Analysis of surfactants by mass spectrometry: Coming to grips with their diversity.

Surfactants are surface-active agents widely used in numerous applications in our daily lives as personal care products, domestic, and industrial detergents. To determine complex mixtures of surfactants and their degradation products, unselective and rather insensitive methods, based on colorimetric and complexometric analyses are no longer employable. Analytical methodologies able to determine low concentration levels of surfactants and closely related compounds in complex matrices are required. The recent introduction of robust, sensitive, and selective mass spectrometry (MS) techniques has led to the rapid expansion of the surfactant research field including complex mixtures of isomers, oligomers, and homologues of surfactants as well as their chemically and biodegradation products at trace levels. In this review, emphasis is given to the state-of-the-art MS-based analysis of surfactants and their degradation products with an overview of the current research landscape from traditional methods involving hyphenate techniques (gas chromatography-MS and liquid chromatography-MS) to the most innovative approaches, based on high-resolution MS. Finally, we outline a detailed explanation on the utilization of MS for mechanistic purposes, such as the study of micelle formation in different solvents.

Mass spectrometric characterization of aminophospholipids containing N-(2-hydroxyethyl)glycine in kombu algae extracts.

RATIONALE: 1,2-Diacyl-sn-glycero-3-phospho-O-[N-(2-hydroxyethyl)glycines] (PHEGs) are a class of rare aminophospholipids found specifically in brown algae, including kombu seaweed. Despite their potential importance in algal physiology, a comprehensive mass spectrometry (MS) characterization, useful to understand their biological behaviour, is still lacking. METHODS: To establish the structural regiochemical features of PHEGs, we employed hydrophilic interaction liquid chromatography (HILIC). Following separation, the isolated band of PHEGs was analyzed using MS techniques. This included multistage tandem MS experiments, performed in both positive and negative electrospray ionization modes at low and high resolution. RESULTS: By comparing MS/MS and MS3 spectra acquired in negative ion mode, the regiochemical rules for PHEG identification were established. The most abundant PHEG species in kombu seaweed, from both Laminaria ochroleuca (European Atlantic) and Laminaria longissima (Japan), was identified as PHEG 20:4/20:4. Less abundant species included PHEG 20:4/20:5 and hydroxylated forms of both PHEG 20:4/20:4 (i.e. 40:8;O) and 20:4/20:5 (40:9;O). The presence of a lyso PHEG 20:4 was consistently detected but at very low levels. CONCLUSIONS: This study employed MS analysis to elucidate the regiochemical patterns of PHEGs in kombu seaweed. We identified PHEG 20:4/20:4 as the dominant species, along with several less abundant variants, including hydroxylated forms. These findings provide valuable insights into the potential roles and metabolism of PHEGs in brown algae, paving the way for further investigation into their biological functions.

An Amperometric Biosensor Based on a Bilayer of Electrodeposited Graphene Oxide and Co-Crosslinked Tyrosinase for L-Dopa Detection in Untreated Human Plasma.

L-Dopa, a bioactive compound naturally occurring in some Leguminosae plants, is the most effective symptomatic drug treatment for Parkinson's disease. During disease progression, fluctuations in L-DOPA plasma levels occur, causing motor complications. Sensing devices capable of rapidly monitoring drug levels would allow adjusting L-Dopa dosing, improving therapeutic outcomes. A novel amperometric biosensor for L-Dopa detection is described, based on tyrosinase co-crosslinked onto a graphene oxide layer produced through electrodeposition. Careful optimization of the enzyme immobilization procedure permitted to improve the long-term stability while substantially shortening and simplifying the biosensor fabrication. The effectiveness of the immobilization protocol combined with the enhanced performances of electrodeposited graphene oxide allowed to achieve high sensitivity, wide linear range, and a detection limit of 0.84 µM, suitable for L-Dopa detection within its therapeutic window. Interference from endogenous compounds, tested at concentrations levels typically found in drug-treated patients, was not significant. Ascorbic acid exhibited a tyrosinase inhibitory behavior and was therefore rejected from the enzymatic layer by casting an outer Nafion membrane. The proposed device was applied for L-Dopa detection in human plasma, showing good recoveries.

