Beta-N-methylamino-l-alanine: LC-MS/MS Optimization,Screening of Cyanobacterial Strains and Occurrence in Shellfish from Thau,a French Mediterranean Lagoon

β-N-methylamino-l-alanine (BMAA) is a neurotoxic non-protein amino acid suggested to be involved in neurodegenerative diseases. It was reported to be produced by cyanobacteria, but also found in edible aquatic organisms, thus raising concern of a widespread human exposure. However, the chemical analysis of BMAA and its isomers are controversial, mainly due to the lack of selectivity of the analytical methods. Using factorial design, we have optimized the chromatographic separation of underivatized analogues by a hydrophilic interaction chromatography coupled to tandem mass spectrometry (HILIC-MS/MS) method. A combination of an effective solid phase extraction (SPE) clean-up, appropriate chromatographic resolution and the use of specific mass spectral transitions allowed for the development of a highly selective and sensitive analytical procedure to identify and quantify BMAA and its isomers (in both free and total form) in cyanobacteria and mollusk matrices (LOQ of 0.225 and 0.15 µg/g dry weight, respectively). Ten species of cyanobacteria (six are reported to be BMAA producers) were screened with this method, and neither free nor bound BMAA could be found, while both free and bound DAB were present in almost all samples. Mussels and oysters collected in 2009 in the Thau Lagoon, France, were also screened, and bound BMAA and its two isomers, DAB and AEG, were observed in all samples (from 0.6 to 14.4 µg/g DW), while only several samples contained quantifiable free BMAA.     

Toxicity Screening of a Gambierdiscus australes Strain from the Western Mediterranean Sea and Identification of a Novel Maitotoxin Analogue

Dinoflagellate species of the genera Gambierdiscus and Fukuyoa are known to produce ciguatera poisoning-associated toxic compounds, such as ciguatoxins, or other toxins, such as maitotoxins. However, many species and strains remain poorly characterized in areas where they were recently identified, such as the western Mediterranean Sea. In previous studies carried out by our research group, a G. australes strain from the Balearic Islands (Mediterranean Sea) presenting MTX-like activity was characterized by LC-MS/MS and LC-HRMS detecting 44-methyl gambierone and gambieric acids C and D. However, MTX1, which is typically found in some G. australes strains from the Pacific Ocean, was not detected. Therefore, this study focuses on the identification of the compound responsible for the MTX-like toxicity in this strain. The G. australes strain was characterized not only using LC-MS instruments but also N2a-guided HPLC fractionation. Following this approach, several toxic compounds were identified in three fractions by LC-MS/MS and HRMS. A novel MTX analogue, named MTX5, was identified in the most toxic fraction, and 44-methyl gambierone and gambieric acids C and D contributed to the toxicity observed in other fractions of this strain. Thus, G. australes from the Mediterranean Sea produces MTX5 instead of MTX1 in contrast to some strains of the same species from the Pacific Ocean. No CTX precursors were detected, reinforcing the complexity of the identification of CTXs precursors in these regions.     

固相萃取-GC/LC-MS/MS测定茶叶中79种农药残留

建立了一套以一次固相萃取前处理方法,运用气相色谱-串联质谱（GC-MS/MS）和液相色谱-串联质谱（LC-MS/MS）两种检测技术,测定茶叶中79种农药残留的可靠、快速、高通量检测方法。该方法用20βmL乙腈一次均质提取,分取提取液10βmL,用乙腈+甲苯（3∶1）20βmL洗脱过Carbon/NH₂小柱净化,用5βmL乙腈定容混匀,于GC-MS/MS和LC-MS/MS同时检测。结果表明,79种农药在0.01~0.40βmg·L^-1范围内线性良好,相关系数（R²）在0.995以上;高、低、中3种水平加标回收率在67.3%~130.8%内;相对标准偏差（RSD）在15%内;98.7%的农药定量限（LOQ）≤0.01βmg·kg^-1;使用多种类茶叶实际检测,结果均合格。因此,该方法能同时检测含有机磷、有机氯、拟除虫菊酯类、氨基甲酸酯类和有机杂环类5大类农药,更有利于大批量茶叶样品的多农残检测。     

Analysis of the Toxicity and Histopathology Induced by the Oral Administration of Pseudanabaena galeata and Geitlerinema splendidum (Cyanobacteria) Extracts to Mice

