The Use of Solid-Phase Extraction Columns to Effect Simple Offline LC/MS, LC/NMR, and LC/FTIR

Wilcox, C.D.; Phelan, Richard M.

doi:10.1093/chromsci/24.4.130

Cited by 17 publications

(4 citation statements)

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“…Silica-based C 8 material was used in this HPLC-SPE-MS experiment both in the analytical and in the trapping columns [33]. With respect to NMR applications, Wilcox and Phelan reported already in 1986 a procedure consisting of a reversed-phase HPLC separation, collection of HPLC fractions using an automatic fraction collector, dilution of the frac-tions with water, solid-phase extraction of the diluted fractions using C 18 SPE cartridges, and elution of the analyte from the cartridges for 1 H-NMR at 250 MHz [34]. This off-line sequence of HPLC, SPE and NMR operations can be regarded as a prototype of modern HPLC-SPE-NMR experiments.…”

Section: Early Combinations Of Post-column Spe With Hplc-nmrmentioning

confidence: 99%

Hyphenated NMR Methods in Natural Products Research, Part 2: HPLC-SPE-NMR and Other New Trends in NMR Hyphenation

2005

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IntroductionIn the first part of this review [1], the use of direct NMR hyphenation in natural products research has been discussed. The direct HPLC-NMR methods were defined as methods in which the NMR data acquisition is performed on the HPLC column eluate [1]. This implies either a direct connection between the NMR spectrometer and the HPLC apparatus, or use of storage capillaries in which the HPLC eluate is temporarily stored prior to acquisition of NMR data.Many useful results related to natural products have been obtained using direct HPLC-NMR methods [1] [30]. However, the direct combination of state-of-the-art separation technology with the most powerful and versatile tool for structure elucidation of organic molecules in solution suffers from various practical problems. In short, these practical limitations are due to somewhat contradictory requirements of HPLC and NMR with respect to solvents and time-scale of the experiment, and thus compromises are necessary in order to hyphenate these two techniques. For example, 1 H-NMR spectra are preferably acquired in deuterated solvents, but use of deuterated solvents for HPLC is expensive and the selection is limited. Some useful HPLC eluents, such as buffers with high ionic strengths, are directly undesirable in direct HPLC-NMR hyphenation. Gradient elution of HPLC columns, required in most separations, implies constantly changing magnetic susceptibility and field homogeneity in the NMR flowprobe, not to mention variations of analyte chemical shifts with solvent composition. Hyphenated NMR Methods in Natural Products AbstractThis review describes the principles and performance of a novel and highly promising hyphenated technique, HPLC-SPE-NMR, which is based on post-column analyte trapping by solid-phase extraction. The analytes are subsequently eluted from the SPE cartridges using deuterated solvents. This indirect HPLC-NMR hyphenation offers numerous advantages compared to direct HPLC-NMR methods. Multiple trapping leads to a dramatic increase of analyte amounts available for NMR, enabling acquisition of high-quality 2D NMR data within a short time. Other new developments, including combination of solenoidal coil capillary flow-probes with microflow HPLC, are also discussed. Fast extract dereplication using these techniques enables focusing of isolation efforts on truly novel and promising natural products, based on precise structural data obtained with crude extracts or fractions.

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Section: Early Combinations Of Post-column Spe With Hplc-nmrmentioning

confidence: 99%

Hyphenated NMR Methods in Natural Products Research, Part 2: HPLC-SPE-NMR and Other New Trends in NMR Hyphenation

2005

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“…LC-SPE-NMR is the latest step in a long series of developments in LC-based on-line spectroscopy. Predecessors employing off-line LC-NMR were to be found in the late 1980s [53] but these early approaches were of limited use due to the low sensitivity of the NMR probes at this time. The concept was revived with the advent of newer NMR flow cells [54,55], and now cryogenicallycooled flow probes and peak collection with a sophisticated SPE interface are used [50].…”

Section: Lc-spe-nmrmentioning

confidence: 99%

Natural Product Analysis over the Last Decades

Marston

Hostettmann²

2009

Planta Med

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Progress in natural product chemistry has always been strongly linked to innovations in analytical technology. The characterisation of metabolites in complex mixtures requires sophisticated techniques, which should provide good sensitivity and selectivity as well as structural information on the constituents of interest. This review outlines the most important chromatographic and spectral techniques which have been introduced in the field of natural products. Although there has been a very rapid evolution of methods over the last 50 years, the introduction of highthroughput screening programmes require even more efficient and sensitive methodologies which yield adequate on-line information for metabolite structure determinatio

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“…Modern LC-SPE-NMR had its conceptual predecessors in the late 1980s [12], but these early approaches were of limited use due to the low sensitivity of the NMR probes of that time. The concept was revived with the advent of newer NMR flow cells [13], [14].…”

mentioning

confidence: 99%

Method Development Spurs Scientific Progress

Hamburger¹

2005

Planta med

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The Use of Solid-Phase Extraction Columns to Effect Simple Offline LC/MS, LC/NMR, and LC/FTIR

Cited by 17 publications

References 0 publications

Hyphenated NMR Methods in Natural Products Research, Part 2: HPLC-SPE-NMR and Other New Trends in NMR Hyphenation

Hyphenated NMR Methods in Natural Products Research, Part 2: HPLC-SPE-NMR and Other New Trends in NMR Hyphenation

Natural Product Analysis over the Last Decades

Method Development Spurs Scientific Progress

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