Mass spectrometry of natural organic phosphorus

This article provides a review of the use of modern mass spectrometry (MS) for quantitative and qualitative measurements of organic phosphorus compounds in nature. Included is a brief discussion of recent developments in large molecule mass spectrometry, focusing on time-of-flight (TOF) and ion cyclotron resonance (ICR) mass analysis techniques, as well as electrospray (ESI) and inductively coupled plasma (ICP) ionization. The use of ICP with high-resolution mass spectrometry for quantitative measurements of total phosphorus and as a detector coupled to HPLC and CE for defining organic phosphorus speciation is demonstrated using results from a study of phosphorus cycling in a treatment wetland. Qualitative identifications of individual phosphorus compounds by ultrahigh resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) is demonstrated using dissolved organic phosphorus isolated from this same wetland.     

Sample preparation for organic acids in biological fluids

A review of sample preparation methods for organic acids in biological fluids, in particular serum and urine, is presented. It covers techniques on organic acid determination without sample preparation, release of organic acids from binding locations, removal of proteins by protein precipitation and ultrafiltration, isolation of the organic acids by liquid-liquid and liquid-solid extraction, purification of the extract, derivatization and pre-fractionation. The various alternative sample preparation steps are compared and critically discussed. Examples of applications including profile analysis of organic acids by gas chromatography (GC), determination of particular organic acids by GC or liquid chromatography and determination of fatty acids as a distinct chemical class of acids demonstrate that the kind of sample preparation chosen depends strongly on the analytical aims.     

Determination of trace organic carbon and nitrogen in the presence of carbonates in anorganic bovine bone graft materials

The widespread concern of bovine spongiform encephalopathy (mad cow disease) has raised questions about the possibility of residual organic material in bovine-derived bone graft materials. Conflicting reports have shown both the presence and the absence of organic materials in bone derived products. This study compared residual organic levels in two commercial bone graft products: a bovine bone product treated chemically and at low temperature, and a bovine bone product treated at high temperature. In this study, organic carbon, the primary constituent of organic materials, is defined as carbon that is not liberated as CO₂ upon acidification (i.e. non-carbonate carbon). Three approaches to the determination were used: (1) organic carbon was calculated as the difference between total carbon determined by high temperature combustion and carbonate carbon determined by acid evolution of CO₂. (2) Organic carbon was determined by measuring total carbon by high temperature combustion of a sample that had been pretreated with acid to remove all carbonate. (3) The total organic carbon remaining in solution after acid dissolution was determined. In addition, organic nitrogen was determined as the difference between total Kjeldahl and ammonia nitrogen. Total nitrogen values were confirmed using an instrumental nitrogen analyzer. No detectable organic carbon or organic nitrogen was observed in the high temperature bone product. In the low temperature treated bovine product, however, approximately 2000 μg/g organic carbon was measured by all three methods, as well as 15 μg/g organic nitrogen.     

Comparative analysis of the organic acid content of vinegar by capillary electrophoresis and ion-exclusion chromatography with conductimetric detection

Summary Ion-exclusion chromatography (IEC) and capillary electrophoresis (CE) have been compared for determination of organic acids in samples of Sherry wine vinegar. The accuracy of each technique was evaluated by use of the standard addition method. There were no differences between the techniques at a significance level of 5%, except for determination of malic acid by CE. Both analytical methods were used to analyse sixteen samples of Sherry wine vinegar supplied by different producers. The regression coefficients (r ²) for analysis by IEC and CE exceeded 0.94 for all acids. Results from both methods were in good agreement and the methods are sufficiently selective and sensitive to be applied directly to sherry wine vinegars.     

Photosensitized degradation of organic pollutants in water: processes and analytical applications

Photosensitized degradation has been used to remove a broad range of organic pollutants, generally with mineralization to CO₂ and other inorganic products such as Cl⁻ and . TiO₂ and Fe³⁺ are the photosensitizers mainly used to accelerate the degradation of persistent organic chemicals. Various analytical techniques were used to identify the degradation products and to monitor the degradation kinetics. Chromatographic techniques such as high-performance liquid chromatography (HPLC), gas chromatography (GC) and ion-exchange were used. Other analytical techniques, such as total organic carbon analysis, UV–visible spectrophotometry, spectrofluorimetry, and potentiometry, were also used. When the photodegradation is carried out in water, extraction methods such liquid–liquid extraction or solid-phase extraction need to be used, followed by GC or HPLC analysis. We review the analytical methods used for the identification of the products formed in photodegradation studies. Kinetic studies of the degradation are also reported.     

Surface ionization of organic compounds and its applications

Surface ionization of organic compounds in a weak external electric field involving the formation of many-atomic positive ions is considered (including specific features of the phenomenon, its major characteristics, experimental techniques used and possible applications).

