Purpose: Vitamin D, a fat-soluble secosteroid, has a significant role in bone metabolism and helps calcium absorption in the body. Since vitamin D concentration is altered in fortified foods and dietary supplements, the actual amount of vitamin D may differ from the label value. Methods: In this study, the concentrations of vitamin D2 and D3 of fortified bread sample were analytically determine...

A novel LC-MS-MS assay that simultaneously detects and quantitates 78 drugs and metabolites was developed and validated for chronic pain management. Urine specimen was diluted and mixed with internal standards (ISs) before injected into LC-MS-MS. Seventy-two analytes were detected with positive electrospray ionization mode and the remaining six analytes with negative mode. Two separate gradient...

Improved methods for quickly identifying neutral organic compounds and differentiation of analytes with similar chemical structures are widely needed. We report a new approach to effectively "fingerprint" neutral organic molecules by using (19)F NMR and molecular containers. The encapsulation of analytes induces characteristic up- or downfield shifts of (19)F resonances that can be used as mult...

a new method was developed for the spectral resolution by further determination of three- and  four-component  mixtures  of  drugs in urine samples through  the complementary application of multivariate curve resolution-alternating least squares with correlation  constraint. in the current study, a simple method was proposed to construct a calibration set for the mixture of drugs in the presenc...

BACKGROUND The stability and stoichiometric changes of analytes in plasma and serum after prolonged contact with blood cells in uncentrifuged Vacutainer tubes were studied. METHODS We simultaneously investigated the stability of 24 analytes (a) after prolonged contact of plasma and serum with blood cells and (b) after immediate separation of plasma and serum (centrifuged twice at 2000g for 5 ...

A mass spectrometric method has been delineated for the identification of the epoxide functionalities in unknown monofunctional analytes. This method utilizes gas-phase ion/molecule reactions of protonated analytes with neutral trimethyl borate (TMB) followed by collision-activated dissociation (CAD) in an ion trapping mass spectrometer (tested for a Fourier-transform ion cyclotron resonance an...

Isatins, derivatives of indole, represent important class of compounds belonging to nitrogen heterocycles. These compounds comprise synthetically vital substrates that are used as precursors for drug synthesis and raw materials for heterocycles etc. Research in this group of compounds has engrossed interest among scientific community in recent and past as Isatins are known to possess immense bi...

A new simple, sensitive and LC-MS/MS method for quantification of spironolactone and its metabolite, canrenone, in human plasma is proposed. The analytes were analysed on a C18 column at 48 oC, by using a mobile phase of 58 % methanol, 42 % 10 mmol dm ammonim acetate in water and a flow rate of 1 mL/min. The detection of both analytes in plasma was performed as follows: ESI+, EIC (m/z 169;187;2...