Fast chromatography

Conventional chromatography is a slow method of analysis. The retention times are often longer than an hour when separating components of a complex mixture. To reduce these times, influence can be brought to bear upon several parameters. The most obvious requires the use of a shorter column and so as not to lose efficiency, the diameter of the capillary column should be reduced (cf. expression 

The stationary phase should be a thin film (0.1pm) and the column must operate with a steep programmed temperature gradient (e.g. 100 °C/min), now possible with modern GC instruments. Detector-response time also plays a significant role in achieving the best peak fidelity. 

The detector must be able to store almost immediately the rapid variations in concentration at the moment of each analyte s elution. For detection by mass spectrometry there is good reason to be attentive to the speed of the sweep of the miz ratio a slow sequential sweep may lead to a situation in which the concentration in the ionization chamber is not the same from one end of the recording to the other. The TOF-MS (cf. paragraph 16.5) does not suffer from this inconvenience. 

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Fast chromatography involves the use of narrow-bore columns (typically 0.1-mm i.d.) that will require higher inlet pressures compared with the conventional wide-bore capillary columns. These columns require detectors and computing systems capable of fast data acquisition. The main disadvantage is a much-reduced sample loading capacity. Advances in GC column technology, along with many of the GC-related techniques discussed below, were recently reviewed by Eiceman et... 

The use of GC-MS in polymer/additive analysis is now well established. Various GC-based polymer/additive protocols have been developed, embracing HTGC-MS, GC-HRMS and fast GC-MS with a wide variety of front-end devices (SHS, DHS, TD, DSI, LD, Py, SPE, SPME, PTV, etc.). Ionisation modes employed are mainly El, Cl (for gases) and ICPI (for liquid and solid samples). Useful instrumental developments are noticed for TD-GC-MS. GC-SMB-MS is a fast analytical tool as opposed to fast chromatography only [104]. GC-ToFMS is now about to take off. GC-REMPI-MS represents a 3D analytical technique based on compound-selective parameters of retention time, resonance ionisation wavelength and molecular mass [105]. 

Figure 4.4 depicts a LC/MS assay utilizing fast chromatography.8 The throughput of the assay, which used a 4 x 20 mm C4 column, was limited only by the cycle time of the autosampler. Heart-cut column switching was not required because of the little background interference above m/e 300 in a thermospray mass chromatogram. 

In 1995, when HPLC/MS/MS was becoming the premier tool for PK assays, chromatographic sample cycle times were typically 10 to 12 min. At 10 min per sample, 16 hr were required to process 96 samples. By 2000, scientists used shorter HPLC columns and per-sample cycle times decreased to 5 to 6 min. At 5 min per sample, it takes about 8 hr to assay one 96-well plate of samples. As a result, parallel HPLC became popular Korfmacher et al.154 described a two-column system and an MS vendor produced a triple quadrupole system designed to work with four HPLC columns.16155-158 Advances in fast chromatography continued and by 2005, sample cycle times of 1 to 2 min became common.21 87 159-161 At 2 min per sample, 3 hr are required to assay one 96-well plate of samples. 

Another approach in GC is that of using more power in the separation by doing GCxGC. In this approach, a second column is used with a different type of stationary phase than the primary stationary phase, and fast chromatography using TOF-MS as the detector is carried out [39]. This technique uses only TOF-MS as the detector since it has the most sensitivity for fast-eluting peaks. The method has been applied to complicated matrix analysis. 

With the advent of API sources, LC/MS/MS allows the facile development of quantitative methods that are sensitive, selective, robust, and amenable to the rapid analysis of a majority of small molecules. In order to achieve high-throughput bioanalysis in support of pharmacokinetic studies, many approaches have been reported utilizing automated sample preparation and reducing analysis time by pooling samples, parallel analysis, and fast chromatography. 25,26,152,153... 

Off-line chemical analysis in labs to a large extent snbstitnted by at-line analysis - e.g., spectroscopy, fast chromatography, imaging, and sensor arrays. Mnltivariate calibration nsed to convert PAT data to traditional space (e.g., concentrations, disintegration rate). 

C. E. Bioanalytical applications of fast chromatography to high-throughput liquid chromatography/ tandem mass spectrometric quantitation. Rapid Commun... 

Development of new HPLC stationary phases is ongoing. A multimodal phenylpropanolamine-coated silica column was recently prepared and applied to the quantitation of ascorbic acid in orange juice and the separation of ascorbic acid from its epimer, isoascorbic acid (Table 28) (199). Other examples include new bonded phases and columns made of continuous porous rods that permit fast chromatography with low backpressure and high resolution (200-202). 

Romanyshyn, L., Tiller, P. R., and Hop, C. E. (2000). Bioanalytical applications of fast chromatography to high-throughput liquid chromatography/tandem mass spectrometric quantitation. Rapid Commun. Mass Spectrom. 14 1662-1668. 

What is a fast chromatography system and do I need it for my laboratory ... 

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. 

Some groups have evaluated ultra-fast chromatography separations (so-called ballistic, pseudo-chromatography) in order to provide a snapshot of the sample purity [42, 43], The major drawback to the ballistic chromatography technique is that column resolution is reduced when operating at these sub-optimal linear velocities. Also, the pseudo-chromatography approach is best suited to applications where purity assessment is secondary to rapid compound prohling. 

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