Post-column chromatograms

Figure 5.58 Reconstructed LC-MS-MS ion chromatograms for selected-reaction monitoring of methoxyfenozide using the m/z 367 to m/z 149 transition from the continual post-column infusion of a standard solution of analyte during the HPLC analysis of a...

FIGURE 1.9 Multiple reaction monitored ion chromatograms for desloratadine (top), 3-hydroxydesloratadine (middle), and phosphatidylcholine monoester (bottom) during post-column infusion and subsequent injection of a SPEC(R) MPl-extracted control blank plasma sample.111 (Reproduced with permission from Elsevier.)... 

HPLC analysis of furosine (-peak II) in hydrolyzates of non-exposed- (bottom), buffer-exposed (middle), and glucose-exposed (top) dentin samples. Dentin was not reduced prior to hydrolysis. Only the relevant parts of the chromatograms are shown. Amino acids are visualized after post-column labelling with a fluorescent dye. I lysine, II furosine. III homoarginine (internal standard). Column Merck Polyspher AA-NA 120 x 4.6 mm flow 0.2 ml/min gradient pH 5.0 -10.2 postcolumn reagent 0.2 ml/min fluorescence Xgx 330 nm, 440 nm 100-yl injections in buffer pH 2. 

Figure 9 shows the LC/MS-ESI mass chromatograms of a 25pg/)J.L Semtex sample (a plastic explosive containing RDX and PETN) with post-column introduction of ammonium nitrate [17]. FIPLC separation was achieved with a CIS column (100 X 2.1mm, 5 0,m particle size), using an isocratic mobile phase of methanol-water (70 30), at a flow rate of 150 0,L/min. 

Fig. 3.7 Normal-phase-HPLC chromatograms of PA fractions generated by differential solvent extraction of crude GSE (protocol 1). (a) Fraction 1, (b) Fraction 2, (c) Fraction 3, (d) Fraction 4, (e) Fraction 5, and (f) Fraction 6. Compounds were detected with post-column deiivatization using DMACA...

Fig. 13.7 Post-column infusion study of a ballistic gradient. The matrix effects can be seen at the early part of the chromatogram, but the later part of the chromatogram where the analytes should elute did not show matrix effects. Adapted from [99], with permission from John Wiley and Sons.

FIGURE 14.8 Overlay of Mn(II), Co(II), Cd(II), and Zn(II) chromatograms obtained on a lysine modified monolith. Eluent 3mM KCl, pH 4.5 Flow rate 2mL/min. Detection post-column reaction with PAR, absorbance at 495 nm. (From Sugrue, E. et al., J. Chromatogr. A, 1075, 167, 2005. Copyright 2005. With permission from Elsevier.)... 

Fig. 6.1.9A-C Electrochemical detector (a) and florescence chromatograms (b), the latter generated following post-column oxidation. A Standards - 50 nM. 1 BH4 (retention time = 5.12 min) 2 dihydroneop-terin (retention time = 4.17 min), lox oxidized BH4 generated by electrochemical detector oxidation. N.B. This peak is variable in height/area and is not used for quantification ...

Figure 11.2 (a) LC-LC system with post-column reaction detection for the determination of ampicillin in plasma (b) Chromatogram of plasma sample (collected 10 min after oral administration of 670 p,mol of ampicillin) containing 1.26 jlM ampicillin (amp). Reprinted from Journal of Chromatography, 567, K. Lanbeck-Vallen et al., Determination of ampicillin in biological fluids by coupled-column liquid chromatography and post-column derivatization, pp. 121-128, copyright 1991, with permission from Elsevier Science. 

Fig. 6.6 Detection of matrix-suppression components at the analyte retention time and at late elution. The chromatogram of the drug analyte is superimposed on the post-column infusion trace of the matrix extract. The chromatography was reversed-phase with a short run time of 3 min. The retention time of the...