Information is presented on the adsorption of compounds of complex composition which was obtained in studying the phenomenon. A detailed analysis is made of the reactions of particles in the adsorbed layer, as well as of the methods of determining the binding energies of the particles undergoing ionization (primary molecules and many-atomic radicals and complexes produced on the surface) to the surface, and of their lifetimes on the surface against thermal desorption in the charged and neutral states.

Vast possibilities are shown to open up by using the thermally equilibrium processes of many-atomic particle ionization occurring on the surface for the determination of the properties of molecules, radicals and complexes (e.g. thermal stability, the weakest bond energies in ions, ionization potentials of the particles analyzed).

The physicochemical aspects of the surface ionization-based detection of organic compounds and of its applications to analytical mass spectrometry, gas chromatography and analytical chemistry of the atmosphere are considered. Attention is focused upon the fact that the high ionization coefficients observed for a number of compounds ensure a record-high sensitivity when using surface ionization-based detection.     

Sample preparation for gas chromatographic determination of halogenated volatile organic compounds in environmental and biological samples

In this review, the wide spectrum of the techniques of isolation and/or preconcentration and final determination of halogenated volatile organic compounds (HVOCs) in water, air, soil, sediment and biological fluids are presented and discussed. The techniques discussed are solvent microextraction, solid phase extraction, gas extraction (static and dynamic techniques), membrane processes and passive sampling. Also, direct techniques, such as direct aqueous injection into gas chromatography (GC) column and membrane inlet mass spectrometry, are presented. Main attention is paid to the practical application of these techniques during all HVOCs determination.     

Determination of organic acids and ketones in contaminated soils

Hydrocarbons and metabolites from biodegradation in soil have been isolated and separated using Soxhlet extraction, with n-heptane and dichloromethane, combined with solid-phase extraction on silica gel and basic aluminum oxide using n-pentane, dichloromethane, methanol, and sulfuric acid – methanol as eluents. This procedure can be used for determination of metabolites both in laboratory-prepared soil samples containing mineral oils and in actual contaminated soil. After microbiological degradation, organic acids and ketones which were not original components of the diesel fuel and lubricating oil contaminating the soil samples were identified using capillary gas chromatography – mass spectrometry in batch-soil experiments. Predominantly alicyclic and branched-chain aliphatic organic acids and diacids, and aromatic ketones, were found to be formed after a few weeks degradation.     

Coupled reversed-phase and ion chromatographic system for the simultaneous identification of inorganic and organic explosives

There are many methods available to detect and positively identify either organic or inorganic explosives separately, however no one method has been developed which can detect both types of explosive species simultaneously from a single sample. In this work, a unique coupled-chromatographic system is reported for the simultaneous determination of both organic and inorganic explosive species and is used for pre-blast analysis/identification purposes. This novel approach is based on the combination of reversed-phase high performance liquid chromatography and ion chromatography which allows trace levels of organic and inorganic explosives to be determined simultaneously from a single sample. Using this procedure, a 20 min reversed-phase separation of organic explosives is coupled to a 16 min ion-exchange separation of anions present in inorganic explosives, providing a complete pre-blast analysis/identification system for the separation and detection of a complex mixture containing organic and/or inorganic explosive species. The total analysis time, including sufficient column re-equilibration between runs, was <25 min using the coupled system. By this method, the minimum resolution for the organic separation was 1.16 between nitroglycerin and tetryl and the detection limits ranged from 0.31 mg L(-1) for cyclotetramethylene tetranitramine (HMX) and 1.54 mg L(-1) for pentaerythrite tetranitrate (PETN), while the minimum resolution for the inorganic separation was 0.99 between azide and nitrate, and the detection limits ranged from 7.70 μg L(-1) for fluoride and 159.50 μg L(-1) for benzoate.     

Identification and characterization of organic nanoparticles in food

Interest in nanoparticles (NPs) has increased explosively over the past two decades. Using NPs, high loadings of vitamins and health-benefit actives can be achieved in food, and stable flavors as well as natural food-coloring dispersions can be developed. Detection and characterization of NPs are essential in understanding the benefits as well as the potential risks of the application of such materials in food. While many such applications are described in the literature, methods for detection and characterization of such particles are lacking. Organic NPs suitable for application in food are lipid-, protein- or polysaccharide-based particles, and this review describes current analytical techniques that are used, or could be used, for identification and characterization of such particles in food products. We divide the analytical approaches into four sections: sample preparation; separation; imaging; and, characterization.We discuss techniques and reported applications for NPs or otherwise related particle compounds. The results of this investigation show that, for a successful characterization of NPs in food, at least some kind of sample preparation will be required. While a simple sample preparation may be satisfactory for imaging techniques for known analytes, for other techniques, a further separation using chromatography, field-flow fractionation or ion-mobility separation is necessary. Subsequently, photon-correlation spectroscopy and especially mass spectrometry techniques as matrix-assisted laser desorption/ionization combined with time-of-flight mass spectrometry, seem suitable techniques for characterizing a wide variety of organic NPs.     

