ABSTRACT: Increasing the sensitivity and resolution of LC/MS instruments has been an ongoing focus for instrument manufacturers. As a result of this increased sensitivity of today’s analytical instrumentation, the choice of high purity solvents can greatly influence the test results that are achieved.

INTRODUCTION: To meet the needs of the most demanding ultra-high pressure liquid chromatography (UHPLC) and mass spectrometry research and analytical testing applications, such as proteomics, drug discovery, pharmacokinetics, and clinical research, instrumentation is not the only parameter to be considered. Solvent design and selection is also very important. Performance of three specific solvents, (1) Acetonitrile, (2) Methanol, and (3) Water was examined in detail and the solvents were assessed for their suitability in selected LC/MS applications. In particular, the impact of packaging materials on the quality of LC/MS solvents was evaluated. The performance of LC/MS grade solvents was compared using LC/UV/MS gradient, MS infusion, and trace metals analysis. One way to ensure that high purity LC/MS grade solvents meet stringent purity requirements is by improving the packaging associated with the storage and delivery of these solvents. For example, certain containers can leach metal ions during storage, and lead to the formation of metal adducts, which can adversely impact test results.

EXPERIMENTAL CONDITIONS:
 Materials:
• LC/MS grade Acetonitrile, Methanol, and Water from various suppliers
• J.T.Baker® ULTRA LC/MS™ solvents
• Standards (Sulfadimethoxine, Chloraphenicol)

METHODS:
• LC/MS gradient (Waters ACQUITY UPLC® System/LCT TOF mass spectrometer)
• Positive/Negative ESI (electrospray ionization)
• Direct infusion to mass spectrometer (Waters Quattro Micro)
• Trace metals (Perkin-Elmer ICP-MS)

RESULTS : Results indicate that J.T.Baker® ULTRA LC/MS™ solvents and solvent packaging show better performance than other traditional LC/MS grade solvents. The J.T.Baker® ULTRA LC/MS™ water packaged in the borosilicate bottle maintained sodium levels < 9 ppb in two months while material packaged in amber glass bottles presented sodium levels > 150 ppb. Sodium metal adducts (m/z 333) were also reduced. The J.T.Baker® ULTRA LC/MS™ grade exhibited adducts of 40% compared to 150% for the material packed in amber glass bottles.

CONCLUSIONS:  Based on the data compiled for the study, the test results indicate that J.T.Baker® ULTRA LC/MS™ solvents are more suitable for use on UHPLC and high sensitivity mass spectrometry instrumentation. J.T.Baker® ULTRA LC/MS™ solvents also offer better performance than the other brands tested by delivering:
• Lower trace metals
• Reduced adduct formation
• Minimal suppression

REFERENCES / TRADEMARKS 

ACQUITY UPLC System™ and Quattro Micro™ are trademarks of Waters Technologies Corporation.
Other trademarks are owned by Avantor Performance Materials, Inc. or its affiliates unless otherwise noted.