Selective extraction of levoglucosan and its isomers from complex matrices using ligand exchange-solid phase extraction for analysis by liquid chromatography-electrospray ionization-tandem mass spectrometry.

The analysis of trace quantities of monosaccharide anhydrides (MAs) in sediments is complicated by the lack of fast and reliable technologies to selectively extract these water-soluble non-ionic compounds from samples of complex composition. Here we describe a solid phase extraction method that takes advantage of the affinity between monosaccharide anhydrides (MAs) and immobilized Na+ ions related to ligand-exchange processes (LE-SPE). The capacity factor of LE-SPE columns was enhanced by using non-aqueous mobile phases such as DCM/MeOH mixtures. We have used the unique properties of LE-SPE columns to selectively extract MAs from lacustrine, coastal, and deep-sea oceanic sediment samples. The analytical procedure produces extracts with low ion suppression effects (0-20%), resulting in ideal conditions for MAs quantification with LC-ESI-MS/MS systems irrespective of the sedimentary matrix and MAs concentration. The analytical method yields repeatable concentration values (RSD of 9-23% for levoglucosan and 15-34% for mannosan and galactosan) and an IS recovery of 45-70%. The instrumental dynamic range is 10-10000 pg injected, but in practice, the methodological lower limit of quantification is constrained by sample contamination during processing. The combination of LE-SPE and LC-ESI-MS/MS has the potential to produce sensitive and reliable technologies to analyze saccharides and amino acids in environmental and biological samples.

Analysis of levoglucosan and its isomers in atmospheric samples by ion chromatography with electrospray lithium cationisation - Triple quadrupole tandem mass spectrometry.

Biomass burning (BB) emissions are a significant source of particles to the atmosphere, especially in the Southern Hemisphere, where the occurrence of anthropogenic and natural wild fires is common. These emissions can threaten human health through increased exposure, whilst simultaneously representing a significant source of trace metals and nutrients to the ocean. One well known method to track BB emissions is through monitoring the atmospheric concentration of specific monosaccharide anhydrides (MAs), specifically levoglucosan and its isomers, mannosan and galactosan. Herein, a new method for the determination of levoglucosan and its isomers in marine and terrestrial aerosol samples is presented, which delivers both high selectivity and sensitivity, through the coupling of ion chromatography and triple quadrupole tandem mass spectrometry. Optimal chromatographic conditions, providing baseline separation for target anhydrosugars in under 8 min, were obtained using a Dionex CarboPacⓇ PA-1 column with an electrolytically generated KOH gradient. To improve the ionisation efficiency for MS detection, an organic make-up solvent was fed into the IC column effluent before the ESI source, and to further increase both sensitivity and selectivity, cationisation of levoglucosan was investigated by adding salts into the make-up solvent, namely, sodium, ammonium and lithium salts. Using positive lithium cationisation with 0.5 mM lithium chloride in methanol as the make-up solvent, delivered at a flow rate of 0.02 mL min-1, the levoglucosan response was improved by factors of 100 and 10, comparing to negative ionisation and positive sodium cationisation, respectively. Detection was carried out in SRM mode for quantitation and identification, achieving an instrumental LOD of 0.10, 0.12 and 0.5 µg L-1 for levoglucosan, mannosan and galactosan, respectively. Finally, the method was applied to the analysis of 41 marine and terrestrial aerosol samples from Australia, its surrounding coastal waters and areas within the remote Southern Ocean, covering a large range of BB marker concentrations.

Methods for the determination of levoglucosan and other sugar anhydrides as biomass burning tracers in environmental samples - A review.

Nowadays, there is a great pressure on finding an alternative source of energy. One such source is biomass combustion. Biomass is any organic matter such as wood, crops, seaweed, and animal wastes that during combustion emits energy but also smoke and solid residue. Biomass burning tracers, such as levoglucosan, mannosan and galactosan, are sugar anhydrides produced during burning of biomass that contain cellulose and hemicellulose. Analysis of environmental samples for tracers is the source of information about the type of biofuel burned. In this article, a literature review of the preparation and determination of biomass burning tracers for environmental samples was presented. The review discusses the preparation of different samples (particulate matter, soils, sediments, biological samples), extraction, derivatization, and determination. Amongst determination methods the most popular was gas chromatography with mass spectrometry but other techniques were also used, such as high-performance liquid chromatography with aerosol charge detection, capillary electrophoresis with pulsed amperometric detection, and ion chromatography with pulsed amperometric detection.

