GB/T 29022-2012 Particle size analysis Dynamic light scattering (DLS) GB/T29022-2012 |tt||Standard compression package decompression password: www.bzxz.net
This standard specifies the method of measuring the average particle size and particle size distribution of submicron-nano particles or droplets dispersed in liquid using dynamic light scattering (DLS). This standard is applicable to a wide range of concentrations and can measure suspensions from low to high concentrations. For low-concentration suspension samples, dynamic light scattering is the same as photon correlation spectroscopy; for high-concentration suspension samples, in addition to the correct interpretation of the test results, specific requirements are also put forward for the measurement device, sample preparation, etc.
This standard was drafted in accordance with the rules given in GB/T1.1-2009.
This standard uses the translation method equivalent to ISO22412:2008 "Particle Size Analysis Dynamic Light Scattering Method" (DLS) (English version).
This standard is proposed and managed by the National Technical Committee for Particle Characterization and Sorting and Sieve Standardization (SAC/TC168).
The drafting units of this standard: Beijing Physical and Chemical Analysis and Testing Center, China Machinery Productivity Promotion Center, National Center for Nanoscience and Technology, Beijing Haidian District Product Quality Supervision and Inspection Institute, China Institute of Metrology.
The main drafters of this standard: Zhou Suhong, Gao Yuan, Yu Fang, Wang Xiaoping, Wang Helei, Zou Tao, Wang Qifeng, Zhang Tao, Zhou Yue, Luo Xiaoxuan, Liu Junjie. The
following documents are indispensable for the application of this document. For any dated referenced document, only the dated version applies to this document. For any undated referenced document, its latest version (including all amendments) applies to this document.
GB/T19627—2005 Particle size analysis-Photon correlation spectroscopy (ISO13321:1996, IDT)
Foreword I
Introduction II
1 Scope1
2 Normative references1
3 Terms and definitions1
4 Symbols2
5 Principle3
6 Calculation of average particle size and polydispersity index3
7 Instrument4
8 Preparatory work4
9 Measurement steps5
10 System calibration6
11 Repeatability6
12 Test report6
Appendix A (Informative) Correlation function and frequency analysis7
Appendix B (Informative) Concentration effect 11
References 13

ICS 19. 120
National Standard of the People's Republic of China
GB/T 29022--2012/1IS0 22412:2008 Particle size analysis
Dynamic light scattering (DLS)
Particle sizc analysis-Dynamic light scattering (DLS)(ISO 22412.2008.IDT)
Published on December 31, 2012
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Administration of Standardization of the People's Republic of China
Implemented on October 1, 2013
GB/T 29022—2012/IS0 22412:2008 Foreword
Normative references
Terms and meanings
Calculation of average particle size and polydispersity index
Preparatory work
Measurement steps
System calibration·
Repeatability·
12 Test report
Appendix A (informative)
Correlation function and frequency analysis
Appendix B (informative) Concentration effect
References
This standard was drafted in accordance with the rules given in G8/T1.1-2009. GB/T29022-2012/ISO22412.200B This standard uses the translation method and is equivalent to ISO22412:2008 "Particle size analysis - Dynamic light scattering method" (DLS) (English version). This standard is proposed and managed by the National Technical Committee for Particle Characterization and Sorting and Screen Standardization (SAC/TC168). The drafting units of this standard are: Beijing Physical and Chemical Analysis Testing Center, China Machinery Productivity Promotion Center, National Center for Nanoscience and Technology, Beijing Haidian District Product Quality Supervision and Inspection Institute, China Institute of Metrology. The main drafters of this standard are: Zhou Suhong, Gao Yuan, Yu Fang, Wang Xiaoping, Wang Helei, Zou Tao, Wang Minfeng, Zhang Tao, Zhou Yue, Luo Xiaoxuan, Liu Junjie. GB/T 29022—2012/IS0 22412:2008 Introduction
Currently, dynamic light scattering (DLS) has become a routine method for measuring the size of submicron-nanometer particles. The successful application of this technology mainly lies in: the average particle size and its distribution can be calculated within a few minutes, and easy-to-use commercial instruments have been launched. Nevertheless, the correct use of the instrument and the interpretation of the measurement results still need to be cautious. For this purpose, GB/T19627-2005 "Particle Size Analysis Photon Correlation Spectroscopy" was promulgated. It specifies the necessary steps for the correct determination of particle size using photon correlation spectroscopy. To avoid the influence of multiple scattering, the instruments specified in GB/T19627 are limited to measuring the particle size of low-concentration samples. At present, instruments that minimize this limitation are already available. Therefore, it is necessary to establish a dynamic light scattering method standard suitable for determining the particle size of dispersed systems over a wide concentration range so that there can be good consistency in measurement accuracy and reproducibility between experiments. A number of techniques have been developed for dynamic light scattering. These techniques can be classified according to the following two methods: a) differences in data analysis (phase analysis and rate analysis); b) differences in optical devices (homodyne and heterodyne detector optical systems). .Some new instruments have optional fixed or movable sample cells. Although dynamic light scattering (LLS) can determine particle size distribution, this standard is limited to two parameters related to the description of particle size distribution: average particle size and polydispersity index. There are many methods that can be used to calculate the full particle size distribution. However, these methods are not mature enough to be included in international standards. Therefore, in this standard, no corresponding standardized calculation methods are included. 1 Scope
GB/T 29022—2012/ISO 22412:2008 Particle size analysis Dynamic light scattering (DLS)
This standard specifies the method for measuring the average particle size and particle size distribution of submicron-nanometer particles or droplets dispersed in liquid using dynamic light scattering (DLS).