Untargeted metabolomic analysis by ultra-high-resolution mass spectrometry for the profiling of new Italian wine varieties.

The chemical composition of wine samples comprises numerous bioactive compounds responsible for unique flavor and health-promoting properties. Thus, it's important to have a complete overview of the metabolic profile of new wine products in order to obtain peculiar information in terms of their phytochemical composition, quality, and traceability. To achieve this aim, in this work, a mass spectrometry-based phytochemical screening was performed on seven new wine products from Villa D'Agri in the Basilicata region (Italy), i.e., Aglianico Bianco, Plavina, Guisana, Giosana, Malvasia ad acino piccolo, Colata Murro and Santa Sofia. Ultra-high-resolution mass spectrometry data were processed into absorption mode FT-ICR mass spectra, in order to remove artifacts and achieve a higher resolution and lower levels of noise. Accurate mass-to-charge ratio (m/z) values were converted into putative elemental formulas. Therefore, 2D van Krevelen diagrams were used as a tool to obtain molecular formula maps useful to perform a rapid and more comprehensive analysis of the wine sample metabolome. The presence of important metabolite classes, i.e., fatty acid derivatives, amino acids and peptides, carbohydrates and phenolic derivatives, was assessed. Moreover, the comparison of obtained metabolomic maps revealed some differences among profiles, suggesting their employment as metabolic fingerprints. This study shed some light on the metabolic composition of seven new Italian wine varieties, improving their value in terms of related bioactive compound content. Moreover, different metabolomic fingerprints were obtained for each of them, suggesting the use of molecular maps as innovative tool to ascertain their unique metabolic profile.

Development and Validation of a Reversed-Phase HPLC Method with UV Detection for the Determination of L-Dopa in Vicia faba L. Broad Beans.

L-Dopa (LD), a substance used medically in the treatment of Parkinson's disease, is found in several natural products, such as Vicia faba L., also known as broad beans. Due to its low chemical stability, LD analysis in plant matrices requires an appropriate optimization of the chosen analytical method to obtain reliable results. This work proposes an HPLC-UV method, validated according to EURACHEM guidelines as regards linearity, limits of detection and quantification, precision, accuracy, and matrix effect. The LD extraction was studied by evaluating its aqueous stability over 3 months. The best chromatographic conditions were found by systematically testing several C18 stationary phases and acidic mobile phases. In addition, the assessment of the best storage treatment of Vicia faba L. broad beans able to preserve a high LD content was performed. The best LD determination conditions include sun-drying storage, extraction in HCl 0.1 M, chromatographic separation with a Discovery C18 column, 250 × 4.6 mm, 5 µm particle size, and 99% formic acid 0.2% v/v and 1% methanol as the mobile phase. The optimized method proposed here overcomes the problems linked to LD stability and separation, thus contributing to the improvement of its analytical determination.

Biomolecules from snail mucus (Helix aspersa) conjugated gold nanoparticles, exhibiting potential wound healing and anti-inflammatory activity.

In this work, for the first time, snail slime from garden snails "Helix Aspersa Müller", has been used to induce the formation of eco-friendly gold nanoparticles (AuNPs-SS) suitable for biomedical applications. An AuNPs-SS comprehensive investigation was performed and AuNPs with an average particle size of 14 ± 6 nm were observed, stabilized by a slime snail-based organic layer. Indeed, as recognized in high-resolution MALDI-MS analyses, and corroborated by FESEM, UV-Vis, ATR-FTIR, and XPS results, it was possible to assess the main presence of peptides and amino acids as the main components of the slime, that, combined with the AuNPs confers on them interesting properties. More specifically, we tested, in vitro, the AuNPs-SS safety in human keratinocytes and their potential effect on wound healing as well as their anti-inflammatory properties in murine macrophages. Moreover, the AuNPs-SS treatment resulted in a significant increase of the urokinase-type plasminogen activator receptor (uPAR), essential for keratinocyte adhesion, spreading, and migration, together with the reduction of LPS-induced IL1-ß and IL-6 cytokine levels, and completely abrogated the synthesis of inducible nitric oxide synthase (iNOS).

Coceth sulfate characterization by electrospray ionization tandem mass spectrometry.

