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Measurement of size and number concentration of polystyrene particles
Colloids and Surfaces A: Physiochemical and Engineering Aspects 153 Ž1999. 467]469
Measurement of size and number concentration of polystyrene particles Masa-aki KitajimaU , Yoshikazu Fukai Tsukuba Research Laboratory, JSR Corporation, 25 Miyukigaoka, Tsukuba 305, Japan
Abstract Traceability of the transmission electron microscopic ŽTEM. method for the determination of the diameter of polystyrene latex ŽPSL. particles was established by calibrating the internal length standard by a method traceable to the international length standard, the wavelength of the iodine stabilized helium]neon laser system. The TEM method uses a diffraction grating replica as internal length standard to compensate the magnification of the TEM ŽKatsuta et al., 6th Symposium on Aerosol Science and Technology, 1988, p. 64; Katsuta et al., J. Aerosol Res. 2 Ž2. Ž1987. 134.. Shrinkage of the PSL particles by the electron beam was also compensated for by extrapolating the shrinkage to time zero. Diameters of National Institute of Standards and Technology ŽNIST. standard reference material ŽSRM. PSL particles were measured according to the TEM method, and differences between the average diameters of NIST and those of the TEM method were as large as a few nanometres for both nominal 0.3 mm ŽSRM 1691. and 1 mm ŽSRM 1690. NIST SRMs. The particle number concentrations were determined by direct observation with a scanning electron microscope ŽSEM. of a PSL suspension on a silicone wafer. Q 1999 Elsevier Science B.V. All rights reserved. Keywords: Polystyrene particle; PSL; TEM; SEM; Traceability
1. Introduction The TEM method originally developed by Katsuta et al. used a diffraction grating replica as the internal length standard, and the diffraction grating replica itself was calibrated by a catalase crystal lattice. The pitch width of the catalase crystal lattice determined by X-ray diffraction
U
Corresponding author.
method was not explicitly traceable to the international or national standard of length because of a lack of traceability of X-ray wavelength to the length standard Žlaser wavelength.. We established the traceability of the TEM method by calibrating the diffraction grating replica with a laser diffractometer whose wavelength is traceable to the international standard of length. Here we report the diameters of NIST SRM PSL particles determined by the TEM method using the calibrated diffraction grating replica.
0927-7757r99r$ - see front matter Q 1999 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 7 - 7 7 5 7 Ž 9 8 . 0 0 5 3 5 - 4
M.-aki Kitajima, Y. Fukai r Colloids Surfaces A: Physiochem. Eng. Aspects 153 (1999) 467]469
468
Table 1 Diameters of NIST SRM particles SRM no.
1691 1690
NIST
TEM method
Average diameter Žmm.
Uncertainty Žmm.
Method
Average diameter Žmm.
Uncertainty Žmm.
0.895 0.269
0.008 0.007
TEMa Light scattering
0.896 0.267
0.006 0.003
Diameters of NIST SRM PSL particles were determined by the TEM method. a SRM a1690 was used as internal size standard.
2. Experimental 2.1. Measurement of diameters PSL particles were dried on a carbon-deposited film and observed by TEM equipped with a liquid nitrogen trap to reduce contamination in the measuring chamber. An internal standard, certified diffraction grating replica, was observed before and after daily observation of particles, under the same observation conditions. Shrinkage of
PSL diameters under electron beam exposure was compensated by extrapolating the time-dependent shrinkage to time zero. 2.2. Measurement of particle numbers A PSL suspension in pure water was adjusted to ; 1 = 10 6 particlesrml, based on counting by a liquid borne particle counter. Precisely 1 ml of the suspension was dropped onto a small hydrophilic area on a silicone wafer and was
Fig. 1. Traceability system of the TEM method. U Primary measurement standard ŽJapan national standard.. NRLM laser wavelength standard Žiodine-stabilized helium]neon laser. is the national standard of length. UU Secondary measurement standard of the accredited calibration laboratory, Japan Quality Assurance Organization ŽJQA.. UUU Working standard of the TEM method.