Cyanobacteria are common members of the freshwater microbiota in lakes and drinking water reservoirs, and are responsible for several cases of human intoxications in Brazil. Pseudanabaena galeata and Geitlerinema splendidum are examples of the toxic species that are very frequently found in reservoirs in Sao Paulo, which is the most densely populated area in Brazil. In the search for toxic strains collected from water reservoirs and maintained in the Cyanobacterial Culture Collection (CCIBt) of the Institute of Botany of Brazil, the acetic acid extracts (AE) of P. galeata CCIBt 3082 and G. splendidum CCIBt 3223 were analyzed by planar chromatography, which indicated the absence of cyanotoxins. Animal tests were then carried out, and both extracts were found to induce toxic effects in mice when administered intraperitoneally. The present study aimed to investigate whether the oral ingestion of the above mentioned cyanobacteria extracts would also induce toxic effects in mice. Necropsy and histopathological studies were conducted using tissue samples from the animals, which were euthanized one week after the administration of the extracts. The AE of P. galeata did not cause death but did induce transient symptoms, including eyebrow ptosis, straub tail, and pain. The euthanized animals presented hemorrhage in the liver, whereas the histological analysis showed disorganization of the hepatic parenchyma, necrosis, hyperemia, and proximity of the centrilobular vein in the liver. In addition, alterations in the convoluted tubules of the kidneys were observed, and the lungs were unaffected. The AE of G. splendidum caused only one death, and induced transient symptoms, such as dyspnea, paralysis, and pain, in the other mice. The necropsy of the euthanized mice showed hemorrhage in the lungs and liver. The lungs presented hemorrhagic focuses, alveolar collapse, and granulomatous foci. The liver presented hemorrhagic and enlarged sinusoids, hyperemia, proximity of the centrilobular vein, and disorganization of the hepatic parenchyma. Some areas also exhibited an inflammatory infiltrate and calcified tissue inside blood vessels. Necrosis and rupture of the convoluted tubule cells were observed in the kidneys. Further analysis of the both extracts indicated the lack of hemolytic activity, and the presence of two unknown anti-AChE substances in the AE of G. splendidum. Thus, P. galeata and G. splendidum are producers of novel toxins that affect mammals when administered orally.     

A Metabolomics-Based Toolbox to Assess and Compare the Metabolic Potential of Unexplored,Difficult-to-Grow Bacteria

Novel high-throughput cultivation techniques create a demand to pre-select strains for in-depth follow-up studies. We report a workflow to identify promising producers of novel natural products by systematically characterizing their metabolomes. For this purpose, 60 strains from four phyla (Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes) comprising 16 novel species and six novel genera were cultivated from marine and terrestrial sources. Their cellular metabolomes were recorded by LC-MS/MS; data analysis comprised databases MS/MS matching, in silico compound assignment, and GNPS-based molecular networking. Overall, 1052 different molecules were identified from 6418 features, among them were unusual metabolites such as 4-methoxychalcone. Only a minor portion of the 755 features were found in all phyla, while the majority occurred in a single phylogroup or even in a single strain. Metabolomic methods enabled the recognition of highly talented strains such as AEG42_45, which had 107 unique features, among which a family of 28 potentially novel and related compounds according to MS/MS similarities. In summary, we propose that high-throughput cultivation and isolation of bacteria in combination with the presented systematic and unbiased metabolome analysis workflow is a promising approach to capture and assess the enormous metabolic potential of previously uncultured bacteria.     

Simultaneous Determination of Fucoxanthin and Its Deacetylated Metabolite Fucoxanthinol in Rat Plasma by Liquid Chromatography-Tandem Mass Spectrometry

Fucoxanthin and its deacetylated metabolite fucoxanthinol are two major carotenoids that have been confirmed to possess various pharmacological properties. In the present study, fucoxanthinol was identified as the deacetylated metabolite of fucoxanthin, after intravenous (i.v.) and intragastric gavage (i.g.) administration to rats at doses of 2 and 65 mg/kg, respectively, by liquid chromatography-tandem mass spectrometric (LC-MS/MS) analysis. Next, an accurate and precise LC-MS/MS method was developed to quantitatively determine fucoxanthin and fucoxanthinol in rat plasma. Plasma samples were resolved by LC-MS/MS on a reverse-phase SB-C18 column that was equilibrated and eluted with acetonitrile (A)/aqueous 0.1% formic acid (B; 92/8, v/v) at a flow rate of 0.5 mL/min. Analytes were monitored by multiple-reaction monitoring (MRM) under positive electrospray ionization mode. The precursor/product transitions (m/z) were 659.3→109.0 for fucoxanthin, 617.2→109.0 for fucoxanthinol, and 429.4→313.2 for the internal standard (IS). Calibration curves for fucoxanthin and fucoxanthinol were linear over concentrations ranging from 1.53 to 720 and 1.17 to 600 ng/mL, respectively. The inter- and intraday accuracy and precision were within ±15%. The method was applied successfully in a pharmacokinetic study and the resulting oral fucoxanthin bioavailability calculated.     

