Monitoring of wine aging process by electrospray ionization mass spectrometry

The characterization of wine samples by direct insertion electrospray ionization mass spectrometry (ESI-MS), without pre-treatment or chromatographic separation, in a process denominated fingerprinting, has been applied to several samples of wine produced with grapes of the Pinot noir, Merlot and Cabernet Sauvignon varieties from the state o Rio Grande do Sul, in Brazil. The ESI-MS fingerprints of the samples detected changes which occurred during the aging process in the three grape varieties. Principal Component Analysis (PCA) of the negative ion mode fingerprints was used to group the samples, pinpoint the main changes in their composition, and indicate marker ions for each group of samples.

Analysis of acylcarnitine profiles in umbilical cord blood and during the early neonatal period by electrospray ionization tandem mass spectrometry

Acylcarnitine profiling by electrospray ionization tandem mass spectrometry (ESI-MS/MS) is a potent tool for the diagnosis and screening of fatty acid oxidation and organic acid disorders. Few studies have analyzed free carnitine and acylcarnitines in dried blood spots (DBS) of umbilical cord blood (CB) and the postnatal changes in the concentrations of these analytes. We have investigated these metabolites in healthy exclusively breastfed neonates and examined possible effects of birth weight and gestational age. DBS of CB were collected from 162 adequate for gestational age neonates. Paired DBS of heel-prick blood were collected 4-8 days after birth from 106 of these neonates, the majority exclusively breastfed. Methanol extracts of DBS with deuterium-labeled internal standards were derivatized before analysis by ESI-MS/MS. Most of the analytes were measured using a full-scan method. The levels of the major long-chain acylcarnitines, palmitoylcarnitine, stearoylcarnitine, and oleoylcarnitine, increased by 27, 12, and 109%, respectively, in the first week of life. Free carnitine and acetylcarnitine had a modest increase: 8 and 11%, respectively. Propionylcarnitine presented a different behavior, decreasing 9% during the period. The correlations between birth weight or gestational age and the concentrations of the analytes in DBS were weak (r £ 0.20) or nonsignificant. Adaptation to breast milk as the sole source of nutrients can explain the increase of these metabolites along the early neonatal period. Acylcarnitine profiling in CB should have a role in the early detection of metabolic disorders in high-risk neonates.

Espectrometria de massas com ionização por "electrospray" aplicada ao estudo de espécies inorgânicas e organometálicas

Although electrospray ionization mass spectrometry (ES-MS) has been extensively applied to study organic and biochemical species, it is also specially suitable to study inorganic and organo-metallic species. Such species, even those that are low-volatile or thermo-unstable, can be easily ionized or simply transferred from liquid to gas phase by electrospray. However, chemical transformations frequently occur during the process. This paper discusses the fundamental aspects of electrospray ionization as well as its analytical applicability to inorganic and organo-metallic species in order to spread the technique and make its characteristics more familiar to potential users.

Espectrometria de massas com ionização por "electrospray": processos químicos envolvidos na formação de íons de substâncias orgânicas de baixo peso molecular

An overview of the current literature on the chemical processes involved in the ion formation from low molecular weight organic compounds by electrospray ionization mass spectrometry is given.

Plasma free and total carnitine measured in children by tandem mass spectrometry

Free and total carnitine quantification is important as a complementary test for the diagnosis of unusual metabolic diseases, including fatty acid degradation disorders. The present study reports a new method for the quantification of free and total carnitine in dried plasma specimens by isotope dilution electrospray tandem mass spectrometry with sample derivatization. Carnitine is determined by looking for the precursor of ions of m/z = 103 of N-butylester derivative, and the method is validated by comparison with radioenzymatic assay. We obtained an inter- and intra-day assay coefficient of variation of 4.3 and 2.3, respectively. Free and total carnitine was analyzed in 309 dried plasma spot samples from children ranging in age from newborn to 14 years using the new method, which was found to be suitable for calculating reference age-related values for free and total carnitine (less than one month: 19.3 ± 2.4 and 23.5 ± 2.9; one to twelve months: 28.8 ± 10.2 and 35.9 ± 11.4; one to seven years: 30.7 ± 10.3 and 38.1 ± 11.9; seven to 14 years: 33.7 ± 11.6, and 43.1 ± 13.8 µM, respectively). No difference was found between males and females. A significant difference was observed between neonates and the other age groups. We compare our data with reference values in the literature, most of them obtained by radioenzymatic assay. However, this method is laborious and time consuming. The electrospray tandem mass spectrometry method presented here is a reliable, rapid and automated procedure for carnitine quantitation.