Quantification of sugars and organic acids in hygroscopic pharmaceutical herbal dry extracts

Three chromatographic methods have been employed for the determination of hydrophilic compounds, namely carbohydrates and organic acids in herbal dry extracts of Eschscholtzia californica Cham. The hydrophilic compounds were separated from the other components of the dry extracts by solid-phase extraction methods, which were optimised with respect to recovery rates. Carbohydrates were quantified using high-performance anion-exchange chromatography with pulsed amperometric detection. Organic acids were analysed by ion-exclusion chromatography with evaporative light scattering detection and gas chromatography-mass spectrometry. Using the latter method, large amounts of glyceric acid were separated from the extracts of Eschscholtzia californica Cham. This substance together with sugars may be responsible for the increased hygroscopicity and the poor processing behaviour of the extracts.     

加速溶剂萃取-凝胶渗透色谱净化用于食品中有机磷的检测

建立了用气相色谱火焰光度法(CG-FPD)同时分析蔬菜中36种有机磷农药残留的分析方法。采用ASE提取,GPC净化,GC-FPD检测,按照欧盟NO SANCO-10684-2009[1]的要求,分别对蔬菜进行3个水平(10、15、20μg/kg)的加标回收实验,结果显示,36种有机磷的回收率为73.2%～111.3%,方法的相对标准偏差(RSD)均小于15%。该分析方法背景干扰低、灵敏度高,适合输欧蔬菜中多种有机磷残留的测定。     

A rapid method for the determination of organic nitrogen and phosphorus based on a single perchloric acid digestion

Results of nitrogen determinations obtained by perchloric acid digestion of organic matter under reflux were found to be equivalent to those obtained by the conventional sulfuric acid Kjeldahl method. A rapid determination of nitrogen and phosphorus was thus possible after a single perchloric acid digestion. Nitrogen was determined by nesslerization and phosphorus by a conventional molybdenum blue technique. The method devised was found satisfactory for a great variety of natural products and pure organic compounds, including materials containing all kinds of tertiary nitrogen.     

Identification of organic acids in bayer liquors by GC-MS: a comparison using butylation and methylation

Two well known derivatization methods, butylation and methylation, are compared by gas chromatography (GC)-mass spectrometry (MS) to identify organic acids in Bayer liquors. These two derivatization methods should be combined together for the determination of the carboxylic acids. Twenty-four organic acids are identified by GC-MS and 13 organic acids are firstly found in Bayer liquors. The retention times and the carbon number of these seven n-dicarboxylic acids (C(4)-C(10)) are fit into the linear relationship in Microsoft Excel.     

Characterization of medieval proteinaceous painting media using gas chromatography and gas chromatography — mass spectrometry

Proteinaceous organic materials used as ancient painting media were investigated by capillary gas chromatography (GC) and capillary gas chromatography — mass spectrometry (GC/MS). Medieval wall paintings made by the tempera technique were considered and their binding media were studied by the characterization of their main chemical components. The basic methodology is based on the determination of amino acids in samples of paint layers after hydrolysis and derivatization and on the comparison with reference proteinaceous materials. Multivariate chemometric techniques were used to facilitate the recognition of the protein source from chromatographic data. To characterize the binders further, a method was developed for the determination of fatty acids, present as minor components, by GC/MS. The use of fused-silica capillary columns coated with selected stationary phases allowed the separation of amino acid and fatty acid derivatives in a single analytical run.     

固相微萃取-气相色谱/同位素质谱法测定水中挥发性有机物单体碳同位素

建立了采用75μm碳分子筛/聚二甲基硅氧烷(CAR-PDMS)纤维的固相微萃取-气相色谱/同位素质谱联用方法测定水中挥发性有机污染物碳同位素。使用浸入式固相微萃取和顶空固相微萃取方法进行实验确定在低浓度条件下最佳δ13C测试方法。通过使用顶空固相微萃取前处理技术进行单体同位素分析分析灵敏度更高,应用CSIA技术对1,2-二氯乙烯,三氯乙烯,四氯化碳进行单体同位素分析,方法的检出限为70μg/L,与样本的标准偏差小于0.3‰。该法适用于水体中微量挥发性有机污染物的同位素组成测定。     

