Technical Articles

In Part 29 (American Laboratory, Feb 2008), Hubaux-Vos detection limits (H-V DLs) were explained and an illustration was given. read more

As was mentioned in the first article on detection limits (DLs) (Part 26, American Laboratory, June/July 2007), many formulas exist for calculating these values. read more

The subject of detection limits (DLs) is a controversial one, generating many questions and almost endless debate. read more

The previous article (Part 35, American Laboratory, Aug 2009) introduced the concept of significant digits, pointing out that a statistically sound treatment will: 1) result in a formula that depends ... read more

In this series of articles, all of the regression discussions to date have assumed that the replicate preparations of a given concentration have been exact. read more

There are indeed statistical issues related to blanks. To set the stage, a discussion of the concept itself will be helpful. read more

In the previous two columns (January/February and April 2016), we looked at the basic ideas behind control charts, saw how to construct the common X-bar and R charts and discovered that only two ... read more

A true story: one of my former graduate students called me and said, in effect, “Help. I know I’m a good analytical chemist, but my company is making me look like a perfect analytical chemist.” read more

In the last column we discussed the use of pooling to get a better estimate of the standard deviation of the measurement method, essentially the standard deviation of the raw data. read more

The introduction of Quality by Design, a systematic approach to product and process design and development, has shifted the paradigm in HPLC methods development from a retrospective approach to a ... read more