M.-aki Kitajima, Y. Fukai r Colloids Surfaces A: Physiochem. Eng. Aspects 153 (1999) 467]469
469
Table 2 Results of particle counting Diameter Žmm.
Number of measurements
Average particlesrml
Standard deviation
CV Ž% .
0.344 0.506 0.988 0.988 2.094 5.392
8 10 12 10 10 10
1818 1595 1442 991a 1157 1074
73 77 49 41 48 39
4.0 4.8 3.4 4.1 4.2 3.6
a
Based on 1442 particlesrml shown above, the standard PSL suspension was adjusted to 1000 particlesrml.
observed by SEM. The total particle number in the hydrophilic area was counted. 3. Results and discussion Table 1 shows the diameters of NIST SRM 1691, 1690 Žnominal 1 mm and 0.3 mm, respectively. determined by the TEM method, together with those by NIST. Differences in the values obtained by NIST and the TEM method were less than 1% of NIST values for all the three SRM particles. Fig. 1 shows the traceability system of the TEM method. The working standard of length, the diffraction grating replica, was calibrated by the Japan Quality Assurance Organization ŽJQA. with their laser diffractometer, which is traceable to the primary measurement standard ŽJapan national standard., that is, National Research Laboratory of Metrology ŽNRLM. laser wavelength standard Žiodine-stabilized helium]neon laser system..
JQA is the Accredited Calibration Laboratory for ‘laser wavelength’ based on the Japan Calibration System ŽJCSS. as formulated in the Japanese Measurement Law. International intercomparison of iodine-stabilized He]Ne lasers and methane-stabilized He]Ne lasers, which are the methods internationally recommended to realize international length standardization, was carried out between International Bureau of Weights and Measures ŽBIPM. and each laboratory including NRLM and NIST. The relative differences in the wavelength between each laboratory and BIPM were less than 10y1 0 of the BIPM value. Table 2 shows the particle counts by the SEM method for various sizes of PSL particle ranging from 0.344 mm to 5.392 mm. CV values of every 8 to 12 measurements of these particles were less than 5% and did not depend on the particle sizes.
Measurement of size and number concentration of polystyrene particles Masa-aki KitajimaU , Yoshikazu Fukai Tsukuba Research Laboratory, JSR Corporation, 25 Miyukigaoka, Tsukuba 305, Japan
Abstract Traceability of the transmission electron microscopic ŽTEM. method for the determination of the diameter of polystyrene latex ŽPSL. particles was established by calibrating the internal length standard by a method traceable to the international length standard, the wavelength of the iodine stabilized helium]neon laser system. The TEM method uses a diffraction grating replica as internal length standard to compensate the magnification of the TEM ŽKatsuta et al., 6th Symposium on Aerosol Science and Technology, 1988, p. 64; Katsuta et al., J. Aerosol Res. 2 Ž2. Ž1987. 134.. Shrinkage of the PSL particles by the electron beam was also compensated for by extrapolating the shrinkage to time zero. Diameters of National Institute of Standards and Technology ŽNIST. standard reference material ŽSRM. PSL particles were measured according to the TEM method, and differences between the average diameters of NIST and those of the TEM method were as large as a few nanometres for both nominal 0.3 mm ŽSRM 1691. and 1 mm ŽSRM 1690. NIST SRMs. The particle number concentrations were determined by direct observation with a scanning electron microscope ŽSEM. of a PSL suspension on a silicone wafer. Q 1999 Elsevier Science B.V. All rights reserved. Keywords: Polystyrene particle; PSL; TEM; SEM; Traceability
1. Introduction The TEM method originally developed by Katsuta et al. used a diffraction grating replica as the internal length standard, and the diffraction grating replica itself was calibrated by a catalase crystal lattice. The pitch width of the catalase crystal lattice determined by X-ray diffraction
U
Corresponding author.
method was not explicitly traceable to the international or national standard of length because of a lack of traceability of X-ray wavelength to the length standard Žlaser wavelength.. We established the traceability of the TEM method by calibrating the diffraction grating replica with a laser diffractometer whose wavelength is traceable to the international standard of length. Here we report the diameters of NIST SRM PSL particles determined by the TEM method using the calibrated diffraction grating replica.