RATIONALE: The anionic surfactants, among which are alkyl ether sulfates (AESs), are the most used class of surfactants in cleansing applications. The negatively charged head group of AESs is a sulfate moiety linked with a variable number of ethylene oxide units, i.e. a polyethylene glycol chain. The hydrophobic part of an AES is constituted by a linear alkyl chain of carbon atoms, generally obtained from natural fatty acids. Coconut oil fatty acids, including the sodium salts of coceth sulfate (CES) with chemical formula Cx Hy (OCH2 CH2 )n OSO3 Na, are widely used as feedstock for AESs synthesis. CES is added to many cleaning products and detergents defined as non-aggressive. Currently, no detailed structural information concerning the alkyl chain length x and, more importantly, the degree of ethoxylation n has been reported. METHODS: A commercial standard solution of CES was characterized by tandem mass spectrometry, employing direct injection into the electrospray ionization (ESI) source of a a linear quadrupole ion trap mass spectrometer. RESULTS: Two series of oligomeric species, characterized by a C12 and C14 alkyl chains, i.e. [C12 H25 (OCH2 CH2 )nOSO3 ]- and [C14 H29 (OCH2 CH2 )n OSO3 ]- with n ranging from 0 to 7, were successfully identified. The interpretation of these data was very useful for CES identification in three commercial dishwasher cleaning products. CONCLUSIONS: Direct injection MS/MS analysis of CES revealed a well-defined molecular weight distribution and allowed the alkyl chain composition and the number of ethylene oxide units to be to identified.

Profiling of quercetin glycosides and acyl glycosides in sun-dried peperoni di Senise peppers (Capsicum annuum L.) by a combination of LC-ESI(-)-MS/MS and polarity prediction in reversed-phase separations.

Interest in targeted profiling of quercetin glycoconjugates occurring in edible foodstuffs continues to expand because of their recognized beneficial health effects. Quercetin derivatives encompass several thousands of chemically distinguishable compounds, among which there are several compounds with different glycosylations and acylations. Since reference standards and dedicated databases are not available, the mass spectrometric identification of quercetin glycoconjugates is challenging. A targeted liquid chromatography (LC) coupled with tandem mass spectrometry (MS/MS) was applied for screening quercetin glycoconjugates in edible peperoni di Senise peppers (Capsicum annuum L.), protected by the European Union with the mark PGI (i.e., Protected Geographical Indication), and cultivated in Basilicata (Southern Italy). Chromatographic separation was accomplished by reversed-phase liquid chromatography (RPLC) using water/acetonitrile as the mobile phase and detection was performed on a linear ion trap mass spectrometer fitted with an electrospray ionization (ESI) source operating in negative ion mode. A correlation between experimental RP chromatographic retention time and those predicted by partition coefficients (log P) along with MS/MS data and an in-house developed database (named QUEdb) provided deep coverage for sixteen quercetin glycoconjugates. Among them, eleven quercetin glycoconjugates were already described in the literature and five were reported for the first time. These last acyl glycosidic quercetin derivatives were tentatively identified as quercetin-(galloyl-rhamnoside)-hexoside, [C34H33O20]- at m/z 761.1; quercetin-(sinapoyl-hexoside)-rhamnoside, [C38H39O20]- at m/z 815.4; quercetin-(galloyl-caffeoyl-hexoside)-rhamnoside, [C43H39O23]- at m/z 923.0; quercetin-(feruloyl-hexoside)-rhamnoside, [C37H37O19]- at m/z 785.1; and quercetin-(succinyl-rhamnoside)-rhamnoside, [C31H33O18]- at m/z 693.1. Graphical abstract.

Validation of a liquid chromatography coupled with tandem mass spectrometry method for the determination of drugs in wastewater using a three-phase solvent system.

