Liquid chromatography mass detectors

LC-MS (liquid chromatography-mass detector) and LC-NMR (liquid chromatography-nuclear magnetic resonance spectroscopy). 

Ethylenethiourea (ETU) is a toxic decomposition product/metabolite of alky-lenebis(dithiocarbamates). This compound could be generated during processing of treated crops at elevated temperature. Different chromatographic methods to determine the residue levels of ETU have been published. After extraction with methanol, clean-up on a Gas-Chrom S/alumina column and derivatization (alkylation) with bro-mobutane, ETU residues can be determined by GC with a flame photometric detector in the sulfur mode. Alternatively, ETU residues can also be determined by an HPLC method with UV detection at 240 nm or by liquid chromatography/mass spectrometry (LC/MS) or liquid chromatography/tandem mass spectrometry (LC/MS/MS) (molecular ion m/z 103). ... 

Liquid chromatography/mass spectrometry analyses were performed with an ion trap mass spectrometer (LCQ, Thermo Fisher Scientific Inc., MA) equipped with an HPLC system (Agilent, CA Model 1100) connected with a diode-array detector (DAD, G1315A). The sample solution (1-5 p,L) was applied on an Inertsil ODS-3 column (2.1 x 150 mm, 3 p,m, GL... 

LC/MS (Liquid Chromatography/Mass Spectrometry)—Chromatography system in which an HPLC is married to a mass spectrometric detector through an evaporated, ionizing interface. A variety of mass spectrometers are used to produce various LC/MS and LC/MS/MS configurations. MS detectors are universal, mass detectors that provide molecular weight information and can give a definitive identification of separated compounds. 

Recently, the word nano has become a trend in science and technology and some of us think that it is the new generation but, as mentioned above, its root is about 22 years old. NLC and NCE are gaining importance day by day. They are very useful and effective tools for samples of low quantities or having low concentrations of the analytes. Columns of low internal diameter are ideal for use in NLC and NCE, especially with detectors requiring very low flow rates, such as electrospray liquid chromatography/mass spectroscopy (LC/MS). Besides, these columns offer high sensitivity due to their low... 

Liquid chromatography mass spectrometry (LC-MS) is now routinely used in analytical laboratories. Traditional IPRs are non-volatile salts that are not compatible with MS techniques because they play a major role in source pollution that is responsible for reduced signals. Moreover the final number of charged ions that reach the detector is impaired by ion-pair formation actually IPRs added to the mobile phase to improve analytes retention exert a profound effect on analyte ionization. Chromatographers who perform IPC-MS must optimize the eluent composition based on both chromatographic separation and compatibility with online detection requirements. 

The understanding of the effects of sample concentration (sample mass) in field-flow fractionation (FFF) has being obtained gradually with the improvement of the sensitivity (detection limit) of high-performance liquid chromatography (HPLC) detectors. Overloading, which was used in earlier publications, emphasizes that there is an upper limit of sample amount (or concentration) below which sample retention will not be dependent on sample mass injected into the FFF channels [1]. Recent studies show that such limits may not exist for thermal FFF (may be true for all the FFF techniques in polymer separation), although some of the most sensitive detectors on the market were used [2]. 

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