UHPLC chromatography

UHPLC Ultra-High-Pressure Liquid Chromatography... 

UHPLC Ultra-high-pressure liquid chromatography... 

High-Flow HPLC and Turbulent Flow Chromatography, Fast Elution and UHPLC... 

For enhanced throughput, fast RPLC methods using monolithic silica columns [238], small size particles (3 pm) packed columns [173, 195, 226, 235-237, 239, 240], ultra high pressure liquid chromatography (UHPLC) columns packed with sub-2 pm particles [145,196, 227, 245, 247] and 2.6 pm core-shell particles HPLC columns [246] have been proposed for the high-throughput separation and quantification of tamoxifen/metabolites. 

More recently Wang et al. have proposed analytical methods involving the use of UHPLC-MS/MS to determine four opiates and metabolites, live amphetamines, flunitrazepam and its two metabolites, cocaine and its four metabolites in OF. Samples were collected by spitting in a tube, then the fluids were diluted with twice the amount of distilled and deionized water and vortexed for 30 s. Liquid chromatography was performed with a gradient elution and the total run time was 7.5 min. The authors compared ESI, APCI, and APPI. The ion suppression ranged from 45 to 89 % and from 74 to 96 % on APCI and APPI, respectively. The authors... 

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. 

The final concentration of examined FRs can be determined using different techniques. Extracts prepared using techniques mentioned earlier were mostly analyzed using chromatographic techniques, especially for determining the concentration of various organic compounds. In the literature presented in this chapter, the most commonly used techniques were GC coupled with MS [9,93,96,98,102] or with tandem MS/MS [98,100,103]. One author has described the use of different detectors combined with a GC system (pECD) [95]. A few researchers used liquid chromatography. In one case, HPFC coupled with tandem MS/MS was used [99] and in others ultra-HPFC (UHPFC) was combined with a tandem MS/MS detector [100] or a UV detector [101]. The use of UHPLC can shorten the analysis time by up to a factor of ten. 

A much more sensitive technique than NMR is MS detection combined with various separation techniques (e.g., high-performance liquid chromatography, HPLC ultrahigh-performance liquid chromatography, UHPLC capillary electrophoresis, CE gas chromatography, GC) that allow previous separation of metabolites. The application of MS enables analysis of large number of metabolites based on their interactions with the separation system and, above all, on the basis of their molecular weights. 

It is not trivial to build pumps for use at 1000 bar which fulfill the common requirements such as pulse-free flow which is independent of the pressure drop. Nevertheless it is possible the demand for high peak capacity (e.g. needed in proteomics) or for fast method development in industry led to the appearance of such instruments on the market. The technique is called ultra high pressure hquid chromatography (UHPLC). 

Ultra-high-performance liquid chromatography has been increasingly used for the determination of multi-residue or multi-class antibiotics in food (Table 6.1). For example, an UHPLC/ESI-MS/MS method was reported to simultaneously analyze 17 different veterinary drug residues belonging to several classes of antibiotics such as macrolides, tetracyclines, quinolones, and sulfonamides... 

Matrix effects, which result from the interference of LC co-eluting compounds on the ionization of analytes during the ESI process, induce either ion suppression or enhancement. The effects are matrix-dependent, and ultimately affect the LC-MS quantitative results. Several measures, which include sample extraction, clean-up, dilution, and chromatography, are mandatory and effective to reduce matrix effects. Sample extraction and/or clean-up as discussed in Chapter 4 remove the majority of endogenous compounds present in samples, but a small amount often remains in the final sample extracts. Dilution is the simplest clean-up approach and should be considered first as long as the required detection concentrations are achieved. LC or UHPLC separates analytes from some matrices, which definitely helps to reduce matrix effects. However, no matter what procedures are adopted, matrix effects may not be completely eliminated. Consequently, matrix effects need to be evaluated and compensation is made to achieve the... 

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