晋麦47幼苗中一个水分胁迫应答蛋白的SDS-PAGE和Nano LC-MS/MS鉴定

水分胁迫应答蛋白的表达与小麦品种的抗旱性密切相关。为了明确与抗旱相关的水分胁迫D-应答蛋白的表达特点及蛋白组成,对小麦品种晋麦47幼苗进行不同供水量处理,应用SDS-PAGE、纳升级液相色谱-电喷雾串联质谱联用技术(Nano LC-MS/MS),分析了水分胁迫D-应答蛋白条带表达量的变化和蛋白组成。SDS-PAGE检测结果表明,水分胁迫D-应答蛋白条带在-0.5 MPa PEG-6000水溶液胁迫下,6 h出现可见表达,胁迫至48 h时表达量最大,之后,此蛋白条带的表达量又逐渐下降;幼苗胁迫48 h后恢复正常供水,复水72 h后该蛋白消失。切取正常供水和胁迫处理两个条件下SDS-PAGE胶差异表达蛋白条带,经质谱分析分别获得两个阳性结果,且正常供水和PEG-6000胁迫两种处理条件下D-应答蛋白组成一致,均由核酮糖-1,5-二磷酸羧化酶大亚基和磷酸甘油酸变位酶组成(P<0.05);PEG-6000胁迫条件下两个蛋白(亚基)的鉴定得分分别为1 632和88,覆盖率分别为30%和21%;在鉴定的肽段中,有65个肽段同属于核酮糖-1,5-二磷酸羧化酶大亚基,其中35个肽段可信度均超过阈值分数;有5个肽段同属于磷酸甘油酸变位酶,其中4个肽段的可信度超过阈值分数。结果表明该蛋白条带可能主要由核酮糖-1,5-二磷酸羧化酶大亚基等组成。     

First Identification of 5,11-Dideoxytetrodotoxin in Marine Animals,and Characterization of Major Fragment Ions of Tetrodotoxin and Its Analogs by High Resolution ESI-MS/MS

Even though tetrodotoxin (TTX) is a widespread toxin in marine and terrestrial organisms, very little is known about the biosynthetic pathway used to produce it. By describing chemical structures of natural analogs of TTX, we can start to identify some of the precursors that might be important for TTX biosynthesis. In the present study, an analog of TTX, 5,11-dideoxyTTX, was identified for the first time in natural sources, the ovary of the pufferfish and the pharynx of a flatworm (planocerid sp. 1), by comparison with totally synthesized (−)-5,11-dideoxyTTX, using high resolution ESI-LC-MS. Based on the presence of 5,11-dideoxyTTX together with a series of known deoxy analogs, 5,6,11-trideoxyTTX, 6,11-dideoxyTTX, 11-deoxyTTX, and 5-deoxyTTX, in these animals, we predicted two routes of stepwise oxidation pathways in the late stages of biosynthesis of TTX. Furthermore, high resolution masses of the major fragment ions of TTX, 6,11-dideoxyTTX, and 5,6,11-trideoxyTTX were also measured, and their molecular formulas and structures were predicted to compare them with each other. Although both TTX and 5,6,11-trideoxyTTX give major fragment ions that are very close, m/z 162.0660 and 162.1020, respectively, they are distinguishable and predicted to be different molecular formulas. These data will be useful for identification of TTXs using high resolution LC-MS/MS.     

Analytical challenges: determination of tetrodotoxin in human urine and plasma by LC-MS/MS

Tetrodotoxin (TTX) is a powerful sodium channel blocker found in puffer fish and some marine animals. Cases of TTX poisoning most often result from puffer fish ingestion. Diagnosis is mainly from patient's signs and symptoms or the detection of TTX in the leftover food. If leftover food is unavailable, the determination of TTX in the patient's urine and/or plasma is essential to confirm the diagnosis. Although various methods for the determination of TTX have been published, most of them are for food tissue samples. Dealing with human urine and blood samples is much more challenging. Unlike in food, the amount of toxin in the urine and blood of a patient is generally extremely low; therefore a very sensitive method is required to detect it. In this regard, mass spectrometry (MS) methods are the best choice. Since TTX is a very polar compound, there will be lack of retention on conventional reverse-phase columns; use of ion pair reagent or hydrophilic interaction liquid chromatography (HILIC) can help solve this problem. The problem of ion suppression is another challenge in analyzing polar compound in biological samples. This review will discuss different MS methods and their pros and cons.     

