Application Note | TURBIDI.T™
How to measure particle size in a liquid sample with TURBIDI.T™?
- The determination of particle size is important in many fields, such as life sciences (nanomedicine, drug delivery, tissue engineering, bioanalysis), chemical, environmental sciences and industries.
- Turbidimetry is a quick and nondestructive method to estimate particle size following an easy-to-follow procedure.
- Curves of turbidity vs silica particle concentration in distilled water of various sizes were obtained with high precision using the TURBIDI.T™. These curves can be used to build a reference curve for the determination of particle size.
Determining the size of particles is of great importance in various scientific and industrial applications. In pharmaceuticals, the particle size of drugs or drug delivery systems plays a significant role in their bioavailability, dissolution rate, and absorption in the body. In life sciences research and diagnostics, accurate measurement of particle size is crucial for developing and validating analytical methods such as in immunoassays or polymerase chain reaction (PCR) techniques. This characterization is also important in fields such as environmental sciences and pollution monitoring, geology and soil science, materials science and nanotechnology, among others.
The size of particles in a suspension can be estimated by turbidimetric measurements offering a simple, fast and nondestructive approach [1,2]. Turbidity is a parameter that quantifies the decrease in the intensity of a light beam as it passes through a suspension, due to the scattering and absorption of light by suspended particles. The extent of scattering and absorption is influenced by both the size of the particles and their concentration within the suspension. Larger particles tend to scatter and absorb more light, resulting in a steeper slope on the turbidity curve. On the other hand, smaller particles scatter and absorb less light, leading to a gentler slope. By analyzing the turbidity curve, it becomes possible to infer particle size based on the relationship between turbidity and concentration.
In this application note, silica nanoparticles of different sizes in distilled water were measured in the TURBIDI.T™ to illustrate its applicability for particle size estimation. Concentration-turbidity relationships were obtained for each particle size which was used to build a reference curve for estimating particle size of an unknown solution.
MATERIALS AND METHODS
The TURBIDI.T™ (Rheolution Inc., QC, Canada) is a versatile device for measuring the turbidity of solutions within various ranges. The main features include the ability to (1) modify the optical emitter cartridges to accommodate different wavelengths, (2) choose sample holders that align with specific experimental designs, and (3) utilize a wireless tablet for data collection, customization, analysis, and data exportation. Additionally, the device allows for expanded measurement capacity by enabling multiple instruments to be paired with the same tablet.
Formazin standards (FTU) were used to calibrate the TURBIDI.T™ prior testing. The cartridges used for light emission and reception were the Emitt.635 (wavelength of 635 nm) and the Receiv.ViS (wavelength from 400 nm to 1000 nm), respectively.
Silica particles with different sizes (160 nm, 500 nm, and 1000 nm; Alpha Nanotech Inc., BC, Canada) were diluted in distilled water in 5 concentrations: 150, 200, 300, 400 and 500 mg/L. The solutions were stabilized at 25°C and 3 samples of each concentration were transferred in 10 mL vials for testing (n=3). Each vial was well mixed before introducing into the TURBIDI.T™ for the measurement. Average results are expressed as mean ± standard deviation. Simple linear regression was applied to the data of each particle size.
RESULTS AND DISCUSSION
Turbidity values for the different concentrations and sizes of silica particles are presented in Figure 1. Data points represent the mean value of triplicates with small error bars demonstrating the high precision of the measurements. Simple linear regressions were well fit with the experimental data (R²>0.94). Results show that concentration–turbidity correlations depend on particle size, as reflected by the increase in the slopes of the curves from 160 nm to 500 nm, and 1000 nm respectively.
How to determine particle size from turbidity-concentration curves?
A reference curve for the estimation of particle size of an unknown solution can be obtained by plotting the particle sizes above against their respective slope from the turbidity-concentration curves. An unknown solution should then be tested at different concentrations to obtain its own slope (from the turbidity versus concentration curve) which can be used in Figure 2 for the estimation of the size of particles in suspension.
Figure 2: Estimation of silica particle size from a reference curve of particle size versus slope (obtained from turbidity-concentration curves).
The TURBIDI.T™ instrument can be used to estimate the size of suspended particles in solution using a reference curve (particle size versus slopes of the turbidity-concentration curve) obtained with at least 3 points.
- The size of particles in suspension can be easily estimated using the user-friendly TURBIDI.T™ instrument.
- Turbidity versus concentration data can be stored in the tablet via the Soft Matter Analytics™ App, and exploited and exported as needed.
- The availability of different cartridges allows users to modify the wavelength of light emission, which can enhance the accuracy and precision in estimating particle size.
- The capability to work with vials of different sizes allows users to perform measurements with minimal sample volume and eliminates the need for extensive sampling manipulation, contributing to a streamlined and user-friendly experience.
- The flexible testing platform created by connecting multiple units assists with the specific needs of R&D and QC labs, which often involve handling large volumes of samples. It provides a convenient solution to help accommodate the high-throughput demands of these environments.
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The determination of particle size is important in many fields, such as life sciences (nanomedicine, drug delivery, tissue engineering, bioanalysis), chemical, environmental sciences and industries. Turbidimetry is a quick and nondestructive method to estimate particle size following an easy-to-follow procedure. Curves of turbidity vs silica particle concentration in distilled water of various sizes were obtained with high precision using the TURBIDI.TTM. These curves can be used to build a reference curve for the determination of particle size.
A suspension is a mixture in which solid particles (organic or inorganic in nature) are dispersed in a liquid medium, but not dissolved. Suspensions are usually opaque or cloudy and can settle over time due to gravity. They have a broad range of applications and are present in various industrial processes, such as chemical, pharmaceutical, food and beverage, and environmental industries. During the production of pharmaceutical formulations for example, professionals may measure particle concentration to assess whether particles have aggregated or formed larger clusters to optimize the process and ensure product quality.