Ron Majors, editor of "Column Watch" and "Sample Prep Perspectives," has been with 

 for over 26 years. Currently a senior scientist with Agilent Technologies, Wilmington, Delaware, Ron is known industry-wide as one of the premier chromatography experts in the field. He is also a member of 

John Dolan has been writing "LC Troubleshooting" for 

 for over 25 years. One of the industry's most respected professionals, John is currently a principal instructor for LC Resources, Walnut Creek, California He is also a member of 

 a chart covering possible causes and solutions for decreasing (or lower-than-expected) pressure, fluctuating pressure, high back pressure, and increasing pressure.

Pressure