The unique features of silica hydride-based columns are described with a focus on how these columns can expand a laboratory's capabilites in HPLC and LC-MS. Of particular interest is the ability to retain both polar and nonpolar compounds and provide an orthogonal method of analysis for currently existing procedures.
This article describes the factors that affect the selection of columns for two-dimensional (2D) LCÃ-LC separations. The maximum increase in peak capacity compared with single-dimension (1D) separations is obtained by using "orthogonal" systems employing various combinations of separation mechanisms to provide as different separation selectivities as possible for the sample compounds in the first and in the second dimension systems. To obtain best results, matching the chemistry of the stationary phase, column dimensions and mobile phases in the first and in the second dimensions is essential for successful separations, especiall for comprehensive LCÃ-LC.
Getting started on the right foot is important for efficient method development.
How to avoid an expensive shot in the dark.
An ultrahigh-pressure liquid chromatography (UHPLC) method was developed to separate paroxetine from several of its related compounds using a systematic screening protocol that monitors combinations of selectivity factors including column chemistry, organic modifier, and pH. When the best combination of these factors was selected, the method was optimized by varying gradient slope and temperature.
HPLC 2007 was held in Ghent, Belgium in June. Last month, columnist Ron Majors summarized some the important column developments as well as other Symposium highlights. This month, he winds up coverage with additional highlights in the areas of technology and applications. Among the topics covered are stationary phase preparation and characterization, multi-dimensional and comprehensive LC, temperature studies, detectors and an application overview.
This report shows the steps involved in the development of a new polymethyl methacrylate (PMMA) calibration standard for polar organic GPC applications.
Different methods require different strategies.
Cleaning validation is a major analytical application in the pharmaceutical industry. Here, high performance liquid chromatography (HPLC) with charged aerosol detection is compared and contrasted to HPLC with UV detection showing comparable performance and several advantages for charged aerosol detection, especially for analytes that do not contain a chromophore.
In the fourth installment in a series on method development for liquid chromatography (LC), with an emphasis on devloping trouble-free methods quickly. John Dolan started out by considering some of the goals we might have and some method development strategies.
Columnist Ron Majors covers some of the highlights of HPLC 2007 including honorary sessions, best poster awards, and the latest developments in HPLC column technology.
Liquid chromatography (LC) separations performed at elevated temperatures offer the following advantages.
This month's Technology Forum looks at the topic of HPLC/Ion Chromatography Focus and the trends and issues surrounding it. Joining us for this discussion is Chris Pohl, VP and Chief Science Officer at Dionex Corporation, Larry Tucker from Metrohm-Peak, and Yuichi Fusho of Shodex.
In this installment of "Column Watch" columnist Ron Majors revisits expert predictions from a survey conducted in 1987. A cross section of column experts of the time were asked a series of questions on the future directions in high performance liquid chromatography (HPLC) column technology. Now, 20 years later, these predictions are contrasted against current column technology. In many cases, the experts were entirely correct, while in other cases, they were dead wrong. Some current trends were not even considered 20 years ago. The author backs up his analysis with current survey information.
Flash chromatography was first introduced by W.C. Still in 1978. The following report published in the June 2006 issue of LCGC North America provided a good overview of the technique.
Faster isn't always better
Modern gas chromatography (GC) capillary columns are rugged and forgiving but some care should be taken when handling and using these high-efficiency columns. In this instalment of "Column Watch", the authors discuss the issues surrounding avoiding column breakage, stationary phase damage and column contamination. Prolonging the life of a column by keeping an oxygen-free system, providing a cleaner sample and not exceeding the upper temperature limit of the stationary phase are highlighted in this practical discussion.
An evaporative light scattering (ELS) detector is a powerful detection tool if the solutes are less volatile than the eluent. Three main processes occur successively: nebulization, evaporation of the liquid chromatographic (LC) effluent and measurement of the light scattering by the residual particles. This leads to a non-linear calibration curve such as, A= a.m b where A is the peak area,m the sample mass and b the response coefficient measured as the slope of Log A = b>Log m + Log a.
Column temperature plays an important role in controlling peak spacing (selectivity) in reversed-phase liquid chromatography (LC) separations. Temperature has long been known to affect retention time, and more recently, its use in adjusting selectivity has gained popularity (see reference 1 for a review of temperature selectivity). In preparation of a paper for the most recent Pittsburgh Conference, I had an opportunity to reexamine some data that compare temperature selectivity with other variables used to control selectivity in LC separation. This month's instalment of "LC Troubleshooting" examines temperature selectivity and its relationship to pH selectivity.
This article describes the use of ultrahigh-pressure liquid chromatography (UHPLC) in pharmaceutical analysis of drug substances and drug products with UV absorption detection.
Getting started on the right foot is important for efficient method development.
In early 2007, a web-based HPLC columns survey was conducted. Current usage was compared to a 1997 survey.
High-performance liquid chromatography (HPLC) is a powerful tool for the enantioselective separation of chiral drugs. However, the selection of an appropriate chiral stationary phase (CSP) and suitable operating conditions is a bottleneck in method development and a time- and resource-consuming task. Multimodal screening of a small number of CSPs with broad enantiorecognition abilities has been recognized as the best strategy to achieve rapid and reliable separations of chiral compounds. This paper describes the generic screening strategy developed at Johnson & Johnson Pharmaceutical Research and Development (J&J PRD) to successfully develop enantioselective HPLC methods for chiral molecules of pharmaceutical interest.
lthough liquid chromatography (LC) is most commonly associated with analytical techniques that are found inside the laboratory, LC also has been used in industrial applications for separation of a wide range of products for decades. The technique recently has been applied to requirements in the pharmaceutical and biotechnology industries, both inside the laboratory and in industrial settings. With global sales of over $1.7 billion, the market for preparative LC has encountered a stellar growth over the past few years.
The topic of this month's instalment of "LC Troubleshooting" was prompted by a manuscript I recently reviewed and a question I received from a reader of this column. Both inputs related to the variability of retention times observed in liquid chromatography (LC) methods. Variable retention is a topic that has been touched on many times over the history of this column, sometimes just in passing and other times in depth. Yet, it seems to be a problem that keeps recurring, so I think it is worth considering again.
