EMSURE® Granulated Salts
Introduction
Analytical chemistry workflows often encounter practical limitations when using traditional powdered salts due to their tendency to clump, form dust, and absorb moisture. EMSURE® granulated salts produced to the highest analytical grade, have been formulated to overcome these limits by providing improved flowability, chemical stability, and reliable analytical performance, while maintaining purity and specifications.
Features and Benefits
- Analytical grade purity: EMSURE® granulated salts retain the high chemical purity associated with EMSURE® products, ensuring consistent results in quantitative and qualitative analyses.
- Improved flowability: The granular format allows for improved material handling due to its free-flowing nature. This results in reduced product loss during transfer and promotes operational safety by minimizing the need for manual intervention.
- Specification retention: Despite the change in physical form, the granulated salts use the same high-quality raw materials and maintain the original chemical specifications.
- Reduced dust formation: The dry granulation process significantly reduces dust formation compared to powdered salts. This lowers the risk of contamination and exposure, contributing to a safer laboratory environment.
- Chemical stability: The granules maintain their integrity under typical storage and handling conditions, providing stable performance over time across a range of analytical procedures.
Dry Granulation Process
EMSURE® granulated salts are manufactured using the dry granulation method (Figure 1) that does not involve liquid binders or water. Dry granulation is a compaction-based technique used to convert fine salt powders into mechanically stable, free-flowing granules. This technique preserves the chemical composition and analytical performance of the raw materials. The resulting product is suitable for applications in wet chemistry and other analytical disciplines that demand high reproducibility and reliability.
Figure 1.Schematic representation of the dry granulation process.
Processing Steps in Dry Granulation
- Bulk material feeding: Dry granulation begins with the introduction of fine salt powder into a feed hopper.
- Compression into plates (ribbon formation): The powder is then compressed between two counter-rotating rollers, forming a dense ribbon or plate. This roller compaction process is precisely controlled through adjustments in roller pressure, feed rate, and roller gap.
- Milling to granules: The compacted plates are subsequently milled into granules using a rotor-based system. Fine particles are typically reused to maximize process efficiency.
The following parameters demonstrate the technical superiority of granulated salts over traditional powdered forms:
Particle size
Figure 2.Particle size distribution of EMSURE® granulated di-Sodium hydrogen phosphate dihydrate.
Particle size distribution is a critical parameter influencing the performance of granulated salts. A high proportion of fine particles increases the risk of clumping, thereby diminishing the functional advantages of the granulated form.
One of the defining features of EMSURE® granulated salts is their precisely controlled particle size distribution, achieved through an optimized dry granulation process. As seen in Figure 2, the majority of the granules fall within the 4.0–6.3 mm range, accounting for over 45% of the total mass. An additional ~20% of particles are within the 2.8–4.0 mm and 6.3–8.0 mm fractions, contributing to a narrow, well-defined distribution. Minimal presence of fines (<1 mm) and oversized particles (>8 mm) highlights the precision of the compaction and milling process.
This controlled particle size distribution results in improved flow properties, reduced dust generation, and optimized solubility profiles, which are essential characteristics for high-purity reagents used in analytical workflows. The uniform granule morphology of EMSURE® salts enables consistent weighing and dissolution, thereby minimizing variability during preparation and ensuring reliable performance in critical applications.
Flowability
A key functional advantage of EMSURE® granulated salts is their superior flowability. In contrast to conventional powdered salts, which are prone to clumping and flow obstruction, the granulated form exhibits free-flowing behavior. This facilitates precise material handling, enabling accurate measurement and efficient transfer without the need for mechanical agitation or scraping. Enhanced flow properties also contribute to reduced material loss and lower risk of spillage, thereby improving operational safety and efficiency in laboratory workflows.
Dissolution
Although powdered salts generally exhibit faster dissolution rates due to their higher specific surface area, the tendency to form aggregates upon exposure to ambient moisture can adversely affect dissolution kinetics. EMSURE® granulated salts are designed to provide a balance between dissolution rate and reproducibility. While the initial dissolution rate may be marginally lower under ideal conditions compared to powdered forms, the granulated salts offer greater consistency and predictability, particularly under variable environmental conditions. This stability mitigates the analytical variability often introduced by clumped or partially dissolved material.
Figure 3.Dissolution profiles of two sodium dihydrogen phosphate monohydrate samples.
Figure 3 illustrates the dissolution profiles of two sodium dihydrogen phosphate monohydrate samples, COMP (compressed EMSURE® granules, in blue) and Crys (crystalline powder, in red), measured by Focused Beam Reflectance Measurement (FBRM). In this study, 80 g of each salt type was dispersed in 800 mL of purified water at ambient temperature under constant stirring at 250 rpm. Real-time particle count was recorded to evaluate dissolution kinetics. The EMSURE® granulated salt (COMP) shows a gradual, steady decline in particle count, reflecting a controlled and consistent dissolution process with minimal fluctuation. In contrast, the crystalline powder dissolves more rapidly.
Abrasion Resistance
The mechanical integrity of salt granules during storage, handling, and transport is a critical parameter influencing material performance and analytical reliability. Fine particle formation due to granule abrasion not only affects flow and dosing behavior but can also introduce variability and contamination into analytical workflows. To address these concerns, EMSURE® granulated salts are subjected to abrasion testing to evaluate their resistance to particle degradation.
Figure 4.Abrasion stability of EMSURE® sodium dihydrogen phosphate monohydrate over 12 months.
Abrasion resistance of these granulated salts was assessed using a standardized abrasion drum apparatus containing ceramic balls. Samples were subjected to rotational motion at 20 rpm for a duration of 10 minutes. Post-treatment, the mass fraction of particles <500 μm was quantified to determine the extent of mechanical breakdown. Figure 4 presents the abrasion data for two EMSURE® sodium dihydrogen phosphate monohydrate pack sizes (1 kg and 5 kg) over a 12-month period. Across all time points, both formats exhibited abrasion levels well below the 10% threshold, indicating granule stability under real-world storage conditions.
Figure 6.Abrasion resistance of four EMSURE® granulated salts.
The mechanical robustness of EMSURE® granulated salts is also demonstrated in the abrasion test results (Figure 5) for four common salt types. Sodium chloride and ammonium sulfate exhibited minimal particle breakdown (<3%), confirming their high structural stability. Even more abrasion-prone materials like di-sodium hydrogen phosphate dihydrate and sodium acetate trihydrate maintained acceptable integrity under standardized testing. These results highlight the consistent quality of EMSURE® salts, offering low dust, high reproducibility, and clean handling, regardless of the material’s fragility.
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