Análise quiral por espectrometria de massas através da utilização do método cinético

Novel and quantitative mass spectrometry methods for rapid and accurate enantiomeric excess determination are presented. These methodologies use electrospray ionization (ESI) and mass spectrometry (MS) to detect and analyze, via collision-induced dissociation (CID), mass-selected transition metal complexes that promote enantio especific interactions. The data from CID are conveniently treated by the kinetic method, a sensitive linear free energy method of treating mass spectrometric results. Four different variations of this methodology are described: single ratio method (S R), quotient ratio method (Q R), fixed ligand method (S Rfixed), and quotient ratio method with fixed ligand (Q Rfixed). These individual methods are compared and their main features discussed in detail.

Eletroforese capilar acoplada à espectrometria de massas (CE-MS): vinte anos de desenvolvimento

CE-MS has been increasingly used for analysis of a vast array of compounds. This article reviews the different electrophoretic modes, interfaces and mass analyzers that are commonly used in the CE-MS coupling, as well as the technique advantages and performance characteristics. A large compilation of CE-MS applications is also presented. Therefore, this review is both a guide for beginners and a collection of key references for people who are familiar to the technique. Furthermore, this is the first CE-MS review published in a Brazilian journal and marks the installation of the first two commercial CE-MS units in Sao Paulo State.

Avaliação da eficiência das técnicas ESI-MS e ATR/FTIR na determinação de adulteração de BX com querosene e óleo residual

Direct infusion electrospray ionization mass spectrometry in the negative ion mode, ESI(-)-MS and Fourier transform infrared spectroscopy (FTIR) were used together with partial least squares (PLS) as a tool to determine B3 adulteration (B3 - mixture of 3% v/v of biodiesel in diesel) with kerosene and residual oil.

Estudo por espectrometria de massas de soluções de hidróxi(tosilóxi)iodobenzeno: propostas para mecanismos de desproporção

Solutions of [hydroxy(tosyloxy)iodo]benzene (HTIB or Koser's reagent) in acetonitrile were analyzed using high resolution electrospray ionization mass spectrometry (ESI-MS) and electrospray ionization tandem mass spectrometry (ESI-MS/MS) under different conditions. Several species were characterized in these analyses. Based on these data, mechanisms were proposed for the disproportionation of the iodine(III) compounds in iodine(V) and iodine(I) species.

Preparative separation of polyphenols from artichoke by polyamide column chromatography and high-speed counter-current chromatography

An efficient method for the rapid separation and purification of polyphenols from artichoke by polyamide column chromatography in combination with high-speed counter-current chromatography (HSCCC) was successfully built. The crude ethanol extracts from dry artichoke were first pre-separated by polyamide column chromatography and divided in two parts as sample 1 and sample 2. Then, the samples were further separated by HSCCC and yielded 7.8 mg of chlorogenic acid (compound I), 24.5 mg of luteolin-7-O-β-D-rutinoside (compound II), 18.4 mg of luteolin-7-O-β-D-glucoside (compound III), and 33.4 mg of cynarin (compound IV) with purity levels of 92.0%, 98.2%, 98.5%, and 98.0%, respectively, as determined by high-performance liquid chromatography (HPLC) method. The chemical structures of these compounds were identified by electrospray ionization-mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR).

Preparative separation of C19-diterpenoid alkaloids from Aconitum carmichaelii Debx by pH‑zone-refining counter-current chromatography

The technique of pH-zone-refining counter-current chromatography was successfully applied to preparatively separate three C19-diterpenoid alkaloids from the crude extracts of Aconitum carmichaelii for the first time using a two-phase solvent system of petroleum ether-ethyl acetate-methanol-water (5:5:1:9, v/v/v/v). Mesaconitine (I), hypaconitine (II), and deoxyaconitine (III) were obtained from 2.5 g of the crude alkaloids in a one-step separation; the yields were 4.16%, 16.96%, and 5.05%, respectively. The purities of compounds I, II, and III were 93.0%, 95%, and 96%, respectively, as determined by HPLC. The chemical structures of the three compounds were identified by electrospray ionization mass spectrometry (ESI-MS) and NMR.

DIRECT INFUSION ESI-MS APPLIED IN THE DETECTION OF BYPRODUCTS DUE TO REDUCTIVE DEGRADATION OF ACETAMIPRID BY ZERO-VALENT IRON

This study investigated the reductive degradation of acetamiprid (5 mg L-1) in aqueous medium (at pH 2.0) induced by zero-valent iron (50 mg). The process was monitored using high-performance liquid chromatography (HPLC) to determine the degradation rate as a function of reaction time, and direct infusion electrospray ionization mass spectrometry (DI-ESI-MS) to search for (and potentially characterize) any possible byproducts formed during degradation. The results obtained via HPLC showed that after 60 min, the degradation of the substrate reached nearly 100% in an acidic medium, whereas the mineralization rate (as determined by total organic carbon measurements) was as low as 3%. Data obtained by DI-ESI-MS showed that byproducts were formed mainly by insertions of hydrogen atoms into the nitrile, imine, and pyridine ring moieties, in addition to the observation of chlorine substitution by hydrogen replacement (hydrodechlorination) reactions.