This standard is applicable to a wide concentration range and can measure suspensions from low to high concentrations. For low-concentration suspension samples, dynamic light scattering is the same as photon correlation spectroscopy; for high-concentration suspension samples, in addition to the correct interpretation of the test results, specific requirements are also put forward for the measurement device, sample preparation, etc. Note: The photon correlation multiplication method applicable to low-volume suspension samples has been specified in GB/T19627—2005/ISO13321:1996. 2 Normative references
The following documents are indispensable for the application of this document. For dated references, only the dated version applies to this document. For undated references, the latest version (including all amendments) applies to this document. GB/T19627-2005 Particle size analysis Photon correlation spectroscopy (ISO13321:1996, IDT) 3 Terms and definitions
The terms and definitions defined in GB/T19627--2005 and the following terms and definitions apply to this document. 3.1
Average particle diameter
average particle diameter
(dynamic light scattering) Harmonic intensity weighted arithmetic mean particle diameter. : The unit of average particle diameter is nm. Its typical range is from 1 nm to about 1 000 nm. 3.2
Polydispersity indexPI
A dimensionless quantity used to describe the width of particle size distribution. [GB/T19627—2005, definition 2.2]
Note: For monodisperse samples, the typical PI is less than 0,1,3.3
scattering volume
The cross section of the incident laser beam observed by the detection optical system, [GB/T 19627—2005, definition 2. 3]3.4
scattering intensity, count rate, photocurrentscattered intensityIs
The intensity of light scattered by particles in the scattering volume. In fact, it is the light per unit time measured by the detector that is proportional to the scattering intensity1
GB/T29022—2012/IS022412:200B pulse number or photodetector current,
Instrument qualification
qualfication
Factory qualification is performed using standard substances according to the instructions for use of the dynamic light scattering instrument. 3.6
Validation
Confirmation of all performance indicators within the scope of the method using standard substances. Symbols
The symbols used in this standard are shown in Table 1
Symbol
gn)(t)
ci (t)
Distribution function of decay rate or reciprocal of characteristic frequencyTranslation diffusion coefficient
Combined diffusion coefficient
Self-diffusion coefficient
Normalized electric field related coefficient
Intensity related coefficient
Scattered intensity, count rate photocurrent
Refractive index of dispersion medium
Power spectrum
Dispersion index
Light intensity weight basis of particle size r
Scattered volume
Diameter of spherical particles
Average particle size
Decay rate (decay line width) and characteristic frequency decay rate Weighted intensity average value
Viscosity of dispersion medium
Scattering angle
Wavelength of light in vacuum
Accumulation method to obtain the light intensity weight Two drinking factors of particle size distribution Particle density
Correlation time
Volume fraction of particles
Angular frequency
Arbitrary unit
In°/s
Arbitrary unit
Arbitrary unit
Dimensionless number
Arbitrary unit
Arbitrary unitwww.bzxz.net
Arbitrary unit
Arbitrary unit
5 Principle
5.1 General
GB/T29022—2012/IS022412:2008Nano/submicron particles suspended in a liquid continue to perform irregular Brownian motion due to the interaction with the molecules of the suspension medium. In the Stokes-Einstein theory of Brownian motion [1S], at very low concentrations, the motion of the particles is determined by the viscosity of the suspension fluid, the temperature and the particle size. When the temperature and viscosity are known, the particle size can be determined by measuring the motion of the particles in the liquid: at low concentrations, this particle size is referred to as the hydrodynamic particle size (see GB/T19627-2005). When the concentration increases, the measurement results are related to multiple light scattering and the interaction between particles. The influence of multiple light scattering can be eliminated by the measurement device. The phase interaction between particles means that only the apparent particle size can be measured (see Appendix B). Dynamic light scattering technology [15,17,18] uses optical methods to detect the motion of particles. The suspended particles are illuminated by a coherent light source, and their motion causes the scattering position to change with time, causing the phase of the scattered light to change with time. The change of the phase of scattered light with time can be regarded as the change of its phase drift with time, or as the frequency shift relative to the center frequency of the light source. By measuring for a long enough time, the irregular particle motion forms a distribution of phase shift or frequency shift of the incident light. 5.2 DLS optical detector
5.2.1 Use a coherent light as a reference light, and through the interference of light waves, make the spectrum have a certain frequency shift relative to the center frequency. For dynamic light scattering, the frequency shift is between 1Hz and 100 kHz, which can be easily detected by an appropriate frequency electronic spectrometer. Two commonly used reference light methods are shown in Figure 1.
