursor material, aluminum nitrate nonahydrate (Al(NO3)3·9H2O). Thermal decomposition of the precursor was successfully carried out to synthesize alumina (Al2O3) nanoparticles at 1 wt.% concentration. A thermogravimetric analysis (TGA) confirmed a complete thermal decomposition of aluminum nitrate nonahydrate to alumina nanoparticles. A transmission electron microscope (TEM) was employed to confirm the size and shape of the in situ formed nanoparticles; the result showed that they are spherical in shape and the average size was 28.7 nm with a standard deviation of 11.7 nm. Electron dispersive X-ray spectroscopy (EDS) confirmed the observed nanoparticles are alumina nanoparticles. A scanning electron microscope (SEM) was employed to study microstructural changes in the salt. A differential scanning calorimeter (DSC) was employed to study the heat capacity of the in situ synthesized nanofluid. The result showed that the heat capacity was enhanced by 21% at 550 °C in comparison with pure carbonate salt eutectic. About 10-11 °C decrease of the onset melting point of the binary carbonate salt eutectic was observed for the in situ synthesized nanofluids.

Linking carrier morphology to the powder mechanics of adhesive mixtures for dry powder inhalers via a blend-state model

The aim of this study was to investigate how the carrier morphology affects the expression of blend states in adhesive mixtures as a function of surface coverage ratio (SCR) and to identify where transitions between the different states occur. Adhesive mixtures of five lactose carriers with varying contents of lactose fines, corresponding to blends with different SCR ranging from 0 to 6, were produced by low-shear mixing. The powder mechanics of the mixtures were characterized by bulk density, compressibility and permeability. The appearance of the carriers and blends was studied by scanning electron microscopy, light microscopy and atomic force microscopy. The size and morphology of the carriers had a crucial impact on the evolution of the blend state, and affected the powder mechanical properties of the mixtures. It was found that smaller carriers with little or no surface irregularities were more sensitive to additions of fines resulting in self-agglomeration of fines at relatively low SCR values. On the contrary, carriers with irregular surface structures and larger sizes were able to reach higher SCR values before self-agglomeration of fines occurred. This could be attributed to an increased deagglomeration efficiency of irregular and larger carriers and to fines predominantly adhering to open pores.

Optimization of the Cohesion Index in the SeDeM Diagram Expert System and application of SeDeM Diagram: An improved methodology to determine the Cohesion Index

In this study, we suggest optimizing the methodology to determine the Cohesion Index (Icd) in order to avoid mistaken characterizations due to powder bulk density. For this purpose, five different excipients, with different bulk densities and of different chemical nature, were compressed at different heights. Their compression and their tablet characterization enable establishing a powder weight for compression in accordance with its bulk density. Therefore, the resulting tablet will have a height within a defined range of heights where it has no critical effects on its hardness. Then, the impact of this optimization is shown in a formula development, one of the main SeDeM's applications. A mathematical equation was used to calculate the theoretical amount of excipient to formulate the API according to both methodologies. The compression results demonstrate that the characterization with the NM-Icd is more accurate than the previous one while preserving its simplicity.

On the effects of blending, physicochemical properties, and their interactions on the performance of carrier-based dry powders for inhalation - A review

Blending drug and carrier powders to produce homogeneous drug-carrier adhesive mixtures is a key step in the production of dry powder inhaler (DPI) formulations. Although the blending conditions can result in different conclusions or probably change the outcome of a study entirely if being selected differently, there is a scarcity of data on the influence of blending processes on the physicochemical properties of bulk powder formulations and the follow-on effects on DPI performance. This paper provides an overview of the interactions between variables related to blending conditions (e.g. blending equipment, time, speed and sequence as well as environmental humidity) and powder physicochemical properties (e.g. size distribution, shape distribution, density, anomeric composition, electrostatic charge, surface, and bulk properties), and their effects on the performance of adhesive mixtures for inhalation in terms of drug content homogeneity, drug-carrier adhesion, and drug aerosolisation behaviour. The relevance of carrier payload, batch size and segregation was also discussed. Challenges and future directions were identified. This review therefore contributes towards a better understanding of the blending process, powder physicochemical properties, and their interlinked effects on the fundamental understanding of adhesive mixtures for inhalation. The knowledge gained is essential to ensure optimum blending and thereby controlled functionality of DPIs.

