A rapid and high resolution separation of lanthanides by HPLC technique has been developed using Di-(2-ethylhexyl) phosphoric acid (HDEHP) coated reverse phase column and α-hydroxy isobutyric acid as the complexing reagent for elution. A gradient elution technique has been developed for achieving the separation of the entire lanthanide series. Isocratic elution procedure has also been developed...

A reversed-phase gradient elution system is described for the simultaneous separation of the type I and type III isomers of 8-, 7-, 6-, 5- and 4-carboxylated porphyrins and isocoproporphyrins. The method, adaptable for isocratic and stepwise separation of individual groups of isomers, is also suitable for preparative isolation of pure porphyrins. The analyses of porphyrin isomers in the urine a...

A sensitive and selective high-performance liquid-chromatographic assay for ibuprofen and its major metabolites in biological fluids is described. To ensure good chromatographic separation the drug and metabolites were run on a gradient elution system and detected with a variable wavelength detector set at 220 nm. A second, more rapid, isocratic system is also described for the detection of onl...

Vitamin A (retinol), its metabolites and analogues have been heavily focused upon due to their clinical value and utility. Retinol can be used as a reflection of dietary or nutritional status, while the retinol analogues (isotretinoin, tretinoin, etretinate) are being proven as potent dermatologic and anti-tumor agents. High-performance liquid chromatography (HPLC) has been demonstrated to be a...

A new flow-dependent separation selectivity (FDSS) effect was discovered in isocratic HPLC. Significant changes in chromatographic selectivity were achieved by simple variation of the mobile phase flow rate. The FDSS effect was observed for a core-shell stationary phase using silica particles as a core and a Zr-based metal-organic framework (UiO-66) as a shell.

A rapid, reversed-phase "high-performance" liquid-chromatographic separation of the five naturally occurring cyclic ribonucleotides is described. The separation, optimized for the measurement of these compounds in biological samples, is short (25 min), sensitive (50-100 pmol), and requires no sample pre-concentration steps. We also report an alternative isocratic elution mode, optimized for a r...

An isocratic ion pair RP-HPLC method with UV-Vis detection has been developed and validated for simultaneous analysis of 4-nitrophenol (PNP), 4-nitrophenyl β-glucuronide (PNP-G), and 4-nitrophenyl sulfate (PNP-S) in rat bile samples using 4-ethylphenol (ETP) as internal standard. Chromatographic separation was achieved on a C(18) column by isocratic elution with a mobile phase consisted of meth...

an ion chromatography (ic) method for simultaneous determination of benzoic, salicylic and sorbic acids was developed. in this method the samples were purified by solid-phase extraction. the analytes were then eluted with methanol from c18 cartridge. the separation was performed on ion-exclusion column by an isocratic elution with 0.25 mmol /l sulfuric acid solution containing 20% (v/v) acetone...