Maternal plasma advanced glycation end products concentrations in response to oral 50-gram glucose load in mid-pregnancy: a pilot study.

BACKGROUND: Accumulating evidence documents the initiation of diverse physiologic and biochemical responses subsequent to an oral glucose load. OBJECTIVES: We sought to evaluate the extent to which acute hyperglycemia, resulting from a 50-gram glucose load, contributes to changes in maternal plasma concentrations of advanced glycation end products (AGEs), a heterogeneous group of molecules formed from the non-enzymatic reaction of reducing sugars with free amino groups of proteins, lipids, and nucleic acids. METHODS: Blood specimens were collected from each participant in mid-pregnancy using standard procedures before and after a 50-gram oral glucose load. Maternal plasma methylglyoxal (MG), pentosidine and N(epsilon)-(carboxymethyl)lysine (CML) (free and bound) were measured by HPLC-MS/MS method. Non-parametric methods were employed for statistical analysis. RESULTS AND CONCLUSIONS: Median plasma MG increased 1.27 fold as a result of acute hyperglycemia. Median bound CML concentrations were elevated 21% in post-load plasma samples as compared with pre-load samples, while median free pentosidine concentrations were 51% lower (both p-values < 0.05). Future studies of larger populations and longer periods of follow-up are warranted to investigate the consequences of acute and chronic hyperglycemia on placental function and fetal development.

Use of conventional bioanalytical devices to automate DBS extractions in liquid-handling dispensing tips.

BACKGROUND: Conventional liquid-handling devices were employed, along with an improved punching device, to semi-automate dried blood spot (DBS) extraction of alprazolam, α-hydroxyalprazolam and midazolam from human whole blood. Liquid-handling devices were used to add internal standard to the DBS cards and to extract the analytes from the DBS, in order to be analyzed by HPLC-MS/MS. RESULTS: The technique was shown to be accurate (±12.0%) and precise (10.3%) across the dynamic range of the assay. CONCLUSION: The semi-automated extraction reduced sample preparation time by more than 50% when compared with more conventional DBS manual extraction methods.

Validation of HPLC-MS/MS methods for analysis of loxapine, amoxapine, 7-OH-loxapine, 8-OH-loxapine and loxapine N-oxide in human plasma.

BACKGROUND: Two ESI-LC-MS/MS methods were validated for the quantitative analysis of loxapine, amoxapine, 7-OH-loxapine, 8-OH-loxapine and loxapine N-oxide in human K(2)EDTA plasma. Cation-exchange solid-phase extraction (SPE) was used to extract loxapine, amoxapine and the two hydroxylated metabolites, and organic precipitation was used to quantify loxapine N-oxide. RESULTS: Both methods were shown to be accurate (±13%), intra-assay precision was less than 15%, and inter-assay precision was less than 10% in all instances across the entire dynamic range of the assays (0.0500-50.0 ng/ml for the SPE method and 0.100-25.0 ng/ml for the precipitation method). CONCLUSION: The validated methods for loxapine, amoxapine, 7-OH-loxapine, 8-OH-loxapine and loxapine N-oxide have been used to successfully support clinical trials.

Development and validation of an HPLC-MS/MS method for the analysis of dexamethasone from pig synovial fluid using dried matrix spotting.

BACKGROUND: Dried matrix spot techniques were employed to validate an HPLC-MS/MS assay for the determination of dexamethasone in clear Yorkshire pig synovial fluid using 15 µl of sample. We have adopted the term dried matrix spot to indicate that the techniques used for dried blood spots can be applied to nonblood matrices. The dried matrix spot method employs a color-indicating process developed at Alturas Analytics that enhances the ability to analyze transparent fluids spotted onto collection paper by allowing the analyst to visually verify the location of the dried sample spot. RESULTS: The method was shown to be accurate (±4.3%) and precise (14.2% at the LLOQ and ≤10.0% at all other concentrations) across the dynamic range of the assay. CONCLUSION: The method shows the potential application of dried matrix spot techniques for the analysis of transparent biological fluids.

Extraction of uranium from aqueous solutions by using ionic liquid and supercritical carbon dioxide in conjunction.