0927-7757r99r$ - see front matter Q 1999 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 7 - 7 7 5 7 Ž 9 8 . 0 0 5 3 5 - 4
M.-aki Kitajima, Y. Fukai r Colloids Surfaces A: Physiochem. Eng. Aspects 153 (1999) 467]469
468
Table 1 Diameters of NIST SRM particles SRM no.
1691 1690
NIST
TEM method
Average diameter Žmm.
Uncertainty Žmm.
Method
Average diameter Žmm.
Uncertainty Žmm.
0.895 0.269
0.008 0.007
TEMa Light scattering
0.896 0.267
0.006 0.003
Diameters of NIST SRM PSL particles were determined by the TEM method. a SRM a1690 was used as internal size standard.
2. Experimental 2.1. Measurement of diameters PSL particles were dried on a carbon-deposited film and observed by TEM equipped with a liquid nitrogen trap to reduce contamination in the measuring chamber. An internal standard, certified diffraction grating replica, was observed before and after daily observation of particles, under the same observation conditions. Shrinkage of
PSL diameters under electron beam exposure was compensated by extrapolating the time-dependent shrinkage to time zero. 2.2. Measurement of particle numbers A PSL suspension in pure water was adjusted to ; 1 = 10 6 particlesrml, based on counting by a liquid borne particle counter. Precisely 1 ml of the suspension was dropped onto a small hydrophilic area on a silicone wafer and was
Fig. 1. Traceability system of the TEM method. U Primary measurement standard ŽJapan national standard.. NRLM laser wavelength standard Žiodine-stabilized helium]neon laser. is the national standard of length. UU Secondary measurement standard of the accredited calibration laboratory, Japan Quality Assurance Organization ŽJQA.. UUU Working standard of the TEM method.
M.-aki Kitajima, Y. Fukai r Colloids Surfaces A: Physiochem. Eng. Aspects 153 (1999) 467]469
469
Table 2 Results of particle counting Diameter Žmm.
Number of measurements
Average particlesrml
Standard deviation
CV Ž% .
0.344 0.506 0.988 0.988 2.094 5.392
8 10 12 10 10 10
1818 1595 1442 991a 1157 1074
73 77 49 41 48 39
4.0 4.8 3.4 4.1 4.2 3.6
a
Based on 1442 particlesrml shown above, the standard PSL suspension was adjusted to 1000 particlesrml.
observed by SEM. The total particle number in the hydrophilic area was counted. 3. Results and discussion Table 1 shows the diameters of NIST SRM 1691, 1690 Žnominal 1 mm and 0.3 mm, respectively. determined by the TEM method, together with those by NIST. Differences in the values obtained by NIST and the TEM method were less than 1% of NIST values for all the three SRM particles. Fig. 1 shows the traceability system of the TEM method. The working standard of length, the diffraction grating replica, was calibrated by the Japan Quality Assurance Organization ŽJQA. with their laser diffractometer, which is traceable to the primary measurement standard ŽJapan national standard., that is, National Research Laboratory of Metrology ŽNRLM. laser wavelength standard Žiodine-stabilized helium]neon laser system..
JQA is the Accredited Calibration Laboratory for ‘laser wavelength’ based on the Japan Calibration System ŽJCSS. as formulated in the Japanese Measurement Law. International intercomparison of iodine-stabilized He]Ne lasers and methane-stabilized He]Ne lasers, which are the methods internationally recommended to realize international length standardization, was carried out between International Bureau of Weights and Measures ŽBIPM. and each laboratory including NRLM and NIST. The relative differences in the wavelength between each laboratory and BIPM were less than 10y1 0 of the BIPM value. Table 2 shows the particle counts by the SEM method for various sizes of PSL particle ranging from 0.344 mm to 5.392 mm. CV values of every 8 to 12 measurements of these particles were less than 5% and did not depend on the particle sizes.