) Homodyne
Description:
1—scattered light;
2—unscattered light beam;
3—detector
4—autocorrelator or spectrum analyzer.
Figure 1 DLS optical path diagram
b) Heterodyne
5.2.2 Homodyne detection [see Figure 1a), also known as white reference or Selfie detection. The reference light for frequency or phase difference measurement comes from the mixture of all detected scattered light,
5.2.3 Heterodyne detection [see Figure 1b), also known as reference beat or controllable reference detection. The scattered light is mixed with a part of the incident light. The reference light for frequency or phase difference measurement comes from the unchanged incident light. 5.2.4 The detector output results include frequency distribution or time-varying phase, which represent the particle size of the suspended particles. The detector output signal consists of two parts: the constant represents the average intensity of all collected light; the component that varies with time represents the dynamic light scattering effect. According to the dynamic light scattering theory, the particle size distribution can be obtained by analyzing the component that varies with time. 6 Calculation of mean particle size and polydispersity index
The signal captured by the detector can be analyzed and processed by correlation function analysis or frequency analysis. A brief introduction to these methods is given in Appendix A. Note that the correlation function and the frequency power spectrum are Fourier transform pairs. The particle size distribution obtained in both methods is a set of discrete equations for the particle size z and the corresponding intensity weighting values ​​(AQ, n, i-1, N). The intensity-weighted mean particle size DLs can be obtained from equation (1): 3
GB/T 29022-2012/IS0 22412:20084Q
The polydispersity index PI (or the width of the measured distribution) can be obtained from equation (2): 24m (/-1/)
PI=2u:
Alternatively, the correlation function data can also be analyzed by the accumulation method described in Appendix A.1.3.2, which can also obtain the weighted intensity-converted mean particle size: is and PI. It should be noted that the PI obtained from the cumulative analysis may actually be different from the value obtained in equation (2). 7 Instruments
The following are common laboratory instruments and detailed components. 7.1 Laser Generator
A laser generator produces a monochromatic, polarized light beam whose electric field is perpendicular to the plane formed by the incident light and the detection light (vertical polarization phenomenon). A variety of lasers can be used, such as gas lasers (He-Ne lasers, Ar lasers), solid-state lasers, high-energy diode-pumped solid-state lasers and laser diodes.
7.2 Optical System
A set of lenses is used to focus the incident laser beam into a scattering volume and to detect the scattered light. Optical fibers are usually used as part of the detection system for light transmission.
7.3 Sample Cell
The sample temperature can be controlled and measured with an accuracy of ±0.3°C. 7.4 Photon Detector
Its output is proportional to the intensity of the scattered light. Photomultiplier tubes, avalanche photodiodes or photodiodes are usually used. 7.5 Signal processing unit
It can capture the intensity signal that changes with time and output the autocorrelation function, cross-correlation function or power spectrum of the obtained signal. 7.6 Calculation unit
It can obtain the particle size and particle size distribution through signal processing. Some calculation units can also be used as signal processing units. 8 Preparation
8.1 Instrument placement
The instrument should be placed in a clean environment without electromagnetic interference, mechanical vibration and direct sunlight. Warning: The dynamic light scattering instrument is equipped with low or medium power lasers, and its radiation may cause permanent eye damage. Do not look directly into the laser beam and its reflected beam. When the laser is on, do not place objects with highly reflective surfaces in the path of the beam. Please be sure to comply with the specific regulations on laser radiation safety. 8.2 Sample preparation
The particles of the sample to be tested should have good dispersion in the liquid medium. The dispersion medium should meet the following requirements: a) It will not dissolve, swell or agglomerate the particles to be tested; b) Its refractive index is different from that of the particles to be tested; c) Its refractive index and viscosity are known, and the accuracy should be better than 0.5%; ) Use a very low intensity signal to check whether the instrument is contaminated: meet the principle of low background scattering.