In normal high pressure liquid chromatography, typical sample volumes are 20-200 p.L this can become as little as 1 nL in capillary HPLC. Pretreatment of the sample may be necessary in order to protect the stationary phase in the column from deactivation. By employing supercritical fluids such as carbon dioxide, pretreatment can be bypassed in many instances so that whole samples from industrial and environmental matrices can be introduced directly into the column. This is due to the fact that the fluid acts as both extraction solvent and mobile phase. Post-column electrochemistry has been demonstrated. For example, fast-scan cyclic voltammo-grams have been recorded as a function of time after injection of microgram samples of ferrocene and other compounds in dichloromethane solvent and which are eluted with carbon dioxide at pressures of the order of 100 atm and temperatures of 50°C the chromatogram is constructed as a plot of peak current vs. time [18]. 

Likewise, the luminescence properties of many analytes can be altered in the presenoe of surfactant aggregates (4,7.,8.). Consequently, addition of micelle-forming surfactants (present either in the LC mobile phase or added post-column) can improve the sensitivity of fluorimetric LC detectors (49,482). Micellar spray reagents have been utilized to enhance the fluorescence densitometric detection of dansylamino acids or polycyclic aromatic hydrocarbons (483). The effect was observed for TLC performed on cellulose or polyamide stationary phases with the micellar spray reagent being either CTAC, SB-12, or NaC (483). More recently, use of nonionic Triton X-100 has been found to improve the HPLC detection of morphine by fluorescence determination after post-column derivatization (486) as well as improve the N-chlorination procedure for the detection of amines, amides, and related compounds on thin-layer chromatograms (488). 

Figure 6.5 Chromatogram of tamoxifen and its major metabolites using fluorescence detection with the post-column photochemical reactor switched on (above) and off (below, with attenuation reduced by 10 times). Insert structure of tamoxifen. Peaks are 4-hydroxy-tamoxifen (32 min), tamoxifen (40 min), desmethyltamoxifen (44 min), didesmethyltamoxifen (58 min), tamoxifenol (62 min), others unknown.

Figure 11.7 Typical results of a post-column infusion experiment. In the top chromatogram the separation of the parent drag, its metabolite, and an ANIS is shown. The bottom chromatogram shows the matrix effect on the response of the parent drag. The ion suppression and ion enhancement effects prevent the rehable determination of the target compounds. Reprinted from W.M.A. Niessen, J. Chromatogr. A, 1000 (2003) 413 with permissiom 2003, Elsevier Science BV.

Figure 1. Fluorescence (top, A ciiation = 332 nm, Kn im = 442 nm) and UV (bottom) (254 mn) chromatograms of SFA (500 mg/L) with an injection volume of 80 xL. Eluent and post-column reagent (0.0 mM Cu ) flow rates were 0.7 mL/min. and 0.1 mL/min., respectively.

Figure 3. Quenching of SFA fluorescence chromatograms with addition of Cu. Post-column reagent concentration of Cu " is listed above corresponding chromatogram. Conditions are the same as listed in figure 1.

An important constituent in copper pyrophosphate baths is nitrate, which enhances the maximum permissible current density [31]. Fig. 8-30 shows the respective chromatogram with the separation of nitrate and orthophosphate. The latter is the hydrolysis product of pyrophosphate that is formed during the plating process. The main component pyrophosphate may also be separated on a latexed anion exchanger. It is detected after complexation with ferric nitrate in a post-column reaction by measuring the light absorption (see Section 3.3.5.2). 

Figure 1.7. An ion-exchange HPLC chromatogram of essential amino acids using a cationic sulfonate column and detection with post-column reaction. Note that Na315 and Na740 are prepackaged eluents containing sodium ion and buffered at pH of 3.15 and 7.40, respectively. Trione is a derivatization reagent similar to ninhydrin. Chromatogram courtesy of Pickering Laboratories.

Figure 7.12. HPLC analysis of glyphosate and aminomethylphosphonic acid (AMPA, the primary degradation product of glyphosate) according to U.S. EPA Method 547 using post-column reaction and fluorescence detection. Chromatogram courtesy of Pickering Laboratories.

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