Uranyl ions [UO(2)](2+) in aqueous nitric acid can be extracted into supercritical CO(2) (sc-CO(2)) by using an imidazolium-based ionic liquid with tri-n-butyl phosphate (TBP) as a complexing agent. The transfer of uranium from the ionic liquid to the supercritical fluid phase was monitored by UV/Vis spectroscopy using a high-pressure fiber-optic cell. The form of the uranyl complex extracted into the sc-CO(2) phase was identified to be [UO(2)(NO(3))(2)(TBP)(2)]. The extraction results were confirmed by fluorescence spectroscopy and by neutron activation analysis. This technique has potential applications in the field of nuclear waste management for extracting other actinides.

Fluorescence detection and identification of tagging agents and impurities found in explosives.

The detection and identification of 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), and pentaerythritol tetranitrate (PETN) vapors have proven to be difficult and challenging due to the low vapor pressures of these high explosives. Detecting higher vapor pressure impurity compounds found in TNT and possible tagging agents mandated to be added to plastic explosives (RDX and PETN) would allow for easier vapor detection. The higher vapor pressure nitro compounds of interest are considered to be non-fluorescent; however, once reduced to their amino analogs, they have relatively high quantum yields. The standard reduction products, the reduction products obtained in solution, and the reduction products obtained in vapor phase were analyzed by conventional fluorescence, synchronous luminescence, and derivative spectroscopy. The nitro analogs of the isomers 1,3-diaminobenzene, 1,2-diaminobenzene, and 1,4-diaminobenzene are found as impurities in TNT. We provide for the first time the synchronous luminescence derivative spectra of these isomers; including their individual spectra and a spectrum of an isomeric mixture of the three. Using the standard reduction products associated with these isomers and other aromatic amines, our data suggest that the vapors of two signature impurities, 1,3-dinitrobenzene and 2,4-dinitrotoluene (2,4-DNT), minor impurity compounds, and two possible tagging agents, 2-nitrotoluene (2-NT) and 4-nitrotoluene (4-NT), can be detected and selectively identified using our fluorescence approach. To prove our methodology, we show that we were able to generate, collect, and reduce 2-NT, 4-NT, and 2,4-DNT vapors to their amino analogs. Using our fluorescence approach, these vapors could be detected and selectively identified both individually and in a mixture. Collectively, our data indicate that our method of detecting and identifying higher vapor pressure explosive-like compounds could potentially be used to detect and identify low vapor pressure explosives such as TNT, RDX, and PETN.

Increasing selectivity for TNT-based explosive detection by synchronous luminescence and derivative spectroscopy with quantum yields of selected aromatic amines.

The detection of explosive material is at the forefront of current analytical problems. A detection method is desired that is not restricted to detecting only explosive materials, but is also capable of identifying the origin and type of explosive. It is essential that a detection method have the selectivity to distinguish among compounds in a mixture of explosives. The nitro compounds found in explosives have low fluorescent yields or are considered to be non-fluorescent; however, after reduction, the amino compounds exhibit relatively high fluorescence. We discuss how to increase selectivity of explosive detection using fluorescence; this includes synchronous luminescence and derivative spectroscopy with appropriate smoothing. By implementing synchronous luminescence and derivative spectroscopy, we were able to resolve the reduction products of one major TNT-based explosive compound, 2,4-diaminotoluene, and the reduction products of other minor TNT-based explosives in a mixture. We also report for the first time the quantum yields of these important compounds. Relative quantum yields are useful in establishing relative fluorescence intensities and are an important spectroscopic measurement of molecules. Our approach allows for rapid, sensitive, and selective detection with the discrimination necessary to distinguish among various explosives.

Fluorescence of aromatic amines and their fluorescamine derivatives for detection of explosive vapors.

Nitroaromatics (such as dinitrotoluene, trinitrotoluene, and nitrobenzene) found in explosive vapors from buried landmines can be reduced to aminoaromatics by a novel process involving Pd metal nanocatalysts prepared in supercritical fluid carbon dioxide and supported on multi-walled carbon nanotubes. These aminoaromatics are fluorescent and, if desired, the fluorescence yield can be increased and the fluorescence maxima shifted further toward the red by reaction with appropriate derivatizing agents such as fluorescamine. Corrected spectra for these chemicals and their derivatives are included. Subpicomolar detection limits have already been achieved using a laboratory spectrofluorometer with a 150 W Xe arc lamp. Using lasers as excitation sources, this approach has the potential for developing a field sensor competitive with other methods currently used for detecting explosive vapors from land mines.