The proposed model is based on the measurement of the retention times of 346 tryptic peptides in the 560- to 4,000-Da mass range, derived from a mixture of 17 protein digests. These peptides were measured in HPLC-MALDI MS runs, with peptide identities confirmed by MS/MS. The model relies on summation of the retention coefficients of the individual amino acids, as in previous approaches, but add...

A liquid chromatography coupled with mass spectrometry method was developed and validated to determine omeprazole and domperidone simultaneously in dog plasma. Chromatographic separation was performed on a Narrow Bore C(18) column using methanol-10 mM ammonium acetate (68:32, v/v) as the mobile phase at the flow rate of 0.2 mL/min. The chromatographic separation was achieved in less than 7 min....

We describe a simple method for extraction of estrogens that is efficient over the whole polarity range of estrogen metabolites in urine and plasma. A small reversed-phase C18 cartridge (Sep-Pak C18, Waters Associates, Inc.) is used for this purpose. After application of the biological fluid, followed by an aqueous wash, estrogens are eluted in 3 mL of methanol. For urine the pH should be kept ...

A simple and sensitive high performance liquid chromatographic method with electrochemical detection is described for the quantitative determination of the amoxycillin and clavulanic acid in pharmaceutical dosage forms. Separation of sample components occurs on a reversed phase C18 column with a mobile phase consisting of methanol-water-phosphate buffer. For the amperometric detection, the pote...

Sirolimus (rapamycin) has a macrolide structure and is under clinical investigation as an immunosuppressant after organ transplantation. An HPLC/mass spectrometry assay to quantify sirolimus in blood was developed. 28-O-Acetyl sirolimus was used as internal standard. Blood samples were extracted with C18 columns. The extracts were injected into an HPLC system and isocratically eluted with metha...

The most common detection method for the analytical separation techniques of HPLC and capillary electrophoresis (CE) is absorbance measurement in the deep-UV range (below 300 nm) as a large number of organic species absorb in this wavelength region. Conventional UV detectors are based on deuterium discharge lamps coupled to a monochromator for wavelength selection. Light-emitting diodes (LEDs) ...

Edelfosine is a synthetic alkyl ether phospholipid that represents a promising class of antitumor agents. However, analytical methods to measure these type compounds are scarce. The lack of a reliable methodology to quantify edelfosine is a major problem in ongoing and scheduled preclinical and clinical trials with this drug. We evaluated the applicability of high-performance liquid chromatogra...

This paper describes the analysis procedure and results for environmental herbicide samples by a negative ESI LC-MS/MS method. After the preparation of aqueous and soil samples, the extracts are directly injected into a high performance liquid chromatography system coupled to negative eletrospray ionization (ESI-) tandem mass spectrometry. The sample preparation incorporates modified hydrolysis...

This fit-for-purpose method was designed in response to recent and proposed food standards, both international and national, that limit inorganic arsenic rather than total, organic, or individual arsenic species such as arsenite (As) and arsenate (As). In this method, As is intentionally oxidized to As with H2O2 during sample preparation, converting all inorganic arsenic (the sum of As III and ...