Pharmaceuticals constitute one of the most important emerging classes of environmental pollutants. A three-phase solvent system of water, water containing 0.1% of formic acid and acetonitrile was successfully used to separate, by liquid chromatography with mass spectrometry (LC-MS), polarity-matched pharmaceuticals, that is, carbamazepine, clarithromycin, and erythromycin, as well as amoxicillin and metformin. Despite of polarity similarities, these pharmaceuticals were completely resolved in the analytical run time of 15 min. The optimized three-phase solvent system based-method was validated for the simultaneous analysis of six matched-polarity pharmaceuticals in wastewater samples. Good linearity (coefficient of determination more than 0.993) and precision (relative standard deviation less than 15.66%) were achieved. Recovery of analytes from the wastewater was between 0.70 and 1.18. Limits of detections ranged from 0.0001 to 0.5114 µg/L. No significant matrix effect, evaluated by post extraction addition, was observed in the electrospray ionization (ESI) source. Then, this methodology has been successfully applied to environmental study of pharmaceutical residues occurring in influent and effluent wastewater samples, from the main wastewater treatment plant in Potenza (Basilicata, Southern Italy).

Effect of pH and mobile phase additives on the chromatographic behaviour of an amide-embedded stationary phase: Cyanocobalamin and its diaminemonochloro-platinum(II) conjugate as a case study.

Several mobile phase additives (i.e., organic acids and their ammonium salts) were used to modulate the chromatographic retention of cyanocobalamin and its cis-diaminemonochloroplatinum(II) conjugate, depending on the specific nature of the stationary phase. Regardless of the mobile phase additive, the positively charged cyanocobalamin-cis-diaminemonochloroplatinum(II) conjugate was systematically less retained than cyanocobalamin on a conventional octadecyl-silica column. In contrast, the amide-embedded C18 column exhibited a progressive increase in the conjugate retention time upon changing the mobile phase additive from organic (acetic, formic and trifluoroacetic) acids to ammonium salts, ultimately leading to an inversion of the elution order. This change of retention was interpreted by invoking the interplay between hydrophobic interactions, hydrogen bonding between the conjugate and the polar amide groups and the ion-pairing ability of the lyophilic counterions, whereby the acetate anion was found to be the most suitable to control the solute retention.

Interactions between elastin-like peptides and an insulating poly(ortho-aminophenol) membrane investigated by AFM and XPS.

This investigation was undertaken to explore the mutual recognition of the pentapeptide (ValGlyGlyValGly)n, a hydrophobic elastin-like peptide (ELP), suspended in deionized water in monomer (n = 1) and trimer (n = 3) forms and the outer surface of a very thin, insulating polymer, poly(ortho-aminophenol) (PoAP), electrochemically grown on a platinum foil by cyclic voltammetry in a neutral medium (phosphate-buffered saline, I = 0.1M) immersed in the suspension. As a prior task, the proved propensity of the ValGlyGlyValGly sequence, at the given minimal length (three or more repeats), to self-assemble into amyloid-like fibrils when solubilized in an aqueous environment was considered within the framework of testing PoAP surfaces for the specific detection of amyloid precursors. From our knowledge of the chemical structure and physical properties of both biomacromolecule families obtained in previous studies, we focused on the efficacy of the binding sites offered to ELP fibrils by PoAP in its as-prepared form or properly modified either by postsynthesis oxidation or by adsorption/entrapping of ELP monomer(s) with or without protecting terminal groups. Consistent with all methods of preparation, the best surfaces, recognizable by the trimer fibrils, are those modified to carry a larger number of carbonyls, particularly by entrapment of ELP monomer(s) during PoAP electrosynthesis using an imprinting-inspired method. The degree of attachment of fibrillar aggregates, detected by atomic force microscopy and X-ray photoelectron spectroscopy, provides unequivocal evidence of the cooperative forces involving PoAP-ELP interactions. The results obtained suggest the prospect of using the proposed Pt/PoAP/ELP systems as biodetectors in Alzheimer disease. Graphical abstract Synthesis steps of Pt/PoAP/ELP electrodes for amyloid detection. AFM = Atomic Force Microscopy, CV = Cyclic Voltammetry, ELPs = Elastin like Peptides, PoAP = Poly ortho-Aminophenol, Pt = Platinum, XPS = X-ray Photoelectron Spectroscopy.

Determination of soyasaponins in Fagioli di Sarconi beans (Phaseolus vulgaris L.) by LC-ESI-FTICR-MS and evaluation of their hypoglycemic activity.