Gas phase transformation from organic acid to organic sulfuric anhydride: Possibility and atmospheric fate in the initial new particle formation.

New particle formation (NPF) process has been observed frequently in various environments and produces a large fraction of atmospheric aerosols. However, the chemical species participating in the nucleation as well as the corresponding nucleation mechanism in the atmosphere still remain ambiguous. Recent research by Leopold et al. shows that cycloaddition reaction of SO3 to carboxylic acids could contribute to the formation of organic sulfuric anhydride which would have lower vapor pressure compared with the corresponding carboxylic acid and hence kick-start new particle formation in the gas phase. In the present study, energy profile for the formation of 3-methyl-1,2,3-butanetricarboxylic sulfuric anhydride (MBTCSA) through the cycloaddition of SO3 to 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA) has been investigated using computational methods. As a result, such a process would be effectively barrierless for one of the terminal carboxy group and has very low energy barriers for the other two carboxy groups (0.6 and 2.8 kcal/mol, respectively), indicating the whole process is a plausible gas phase pathway to MBTCSA formation. Furthermore, by evaluating the stability of the generated atmospheric clusters through topological and kinetic analysis, interaction between atmospheric nucleation precursor with MBTCSA is found to be more thermodynamically favourable and stronger than those with sulfuric acid and MBTCA which is identified from further-generation oxidation of a-pinene. Hence MBTCSA is speculated to be a potential participator in the initial new particle formation and the further particles growth.

Lysine Propionylation To Boost Sequence Coverage and Enable a "Silent SILAC" Strategy for Relative Protein Quantification.

Quantification in proteomics largely relies on the incorporation of stable isotopes, with protocols that either introduce the label through metabolic incorporation or chemical tagging. Most methods rely on the use of trypsin and/or LysC to generate labeled peptides. Although alternative proteases can enhance proteome coverage, generic quantitative methods that port over to such enzymes are lacking. Here we describe a quantification strategy amenable to most proteases, which involves propionylation of metabolically labeled lysine, using a "silent stable isotope labeling by amino acids in cell culture (SILAC)" strategy that reveals isotopic labels on second-stage mass spectrometry (MS2) fragmentation in a tandem mass tag (TMT)-like manner. We selectively propionylated lysine residues prior to digestion to generate pure ArgC-like digestion for trypsin and novel ArgN-like digestions for LysargiNase, by restricting digestion at lysine. The modification offers highly complementary sequence coverage, and even enhanced protein identification rates in certain situations (GluC digestion). Propionylated lysine residues were present in the majority of identified peptides generated from digests of cell lysates and led to the consistent release of an intense cyclic imine reporter ion at mass-to-charge ratio ( m/ z) 140 using higher-energy collisional dissociation. We grew A549 cells in media containing either l-1-13C-lysine or l-6-13C-lysine, to generate proteins that share the same accurate mass when paired. Peptides were indistinguishable on the first-stage mass spectrometry (MS1) level and, upon fragmentation, released reporter ions at m/ z 140 and m/ z 141, without otherwise affecting sequence ion mass. The quantification approach is independent of the number of peptide lysines and offers a new strategy for quantitative proteomics.

Study of polar organic compounds in airborne particulate matter of a coastal urban city.

Two classes of polar organic compounds, dicarboxylic acids (DCAs) and sugars/sugar anhydrides (S/SAs), were measured in airborne particulate matter in the area of Thessaloniki, northern Greece. The target compounds were measured simultaneously in two particle fractions PM10 and PM2.5 during cold and warm periods by employing extraction in an ultrasonic bath with a mixture of MeOH/DCM (1:2 v/v), derivatization with BSTFA-TMCS and GC-MS for analysis. At both fractions, phthalic was the predominant carboxylic acid during cold season and a-ketoglutaric acid in warm season, followed by maleic and malic. Levoglucosan was the dominant sugar anhydride during the cold and arabitol during the warm season. In total, the distribution of DCAs seemed to favor the PM2.5 particle fraction, probably due to anthropogenic emissions and photochemical formation. The relative contribution of DCAs to PM2.5 fraction was 0.9-3.2% in cold and 0.9-7.0% in warm period. Regarding S/SAs, levoglucosan was also predominantly distributed in fine particles, with relative contribution to this fraction 0.1-6.3% in cold and <0.65% in warm season, suggesting impact of biomass burning emissions. In contrast, arabitol, fructose, and glucose were mainly found in coarse fraction, possibly due to their biogenic origin. Negative correlation of target compounds with temperature and total solar radiation suggested the contribution of seasonal dependant local sources. Positive relationship with NO and NO2 oxidants and relative humidity showed secondary formation of polar compounds or enhanced gas-to-particle conversion.