Multispectral UV imaging for fast and non-destructive quality control of chemical and physical tablet attributes

Monitoring of tablet quality attributes in direct vicinity of the production process requires analytical techniques that allow fast, non-destructive, and accurate tablet characterization. The overall objective of this study was to investigate the applicability of multispectral UV imaging as a reliable, rapid technique for estimation of the tablet API content and tablet hardness, as well as determination of tablet intactness and the tablet surface density profile. One of the aims was to establish an image analysis approach based on multivariate image analysis and pattern recognition to evaluate the potential of UV imaging for automatized quality control of tablets with respect to their intactness and surface density profile. Various tablets of different composition and different quality regarding their API content, radial tensile strength, intactness, and surface density profile were prepared using an eccentric as well as a rotary tablet press at compression pressures from 20MPa up to 410MPa. It was found, that UV imaging can provide both, relevant information on chemical and physical tablet attributes. The tablet API content and radial tensile strength could be estimated by UV imaging combined with partial least squares analysis. Furthermore, an image analysis routine was developed and successfully applied to the UV images that provided qualitative information on physical tablet surface properties such as intactness and surface density profiles, as well as quantitative information on variations in the surface density. In conclusion, this study demonstrates that UV imaging combined with image analysis is an effective and non-destructive method to determine chemical and physical quality attributes of tablets and is a promising approach for (near) real-time monitoring of the tablet compaction process and formulation optimization purposes.

Tribo-electrification and Powder Adhesion Studies in the Development of Polymeric Hydrophilic Drug Matrices

The generation of tribo-electric charge during pharmaceutical powder processing can cause a range of complications, including segregation of components leading to content uniformity and particle surface adhesion. This phenomenon becomes problematical when excipients are introduced to a powder mixture alongside the highly charging active pharmaceutical ingredient(s) (APIs). The aim of this study was to investigate the tribo-electric charging and adhesion properties of a model drug, theophylline. Moreover, binary powder mixtures of theophylline with methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC), having different polymer to drug ratios, were formed in order to study the impact of polymer concentration, particle size, substitution ratio and molecular size on the tribo-electric charging and surface adhesion properties of the drug. Furthermore, the relationship between tribo-electric charging and surface adhesion was also studied. The diversity in physicochemical properties of MC/HPMC has shown a significant impact on the tribo-electric charging and adhesion behaviour of theophylline. It was found that the magnitude of electrostatic charge and the level of surface adhesion of the API were significantly reduced with an increase in MC and HPMC concentration, substitution ratios and molecular size. In addition, the tribo-electric charge showed a linear relationship with particle surface adhesion, but the involvement of other forces cannot be neglected.

Assessment of hyaline cartilage matrix composition using near infrared spectroscopy

Changes in the composition of the extracellular matrix (ECM) are characteristic of injury or disease in cartilage tissue. Various imaging modalities and biochemical techniques have been used to assess the changes in cartilage tissue but lack adequate sensitivity, or in the case of biochemical techniques, result in destruction of the sample. Fourier transform near infrared (FT-NIR) spectroscopy has shown promise for the study of cartilage composition. In the current study NIR spectroscopy was used to identify the contributions of individual components of cartilage in the NIR spectra by assessment of the major cartilage components, collagen and chondroitin sulfate, in pure component mixtures. The NIR spectra were obtained using homogenous pellets made by dilution with potassium bromide. A partial least squares (PLS) model was calculated to predict composition in bovine cartilage samples. Characteristic absorbance peaks between 4000 and 5000 cm(-1) could be attributed to components of cartilage, i.e. collagen and chondroitin sulfate. Prediction of the amount of collagen and chondroitin sulfate in tissues was possible within 8% (w/dw) of values obtained by gold standard biochemical assessment. These results support the use of NIR spectroscopy for in vitro and in vivo applications to assess matrix composition of cartilage tissues, especially when tissue destruction should be avoided.

Tribo-electric charging and adhesion of cellulose ethers and their mixtures with flurbiprofen

