有毒猪油中有机锡的GC-MS测定

用固相微萃取法富集猪油中挥发性杂质, 经色谱分离, 质谱测定, 确定了杂质的成分, 发现有毒猪油中存在６ 种与有机锡化合物有关的杂质, 它们是合成有机锡的原料和副产物,依据这些杂质推断其合成路线, 最终确定有机锡化合物为二硫代醋酸异辛酯二丁基锡。 该法准确, 简便。     

HPLC Coupled with in-line photolysis, hydride generation and flame atomic-absorption spectrometry for the speciation of tin in natural waters

The use of an in-line photolysis coil in a continuous-flow system of high-performance liquid chromatography coupled with hydride generation and flame atomic-absorption spectrometry for the speciation of tin in natural waters is described. Irradiation with ultraviolet light is shown to convert tributyltin into organic tin(IV), from which a volatile hydride can be produced in the conventional way. The effect of various conditions on the analytical performance is discussed. A detection limit of 2 ng for tin was obtained, and the tin species could be completely separated within 6 min. Use of the technique for quantification of tributyltin compounds in local coastal waters is described.     

Determination of organometallic compounds by capillar gas chromatography – inductively coupled plasma mass spectrometry

The separation and detection of volatile organometallic compounds containing tin, iron, and nickel has been achieved using capillary GC–inductively coupled plasma–mass spectrometry (capillary GC-ICP-MS). Detection limits range from 3.0 to 7.0 pg/s. The presence of volatile organotin compounds in a harbor sediment has been confirmed. The retention range of the organometallic compounds analyzed by capillary GC-ICP-MS has been extended considerably beyond that possible in earlier studies (retention indices up to 3400).     

Analytical Methods for Speciation of Organotins in the Environment

The growing awareness over the environmental fate of organotin compounds is reflected in the large number of analytical methods developed for their separation. Organotin compounds have varying degrees of toxicological properties, depending on the nature and number of alkyl groups bonded to the tin atom. Most of the analytical speciation methods applied to actual environmental media have involved prior derivatization to transform organotin compounds into volatile hydrophobic analytes amenable to separation and identification by gas chromatography coupled to a sensitive and selective tin-detector. Evidence exists that members of the same homologous series are related by environmental degradation pathways. Chemical treatment prior to analysis, or high temperatures associated with gas chromatography separation, may alter the relative amounts of organotins in samples and blur the true environment picture. To avoid species redistribution that may occur during derivatization or gas speciation analysis, methods based on liquid chromatography and supercritical fluid chromatography have been investigated. This review documents analytical methods for determination of tin and speciation of organotin compounds, in the hope that it will be of value to those interested in initiating a programme for assessing the impact of such species on the environment.     

Biotransformation of tributyltin chloride in the presence of resting-cell suspensions of pure strains of microorganisms

We describe the degradation of tributyltin chloride by several strains of fungi, yeasts and bacteria under resting-cell conditions in phosphate buffer, with low initial concentrations of substrate. Yields of biotic conversion of tributyltin ranging from 10 to 77% were observed after a five-day incubation at 28°C. In most cases, dibutyltin and monobutyltin compounds and a fraction of volatile products were formed. Volatile tin compounds essentially included derivatives of monobutyltin and traces of other organomethyltins (mono-, di-, and trimethyltins; di- and tri-butyltins), probably as the corresponding organostannanes. Compared with conditions in which the substrate was incubated with growing microorganisms, higher yields of degradation and substantial amounts of volatile products were obtained.     

Investigations of reactions involved in electrothermal atomic absorption procedures: Part 11. A theoretical and experimental investigation of factors influencing the determination of tin

Factors of importance for the determination of tin by graphite-furnace atomic absorption spectrometry have been investigated. Losses of tin during the drying and ashing stages were monitored by use of radioactivity measurements. It was found that tin could be lost at 100°C when ordinary graphite or glassy carbon surfaces were used. However, if the sample was dispensed into a droplet of ammonia, no losses occurred until 800°C, independent of the graphite surface, because tin is stabilized as SnO₂ (s,l) and chloride is removed as ammonium chloride. High-temperature equilibrium calculations indicate that tin forms volatile oxides, halides and sulphides which are stable up to relatively high temperatures. As is shown experimentally with commercial non-isothermal atomizers, these molecules might be removed from the system before their decomposition temperature is reached. A recently developed constant-temperature furnace was used to vaporize the sample into an environment of high and constant temperature, in which interference effects from chlorine and sulphur were minimized, as predicted by theory.     