Analysis of octenylsuccinate rice and tapioca starches: Distribution of octenylsuccinic anhydride groups in starch granules.

Characterization of the fine structure of octenylsuccinic anhydride (OSA) starch would lead to a better understanding of functional properties. OSA rice and tapioca starches were analyzed using microscopy, liquid chromatography and nuclear magnetic resonance. Chain length distribution of amylopectin changed significantly (P<0.05) after OSA esterification. Weight averaged degree of polymerization (DPw) decreased significantly (P<0.05) from 16.47 to 13.29 and from 14.87 to 12.47 in native and OSA rice and tapioca starches, respectively. The chain length distribution of pure amylopectin fractions suggested that OSA groups were not present in the amylopectin portion of the starch. (1)H NMR analysis of pure amylose and amylopectin fractions indicated that OSA substitution was present only in amylose fractions of rice and tapioca starches. Esterification with 3% OSA results in starch that has OSA substituted mainly on amylose chains or possibly on amylopectin chains that have been hydrolyzed from the amylopectin molecules during esterification.

Validation of an assay for the determination of levoglucosan and associated monosaccharide anhydrides for the quantification of wood smoke in atmospheric aerosol.

Biomass burning is becoming an increasing contributor to atmospheric particulate matter, and concern is increasing over the detrimental health effects of inhaling such particles. Levoglucosan and related monosaccharide anhydrides (MAs) can be used as tracers of the contribution of wood burning to total particulate matter. An improved gas chromatography-mass spectrometry method to quantify atmospheric levels of MAs has been developed and, for the first-time, fully validated. The method uses an optimised, low-volume methanol extraction, derivitisation by trimethylsilylation and analysis with high-throughput gas chromatography-mass spectrometry (GC-MS). Recovery of approximately 90 % for levoglucosan, and 70 % for the isomers galactosan and mannosan, was achieved using spiked blank filters estimates. The method was extensively validated to ensure that the precision of the method over five experimental replicates on five repeat experimental occasions was within 15 % for low, mid and high concentrations and accuracy between 85 and 115 %. The lower limit of quantification (LLOQ) was 0.21 and 1.05 ng m(-3) for levoglucosan and galactosan/mannosan, respectively, where the assay satisfied precisions of ≤20 % and accuracies 80-120 %. The limit of detection (LOD) for all analytes was 0.105 ng m(-3). The stability of the MAs, once deposited on aerosol filters, was high over the short term (4 weeks) at room temperature and over longer periods (3 months) when stored at -20 °C. The method was applied to determine atmospheric levels of MAs at an urban background site in Leicester (UK) for a month. Mean concentrations of levoglucosan over the month of May were 21.4 ± 18.3 ng m(-3), 7.5 ± 6.1 ng m(-3) mannosan and 1.8 ± 1.3 ng m(-3) galactosan.

Assessment of groundwater quality of the Tatlicay aquifer and relation to the adjacent evaporitic formations (Cankiri, Turkey).