The pervasiveness of tribo-electric charge during pharmaceutical processing can lead to the exacerbation of a range of problems including segregation, content heterogeneity and particle surface adhesion. The excipients, hydroxypropyl methylcellulose (HPMC) and methylcellulose (MC), are often used in drug delivery systems and so it is important to understand the impact of associated factors on their charging and adhesion mechanisms, however, little work has been reported in this area. Such phenomena become more prominent when excipients are introduced to a powder mixture alongside the active pharmaceutical ingredient(s) (APIs) with inter- and intra-particulate interactions giving rise to electrification and surface adhesion of powder particles. The aim of this study was to understand the impact of material attributes (particle size, hydroxypropyl (Hpo) to methoxyl (Meo) ratio and molecular size) on the charging and adhesion characteristics of cellulose ethers. Furthermore, a poorly compactible and highly electrostatically charged drug, flurbiprofen, was used to develop binary powder mixtures having different polymer to drug ratios and the relationship between tribo-electric charging and surface adhesion was studied. Charge was induced on powder particles and measured using a custom built device based on a shaking concept, consisting of a Faraday cup connected to an electrometer. The diversity in physicochemical properties has shown a significant impact on the tribo-electric charging and adhesion behaviour of MC and HPMC. Moreover, the adhesion and electrostatic charge of the API was significantly reduced when MC and HPMC were incorporated and tribo-electric charging showed a linear relationship (R(2)=0.81-0.98) with particle surface adhesion, however, other factors were also involved. It is anticipated that such a reduction in charge and particle surface adhesion would improve flow and compaction properties during processing.

In-line quantification of two active ingredients in a batch blending process by near-infrared spectroscopy: influence of physical presentation of the sample

The aim of this study was to apply near-infrared (NIR) spectroscopy to the simultaneous in-line monitoring of two active pharmaceutical ingredients (APIs) in a pharmaceutical batch blending process. The formulation under study consisted of a high load API (A1), one polymer, a second API (A2) and one lubricant. Additionally, the effects of the presentation of A1 on the spectral data were evaluated. For this purpose, the high load active was blended either as a cohesive powder or as a free flowing material. For improving the flow behavior of the high load active a melt-granulation (MG) step was performed. The NIR spectra of the high load API (A1) before and after MG showed that the polymer wavelength absorption band was the most affected, this wavelength range was also associated with the water band region. Thus, these frequencies carried information from the melt-granulation process and could be influenced by the water content. For the APIs quantification, independent partial least squares (PLS-1) models for each API were generated. Furthermore, a PLS-2 model was also developed for the simultaneous quantification of each API. The PLS models were used for the in-line blend uniformity monitoring of both APIs.

Towards better process understanding: chemometrics and multivariate measurements in manufacturing of solid dosage forms

The manufacturing of tablets involves many unit operations that possess multivariate and complex characteristics. The interactions between the material characteristics and process related variation are presently not comprehensively analyzed due to univariate detection methods. As a consequence, current best practice to control a typical process is to not allow process-related factors to vary i.e. lock the production parameters. The problem related to the lack of sufficient process understanding is still there: the variation within process and material properties is an intrinsic feature and cannot be compensated for with constant process parameters. Instead, a more comprehensive approach based on the use of multivariate tools for investigating processes should be applied. In the pharmaceutical field these methods are referred to as Process Analytical Technology (PAT) tools that aim to achieve a thorough understanding and control over the production process. PAT includes the frames for measurement as well as data analyzes and controlling for in-depth understanding, leading to more consistent and safer drug products with less batch rejections. In the optimal situation, by applying these techniques, destructive end-product testing could be avoided. In this paper the most prominent multivariate data analysis measuring tools within tablet manufacturing and basic research on operations are reviewed.

Evaluation of a sieve classification method for characterization of low-dose interactive mixtures

This study investigated a sieve classification method for evaluating carrier materials and particle size fractions, which could be a valuable tool in the early development of pharmaceutical dosage forms containing low-dose interactive mixtures. When developing new products based on interactive mixtures, it is essential to ensure that the drug particles are successfully deagglomerated and have adhered to the carrier particles. In this study, the effect on the demixing potential (DP) of low-dose interactive mixtures was assessed for various carrier particle sizes and surface textures. The model drug used was sodium salicylate and the tested carriers were lactose, mannitol, and isomalt. The results showed that the lowest DPs, i.e. the most mechanically stable mixtures, were obtained with lactose. Furthermore, for interactive mixtures, small carrier particles and/or a narrow carrier particle size range are essential for obtaining a low DP and high homogeneity. Calculation of the DP provided a reliable estimate of the quality of the low-dose interactive mixtures used in this study.

Lactose characteristics and the generation of the aerosol

The delivery efficiency of dry-powder products for inhalation is dependent upon the drug formulation, the inhaler device, and the inhalation technique. Dry powder formulations are generally produced by mixing the micronised drug particles with larger carrier particles. These carrier particles are commonly lactose. The aerosol performance of a powder is highly dependent on the lactose characteristics, such as particle size distribution and shape and surface properties. Because lactose is the main component in these formulations, its selection is a crucial determinant of drug deposition into the lung, as interparticle forces may be affected by the carrier-particle properties. Therefore, the purpose of this article is to review the various grades of lactose, their production, and the methods of their characterisation. The origin of their adhesive and cohesive forces and their influence on aerosol generation are described, and the impact of the physicochemical properties of lactose on carrier-drug dispersion is discussed in detail.

