Response of Laser Diffraction Particle Sizer to Anisometric Particles

Gabas, Nadine; Hiquily, N.; Laguérie, C.

doi:10.1002/ppsc.19940110203

Cited by 67 publications

(33 citation statements)

References 11 publications

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“…Since in LD the latter varies in function of their orientation, the classic Cauchy theorem explains that the expected projected area of a randomly oriented convex body is one quarter of its total surface area [36,37]. Additionally, Gabas et al [38] suggested the lowest and highest number weighted diffraction diameter to relate to the minimum and maximum particulate projected area, respectively. In-line with these observations, Matsuyama et al [39] mentioned that for elongated particles with an aspect ratio of ca.…”

Section: Introductionmentioning

confidence: 99%

Particle shape and orientation in laser diffraction and static image analysis size distribution analysis of micrometer sized rectangular particles

Tinke¹,

Carnicer

Govoreanu³

et al. 2008

Powder Technology

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A systematic study has been described on the laser diffraction (LD) and static image analysis (SIA) of rectangular particles [1]. To rule out powder sampling, sample dispersion and particle orientation as a possible root cause for differences in size distribution profile, powder samples were initially immobilized by means of a dry disperser onto a glass plate. For a defined region of the glass plate the diffraction pattern as induced by the dispersed particles, and the 2D dimensions of the individual particles were measured by LD and optical microscopy, respectively. Correlation between LD and SIA could be demonstrated considering the scattering intensity of the individual particles as the most dominating factor. For both spherical and rectangular particles, theory explains the latter to relate to the square of their projected area. In traditional LD, the size distribution profile is dominated by the maximum projected area of the particles (A), and the diffraction diameters of a rectangular particle with length L and breadth B are perceived by the LD instrument to correspond by approximation with spheres having a diameter of ∅ L and ∅ B , respectively. Weighting for differences in scattering intensity between spherical and Page 3 of 56 rectangular particles exlains each rectangular particle to contribute to the overall LD volume probability distribution proportional to A 2 /L and A 2 /B. Accordingly, for rectangular particles this scattering intensity weighted diffraction diameter (SIWDD) concept explains an overestimation of their shortest dimension and an underestimation of their longest dimension. For this study various samples have been analysed with the longest dimension of the particles ranging from ca. 10 to 1000 µm. For a variety of pharmaceutical powders all with a different rectangular particle size and shape, the demonstrated correlation between LD and SIA aims to facilitate the user in a better validation of LD methods based on SIA data.

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Section: Introductionmentioning

confidence: 99%

Particle shape and orientation in laser diffraction and static image analysis size distribution analysis of micrometer sized rectangular particles

Tinke¹,

Carnicer

Govoreanu³

et al. 2008

Powder Technology

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“…Whereas Equation 1 would call for 2 points located at 1.7 μm (breadth) and~12 μm (longest dimension) in the description of the LD behavior in terms of IA size descriptors, the actual plot is that of an apparent bimodal distribution as predicted by Matsuyama et al 14 The apparent bimodality is a result of the convolution of the multiple contributions to the LD data that are dominated by the breadth and length contributions in the case of approximately rectangular particles (as indicated for monodispersed rods by Gabas et al 7 ). This apparent bimodal distribution is not easily described in terms of a small number of image analysis size descriptors.…”

Section: E6mentioning

confidence: 99%

“…Recently conducted experimental and theoretical studies 20,21 on the orientation of solids in laminar flow pipes have shown that laminar flow conditions characterized by even modest Reynold's numbers (9100) result in the flow orientation of particles with little dependence on particle AR or density. Therefore, as particles are flow oriented, only the cross-sectional areas of primarily single faces of the particles are measured during the particles' transit through the flow cell and the resulting ensemble data, as shown by Gabas et al, 7 cannot be successfully translated into an ESVD distribution measurement when the criteria for the valid application of the Fraunhofer theory are met.…”

Section: Cumulative Area Percentage Versus Cumulative Volume Percentagementioning

confidence: 99%

“…The first reason appears to be that previous investigators [7][8][9][10][11][12][13] chose only a single size descriptor from the many available from IA. The most common size descriptors chosen were based on the equivalent circular area diameter (ECAD) or the equivalent spherical volume diameter (ESVD).…”

Section: Introductionmentioning

confidence: 99%

“…The most common size descriptors chosen were based on the equivalent circular area diameter (ECAD) or the equivalent spherical volume diameter (ESVD). It has been known since the work of Gabas et al 7 that for nonspherical particles, the interpretation of the diffraction events occurring from each of the chords that can be drawn across the cross-sectional area projection of a particle (Feret diameters) does not lead to a single description of ESVD or ECAD. In reality, the LD psa data, even for mono-sized nonspherical test samples, are a combination of particle breadth, longest dimension, and eventually other particle dimensional measurements for more complex shapes.…”

Section: Introductionmentioning

confidence: 99%

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Graphical comparison of image analysis and laser diffraction particle size analysis data obtained from the measurements of nonspherical particle systems

et al. 2006

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The purpose of this paper is to describe results from the use of a set of Excel macros written to facilitate the comparison of image analysis (IA) and laser diffraction (LD) particle size analysis (psa) data. Measurements were made on particle systems of differing morphological characteristics including differing average aspect ratios, particle size distribution widths and modalities. The IA and LD psa data were plotted on the same graph treating both the weighting and the size unit of the LD psa data as unknowns. Congruency of the IA and LD plots was considered to indicate successful experimental determination of the weighting and size unit. The weighting of the resulting LD psa data (so-called volume-weighted) is shown to be better correlated with IA area-weighted data. The size unit of LD psa data is shown to be a function of particle shape. In the case of high aspect ratio particles characterized by approximately rectangular faces the LD psa data is shown to be a function of multiple particle dimensions being related to IA size descriptors through a simple variation of the law of mixtures. The results demonstrate that successful correlations between IA and LD psa data can be realized in the case of non-spherical particle systems even in the case of high aspect ratio particles; however, the inappropriateness of the application of the Equivalent Spherical Volume Diameter and the Random Particle Orientation assumptions to the interpretation of the LD psa results must first be acknowledged. Correlation permits cross validation of IA and LD psa results increasing confidence in the accuracy of the data from each orthogonal technique.

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Transformation of Diffraction Pattern due to Ellipsoids into Equivalent Diameter Distribution for Spheres

Matsuyama

Yamamoto

Scarlett

2000

Part. Part. Syst. Charact.

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Response of Laser Diffraction Particle Sizer to Anisometric Particles

Cited by 67 publications

References 11 publications

Particle shape and orientation in laser diffraction and static image analysis size distribution analysis of micrometer sized rectangular particles

Particle shape and orientation in laser diffraction and static image analysis size distribution analysis of micrometer sized rectangular particles

Graphical comparison of image analysis and laser diffraction particle size analysis data obtained from the measurements of nonspherical particle systems

Transformation of Diffraction Pattern due to Ellipsoids into Equivalent Diameter Distribution for Spheres

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