November 1999

Monoliths are chromatography sorbents cast into columns as a single continuous piece in contrast with regular chromatographic sorbents, which are packed as individual particles. The guest authors compare three such novel sorbents with a conventional particle-packed column.

The author describes an ultrathin-layer agarose gel electrophoresis approach that combines the advantages of the multilane format of conventional slab and the performance of capillary gel electrophoresis.

In part I, Hinshaw described a simple experiment with coins to explain the statistical nature of separations and to impart a better understanding of the physical processes inside the column. In part II, he compares this coin-toss simulation with chromatographic columns and describes differences between the analogy and real-world situations.

Displacement chromatography is a viable alternative to elution chromatography, but the biotechnology industry has yet to fully exploit this technique. The authors present results of a pilot-scale ion-exchange displacement process developed for the removal of variants from recombitant human brain-derived neutrotrophic factor.

Readers submit questions about how to isolate the source of carryover in LC methods, mobile-phase temperature effects, and the care of cleaning of columns.

Krull and Swartz examine validating cleaning methods for pharmaceutical manufacturing equipment and look at general requirements and specific cleaning procedures, sampling types, and analytical methods.