Soyasaponins are oleanene-type triterpenoid saponins, naturally occurring in many edible plants that have attracted a great deal of attention for their role in preventing chronic diseases. The aim of this study was to establish the distribution and the content of soyasaponins in 21 ecotypes of Fagioli di Sarconi beans (Phaseolus vulgaris, Leguminosae). High-performance reversed-phase liquid chromatography (RPLC) with positive electrospray ionization (ESI(+)) and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (MS) in conjunction with infrared multiphoton dissociation (IRMPD) was applied for the unambiguous identification of soyasaponins Ba (m/z 959.5213, [C48H79O19]+), Bb (m/z 943.5273, [C48H79O18]+), Bd (m/z 957.5122, [C48H77O19]+), and Be (m/z 941.5166, [C48H77O18]+), which are the only commercially available reference standards. In addition, the several diagnostic product ions generated by IRMPD in the ICR-MS cell allowed us the putative identification of soyasaponins Bb' (m/z 797.4680, [C42H69O14]+), αg (m/z 1085.5544, [C54H85O22]+), ßg (m/z 1069.5600, [C54H85O21]+), and γg (m/z 923.5009, [C48H75O17]+), establishing thus their membership in the soyasaponin group. Quantitative and semiquantitative analysis of identified soyasaponins were also performed by RPLC-ESI(+) FTICR-MS; the total concentration levels were found ranging from 83.6 ± 9.3 to 767 ± 37 mg/kg. In vitro hypoglycemic outcomes of four soyasaponin standards were evaluated; significant inhibitory activities were obtained with IC50 values ranging from 1.5 ± 0.1 to 2.3 ± 0.2 µg/mL and 12.0 ± 1.1 to 29.4 ± 1.4 µg/mL for α-glucosidase and α-amylase, respectively. This study represents the first detailed investigation on the antidiabetic activity of bioactive constituents found in Fagioli di Sarconi beans. Graphical abstract The first detailed RPLC-ESI(+) FTICR-MS investigation of the qualitative and semiquantitative profile of soyasaponins, occurring in 21 ecotypes of Fagioli di Sarconi beans (P. vulgaris L.).

Sequence protein identification by randomized sequence database and transcriptome mass spectrometry (SPIDER-TMS): from manual to automatic application of a 'de novo sequencing' approach.

Sequence protein identification by a randomized sequence database and transcriptome mass spectrometry software package has been developed at the University of Basilicata in Potenza (Italy) and designed to facilitate the determination of the amino acid sequence of a peptide as well as an unequivocal identification of proteins in a high-throughput manner with enormous advantages of time, economical resource and expertise. The software package is a valid tool for the automation of a de novo sequencing approach, overcoming the main limits and a versatile platform useful in the proteomic field for an unequivocal identification of proteins, starting from tandem mass spectrometry data. The strength of this software is that it is a user-friendly and non-statistical approach, so protein identification can be considered unambiguous.

Structural characterization of major soyasaponins in traditional cultivars of Fagioli di Sarconi beans investigated by high-resolution tandem mass spectrometry.

Major soyasaponins, i.e., soyasaponins I, V, ßg, and αg from traditional Fagioli di Sarconi beans (Phaseolus vulgaris L., ecotype Tabacchino), were analyzed by reversed-phase liquid chromatography-mass spectrometry (MS) using high-resolution Fourier transform ion cyclotron resonance (FTICR) MS on electrospray ionization in positive-ion mode. Fagioli di Sarconi beans are protected by the European Union [Commission Regulation (EC) No 1263/96] with the mark PGI (for "Protected Geographical Indication"), and are cultivated in Basilicata (southern Italy). Protonated adducts of soyasaponins I, V, ßg, and αg were observed at m/z 943.5262, 959.5213, 1069.5583, and 1085.5534, respectively. Gas-phase dissociation of soyasaponins by infrared multiphoton dissociation FTICR MS was performed using a CO2 laser source at a wavelength of 10.6 µm. Most of the fragment ions were identified unambiguously by using the high-resolution and accurate mass value provided by the FTICR mass spectrometer. All soyasaponins exhibit a sequential and neutral loss of sugar moieties at relatively short irradiation times (i.e., less than 50 ms). When the pulse length was increased, a more pronounced fragmentation occurred, with several signals in the lower part of the mass spectrum. In the case of soyasaponins ßg and αg, the occurrence of the conjugated product ion at m/z 127.0389 ([C6H6O3 + H](+), 2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one) was evidenced. Coupling reversed-phase liquid chromatography with high-performance FTICR MS in combination with infrared multiphoton dissociation tandem MS proved to be very promising for the structural characterization of soyasaponins, and is also suitable for the rapid and accurate structural investigation of other saponins. Graphical Abstract Representative Infrared Multiphoton Dissociation (IRMPD)-FTICR MS spectra of main group B saponins in Fagioli di Sarconi beans.

