|
|
General Description
In an HPLC system, the most common sources of particles are insoluble mobile phase salts, pump seals, and dust or other materials in an unfiltered sample. Sometimes the solubility of a salt is not a problem until mobile phase components are mixed, thereby increasing the concentration of organic component or changing the pH. To avoid problems, be sure the concentration of organic component will not exceed the solubility of any salt you are using. Test the water by transferring about 5mL of your organic mobile phase component into a vial, adding water, dropwise, and looking for cloudiness. Repeat this test with your buffer solution(s). Even "purified" water sometimes can cause problems. We once traced a precipitate problem to water with a high concentration of CaCO3 that had not been detected by the conductivity detector. At low pH there was no problem, but when the water was used to make a pH 7 phosphate buffer the CaCO3 precipitated on contact with a 40% acetonitrile solution.
You can minimize particle problems by protecting your columns with in-line frit filters and guard columns (refer to the Products section for an extensive selection of these items). For more information on preventing and correcting mechanical fouling of HPLC columns, refer to Bulletin 781.
|
|
