On-line multidimensional liquid chromatographic determination of polynuclear aromatic hydrocarbons in complex samples

On-line multidimensional liquid chromatography and capillary electrophoresis systems for peptides and proteins

“…The interfacing of NP and RP systems is particularly difficult, due to mobile phase immiscibilities. To overcome this problem, Sonnefeld et al [32] used a system in which the fraction of interest was transferred from the first (NP) column to a packed precolumn and the NP eluent was removed by passage of an inert gas and vacuum. Once the solvent was removed, the analytes were desorbed from the precolumn using a RP eluent and transferred to the second (RP) column.…”

Simple interface for gradient elution CEC and coupled HPLC-CEC

“…HPLC-HPLC is a well known procedure for increasing the resolution of complex mixtures [8][9][10], while HPLC has been coupled to capillary electrophoresis (CE) by Jorgenson [11] in an interface based on the principle that the mobile phase from the first column is isolated from the second column; a similar principle is used in this work. The interface allows the coupling of normal phase HPLC to reverse phase CEC; this requires a complex arrangement of valves [12] when carried out with conventional HPLC columns.…”

Two-dimensional high performance liquid chromatography for the separation of complex mixtures of explosives and their by-products

“…Approaching the full potential of 2-D separation predicted by theory requires both the use of separation mechanisms as different as possible (orthogonal) in the two dimensions and the conservation of the peak capacities of the single columns under coupling conditions. Several combinations of mechanisms with high dissimilarity are conceivable [14]: exclusion -ion exchange [15], exclusion -reversed phase [16,17], ion exchangereversed phase [18][19][20][21][22][23], normal phase -reversed phase [24,25], normal phase (plain silica) -normal phase (electron pair acceptor or donator ligand), reversed phase (alkyl ligand) -reversed phase (electron pair acceptor or donator ligand), reversed phase (alkyl ligand) reversed phase (ion pairing eluent), reversed phasechiral reversed phase (or chiral eluent) [26][27][28], normal phase -chiral normal phase, and ion exchange -chiral phase [29,30]. As indicated by the references, some of these systems have already been elaborated.…”