One of the most important hydrogeologic problems in and adjacent areas of evaporitic formations is severe quality degradation of groundwaters. These kinds of groundwaters contain high content of dissolved solids and generally have some limitations for use. Tatlicay basin (north-central Turkey) is an example to effects of the evaporites on groundwater quality in the adjacent alluvium aquifer. Gypsum and anhydrites in the two evaporite formations (Bayindir and Bozkir) effect of the groundwater quality in the alluvium adversely, by dissolution of the evaporites by surface drainage and infiltration into the alluvium aquifer (widespread effect) and by infiltration of low quality gypsum springs (local effect) into the aquifer. Evaporitic formations significantly increased EC, TDS, Ca and SO(4) parameters in the alluvium aquifer in the central and downstream regions. EC has increased roughly from 500-800 to 1,700-2,000 µS/cm, Ca has roughly increased from 3-4 to 10 meq/l, SO(4) has increased 0.5-1 to 11-12 meq/l. Consequently, three clusters were distinguished in the basin; (1) nonevaporitic waters in low TDS, Na, Ca, Mg, Cl and SO(4), (2) diluted waters in high TDS and relatively high Cl, moderate-relatively high Na, Ca, Mg, SO(4), (3) gypsum springs in highest TDS, Ca, SO(4), but moderate Mg and low Na, Cl.

Analysis of trimethyl carboxyphosphate by gas chromatography-mass spectrometry.

Analysis of trimethyl carboxyphosphate samples by gas chromatography-mass spectrometry, using typical conditions resulted in significant decomposition of the analyte. Optimization of injection conditions, including conditioning of the injection port liner, produced a dramatic increase in observed peak areas and afforded an effective method for detection of trimethyl carboxyphosphate at the <1 microg mL(-1) level.

Dimethylthioarsinic anhydride: a standard for arsenic speciation.

Dimethylthioarsinic acid (DMTA(V)) has recently been identified in biological, dietary and environmental matrices. The relevance of this compound to the toxicity of arsenic in humans is unknown and further exposure assessment and metabolic studies are difficult to conduct because of the unavailability of a well characterized standard. The synthesis of DMTA(V) was accomplished by the reaction of dimethylarsinic acid (DMA(V)) with hydrogen sulfide. The initial reaction product produced is DMTA(V) but multiple products over the course of the reaction are also observed. Therefore, a chromatographic separation was developed to monitor the reaction progress via LC-ICP-MS. In this synthesis, conversion of DMA(V) to DMTA(V) was not taken to completion to avoid the production of side products. The product was isolated from the starting material by standard organic techniques. Single crystal diffraction demonstrated that solid DMTA(V) is present in the form of the oxygen-bridged dimethylthioarsinic anhydride. Dissolution of the anhydride in water produces the acid form of DMTA(V) and the aqueous phase DMTA(V) provided a characteristic molecular ion of m/z 155 by LC-ESI-MS. The synthesis and isolation of dimethylthioarsinic anhydride provides a stable crystalline standard suitable for identification, toxicological study and exposure assessment of dimethylthioarsinic acid.

Speciation of inorganic selenium using capillary electrophoresis-inductively coupled plasma-atomic emission spectrometry with on-line hydride generation.

A novel and simple hydride generator has been developed. The hydride generator has good stability and high gas liquid separation efficiency. The generator serves as an interface of capillary electrophoresis (CE) and inductively coupled plasma atomic emission spectrometry (ICP-AES). This device eliminates the nebulization step and overcomes the common problem of suction flow resulting from the use of nebulization gas in ICP. Selenium compounds that were separated by CE were converted into the corresponding volatile hydrides, followed by ICP-AES measurement. The effects of the concentration of the hydride generating reagents (HCl and NaBH4), the carrier gas flow rate, and heavy metal interference on Se emission intensity were discussed. The relative standard deviations (RSDs) of peak area, based on six determinations of 50 ng mL(-1) standard of Se(IV) and Se(VI), were 1.5% and 1.8%, respectively. The detection limits (3sigma) of peak area were 2.1 ng mL(-1) and 2.3 ng mL(-1) for Se(IV) and Se(VI), respectively. Speciation analysis of inorganic Se(IV) and Se(IV) species using the HG-CE-ICP-AES system was demonstrated in tap and river water samples.

Determination of airborne anhydrides using LC-MS monitoring negative ions of di-n-butylamine derivatives.

