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AquaSep is the clear choice for the discriminating HPLC chromatographer faced with a difficult separation challenge such as polar compounds, compounds requiring a highly aqueous mobile phase or difficult to retain compounds. The AquaSep phase has been specially developed using patented technology for use with highly aqueous mobile phases, including 100% aqueous. Our unique patented approach provides a complete solution to ensure that AquaSep is totally resistant to “phase collapse” under all mobile phase conditions.
ES Industries has conducted extensive research to gain a fundamental insight into the “phase collapse” phenomenon. Our research has uncovered the key fundamental mechanism to explain and ultimately prevent “phase collapse”. The key facet to the mechanism is the relationship between mobile phase operating pressure and surface wettability of the bonded phase/silica particle.
Other column designs have been tried, with limited success, to prevent “phase collapse” from occurring. One of these approaches requires the use of a hydrophilic endcapping after the initial alkyl chain bonding. This approach falls short in two major areas. First, it requires a two-step bonding sequence, which subjects the final product to increased variability that can seriously jeopardize the reliability of HPLC methods. Secondly, the hydrophilic endcapping can be easily damaged by the mobile phase which can considerably shorten column life and lead to unacceptable poor performance for routine chromatographic methods. Given these two major limitations we did not pursue the development of any hydrophilic endcapping approach in the development of a “phase collapse” resistant product. AquaSep, “phase collapse” resistant phase is the result of patented single step bonded silane. The single step bonding procedure minimizes variation and eliminates column damage from the mobile phase.
Our patented silane allows the bonded alkyl chains to remain fully extended in the mobile phase even under highly aqueous conditions. To obtain high aqueous stability and maximum hydrophobic interaction AquaSep relies on our specially developed silane which is bonded to ultra high purity synthetically produced spherical silica. This silane contains an ether linkage placed near the point of attachment to the silica base particle. This ether group is polar enough to allow water to penetrate and hydrate the silica surface preventing the self association of the hydrophobic alkyl chains. This layer of hydration permits the maximum interaction of the alkyl chains with the analytes of interest and prevents any phase collapse.
AquaSep is the best performing aqueous stable phase available commercially. Its performance is the result of a combination of superior technology and strict quality control. AquaSep’s unique performance qualities require a special set of chromatographic test probes. The conventional test probes such as toluene and napthalene fail to adequately test the stability of the phase under highly aqueous mobile phase conditions. The complete quality testing of AquaSep includes a test specifically designed to check performance using 100% aqueous mobile phase. For this test we have selected a series of low molecular weight acids that are difficult to retain and separate on conventional ODS stationary phases. These acids are extremely useful probes to test for variations due to bonding deficiencies and contamination. In addition, the acids actual test the integrity of the phase under 100% aqueous mobile conditions. Chromatographers can be confident that every AquaSep column purchased is thoroughly tested and will not undergo “phase collapse” even when exposed to 100% aqueous mobile phase for an extended period of time.
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