Monitoring the Emergence of Algal Toxins in Shellfish: First Report on Detection of Brevetoxins in French Mediterranean Mussels

In France, four groups of lipophilic toxins are currently regulated: okadaic acid/dinophysistoxins, pectenotoxins, yessotoxins and azaspiracids. However, many other families of toxins exist, which can be emerging toxins. Emerging toxins include both toxins recently detected in a specific area of France but not regulated yet (e.g., cyclic imines, ovatoxins) or toxins only detected outside of France (e.g., brevetoxins). To anticipate the introduction to France of these emerging toxins, a monitoring program called EMERGTOX was set up along the French coasts in 2018. The single-laboratory validation of this approach was performed according to the NF V03-110 guidelines by building an accuracy profile. Our specific, reliable and sensitive approach allowed us to detect brevetoxins (BTX-2 and/or BTX-3) in addition to the lipophilic toxins already regulated in France. Brevetoxins were detected for the first time in French Mediterranean mussels (Diana Lagoon, Corsica) in autumn 2018, and regularly every year since during the same seasons (autumn, winter). The maximum content found was 345 µg (BTX-2 + BTX-3)/kg in mussel digestive glands in November 2020. None were detected in oysters sampled at the same site. In addition, a retroactive analysis of preserved mussels demonstrated the presence of BTX-3 in mussels from the same site sampled in November 2015. The detection of BTX could be related to the presence in situ at the same period of four Karenia species and two raphidophytes, which all could be potential producers of these toxins. Further investigations are necessary to understand the origin of these toxins.     

Occurrence of Lipophilic Marine Toxins in Shellfish from Galicia (NW of Spain) and Synergies among Them

Lipophilic marine toxins pose a serious threat for consumers and an enormous economic problem for shellfish producers. Synergistic interaction among toxins may play an important role in the toxicity of shellfish and consequently in human intoxications. In order to study the toxic profile of molluscs, sampled during toxic episodes occurring in different locations in Galicia in 2014, shellfish were analyzed by liquid chromatography tandem mass spectrometry (LC–MS/MS), the official method for the detection of lipophilic toxins. The performance of this procedure was demonstrated to be fit for purpose and was validated in house following European guidelines. The vast majority of toxins present in shellfish belonged to the okadaic acid (OA) group and some samples from a particular area contained yessotoxin (YTX). Since these toxins occur very often with other lipophilic toxins, we evaluated the potential interactions among them. A human neuroblastoma cell line was used to study the possible synergies of OA with other lipophilic toxins. Results show that combination of OA with dinophysistoxin 2 (DTX2) or YTX enhances the toxicity triggered by OA, decreasing cell viability and cell proliferation, depending on the toxin concentration and incubation time. The effects of other lipophilic toxins as 13-desmethyl Spirolide C were also evaluated in vitro.     

响应面法优化提取槟榔花总酚的研究

为了探索槟榔花中总酚提取的最佳工艺参数,在单因素试验的基础上以粒径、料液比和提取温度为试验因素,以总酚含量为响应值,采用Box-Behnken响应面分析法进行试验,并应用优化的条件比较了不同干燥方法对槟榔花总酚含量的影响。结果表明,3个因素对槟榔花总酚含量的影响大小顺序为:料液比>提取温度>粒径,槟榔花中总酚提取的最佳工艺参数为:1:35(g:mL)、95℃、0.5～1.0 mm,验证值为25.97 mg/g,试验证明,响应面法对槟榔花中总酚提取条件的优化是可行的,可用于实际预测;不同干燥方法槟榔花总酚含量的影响大小顺序为:炒干>微波干燥>真空冷冻干燥>热风干燥。     

菠萝粉蚧种类调查及发生规律研究

菠萝粉蚧是为害菠萝的粉蚧的统称,是菠萝凋萎病的主要传播媒介,本文对我国菠萝粉蚧的种类和发生规律进行了研究.结果表明:在我国,为害菠萝的粉蚧主要是菠萝洁粉蚧,仅在海南乐东菠萝园发现有新菠萝灰粉蚧危害;菠萝洁粉蚧目前仅限在菠萝上为害;新菠萝灰粉蚧主要为害剑麻,也为害菠萝和粉蕉;我国暂未发现2种粉蚧混合发生的现象.秋季是雷州半岛地区菠萝洁粉蚧自然种群快速增长期,12月下旬菠萝洁粉蚧自然种群数量进入高峰期;气温和降雨量是影响菠萝洁粉蚧自然种群增长的重要因子,高温、低温均不利于菠萝洁粉蚧生长和繁殖,降雨量对菠萝洁粉蚧的自然种群数量具有明显的抑制作用.     