Structural characterization of arginine-vasopressin and lysine-vasopressin by Fourier- transform ion cyclotron resonance mass spectrometry and infrared multiphoton dissociation.

Arginine-vasopressin (AVP) and lysine-vasopressin (LVP) were analyzed by reversed-phase liquid chromatography/mass spectrometry (LC-MS) using Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry (MS) electrospray ionization (ESI) in the positive ion mode. LVP and AVP exhibited the protonated adduct [M+H](+) as the predominant ion at m/z 1056.43965 and at m/z 1084.44561, respectively. Infrared multiphoton dissociation (IRMPD), using a CO(2) laser source at a wavelength of 10.6 µm, was applied to protonated vasopressin molecules. The IRMPD mass spectra presented abundant mass fragments essential for a complete structural information. Several fragment ions, shared between two target molecules, are discussed in detail. Some previously unpublished fragments were identified unambiguously utilizing the high resolution and accurate mass information provided by the FT-ICR mass spectrometer. The opening of the disulfide loop and the cleavage of the peptide bonds within the ring were observed even under low-energy fragmentation conditions. Coupling the high-performance FT-ICR mass spectrometer with IRMPD as a contemporary fragmentation technique proved to be very promising for the structural characterization of vasopressin.

New piperazine and morpholine derivatives: Mass spectrometry characterization and evaluation of their antimicrobial activity.

Recently, pharmaceutical research has been focused on the design of new antibacterial drugs with higher selectivity towards several strains. Major issues concern the possibility to obtain compounds with fewer side effects, at the same time effectively overcoming the problem of antimicrobial resistance. Several solutions include the synthesis of new pharmacophores starting from piperazine or morpholine core units. Mass spectrometry-based techniques offer important support for the structural characterization of newly synthesized compounds to design safer and more effective drugs for various medical conditions. Here, two new piperazine derivatives and four new morpholine derivatives were synthesized and structurally characterized through a combined approach of Fourier transform-ion cyclotron resonance (FT-ICR) and Linear Trap Quadrupole (LTQ) mass spectrometry. The support of both high-resolution and low-resolution mass spectrometric data namely accurate mass measurements, isotopic distribution and MSn spectra, was crucial to confirm the success of the synthesis. These compounds were further evaluated for inhibitory activity against a total of twenty-nine Gram-positive and Gram-negative bacteria to determine the action spectrum and the antimicrobial effectiveness. Results demonstrated compounds' antimicrobial activity against many tested bacterial species, providing an inhibitory effect linked to different chemical structure and suggesting that the new-synthesized derivatives could be considered as promising antimicrobial agents.

Perceiving the chemical language of Gram-negative bacteria: listening by high-resolution mass spectrometry.

Gram-negative bacteria use N-acylhomoserine lactones (AHLs) as their command language to coordinate population behavior during invasion and colonization of higher organisms. Although many different bacterial bioreporters are available for AHLs monitoring, in which a phenotypic response, e.g. bioluminescence, violacin production, and ß-galactosidase activity, is exploited, mass spectrometry (MS) is the most versatile detector for rapid analysis of AHLs in complex microbial samples, with or without prior separation steps. In this paper we critically review recent advances in the application of high-resolution MS to analysis of the quorum sensing (QS) signaling molecules used by Gram-negative bacteria, with much emphasis on AHLs. A critical review of the use of bioreporters in the study of AHLs is followed by a short methodological survey of the capabilities of high-resolution mass spectrometry (HRMS), including Fourier-transform ion cyclotron resonance (FTICR) MS and quadrupole time-of-flight (qTOF) MS. Use of infusion electrospray ultrahigh-resolution FTICR MS (12 Tesla) enables accurate mass measurements for determination of the elemental formulas of AHLs in Acidovorax sp. N35 and Burkholderia ubonensis AB030584. Results obtained by coupling liquid chromatography with a hybrid quadrupole linear ion trap-FTICR mass spectrometer (LC-LTQ-FTICRMS, 7-T) for characterization of acylated homoserine lactones in the human pathogen Pseudomonas aeruginosa are presented. UPLC-ESI-qTOF MS has also proved to be suitable for identification of 3O-C(10)HSL in Pseudomonas putida IsoF cell culture supernatant. Aspects of sample preparation and the avoidance of analytical pitfalls are also emphasized.

