Liquid Chromatography (LC/HPLC)

Since the first Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy was held in 1950, Pittcon, as it is called today, has become a key meeting place where renowned scientists present their pioneering research and developers showcase the latest instruments that make many of those research scientific breakthroughs possible. This two-part article series will present a historical perspective on just a few of the significant scientific advancements that were discussed and demonstrated at Pittcon over the years. Part I will focus on new instruments and techniques that were presented at Pittcon from 1950 to 1980, and Part II will discuss a few of the many notable scientists and their discoveries that have been enabled by advances in mass spectrometry, capillary electrophoresis, and other instrumental techniques since 1980.

Serum protein profiling using mass spectrometry (MS) is one of the most promising approaches for biomarker identification.

What do you do when the sample changes inside the column?

Measurement of chiral purity is a necessary means of quality control for drug substances that exhibit chiral centers. This article describes a simple and practical approach to setting up system suitability and validation for chiral purity assays.

In any field there are often "misconceptions" or "myths" that are perpetuated and passed on to the next generation.

The laboratory life science and analytical instrument industry is comprised of a large, diverse group of organizations that manufacture and distribute their products worldwide. However, overall industry sales are concentrated among a small set of companies. Approximately 950 firms are included in the industry, but only about 100 companies have sales above $50 million.

Software traditionally used to control and process data in analytical instruments is now being expanded to include functions such as automated system monitoring with maintenance feedback alerts and interactive diagnostic routines that enable users to quickly track and resolve the source of many system problems. As a back up to these functions, a second layer of expert support is being made available by some instrument vendors to address more complex servicing issues. For larger or more elaborate instrument installations, monitoring and diagnostic software functions can be integrated with remote servicing expertise in a networked configuration to provide continuous proactive instrument maintenance. The benefits of these innovations include lower and more predictable operating costs, reduced system downtime, and more efficient utilization of the instrument user's time.

Dissolution testing is a mandatory test for the physical evaluation of solid dosage forms such as capsules, tablets, ointments, and creams. The most basic form of testing measures the rate of dissolution or solubility of a drug tablet. Dissolution testing also can be used in ADME and bioavailability studies, release rates of a drug substance under different conditions, as well as provide information as to the efficacy of in-vivo performance.

This month's "LC Troubleshooting" takes a look at the important components that are used to connect various parts of the LC system and how to use them wisely.

2D polymer liquid chromatography is a powerful tool for the deformulation of complex samples; however, it is considered to be very specialized and time-consuming. This article shows how recent hardware and software improvements have led to the technique becoming a method for routine analysis.

Because each sample is unique, you will need to check for carryover under the conditions of each method.

John Dolan addresses two column-related problems reported by readers - the first deals with a column that takes several injections to "settle down" for each batch of samples while the second problem relates to short column life due to early fouling of the column.

The fundamental aim of any computerized system validation should be to define its intended use and then test it to demonstrate that it complies with specification.

The gradient linearity and step tests are two of the most useful performance tests that can be made for a liquid chromatography (LC) system. These check the linearity of gradient generation and the accuracy of mobile phase proportioning. These tests, and examples of problems detected as a result of these tests, have been the subject of at least seven "LC Troubleshooting" columns over the last 18 years.1–7 We strongly recommend that every LC system undergo these tests at least on an annual basis, and preferably semiannually. When a new and different example of a problem detected by these tests is discovered, it is hard to bypass the opportunity to share it with our readers. So this month, you get yet another example of how an LC system can fail.

If cyclohexane is mixed with even low amounts of other solvents, the melting pressure increases remarkably.

The market for high performance liquid chromatography (HPLC) continues to be one of the most dynamic markets of the analytical instruments industry. A few years ago, the HPLC market began showing signs of maturity with little product innovation and slower growth rates. Although innovations in mass spectrometry (MS) helped to fuel growth, HPLC was an afterthought and considered to be a mere inlet to MS. However, the recent development of fast liquid chromatography (LC) systems is energizing the HPLC market.

The popular HPLC 2006 Symposium was held in June in San Francisco, California. It is the premier annual meeting in liquid phase separations technology.

In this article, we present data acquired on a 24-column microparallel LC system using a HPLC technique adapted from a routinely used method for measuring lactic acid.

Carryover is the appearance of an analyte in a run when a clank containing no analyte is injected. In this month's "LC Troubleshooting," John Dolan shows us how to measure it, and some ways to reduce carryover.

After having collected some industry accepted practices for implementing new LC technology, the duo discuss FDA guidance available on the subject with respect to LC, and using some recently introduced LC technology.

In this installment of "Column Watch," Ron Majors traces the developments in modern column design in analytical and preparative configurations and speculates on future directions.

The authors work to develop a universal high performance liquid chromatography method that is capable of simultaneously retaining and separating both cations and anions within a single chromatographic analysis for the purpose of quantification in pharmaceutical products.

Midazolam is a central nervous system depressant that is commonly used as a sedative before surgical or other medical procedures.