9 Measurement steps
Properly install and adjust the equipment, and the operator should be proficient in using the instrument. 9.1 Instrument preheating
Turn on the instrument power switch to preheat. Generally, preheating takes 15rmin~30min to stabilize the laser intensity and heat the sample cell to the required temperature.
9.2 Instrument adjustment
Check the background scattering level of the dispersion medium to ensure that it is within the range specified by the instrument, and record its average scattered light intensity. 9.3 Sample preparation
Put the sample to be tested into the instrument release cell until the temperature is balanced. The accuracy of temperature control and measurement is within ±0.3°C. If the sample to be tested has not reached the equilibrium temperature, the uncertainty of the measured particle size dispersed in water is about 2%/°C. Ensure that there are no bubbles in the sample to be tested.
9.4 Test conditions
Record the sample identification, measurement time, duration, measurement temperature, refractive index, viscosity of the dispersion medium, particle concentration, laser wavelength and scattering angle.
9.5 Test
Check the average scattering intensity of the sample. The scattering intensity must be greater than the intensity of the dispersion medium. For each sample, at least three measurements are made, and the results are recorded and saved.
9.6 Test record
Record the average particle size 2DLs and the dispersion index PI for each measurement. 9.7 Test inspection
At the end of the measurement, check whether the test sample has obvious precipitation. If precipitation occurs, it may be due to agglomeration and rapid sedimentation, or the sample is not suitable for this method.
GB/T29022—2012/IS022412;200810 System calibration
After the initial installation of the instrument, the instrument should be calibrated with standard materials and then calibrated at regular intervals. Failure to calibrate may be caused by particle dispersion, sample preparation (see 8.2) or the instrument itself. It is recommended to use polystyrene particles with a narrow particle size distribution and an average particle size of about 100 μm to calibrate the instrument using the dynamic light scattering method. For the test results of such dispersed particles, the average particle size should be within ±2% of the calibration value, the repeatability should be better than 2%, and the dispersion index PI value should be less than C.1.
11 Resilience
For non-narrowband polystyrene particle dispersions (narrowband polystyrene particle dispersions are described in Chapter 10), the repeatability of the average particle size should be better than 5%.
12 Test Report
The test report should contain at least the following information: 8) Average particle size, the average value and standard deviation of at least 3 measurements. b)
Polydispersity index PI,Mean and standard deviation of at least 3 measurements. When the mean of PI and PI is related to concentration, their values ​​are extrapolated to infinite dilution or to the value at the lowest concentration. Sample information, including: detailed information such as particle shape and uniformity. Sampling method, if known.
Test method and corresponding standard.
Instrument type and model.
Dispersion conditions:
1) Dispersing liquid and its cleaning steps;
Particle concentration:
Dispersant and its concentration;
Dispersion steps,
5) Ultrasonic conditions: frequency and input power (if required). Measurement conditions:
1) Actual concentration;
Viscosity and refractive index of the separation medium;
3) Sample temperature.
Test information:
1) Laboratory name and location;
2) Operator name;
3) Date.
k) All operating details not specified in this standard, or optional auxiliary operating details that may affect the results. 6
Correlation function analysis
A.1. 1 Autocorrelation
Appendix A
(Informative Appendix)
Correlation function and frequency analysis
GB/T29022—2012/IS022412:2008 A monochromatic coherent laser beam illuminates a small volume of the sample in the sample cell. The detector measures the light scattered by the particles in this volume. At a given time, the scattered light in the detector is the sum of the scattered light emitted by all particles in the illuminated volume in the direction of the detector. The intensity of the scattered light is related to its own attenuation value (see A, 1.3). Figure A, 1 is an example of an autocorrelation function. G2()
Explanation ·
G\(t) Autocorrelation function, arbitrary units; - correlation time, in microseconds (μs).
A. 1 Autocorrelation function (normalized)
GB/T19627-2005 provides the necessary steps to obtain the correct particle size by the autocorrelation method. However, it is limited to dilute samples. A. 1. 2 Cross-correlation
Two monochromatic coherent laser beams are focused on the sample, where the two beams intersect and the overlapping part of the two beams forms the measurement volume. Two detectors detect the light scattered by the particles within the scattering angle. In this way, two independent scattering measurements can be made in the same measurement volume, thereby reducing the influence of multiple light scattering effects on the measurement results (see Appendix B). The measured five correlation functions look similar to the autocorrelation function of Figure A. 1. A.1.3 Data Analysis
A,1.3.1 Function Analysis
Autocorrelation or cross-correlation function analysis is used for statistical analysis of scattering intensity fluctuations (see GB/T19627—2005). Usually, the correlation function G() (t) is defined as equation (A,1): G(t) = (I
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