Analysis of ascorbic acid based black powder substitutes by high‐performance liquid chromatography/electrospray ionization quadrupole time‐of‐flight mass spectrometry

Black powder substitutes are an important sub‐group of explosive propellants in the United States because they are readily accessible, and can be used as fillers for improvised explosive devices. Many brands of black powder substitutes incorporate an ascorbic acid fuel source with potassium nitrate (KNO₃) and/or potassium perchlorate (KClO₄) oxidizer(s). A gradient high‐performance liquid chromatography/electrospray ionization quadrupole time‐of‐flight mass spectrometry (HPLC/ESI‐QToFMS) method has been developed for the analysis of both the organic and the inorganic constituents. The HPLC/ESI‐QToFMS method was utilized to examine aqueous extracts of intact samples and post‐burn residues from six different brands of ascorbic acid based powders. Aqueous extracts of the post‐blast residues from two brands of ascorbic acid based propellant were also analyzed. The results showed that both the ascorbic acid fuel and the inorganic oxidizer(s) KClO₄ and/or KNO₃ were successfully detected via the [M–H]^? ion of ascorbic acid and the anions (ClO and NO) of the oxidizers. This method was proven to be a rapid and efficient procedure for the analysis of this class of explosives. The high mass resolution provided by the QToFMS instrument fulfills the degree of certainty required in a court of law. Published in 2010 by John Wiley & Sons, Ltd.     

Porphyrinogen fragmentation profiles by ultra‐high‐performance liquid chromatography/electrospray ionisation tandem mass spectrometry

An ultra‐high‐performance liquid chromatography/electrospray ionisation tandem mass spectrometry system is described for the separation and characterisation of uroporphyrinogen, heptacarboxylic acid porphyrinogen, hexacarboxylic acid porphyrinogen, pentacarboxylic acid porphyrinogen and coproporphyrinogen. The separation was carried out on a 100 mm × 2.1 mm Thermo‐Hypersil BDS column (2.4 µm average particle size) by gradient elution with a mixture of acetonitrile, methanol and 1 mol/L aqueous ammonium acetate buffer, pH 5.16, as eluent. The fragmentation pattern of each compound was established by collision‐induced dissociation tandem mass spectrometry. The most characteristic fragmentation was ring opening at one of the four methylene bridges of the protonated porphyrinogen molecule followed by further cleavages of methylene bridges linking the four pyrrole rings at various points to give product ions with methylenepyrrolenine, methylene‐dipyrrolenine and methylene‐tripyrrolenine structures. Copyright © 2011 John Wiley & Sons, Ltd.     

Characterization of tropane and cinnamamide alkaloids from Scopolia tangutica by high‐performance liquid chromatography with quadrupole time‐of‐flight tandem mass spectrometry

Scopolia tangutica is a traditional Chinese medicine used for antispasmodic, anesthesia, analgesia, and sedation. Its medicinal activity is associated to alkaloid constituents, including tropane and cinnamamide types. Low content of alkaloids in plant makes them difficult to be isolated and identified. The present work developed an effective method to quickly characterize alkaloids from Scopolia tangutica by high‐performance liquid chromatography coupled with quadrupole time‐of‐flight tandem mass spectrometry. Thirteen reference compounds were studied for their fragmentation pathways, including five tropane alkaloids and eight cinnamamide ones. Alkaloid constituent was analyzed by an optimized high‐performance liquid chromatography method and mass spectrometry analysis to achieve systematic characterization of alkaloids from Scopolia tangutica. As a result, 53 compounds were identified, including 21 tropane alkaloids (eight new ones), 18 caffeoyl ones (ten new ones) and 14 dicaffeoyl ones (seven new ones). It was important to provide rich information in phytochemical study and structure‐guided isolation of important compounds from this plant.     