萃取反萃取法研究新峪焦精煤中有机硫的赋存规律

以高含有机硫的新裕焦精煤为研究对象,采用萃取反萃取和分级萃取的分离方法及XPS、GC/MS等分析技术,对原煤和各族组分内不同结构的有机硫分布情况进行了研究,重点考察了各类型有机硫在煤有机质本体结构及族组分中的赋存规律。结果表明,组分总硫基赋存分率则与复杂性程度正好相反;可溶性含硫组分在总溶出物中的分布,相对不同族组分而言总体均衡;可溶性的共轭结构类有机硫主要赋存于煤密中质组中,其次是疏中质组中且以噻吩类为主,较少赋存于煤重质组中;而可溶性的脂肪结构类有机硫则主要赋存于煤重质组和密中质组中,较少赋存于疏中质组中;各族组分内有机硫的萃取率随时间的变化规律具有明显的加和性,族组分内可溶含硫组分的溶出行为相互独立,符合煤嵌布结构模型的基本思想;煤中不同形态有机硫的赋存遵循"相似相溶"原理。     

Determination of complex mixtures of volatile organic compounds in ambient air: canister methodology

Canister methodology is applicable to 150 polar and nonpolar VOCs found in ambient air from parts-per-billion by volume (ppbv) to parts-per-million (ppmv) levels, and has been validated at parts-per-trillion (pptv) levels for a subset of these analytes. This article is a detailed review of techniques related to the collection of volatile organic compounds (VOCs) in evacuated Summa and fused-silica-lined canisters, and their analysis by gas chromatography/mass spectrometry (GC/MS). Emphasis is placed on canister cleaning, VOC stability in canisters, sample dilution, water management, and VOC cryogenic and sorbent preconcentration methods. A wide range of VOC preconcentration and water management methods are identified from the literature, and their relative merits and disadvantages are discussed. Examples of difficulties that commonly arise when processing canister samples are illustrated, and solutions to these problems are provided.     

Non-target screening of organic contaminants in marine salts by gas chromatography coupled to high-resolution time-of-flight mass spectrometry

Gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF MS) has been applied to characterize the organic pollution pattern of marine salt samples collected in saltworks from the Spanish Mediterranean coast. After dissolving the samples in water, a solid-phase extraction was applied reaching with a 250-preconcentration factor. The screening methodology allowed the detection of sample components without any kind of pre-selection of target pollutants. The identity of components detected was established by accurate mass measurements and comparison of experimental full-acquisition spectra with theoretical MS libraries. Several organic pollutants were identified in the samples, like plasticizers - potentially toxic to humans - and fragrances -included within the group of pharmaceuticals and personal care products-, among others. Our results indicate that these contaminants can be found in the marine salt after the crystallization process. GC-TOF MS is a powerful technique for wide-scope screening of (semi)volatile, low-polar organic contaminants, able to investigate the presence of a large number of compounds. Searching of contaminants is not restricted to a target list of compounds. Therefore, unexpected contaminants can be discovered in an efficient way, with better sensitivity and selectivity than other conventional analytical techniques, and making use of the powerful qualitative information provided by full-spectrum acquisition at accurate mass.     

Novel analytical methods for characterising binding media and protective coatings in artworks

Since the first reported analytical studies and technical examinations of art and archaeological objects conducted in the late 18th century, analytical techniques and methods applied to the study of artworks have constantly grown. Among the materials composing the art object, organic compounds used as binding media or protective coatings have attracted the attention of the conservation profession given their noticeable ability for undergoing morphological and chemical changes on ageing. Thus, the aim of this paper is to review the most recent advances in the identification and determination of organic compounds present in art and art conservation materials. Immunofluorescence techniques have been proposed in recent decades as an alternative to the classical and simpler microchemical tests. Besides, a variety of instrumental techniques have also been improved in an attempt to enhance the sensitivity, repeatability and accuracy of the analytical results. Spectroscopic techniques, such as UV-vis, FTIR and Raman spectroscopy, have been coupled with light microscopes for these purposes. Synchrotron radiation FTIR microspectroscopy has also been successfully applied to the analysis of artworks. Mass spectrometry has also been increasingly used as a detector system coupled with a chromatographic device. Chromatographic methods have also improved in recent years. Paper and thin layer chromatographic techniques have been progressively replaced with gas chromatography (GC), pyrolysis-GC, high performance liquid chromatography and capillary electrophoresis. More complex proteomics hyphenated techniques, such as nano-liquid chromatography-nano-electrospray ionisation/collision quadrupole time-of-flight tandem mass spectrometry, have been recently applied to the identification and determination of proteinaceous binders. Microbeam analytical techniques have also been incorporated into the list of advanced instrumental techniques for art conservation purposes. Finally, a number of new instrumental techniques have been proposed as a suitable alternative to the conventional microscopy techniques for morphological studies.