Ovatoxin-a and palytoxin accumulation in seafood in relation to Ostreopsis cf. ovata blooms on the French Mediterranean coast

Dinoflagellates of the genus Ostreopsis are known to cause (often fatal) food poisoning in tropical coastal areas following the accumulation of palytoxin (PLTX) and/or its analogues (PLTX group) in crabs, sea urchins or fish. Ostreopsis spp. occurrence is presently increasing in the northern to north western Mediterranean Sea (Italy, Spain, Greece and France), probably in response to climate change. In France, Ostreopsis. cf. ovata has been associated with toxic events during summer 2006, at Morgiret, off the coast of Marseille, and a specific monitoring has been designed and implemented since 2007. Results from 2008 and 2009 showed that there is a real danger of human poisoning, as these demonstrated bioaccumulation of the PLTX group (PLTX and ovatoxin-a) in both filter-feeding bivalve molluscs (mussels) and herbivorous echinoderms (sea urchins). The total content accumulated in urchins reached 450 μg PLTX eq/kg total flesh (summer 2008). In mussels, the maximum was 230 μg eq PLTX/kg (summer 2009) compared with a maximum of 360 μg found in sea urchins during the same period at the same site. This publication brings together scientific knowledge obtained about the summer development of Ostreopsis spp. in France during 2007, 2008 and 2009.     

Optimization and Validation of a High Throughput UHPLC-MS/MS Method for Determination of the EU Regulated Lipophilic Marine Toxins and Occurrence in Fresh and Processed Shellfish

Under the name of lipophilic marine toxins, there are included more than 1000 toxic secondary metabolites, produced by phytoplankton, with the common chemical property of lipophilicity. Due to toxicological effects and geographical distribution, in European legislation relevant compounds are regulated, and their determination is accomplished with the reference liquid chromatography-tandem mass spectrometry method. In this study a modified ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method has been developed for the identification and quantification of EU-regulated lipophilic toxins. The method optimization included a refinement of SPE-C18 clean-up, in order to reduce matrix interferences. Improved LC conditions and upgraded chromatographic ammonia-based gradient ensured the best separation of all analytes and, in particular, of the two structural isomers (OA and DTX2). Also, different MS parameters were tested, and confirmation criteria finally established. The validation studies confirmed that all parameters were satisfactory. The requirements for precision (RSD% < 11.8% for each compound), trueness (recoveries from 73 to 101%) and sensitivity (limits of quantification in the range 3–8 µg kg⁻¹) were fulfilled. The matrix effect, ranging from −9 to 19%, allowed the use of a calibration curve in solvent (3–320 µg kg⁻¹ in matrix) for quantification of real samples. Method relative uncertainty ranged from 12 to 20.3%. Additionally, a total of 1000 shellfish samples was analysed, providing a first preliminary surveillance study that may contribute to the knowledge of lipophilic marine toxins contamination. Increase in algae proliferation events and intoxication cases, EFSA suggestions for modification of maximum permitted levels and toxicity equivalency factors, and new studies of important toxic effects underline that implementation of reference methods still represents an important task for health and food safety laboratories.     

UPLC-MS/MS法测定水稻中噁唑酰草胺和氰氟草酯及其代谢物的残留及膳食风险评估

建立了使用分散固相萃取的QuEChERS前处理方法,并通过超高效液相色谱串联质谱(Ultra Performance Liquid Chromatography Tandem Mass Spectrometry,UPLC-MS/MS)对糙米、稻壳和秸秆样品中的噁唑酰草胺和氰氟草酯及其代谢物成功进行了定量测定.结果 表明...     