Metabolite identification of tanshinol borneol ester in rats by high‐performance liquid chromatography combined with electrospray ionization quadrupole time‐of‐flight mass spectrometry

Tanshinol borneol ester (DBZ) is a potential drug candidate composed of danshensu and borneol. It shows anti‐ischemic and anti‐atherosclerosis activity. However, little is known about its metabolism in vivo. This research aimed to elucidate the metabolic profile of DBZ through analyzing its metabolites using high‐performance liquid chromatography combined with electrospray ionization quadrupole time‐of‐flight mass spectrometry. Chromatographic separation was performed on an Agilent TC‐C₁₈ column (150 × 4.6 mm, 5.0 μm) with gradient elution using methanol and water containing 0.2% (v/v) formic acid as the mobile phase. Metabolite identification involved analyzing the retention behaviors, changes in molecular weights and MS/MS fragment patterns of DBZ and its metabolites. As a result, 20 potential metabolites were detected and tentatively identified in rat plasma, urine and feces after administration of DBZ. DBZ could be metabolized to O‐methylated DBZ, DBZ‐O‐glucuronide, O‐methylated DBZ‐O‐glucuronide, hydroxylated DBZ and danshensu. Danshensu, a hydrolysis product of DBZ, could further be transformed into 12 metabolites. The proposed method was confirmed to be a reliable and sensitive alternative for characterizing metabolic pathways of DBZ and providing valuable information on its druggability.     

Characterization of carbofuran photodegradation by‐products by liquid chromatography/hybrid quadrupole time‐of‐flight mass spectrometry

The original article to which this Erratum refers was published in Rapid Commun. Mass Spectrom. 2005; 19 : 2193–2202.     

Identification of monovinyl tripropionic acid porphyrins and metabolites from faeces of patients with hereditary coproporphyria by high‐performance liquid chromatography/electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry

The original article to which this Erratum refers was published in Rapid Commun. Mass Spectrom. 2004; 18 : 2309–2316     

Characterization of isochlorogenic acid A metabolites in rats using high‐performance liquid chromatography/quadrupole time‐of‐flight mass spectrometry

Isochlorogenic acid A is widely present in fruits, vegetables and herbal medicines, and is characterized by anti‐inflammatory, hepatoprotective and antiviral properties. However, little is known about its metabolic fate and pharmacokinetic properties. This study is thus designed to investigate the metabolic fate of isochlorogenic acid A. An analytical method based on high‐performance liquid chromatography/quadrupole time‐of‐flight mass spectrometry (HPLC/Q‐TOF MS) was established to characterize the metabolites of isochlorogenic acid A in the plasma, urine and feces of rats. A total of 32 metabolites were identified. The metabolic pathways mainly include hydrolyzation, dehydroxylation, hydrogenation and conjugation with methyl, glucuronic acid, glycine, sulfate, glutathione and cysteine. Moreover, the pharmacokinetic profiles of all the circulating metabolites were investigated. M11 resulting from hydrolyzation, dehydroxylation and hydrogenation was the dominant circulating metabolite after the intragastric administration of isochlorogenic acid A. The results obtained will be useful for further study of elucidating potential bioactive metabolites which can provide better explanation of the pharmacological and/or toxicological effects of this compound.     

Simultaneous determination of niacin and pyridoxine at trace levels by using diode array high‐performance liquid chromatography and liquid chromatography with quadrupole time‐of‐flight tandem mass spectrometry

A highly sensitive and simple diode‐array high‐performance liquid chromatography and liquid chromatography with quadrupole time‐of‐flight tandem mass spectrometry method was developed for the simultaneous determination of niacin and pyridoxine in pharmaceutical drugs, tap water, and wastewater samples. To determine the in vivo behavior of niacin and pyridoxine, analytes were subjected to simulated gastric conditions. The calibration plots of the diode‐array high‐performance liquid chromatography and liquid chromatography with quadrupole time‐of‐flight tandem mass spectrometry method showed good linearity over a wide concentration range with close to 1.0 correlation coefficients for both analytes. The limit of detection/limit of quantitation values for liquid chromatography quadrupole time‐of‐flight tandem mass spectrometry analysis were 1.98/6.59 and 1.3/4.4 μg/L for niacin and pyridoxine, respectively, while limit of detection/limit of quantitation values for niacin and pyridoxine in high‐performance liquid chromatography analysis were 3.7/12.3 and 5.7/18.9 μg/L, respectively. Recovery studies were also performed to show the applicability of the developed methods, and percentage recovery values were found to be 90–105% in tap water and 94–97% in wastewater for both analytes. The method was also successfully applied for the qualitative and quantitative determination of niacin and pyridoxine in drug samples.