Scrambling of autoinducing precursor peptides investigated by infrared multiphoton dissociation with electrospray ionization and Fourier transform ion cyclotron resonance mass spectrometry.

Two synthetic precursor peptides, H(2)N-CVGIW and H(2)N-LVMCCVGIW, involved in the quorum sensing of Lactobacillus plantarum WCFS1, were characterized by mass spectrometry (MS) with electrospray ionization and 7-T Fourier transform ion cyclotron resonance (ESI-FTICR) instrument. Cell-free bacterial supernatant solutions were analyzed by reversed-phase liquid chromatography with ESI-FTICR MS to verify the occurrence of both pentapeptide and nonapeptide in the bacterial broth. The structural characterization of both protonated peptides was performed by infrared multiphoton dissociation using a continuous CO(2) laser source at a wavelength of 10.6 µm. As their fragmentation behavior cannot be directly derived from the primary peptide structure, all anomalous fragments were interpreted as neutral loss of amino acids from the interior of both peptides, i.e., loss of V, G, VG and M, MC, V, CC, from H(2)N-CVGIW and H(2)N-LVMCCVGIW, respectively. Mechanisms of this scrambling are proposed. FTICR MS provides accurate masses of all fragment ions with very low absolute mass errors (<1.6 ppm), which facilitated the reliable assignment of their elemental compositions. The resolving power was more than sufficient to resolve closely isobaric product ions with routine subparts per million mass accuracies. Only the occurrence of pentapeptide was found in the cell-free culture of L. plantarum, grown in Waymouth's medium broth, with a low content of 5.2 ± 2.6 µM by external calibration. Most of it was present as oxidized H(2)N-CVGIW, that is, the soluble disulfide pentapeptide with a level tenfold higher (i.e., 50 ± 4 µM, n = 3).

Dibenzo-p-dioxins and dibenzofurans in human breast milk collected in the area of Taranto (Southern Italy): first case study.

We report on the content of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in 15 breast milk samples of nursing women living in the city of Taranto (Southern, Italy) or nearby. Breast milk samples were collected over the 2008-2009 period and analyzed by gas chromatography coupled with high-resolution mass spectrometry (GC-HRMS) upon accelerated solvent extraction (ASE) using acetone/n-hexane mixture 1:1 (v/v). The method was validated demonstrating good performing features. Profiles of PCDD/PCDF congeners in breast milk samples exhibited a prevalence of PCDFs compared to PCDDs. Toxic equivalents (TEQs in picogram per gram fat) of four breast milk were far above the legal limit for human consumption of 3.0 pg/g; their estimated daily and weekly dietary intake were almost 5-20 and 10-40 times higher, respectively, than the tolerable intake values established by the World Health Organization.

Incorporation of bioactive compounds from avocado by-products to ethyl cellulose-reinforced paper for food packaging applications.

Reinforced films were fabricated by impregnating paper in ethyl cellulose solutions. After solvent evaporation, the infused ethyl cellulose acted as binder of the paper microfibres and occupied the pores and cavities, thus improving the mechanical and barrier properties. To prepare active films, avocado by-products from guacamole industrial production were extracted in ethyl acetate. Then, the extract (optimized to be rich in phenolic compounds and flavonoids and mainly composed by lipids) was incorporated to the paper reinforced with the highest content of ethyl cellulose. In general, the addition of the avocado by-products extract decreased the water uptake and permeability, improved the wettability, and increased the biodegradability in seawater and the antioxidant capacity. In addition, these films acted as barriers and retainers for Escherichia coli and Bacillus cereus. The potentiality of these materials for food packaging was demonstrated by low overall migrations and a similar food preservation to common low-density polyethylene.