叶面喷施不同营养元素对冬小麦产量和品质的影响

为给叶面施肥在小麦生产中的应用提供技术参考,以不同品质类型的2个小麦品种为试验材料,采用二因素随机区组设计,研究了品种和叶面喷施不同营养元素（硼、锌、锰、铁、磷、钾、氮）对小麦产量和品质的影响。结果表明,在底肥和追肥相同的条件下,品种间产量和品质差异显著。喷施不同营养元素处理的千粒重均比对照有所提高,喷施营养元素处理间产量差异显著,其中叶面喷施硼肥产量最高。叶面喷施营养元素对面团吸水率、形成时间、稳定时间、面包体积、面包评分有显著影响,对籽粒蛋白质含量影响不显著,但对不同蛋白组分有显著影响。叶面喷施铁和锌分别提高了籽粒中铁和锌的含量,但喷锰并未增加籽粒中锰的含量。     

冲泡过程中西湖龙井茶黄酮苷类浸出特性及滋味贡献分析

本研究提出了一种基于HPLC的茶叶黄酮苷类物质检测方法,采用此方法分析了西湖龙井茶中黄酮苷类物质在不同冲泡条件下的浸出特性,并通过Dot值（浓度与阈值的比值）分析黄酮苷类物质对茶汤滋味的影响。结果表明：（1）该检测方法可以较好地分离和测定茶叶中11种黄酮苷类物质;（2）传统冲泡条件下,西湖龙井茶中以杨梅素-3-O-半乳糖苷（Myr-gala）和槲皮素-3-O-芸香糖苷（Que-rut）为主,随着冲泡温度的提高和时间的延长,11种黄酮苷类物质除了山柰酚-3-O-芸香糖苷（Kae-rut）外,都呈不同程度的增加,其中槲皮素-3-O-芸香糖苷（Que-rut）和槲皮素-3-O-半乳糖苷（Que-gala）的浸出速率较快,而杨梅素-3-O-鼠李糖苷（Myr-rha）和牡荆素-2"-O-鼠李糖苷（Vit-rha）的浸出速率较慢;（3）通过Dot值分析,槲皮素-3-O-芸香糖苷（Que-rut）、槲皮素-3-O-半乳糖苷（Que-gala）和杨梅素-3-O-半乳糖苷（Myr-gala）的Dot值均高于10,可能是茶汤滋味的重要贡献物质。     

Report on the first detection of pectenotoxin-2, spirolide-a and their derivatives in French shellfish

In the context of the French Phytoplankton and Phycotoxins Monitoring Network (REPHY) programme, shellfish samples were harvested from different locations where harmful algae blooms were known to have occurred. For all shellfish samples found positive by the mouse bioassay for diarrhetic shellfish poisoning (DSP) toxins, liquid chromatography (LC) coupled with mass spectrometry (MS) was used to search for the following lipophilic toxins: okadaic acid (OA), dinophysistoxins (DTXs), pectenotoxins (PTXs), azaspiracids (AZAs), yessotoxins (YTXs), spirolides (SPXs) and gymnodimines (GYMs). In order to investigate the presence of acyl-OAs and/or acyl-DTX-1,-2 (DTX-3), alkaline hydrolysis was performed on all samples, and LC/MS analyses were carried out on the samples before and after hydrolysis. The results revealed different lipophilic toxin profiles as a function of the shellfish sampling location. The primary finding was that all of the samples contained OA and acyl-OA. In addition, other lipophilic toxins were found in shellfish samples: DTX-2, acyl-DTX-2 and SPXs (SPX-A, SPX-desMeC) on the Atlantic coast (Southern Brittany, Arcachon), and pectenotoxins (PTX-2, PTX-2-seco-acid and 7-epi-PTX-2-seco-acid) on the Mediterranean coast (Thau lagoon, the island of Corsica). This paper reports on the first detection of PTX-2, SPX-A and their derivatives in French shellfish.     

基于壳聚糖/氧化石墨烯/硅藻土固相萃取-液相色谱串联质谱测定茶叶中多种农药残留

利用前期合成的壳聚糖/氧化石墨烯/硅藻土固相萃取柱高效吸附茶叶基质,结合超高效液相色谱串联质谱（UPLC-MS/MS）,建立了茶叶中46种农药残留的分析方法。茶叶样品经乙腈提取,固相萃取柱净化,乙腈淋洗等样品前处理,UPLC-MS/MS分析46种农药残留。结果表明,该新型固相萃取净化柱可以高效吸附去除茶叶基质,大大降低基质效应,绿茶、红茶和乌龙茶中农药的基质效应分别下降了4.7%~66.5%,3.2%~35.5%和4.4%~42.8%。在3个加标水平下,46种农药回收率在61.5%~118%线性良好,相关系数（R²）均大于0.98。所建立方法具有吸附剂用量少、省时、无需基质标准溶液、可以检测不同茶类多农残和定量限低等优点。