Column development trends

Different developed analytical method are discussed in this chapter related to the determination of illicit substances in blood (either whole blood, plasma, or serum), OF, urine, and hair. These methods take into consideration the particular chemical and physical composition of the matrix and applies each time a suitable pretreatment to remove interfering and matrix effect, to maximize recoveries and to achieve a suitable enrichment if necessary. For liquid matrices the applications of the most common techniques are considered from simple PPT to SPE and LLE the results of recent works from literature are reported and new trends as online SPE, pSPE, automated LLE (SLE) or MAE are examined. Several stationary phases have been shown to be suitable for determination of illicit drugs Cl8, pentafluorophenyl, strong cation-exchange, and HILIC columns. The trend toward fast chromatography is investigated, both UHPLC and HPLC with appropriate arrangements moreover, results obtained with different ion sources, ESI, A PCI, and APPI are compared. 

This chapter provides an overview of modern HPLC method development and discusses approaches for initial method development (column, detector, and mobile phase selection), method optimization to improve resolution, and emerging method development trends. The focus is on reversed-phase methods for quantitative analysis of small organic molecules since RPLC accounts for 60-80% of these applications. Several case studies on pharmaceutical impurity testing are presented to illustrate the method development process. For a detailed treatment of this subject and examples of other sample types, the reader is referred to the classic book on general HPLC method development by L. Snyder et al.1 and book chapters2,3 on pharmaceutical method development by H. Rasmussen et al. Other resources include computer-based training4 and training courses.5... 

The following general trends in the development of new stationary phases for ion chromatography can be identified new stationary phases matrices and bonding chemistries improvement of column efficiency, trend toward reduction in the diameter of separation column, and new chemistry of the bonded functional groups/ layers.ti i ... 

Several reviews [767,768] and books [51,757,767, 769] deal with SEC in relation to the molecular weight characterisation of synthetic polymers (see also Bibliography). Trends in the development of column technology, detectors and data handling for SEC have recently been discussed [770,771]. The field produces some 1200 papers per year. 

Another current trend in HPLC development is the use of mini- and microbore columns with small diameters, as well as packed capillaries that require... 

Today s petroleum distillation plants are compared with the units in existence in 1925, and a review is presented of the advances during the past 25 years in construction practices and materials, instrumentation, and engineering design, which have made possible the current technology. The theory and application of special processes, such as azeotropic and extractive distillation and Hypersorption, are discussed. The development of molecular distillation and rotary columns is described to indicate possible trends to be expected in the future. 

The development of distillation columns with rotating elements, described by Baker et al. (5) and Willingham et al. (70), indicates a trend which probably will be followed in future developments to reduce the time required to reach equilibrium and hence the time for an efficient fractionation. Hickman s (27) type of molecular distillation will certainly acquire increasing importance for analytical uses as one becomes more concerned with the higher boiling constituents. 

Liquid chromatography is now a mature technique. Instruments are reliable and increasingly computer assisted. Column-to-column reproducibility is ensured by most manufacturers. The quest for the universal detector is about to end with the advent of a sophisticated and miniaturized MS detector. Development of a method can be achieved in a rather short period with available software. The emphasis is on validation more than on how to handle it. Capillary columns are sure to improve, and the trend will be toward many parallel analyses. 

The trend in liquid chromatography has tended to move away from open column toward what is called high pressure liquid chromatography (HPLC) for analytical as well as preparative work. The change in technique is due to the development of high sensitivity, low dead volume... 

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