An air sampling method for simultaneous determination of organic acid anhydrides and isocyanates is presented. Air samples are collected in impinger flasks filled with 0.01 M di-n-butylamine (DBA) in a mixture of toluene-acetonitrile (7:3, v/v) with a 13 millimetre glass fibre filter in series. The amount of anhydrides and isocyanates are determined as their amide and urea derivatives using LC-MS. Four anhydrides, maleic anhydride (MA), phthalic anhydride (PA), tetrahydrophthalic anhydride (TA) and cis-hexahydrophthalic anhydride (HA) and 11 isocyanates could be separated in 9 minutes using gradient elution. Anhydride-DBA derivatives in standard solutions were quantified using LC with chemiluminescent nitrogen detection (CLND). Anhydride-DBA derivatives were found to be stable for at least two months when stored in acetonitrile or toluene in the freezer. The yield of DBA derivatives of anhydrides in the 0.01 M DBA in toluene-acetonitrile (7:3, v/v) was in the range of 70->95%. Using MS and negative electrospray ionisation (ES-) linear calibrations curves were obtained for the anhydrides with correlation coefficients ranging from 0.9970-0.9997. The instrumental detection limit for the anhydrides ranged from 10-30 fmol, based on a signal to noise root mean square (RMS) ratio of 3. Monitoring positive and negative ions simultaneously, both isocyanates and anhydrides could be determined as their DBA derivatives in the same chromatographic run. When air samples were collected during thermal degradation of different coated metal sheets both anhydrides and isocyanates were present in the same samples and all the studied anhydrides were found.

[The working environment control of anhydride hardeners from an epoxy resin system].

Epoxy resins are widely used in adhesives, coatings, materials for molds and composites, and encapsulation. Acid anhydrides such as methyltetrahydrophthalic anhydride are being used as curing agents for epoxy resins. The anhydride hardeners are well-known industrial inhalant allergens, inducing predominantly type I allergies. In the electronic components industry, these substances have been consumed in large quantities. Therefore, safe use in the industry demands control of the levels of exposure causing allergic diseases in the workshop. We conducted a prospective survey of two electronics plants to clarify how to control the atmospheric level of the anhydrides in the work environment. Measurements of the levels of the anhydrides in air started according to the Working Environment Measurement Standards (Ministry of Labour Notification No. 46, 1976) in April 2000, along with improvements in the work environment. A value of 40 micrograms/m3 was adopted as the administrative control level to judge the propriety of the working environment control. A total of 2 unit work areas in both plants belonged to Control Class III. The exposure originated from manual loading, casting, uncured hot resins, and leaks in an impregnating-machine or curing ovens. In order to achieve the working environment control, complete enclosure of the source, installation of local exhaust ventilation, and improvement or maintenance of the local exhaust ventilation system were performed on the basis of the results of the working environment measurement, with the result that the work environment was improved (Control Class I). It became evident that these measures were effective just like other noxious substances.

Anhydride prodrugs for nonsteroidal anti-inflammatory drugs.

PURPOSE: The objective of this study was to synthesize anhydride prodrugs for prolong action to shield the carboxylic acid group from irritative effects and to temporary hydrophobize the drug so that it becomes accessible to aqueous media when the anhydride residue is hydrolyzed. METHODS: Ibuprofen, a nonsteroidal anti-inflammatory agent, was used as a representative drug for anhydride derivatization. Mixed anhydrides of ibuprofen with fatty acids of different chain length were prepared by reacting acid chloride derivatives with the corresponding acid in the presence of acid acceptor and two-phase reaction. Mixed anhydrides were also prepared by dehydration reaction using acetic anhydride and anhydride interchange of symmetric anhydrides. The analgesic effects of mixed anhydride prodrugs were tested using nonsteroidal anti-inflammatory drug rat paw edema model. In vitro degradation of mixed anhydrides and drug release were monitored by high-performance liquid chromatography. RESULTS: Ibuprofen was bound to aliphatic and aromatic acids via an anhydride bond in high reaction yields (>85%) with high mixed anhydride content (>80%). The mix anhydride was purified by chromatography and stored at 4 degrees C to minimize conversion into the symmetric anhydride. These anhydride derivatives hydrolyzed at different time intervals depending on the hydrophobicity of conjugated acid. In vivo testing of the ibuprofen anhydride derivatives for analgesic effect indicated an extended action of the drug for over 24 h as a function of the fatty acid chain length. CONCLUSION: This study demonstrates the promise of anhydride prodrugs for extending drug action and shielding the carboxylic acid group.

Polyanhydrides: an overview.

