Standards are as important in chromatography as columns, mobile phases, injectors and detectors.1 There's hardly an analytical laboratory to be found that does not stress the need for the certification of all components involved in an analysis. Quite remarkably though, standards are not always thought of as being an essential part of a certified analysis because many analysts prepare their own standards, while the other attributes are almost always purchased ready-made from a certified supplier.

The signal-to-noise ratio (S/N) in a liquid chromatography (LC) separation is usually defined as shown in Figure 1. The noise is measured between two lines bracketing the baseline and the signal is measured from the middle of the baseline to the top of the peak. S/N is merely the signal divided by the noise. There are some other ways to determine S/N, but that is not the point of the current discussion. My comments here will apply no matter what technique you use for measurement and calculation of S/N.

Our group started investigating diamond as a potential stationary phase for chromatography in 2005, following a discussion about the possibility of fractionating such abrasive microparticles based on size. I was surprised by the amount of different types of synthetic diamonds that have been manufactured by large-scale industrial production and their easy availability.

I recently had a question regarding some changes that took place in the 2009 edition of the US Pharmacopeia. In USP 32, General Chapter 621,1 the adjustments allowed to meet system suitability for liquid chromatography (LC) methods include a change in column internal diameter of +-25%. A change was made in USP 32 Supplement 2.2 This stated that column internal diameter "can be adjusted provided that the linear velocity is kept constant." The person was not sure how this adjustment of linear velocity should be made and wondered about what effect it would have on column efficiency.

Aqueous-organic mobile phases (for example, water-acetonitrile) have become preferred for high performance liquid chromatography (HPLC) analysis due to their wide availability, high quality, low toxicity, and compatibility with popular detection methods. Selecting the optimum column to work with aqueous mobile phases is an important part of HPLC method development. Given the vast number of choices and the lack of chemical detail about many column products, many analysts do not take time to explore column options in any systematic way.

Periodic maintenance is the mainstay of keeping laboratory instruments running at the peak of performance. Analysts can avoid many problems by proactive evaluation, repair, and replacement of critical system components on a regular basis. The alternative of allowing contamination to build up, syringes to wear out, or septa to leak only results in increased down-time compared to planned maintenance outages. Unplanned maintenance and repair is not predictable and in my experience, most such incidents occur at the worst time.

Pittcon 2010, referred to in its full name as the 61st Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, returned to the massive Orange County Convention Center in Orlando, Florida, from February 28-March 5, 2010. This year's event hosted nearly 1000 instrument manufacturers and 1aboratory suppliers in more than 2000 booths. In addition to attending the exposition, the conferees listened to 2000 technical presentations, checked numerous company seminar rooms, or attended one of 140 short courses.

I was lucky to be around in the beginning of gas chromatography (GC). I heard about it in 1956, made my first injections in 1957, and am still working with it today. I was recently encouraged by LCGC's Editor-in-Chief David Walsh to write up some of the early history that I experienced, which I present here.

Recently, efforts have been devoted to the miniaturization of existing liquid-liquid extraction methods to make them more versatile and powerful. Reducing the use of hazardous organic solvents due to environmental and cost concerns, time reduction, ease of automation, possible online coupling, high-throughput capability, and the small amounts of matrix available are major incentives that have motivated scientists working towards miniaturization.

Bisphenol A (2,2'-bis[4-hydroxyphenyl]propane), or BPA, is a key industrial chemical used to make polycarbonate plastic and epoxy resins and is used to prevent food contamination in canned goods and other food packaging. BPA can be released from these materials and can induce adverse effects in humans including hormonal responses, because it mimics estrogen. BPA is consistently in the news as mothers worry about it leaching from their baby bottles and hikers from their water bottles.

The topics for this month's "LC Troubleshooting" column come from the attendees of some of the method-development and troubleshooting classes that I have taught recently. One of these problems involves a liquid chromatography (LC) method in which an occasional sample gives a peak that is too small. The second case is one in which the analyte peak appears when a drug-free placebo sample is run.

By the time readers are opening the pages of this issue, we will all have turned the calendar on 2009 and left it behind for what will hopefully be a brighter 2010. Humorist Bill Vaughan once famously said of New Year's Eve: "An optimist stays up until midnight to see the new year in. A pessimist stays up to make sure the old year leaves." Given the financial year we all just experienced, my suspicion is there may be a few more people in the latter group than in the former this year. However, here at LCGC, we can't help but be optimistic about 2010.