A systematic, comprehensive strategy that optimizes sample preparation and chromatography to minimize matrix effects in bioanalytical LC/MS/MS assays was developed. Comparisons were made among several sample preparation methods, including protein precipitation (PPT), liquid-liquid extraction (LLE), pure cation exchange solid-phase extraction (SPE), reversed-phase SPE and mixed-mode SPE. The inf...

A gas chromatographic method for the analysis of nine organochlorine pesticides in wildlife urine is described. Reversed-phase solid-phase extraction is utilized to extract the organochlorine pesticides from urine. The pesticides are recovered by elution with hexane-ethyl ether (1:1) and quantified by gas chromatography with electron-capture detection. Method detection limits range from 1.4 to ...

A method for separation and purification of plant hormones auxin and abscisic acid based on mixed mode reversed-phase anion-exchange solid phase extraction and two-dimensional HPLC was developed. Two-dimensional HPLC in "heart cutting" mode was very efficient in the purification of these two hormones. Its purification power is high enough to allow reliable on-line quantification of both hormone...

We here report a reversed-phase HPLC method for the determination of free cortisol in human urine, using methylprednisolone as the internal standard. Before chromatography, samples were extracted with a C18 solid-phase extraction column and the steroids were separated on a LiChrospher 100 C18 column with a mobile phase of methanol/acetonitrile/water (43/3/54 by vol). Linearity, precision, and a...

We present a new procedure for in-gel digestion of proteins introducing a combination of two different 96-well microplates. The two plates have incorporated small capillaries with a length of 2.4 mm in each well, one of which has 75-microm-inner diameter capillaries, whereas the second plate has reversed-phase-type capillaries fixed to it. The initial steps of the in-gel digestion process, comp...

A new antibacterial agent, lysobactin, has been isolated from a species of Lysobacter (ATCC 53042). The antibiotic was recovered from the Lysobacter cell mass by extraction and reversed phase chromatography. Lysobactin is a dibasic peptide with marked activity against Gram-positive aerobic and anaerobic bacteria.

in this study, aniline-formaldehyde polymer was synthesized and then modified with extra aniline as cross-linker in the presence and absence of ni(ii) as the template to produce ion imprinted poly(aniline-formaldehyde) (iipaf) and non imprinted poly(aniline-formaldehyde)(nipaf) the iipaf was subjected to adsorption, preconcentration and determination of ni(ii) ion in environmental samples. the ...

This application presents a fast, easy, and cost-effective method for the determination of 24 pesticide residues in red wine. Sample preparation involves the extraction of pesticides from red wine using the QuEChERS extraction method (AOAC version). The samples then undergo cleanup by dispersive solid-phase extraction (dSPE) using primary secondary amine (PSA) sorbent, which effectively retains...

There is no other naturally occurring defense agent against cancer that has a stronger effect than paclitaxel, commonly known under the brand name of Taxol®. The major drawback for the more widespread use of paclitaxel and its precious precursor, 10-deacetylbaccatin III (10-DAB III), is that they require large-scale extraction from different parts of yew trees (Taxus species), cell cultures, ta...

The separation of tetracyclines (TCs) using reversed-phase liquid chromatography (LC) is proposed. The use of an amide-based stationary phase prevents the interaction of tetracyclines with the residual silanol groups and thus avoids the appearance of tailed peaks. Detection was based on using an UV spectrophotometer and gradient elution with acetonitrile-oxalic acid as mobile phase permitted go...