Compressional behavior of a mixture of granules containing high load of Phyllanthus niruri spray-dried extract and granules of adjuvants: comparison between eccentric and rotary tablet machines

The purpose of this paper was to evaluate the compressional behavior of granules containing high load of a Phyllanthus niruri spray-dried extract in eccentric (ETM) and rotary (RTM) tablet presses. Tablets were constituted by spray-dried extract granules (SDEG, 92%), excipient granules (EXCG, 7.92%), and magnesium stearate (0.08%). SDEG was obtained by dry granulation and EXCG, composed of microcrystalline cellulose (62.9%) and sodium starch glycolate (37.1%), by wet granulation. Particle size distribution was fixed between 0.250 and 0.850 mm. Tablets did not evidence any mechanical failures, such as lamination or capping, or anomalous weight variation in either tablet machine types. Upper and lower tablet surface photomicrographs from ETM and RTM tablets showed differences in porosity and texture. Different RTM speeds suggested the visco-plastic behavior of the formulation, since, by slowing down rotation speeds, the tensile strength of the tablets increased significantly, but the porosity and disintegration time were not affected. Tablets produced in RTM showed lower friability and porosity than ETM tablets, which did not reflect on higher tensile strength. The EXCG distribution at upper and lower surfaces from ETM and RTM tablets was quantified by image analysis and evaluated through statistical methods. Spray-dried extract release was not influenced by the type of equipment or operational conditions to which the compacts were submitted. Construction and operation differences between both tablet presses influenced the final product, since tablets with similar tensile strength, made by distinct tablet machines, exhibited different quality parameters.

Porous hydroxyapatite tablets as carriers for low-dosed drugs

The present study evaluated an innovative technique for the manufacturing of low-dosed tablets. Tablets containing hydroxyapatite and a pore forming agent (50% (w/w) Avicel PH 200/20, 37.5% and 50% corn starch/37.5% sorbitol) were manufactured by direct compression followed by sintering. The influence of pore forming agent (type and concentration), sinter temperature and sinter time on tablet properties was investigated. Sintering (1250 degrees C) revealed tablets with an acceptable friability (<1%). Using 50% (w/w) Avicel PH 200 as pore forming agent resulted in tablets combining the highest porosity (50%) and the highest median pore diameter (5 microm). Aqueous drug solutions (metoprolol tartrate, riboflavin sodium phosphate) were spiked on the tablet surface. The maximum volume of drug solution absorbed was limited (2x100 microl), revealing that these porous carriers were ideal for low dosed formulations. Drug release from the tablets was slow, independent of the drug. To accelerate drug release, tablets were manufactured using a modified gelcasting technique yielding tablets with a median pore size of 60 and 80 microm. Release from these tablets was drastically increased indicating that the permeability of the tablets was influenced by the pore size, shape and connectivity of the porous network. Changing and controlling these parameters made it possible to obtain drug delivery systems providing different drug delivery behaviour.

A Process Analytical Technology approach to near-infrared process control of pharmaceutical powder blending. Part I: D-optimal design for characterization of powder mixing and preliminary spectral data evaluation

Experimental design, multivariate data acquisition, and analysis in addition to real time monitoring and control through process analyzers, represent an integrated approach for implementation of Process Analytical Technology (PAT) in the pharmaceutical industry. This study, which is the first in a series of three parts, uses an experimental design approach to identify critical factors affecting powder blending. Powder mixtures composed of salicylic acid and lactose were mixed in an 8 qt. V-blender. D-optimal design was employed to characterize the blending process, by studying the effect of humidity, component concentration, and blender speed on mixing end point. Additionally, changes in particle size and density of powder mixtures were examined. A near-infrared (NIR) fiber-optic probe was used to monitor mixing, through multiple optical ports on the blender. Humidity, component concentration, and blender speed were shown to have a significant impact on the blending process. Furthermore, humidity and concentration had a significant effect on particle size and density of powder mixtures. NIRS was sensitive to changes in physicochemical properties of the mixtures, resulting from process variables. Proper selection of NIR spectral preprocessing is of ultimate importance for successful implementation of this technology in the monitoring and control of powder blending and is discussed.