Prokaryotic expression of a novel mouse pro-apoptosis protein PNAS-4 and application of its polyclonal antibodies

Mouse PNAS-4 (mPNAS-4) has 96% identity with human PNAS-4 (hPNAS-4) in primary sequence and has been reported to be involved in the apoptotic response to DNA damage. However, there have been no studies reported of the biological functions of mPNAS-4. In studies conducted by our group (unpublished data), it was interesting to note that overexpression of mPNAS-4 promoted apoptotic death in Lewis lung carcinoma cells (LL2) and colon carcinoma cells (CT26) of mice both in vitro and in vivo. In our studies, mPNAS-4 was cloned into the pGEX-6P-1 vector with GST tag at N-terminal in Escherichia coli strain BL21(DE3). The soluble and insoluble expression of recombinant protein mPNAS-4 (rmPNAS-4) was temperature-dependent. The majority of rmPNAS-4 was insoluble at 37°C, while it was almost exclusively expressed in soluble form at 20°C. The soluble rmPNAS-4 was purified by one-step affinity purification, using a glutathione Sepharose 4B column. The rmPNAS-4 protein was further identified by electrospray ionization-mass spectrometry analysis. The search parameters of the parent and fragment mass error tolerance were set at 0.1 and 0.05 kDa, respectively, and the sequence coverage of search result was 28%. The purified rmPNAS-4 was further used as immunogen to raise polyclonal antibodies in New Zealand white rabbit, which were suitable to detect both the recombinant and the endogenous mPNAS-4 in mouse brain tissue and LL2 cells after immunoblotting and/or immunostaining. The purified rmPNAS-4 and our prepared anti-mPNAS-4 polyclonal antibodies may provide useful tools for future biological function studies for mPNAS.

In vitro and in vivo antitumor activity of crude extracts obtained from Brazilian Chromobacterium sp isolates

Natural products produced by microorganisms have been an important source of new substances and lead compounds for the pharmaceutical industry. Chromobacterium violaceum is a Gram-negative β-proteobacterium, abundant in water and soil in tropical and subtropical regions and it produces violacein, a pigment that has shown great pharmaceutical potential. Crude extracts of five Brazilian isolates of Chromobacterium sp (0.25, 2.5, 25, and 250 µg/mL) were evaluated in an in vitro antitumor activity assay with nine human tumor cells. Secondary metabolic profiles were analyzed by liquid chromatography and electrospray ionization mass spectrometry resulting in the identification of violacein in all extracts, whereas FK228 was detected only in EtCE 308 and EtCE 592 extracts. AcCE and EtCE 310 extracts showed selectivity for NCI/ADR-RES cells in the in vitro assay and were evaluated in vivo in the solid Ehrlich tumor model, resulting in 50.3 and 54.6% growth inhibition, respectively. The crude extracts of Chromobacterium sp isolates showed potential and selective antitumor activities for certain human tumor cells, making them a potential source of lead compounds. Furthermore, the results suggest that other compounds, in addition to violacein, deoxyviolacein and FK228, may be involved in the antitumor effect observed.

Measurement of serum estrogen and estrogen metabolites in pre- and postmenopausal women with osteoarthritis using high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry

Although 17β-estradiol (E2) deficiency has been linked to the development of osteoarthritis (OA) in middle-aged women, there are few studies relating other estrogens and estrogen metabolites (EMs) to this condition. We developed a high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) method to measure the levels of six EMs (i.e., estrone, E2, estriol, 2-hydroxyestrone, 2-hydroxyestradiol, and 16a-hydroxyestrone) in healthy pre- and postmenopausal women and women with OA. This method had a precision ranging from 1.1 to 3.1% and a detection limit ranging from 10 to 15 pg. Compared to healthy women, serum-free E2 was lower in the luteal and postmenopausal phases in women with OA, and total serum E2 was lower in postmenopausal women with OA. Moreover, compared to healthy women, total serum 2-hydroxyestradiol was higher in postmenopausal women with OA and total serum 2-hydroxyestrone was lower in both the luteal and follicular phases in women with OA. In conclusion, our HPLC-ESI-MS/MS method allowed the measurement of multiple biochemical targets in a single assay, and, given its increased cost-effectiveness, simplicity, and speed relative to previous methods, this method is suitable for clinical studies.