Polyanhydrides have been considered to be useful biomaterials as carriers of drugs to various organs of the human body such as brain, bone, blood vessels, and eyes. They can be prepared easily from available, low cost resources and can be manipulated to meet desirable characteristics. Polyanhydrides are biocompatible and degrade in vivo into non-toxic diacid counterparts that are eliminated from the body as metabolites. Owing to their usefulness, this review focuses on the development, synthesis methods, structures and characterization of polyanhydrides, which will provide an overview for the researchers in the field. Their in vitro and in vivo degradability, toxicity, biocompatibility and applications are discussed in the subsequent chapters of this special issue on polyanhydrides and poly(ortho esters).

Determination of aliphatic anhydrides and acids by reversed-phase liquid chromatography.

Few chromatography methods have been reported for the determination of anhydrides in mixtures or as mixed anhydrides. The potential reactivity of anhydrides with water and other common eluent components complicates possible schemes for separation and analysis. By optimizing variables that affect hydrolysis, including the stationary phase, conditions can be found to successfully analyze anhydrides as reactive as acetic anhydride. The corresponding acids can be determined at the same time. The effect of the stationary phase on anhydride hydrolysis rates may prove to be a sensitive means of probing stationary phase chemistry.

Properties of polyethylene films with incorporated benzoic anhydride and/or ethyl and propyl esters of 4-hydroxybenzoic acid and their suitability for food packaging.

Benzoic anhydride and ethyl and propyl esters of 4-hydroxybenzoic acid (ETP and PRP, respectively, also termed parabens) incorporated into low density polyethylene (LDPE) film were studied with regard to migration into food and food simulants at 6 degrees C and 25 degrees C, and changes in selected properties of the film were investigated. Antimicrobials were incorporated into polymer film in concentrations of 5 g/kg and 10 g/kg. The addition of parabens into the polymer was more difficult than benzoic anhydride due to their volatility. For benzoic anhydride, 30-40% and 10-20% of the added amount was found to leach from the film into aqueous and olive oil food simulants, respectively. The migration into both water and olive oil followed a very similar course in the case of parabens. Migration levels over 90% and in the range of 70% to 80%, relative to the amount of agent in the film, were determined for ETP and PRP respectively. The incorporation of antimicrobials into the film significantly changed the functional characteristics of the packaging material, i.e. permeability of oxygen, carbon dioxide and water vapour, tensile strength, coefficient of friction, sealing strength and transparency. Shelf life tests with packaged cheese and toasted bread demonstrated the efficiency of the film containing 10 g/kg of BA against mould growth on the food surface during storage at 6 degrees C.

Qualitative and quantitative evaluation of mono- and disaccharides in D-fructose, D-glucose and sucrose caramels by gas-liquid chromatography-mass spectrometry. Di-D-fructose dianhydrides as tracers of caramel authenticity.

The monosaccharide (D-fructose, D-glucose, anhydrosugars), disaccharide (glucobioses) and pseudodisaccharide (di-D-fructose dianhydrides) content of D-fructose, D-glucose and sucrose caramels has been determined by gas-liquid chromatography-mass spectrometry (GLC-MS) of their trimethylsilyl (TMS) or TMS-oxime derivatives. The chromatographic profiles revealed significant differences in the disaccharide/pseudodisaccharide distribution depending on the caramel source: a D-fructose caramel contains prominent proportions of di-D-fructose dianhydrides, a D-glucose caramel mainly D-glucobioses, and a sucrose caramel similar proportions of both disaccharide/pseudodisaccharide series. It is noteworthy that di-D-fructose dianhydrides are found in all three types of caramels and might then be used as specific tracers of the authenticity of caramel, i.e., a product resulting from the controlled heat treatment of food-grade carbohydrates for use as food additives.

Detection of an anhydride intermediate in the carboxypeptidase A catalyzed hydrolysis of a peptide substrate by solid state NMR spectroscopy and its mechanistic implication.

We have detected an anhydride intermediate in the CPA catalyzed proteolytic reaction of Gly-Tyr. It appears that since the zinc-bound water molecule which is believed to attack the scissile amide carbonyl carbon in the hydrolysis reaction is excluded by the N-terminal amino group of Gly-Tyr, the carboxylate of Glu-270 becomes to attack the amide bond to generate the anhydride intermediate.