Use of semiconductor oxide films for the detection of volatile organic compounds in the gas phase

A new type of flow-sensitive detectors of volatile organic compounds based on tin dioxide films modified by transition metal oxides has been proposed. The change on the film electric conductivity upon its contact with a flow of carrier gas containing a detectable compound has been used as an analytical signal. Dependences of analytical signals for some organic compounds on the temperature and film composition have been studied. Gas-chromatographic separation of model mixtures using a thermal catalytic detector has been performed. The possibility of the identification of organic compounds by the relationship between the analytical signals of two films of different compositions has been demonstrated.     

Determination of butyltin species by GC/atomic emission spectroscopy

A commercially available atomic emission detector coupled to a capillary column-containing gas chromatograph (;GC/AE) was utilized to detect organotin compounds. The response for tin was found to be dependent on the flow rate of the make-up gas. At flow rates of 174 cm³ min^?1, 6 × 10^?12 g of tin could be detected. Lower flow rates decreased the sensitivity. Response curves for two different pressures were established and both plots exhibited curvature at low concentrations. Extracted fish and sediment samples were analysed on the GC/AE system. The technique is element-specific. The presence of tin compounds could be confirmed by examining the emission spectra taken at the retention time of the peak.     

GC FPD method for the simultaneous speciation of butyltin and phenyltin compounds in waters

A method is described for the simultaneous determination of nanogram amounts of mono-, di- and tri-butyltin compounds in water. The procedure is based on the conversion of tin compounds to volatile species by Grignard pentylation and analysis using GC with flame photometric detection (GC FPD). The ionic compounds are extracted from diluted acidified (HBr) aqueous solutions by using a pentane-tropolone solution. The extracted organotin compounds are pentylated by a Grignard reagent and purified on a Fluorisil column before analysis by GC FPD. The detection limits are 20 ng dm^?3 for butyltin compounds and 50 ng dm^?3 for phenyltin compounds. Recoveries from spiking experiments in tap-water and natural seawater matrices, in which no organotin compounds were detected, were greater than 90% for most of the alkyltin compounds.     

Isolation of very volatile compounds from the leaves ofLedum palustre using the purge & trap technique

Summary A comparison of different isolation methods for volatile compounds from the leaves ofLedum palustre has been carried out. The aim of the investigation was not to identify all the isolated compounds, though some new compounds were found. Methods used were steam distillation, Soxhlet extraction with n-hexane and the purge & trap technique.The results obtained by the three methods of extraction were compared and it is was found that the very volatile compounds isolated by the purge & trap technique, could not be found by the more conventional methods. The very volatile compounds found by the purge & trap technique were mainly dienals.     

Fluorescent and colorimetric detection of acid vapors by using solid-supported rhodamine hydrazides

Rhodamine hydrazide-based chemosensors that can detect volatile acidic gases in solid state have been developed. The rhodamine hydrazide probes adsorbed on filter paper respond fluorescently and colorimetrically only to volatile acidic gases but not to organic bases nor to other volatile organic compounds (VOCs). Diethyl chlorophosphate (DCP), one of model compounds used for the studies of Chemical Warfare Agent (CWA), could also be detected by using this method.     

The methylation of inorganic tin by humic materials in an aquatic environment

This paper presents a study of methylation of inorganic tin (SnCl₄·5H₂O) by humic materials (humic and fulvic acids) isolated from the sediment of Tianjin Harbor, Tianjin, China, and the effects of pH, salinity, and the concentration of inorganic tin on the production of methyltin were investigated. These humic materials could methylate inorganic tin, and the methyltin product was mainly monomethyltin. Low molecular weight compounds of the humus fraction (i.e. fulvic acid) were more active in the methylation, which could be facilitated by salinity and affected by pH.     

Behaviour of organic pollutants in paper and board samples intended to be in contact with food

This paper deals with the study of volatile compounds present in a set of three paper and board (P&B) samples of different composition, surface treatment, grammage and thickness. The volatile compounds released by the packaging material (P&B) can be trapped on the food and may then affect the safety and health of consumers. To evaluate if the recycled P&B could be used as food packaging material, adsorption studies have been performed with a selection of chemical substances. The adsorption isotherms are provided. Partition coefficients between paper and air have been calculated for a series of volatile compounds used as model compounds to represent different families of contaminants commonly present in P&B. Values from 4 to 3243 were obtained at different temperatures. The analysis of volatile compounds have been carried out by automatic headspace coupled on-line with GC/MS in SIM mode. The results obtained are shown and discussed.     

