Measurement of Cardioactive Drugs in Biological Samples by HPLC

Flanagan, Robert J.; Bhamra, Rupinder; Walker, S.; Monkman, S. C.; Holt, David W.

doi:10.1080/01483918808068362

Cited by 11 publications

(2 citation statements)

References 15 publications

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“…This obviously takes (Flanagan et al, 1988). time, but solvent:water mixtures are easier to evaporate than water alone (azeotropic effect). Compounds such as potassium carbonate may be added to plasma:organic solvent mixtures to 'force' an organic layer to form, thus simplifying extract concentration after removal.…”

Section: Protein Precipitationmentioning

confidence: 99%

Micro‐extraction techniques in analytical toxicology: short review

Flanagan

Morgan

Spencer

et al. 2006

Biomedical Chromatography

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This paper discusses new developments in plasma micro-extraction techniques in the context of established micro-extraction and protein precipitation methodology. Simple liquid-liquid solvent extraction (LLE) of plasma with direct GC or HPLC analysis of the resulting extract has been used for many years. Butyl acetate and methyl t-butyl ether (MTBE) give efficient extraction of many drugs and metabolites from small volumes of plasma or whole blood at an appropriate pH, and form the upper layer, thus simplifying extract removal. Butyl acetate does not interfere with NPD, ECD or MS in GC, whilst MTBE has a relatively low UV cutoff (220 nm). Thus, HPLC eluents that use a high proportion of an organic component allow MTBE extracts to be analysed directly. 'Salting-out' and extractive derivatization using acetic anhydride or phenylboronic acid can be used with appropriate analytes. As regards protein precipitation, an important consideration is lowering the pH, although this is not feasible with acid-labile analytes. More recent developments include sold-phase micro-extraction (SPME) and liquid-phase micro-extraction (LPME). This latter technique especially may prove invaluable as analytes that cannot easily be extracted with LLE can be isolated simply at low cost with a minimum of apparatus.

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Section: Protein Precipitationmentioning

confidence: 99%

Micro‐extraction techniques in analytical toxicology: short review

Flanagan

Morgan

Spencer

et al. 2006

Biomedical Chromatography

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“…Microparticulate strong anion (SAX)-and cation (SCX)-exchange HPLC packings give effi cient separation of acidic (Law and Hussain, 2000;Morgan et al, 2006) and basic (Flanagan et al, 1988(Flanagan et al, , 2001Law and Appleby, 1996) drugs, respectively, given appropriate eluent conditions. The additional selectivity for ionized or protonated analytes off ered by ion-exchange chromatography using 100% methanol eluents containing an ionic modifi er minimizes the potential for interference from neutral species, or species of opposite charge to the analyte(s) of interest since they generally elute close to the void volume of the column (Croes et al, 1995;Morgan et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

HPLC of basic drugs using non‐aqueous ionic eluents: evaluation of a 3 μm strong cation‐exchange material

Morgan

Manwaring

Flanagan

2009

Biomedical Chromatography

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HPLC columns packed with 3 mm particle size HPLC Technology Techsphere SCX (propylsulfonic acid-modifi ed) silica off er considerable advantages over 5 mm SCX packings in the analysis of basic drugs using 100% methanol eluents containing an ionic modifi er such as ammonium perchlorate. The basic drugs studied included clozapine and norclozapine, olanzapine, quinine and quinidine, and amitriptyline, nortriptyline, imipramine and desipramine. The 3 mm column was not only more effi cient for a given column length compared with 5 mm materials, but also elution times were less, a phenomenon observed in reversed-phase systems. The high effi ciencies and excellent peak shapes obtained with the 3 mm SCX-modifi ed packing together with the relatively low back-pressures attained show that such materials deserve serious consideration by laboratories involved in the analysis of basic drugs. Manufacturers should off er such packings as a matter of routine. Alternative ionic modifi ers such as ammonium acetate are available for use with mass spectrometric detection if required.

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Gas and Liquid Chromatography, Column Selection for, in Drug Analysis

Duff

2000

Encyclopedia of Analytical Chemistry

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Within the realm of pharmaceutical drug analyses, two techniques currently dominate the field. High‐performance liquid chromatography (HPLC) is at the forefront, followed somewhat distantly by gas chromatography (GC). HPLC is more prevalent than GC owing mainly to the heat‐labile nature of the majority of drug substances. Still GC continues to play a very active role. In comparison to HPLC and GC, combined, the frequency of use of other techniques is quite small. Perhaps the major reason for this is that chromatography not only involves qualitative and quantitative detection of targeted species, but also provides a medium for isolating these analytes from potential interfering impurities prior to measurement. The proficiency of this combination is unparalleled by any other blending of means to clean up a sample and detect the target compound. These more prominent techniques are often complementary, although each has its own strengths and limitations. General guidelines are given to assist the chromatographer to elect HPLC and/or GC for a particular separation. Considerations for choosing hardware type and sizes, solid support and bonded phase are presented. Particular emphasis is placed on the latest, which is of primary importance for obtaining rugged methods. The reader is directed towards optimum phase selection based on the compound of interest's functional group type, or by its drug activity classification (e.g. barbiturate, cardiovascular, etc.). Assistance in developing new methods frequently arises when starting with an existing published method for a compound with similar structure. This article provides 514 references for more in‐depth separation information. In addition, background knowledge on bonded‐phase chemistry, chromatographic modes of separation, approaches to chromatographic chiral drug discrimination and processes for developing rugged methods is contributed.

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Measurement of Cardioactive Drugs in Biological Samples by HPLC

Cited by 11 publications

References 15 publications

Micro‐extraction techniques in analytical toxicology: short review

Micro‐extraction techniques in analytical toxicology: short review

HPLC of basic drugs using non‐aqueous ionic eluents: evaluation of a 3 μm strong cation‐exchange material

Gas and Liquid Chromatography, Column Selection for, in Drug Analysis

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