Simultaneous determination of polycyclic aromatic hydrocarbon quinones by gas chromatography-tandem mass spectrometry, following a one-pot reductive trimethylsilyl derivatization.

We developed a sensitive and selective method to simultaneously analyze 37 polycyclic aromatic hydrocarbon quinones (PAHQs) with GC-MS/MS and applied the method to the analysis of standard atmospheric particulate matter samples. PAHQs were reduced with zinc granules and dithiothreitol (DTT) and the reductants were immediately converted to their silylated derivatives in a test tube. Two trimethylsilyl (TMS) groups were introduced into PAHQs through the one-pot reductive TMS derivatization. The PAHQs were derivatized with a mixed silylation reagent (BSA+TMCS+TMSI; (3:2:3)), which is one of the combinations of TMS-derivatization reagents with the highest reactivity. The derivatives produced different fragmentation between o-PAHQs and p-PAHQs. Therefore, isomers that have the same molecular weight are difficult to separate on a column were separated by the selected reaction monitoring (SRM) mode using the characteristic fragmentations, allowing separation and detection of all PAHQ derivatives in less than 30min. The instrumental detection limit (IDL) of each PAHQ was 1.2-29fg/injection and the method quantification limit (MQL) was 0.8-78µg/kg sample. For quantification, six deuterated PAHQs were used as internal standards to achieve high analytical precision. We applied the developed method to four standard atmospheric particulate matter samples. Results showed that out of 37 PAHQs, 33 compounds were identified and quantified. Moreover, from the 33 PAHQs, 14 were detected for the first time. Similar values were observed for the concentrations of PAHQs that have been quantified in previous reports. This method has the highest practicality in monitoring PAHQs in atmosphere, combustion exhaust gas, and toxicity evaluation. Thus, the method has the potential to become a standard analytical method for such applications.

Simultaneous spectrophotometric determination of p-benzoquinone and chloranil after microcrystalline naphthalene extraction by using genetic algorithm-based wavelength selection-partial least squares regression.

Microcrystalline naphthalene extraction has been used for the preconcentration of p-benzoquinone and tetrachloro-p-benzoquinone (chloranil), after their reaction by aniline, and later simultaneous spectrophotometric analysis by genetic algorithm-partial least squares (GA-PLS) calibration. The chemical variables affecting the analytical performance of the methodology were studied and optimized. Under the optimum conditions i.e., [aniline] = 0.05 M and [naphthalene] = 2.2% (w/v), preconcentration of 25 ml of sample solution permitted the detection of 0.32 and 0.23 microg ml(-1) for p-benzoquinone and chloranil, respectively. The predictive abilities of partial least squares regression (PLS) and genetic algorithm-partial least squares regression (GA-PLS) were examined for simultaneous determination of two quinones. The GA-PLS shows superiority over other PLS methods due to the wavelength selection in PLS calibration using a genetic algorithm without loss of prediction capacity, provides useful information about the chemical system.

Measurement of the novel antitumor agent 17-(allylamino)-17-demethoxygeldanamycin in human plasma by high-performance liquid chromatography.

A sensitive HPLC assay has been developed to determine the concentration of 17-(allylamino)-17-demethoxygeldanamycin (AAG) in human plasma over the concentration range of 12.5 to 2,500 nM (7.33 to 1,465 ng/mL). After the addition of 1,000 nM geldanamycin as the internal standard, 1 mL samples of human plasma were subjected to solid-phase extraction, via Bond-Elut C18 cartridges, followed by analysis using an isocratic reversed-phase HPLC assay with UV detection. A Phenomenex Kingsorb, 3 micron, C18, 150x4.60 mm column and a Phenomenex Security Guard pre-column, C18 (ODS, Octadecyl), were used to achieve separation. AAG and GM were monitored at 334 and 308 nm, respectively, on a Hewlett-Packard 1050 Diode-Array Detector. The mobile phase, run at a flow-rate of 1 mL/min, was composed of 50% (v/v) 25 mM sodium phosphate (pH 3.00) with 10 mM triethylamine and 50% acetonitrile. HPLC effectively resolved AAG with retention times of 14.60 +/- 0.54 min and the internal standard geldanamycin at 10.72+/-0.38 min (n = 15). This assay was able to measure plasma concentrations of AAG, the lower limit of quantitation being 12.5 nM, at a starting dose of 10 mg/m2 infused intravenously over 1 h in a Phase I clinical trial in adult patients with solid tumors.