Effects of Different Extraction Methods on Vanilla Aroma

To establish the analytic conditions for examining the aroma quality of vanilla pods, we compared different extraction methods and identified a suitable option. We utilized headspace solid-phase microextraction (HS-SPME), steam distillation (SD), simultaneous steam distillation (SDE) and alcoholic extraction combined with gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS) to identify volatile components of vanilla pods. A total of 84 volatile compounds were identified in this experiment, of which SDE could identify the most volatile compounds, with a total of 51 species, followed by HS-SPME, with a total of 28 species. Ten volatile compounds were identified by extraction with a minimum of 35% alcohol. HS-SPME extraction provided the highest total aroma peak areas, and the peak areas of aldehydes, furans, alcohols, monoterpenes and phenols compounds were several times higher than those of the other extraction methods. The results showed that the two technologies, SDE and HS-SPME, could be used together to facilitate analysis of vanilla pod aroma.     

Oral malodor,assessed by closed-loop,gas chromatography,and ion-trap technology

A method is described for the analysis of volatile organic compounds in saliva and tongue coating samples. The techniue is based on an off-line preconcentration step by means of a closed-loop trapping system followed by gas chromatography-ion trap detection. With the closed-loop technique, the volatile organic compounds(VOCs) are released from the matrix and trapped on an adsorbent without interference of water. The VOCs are released from the adsorbent into the gas chromatograph by thermdesorption. After separation, identification of the compounds is performed by ion trap technology. By this technique 82 compounds could be demonstrated in saliva and tongue coating samples. The technique is also used to demonstrate the formation of volatile bacterial fermentation compounds when a protein substrate is added to tongue coating samples. It is considered a very promising tool in further research on oral malodor.     

Structure Motifs of Sodium Stannides on the Tin‐rich Side of the Phase Diagram

The flexibility of the Sn‐Sn bond is acknowledged by the structural variety of compounds which are formed between tin and electropositive metals as minority components. As demonstrated for Na/Sn, already in the case of simple, binary systems a plethora of different structural motifs becomes obvious. Although the phase diagram of sodium and tin has been studied extensively for many years, the series of sodium stannides could be complemented by several new representatives during the last few years.     

Co-NC as adsorbent and matrix providing the ability of MALDI MS to analyze volatile compounds

Traditional matrix does not allow matrix-assisted laser desorption/ionization mass spectrometry(MALDI MS) to analyze volatile compounds,because volatile analytes may vaporize during the sample preparation process or in the high vacuum circumstance of ion source.Herein,we reported a Co and N doped porous carbon material(Co-NC) which were synthesized by pyrolysis of a Schiff base coordination compound.Co-NC could simultaneously act as adsorbent of volatile compounds and as matrix of MALDI MS,to provide the capability of MALDI MS to analyze volatile compounds.As adsorbent,Co-NC could stro ngly adsorb and enrich the volatile compounds in perfume and herbs,and hold them even in the high vacuum circumstance.On the other hand,Co-NC could absorb the energy of the laser,and then transfer the energy to the analyte for desorption and ionization of analyte in both negative and positive ionization modes.Additionally,the background interferences were avoided in the low-mass region(<500 Da) when using Co-NC as matrix,overcoming the challenges of MALDI MS analysis of small molecule compounds.In summary,Co-NC as matrix tremendously extended the application of MALDI MS.     

A simplified procedure for the determination of butyltin species in water

A method is described for the analysis of solutions containing inorganic tin and butyltin compounds. It can be used to determine total tin at a concentration of 20 ng dm^?3 using a 5 dm³ sample. The method is based on solvent extraction with dichloromethane containing tropolone and determination of the tin as inorganic tin by atomic absorption spectroscopy using electrothermal atomization. The extracted butyltin compounds can be separated by paper chromatography and the tin content of the individual spot determined as above. Observations on the stability of butyltin compounds in water at the ～2 mg dm^?3 (Sn) are included.     

顶空-气相色谱-质谱联用分析桂花和叶中挥发性成分

采用谱库检索结合准确质量测定、保留指数、串联质谱技术的多维定性分析策略鉴定化合物, 能够提高定性分析的效率和准确性. 运用顶空-气相色谱-四极质谱、顶空-气相色谱-飞行时间质谱以及顶空-气相色谱-串联质谱联用技术对桂花样品进行了分析检测, 并采用多维定性分析思路对检出的挥发性成分进行了鉴定. 结果共确认出47种挥发性成分, 其中单萜类和倍半萜类化合物为主要组分. 该定性分析策略准确可靠, 可以广泛应用于复杂样品挥发性成分的定性分析中.     

PVC热稳定剂酰胺基硫醇锡的合成

酯基硫醇锡;PVC热稳定剂酰胺基硫醇锡的合成