Analysis of trace levels of domoic acid in seawater and plankton by liquid chromatography without derivatization,using UV or mass spectrometry detection

Quantitation of trace levels of domoic acid (DA) in seawater samples usually requires labour-intensive protocols involving chemical derivatization with 9-fluorenylmethylchloroformate and liquid chromatography with fluorescence detection (FMOC–LC–FLD). Procedures based on LC–MS have been published, but time-consuming and costly solid-phase extraction pre-concentration steps are required to achieve suitable detection limits. This paper describes an alternative, simple and inexpensive LC method with ultraviolet detection (LC–UVD) for the routine analysis of trace levels of DA in seawater without the use of sample pre-concentration or derivatization steps. Qualitative confirmation of DA identity in dubious samples can be achieved by mass spectrometry (LC–MS) using the same chromatographic conditions. Addition of an ion-pairing/acidifying agent (0.15% trifluoroacetic acid) to sample extracts and the use of a gradient elution permitted the direct analysis of large sample volumes (100 μl), resulting in both high selectivity and sensitivity (limit of detection = 42 pg ml⁻¹ by LC–UVD and 15 pg ml⁻¹ by LC–MS). Same-day precision varied between 0.4 and 5%, depending on the detection method and DA concentration. Mean recoveries of spiked DA in seawater by LC–UVD were 98.8% at 0.1–10 ng ml⁻¹ and 99.8% at 50–1000 ng ml⁻¹. LC–UVD exhibited strong correlation with FMOC–LC–FLD during inter-laboratory analysis of Pseudo-nitzschia multiseries cultures containing 60–2000 ng DA ml⁻¹ (r² > 0.99), but more variable results were obtained by LC–MS (r² = 0.85). This new technique was used to confirm the presence of trace DA levels in low-toxicity Pseudo-nitzschia spp. isolates (0.2–1.6 ng ml⁻¹) and in whole-water field samples (0.3–5.8 ng ml⁻¹), even in the absence of detectable Pseudo-nitzschia spp. cells in the water column.     

Simultaneous Multielement Study of the Binding of Metals in Solution by an Algal Biomass,Chlorella Vulgaris

Abstract

The adsorption process of four metals in solution (Pb, Cu, Zn, Cd) to Chlorella Vulgaris will be described and compared to a previous study using three metals (Pb,Cu,Zn) in solution. The binding capacity of Chlorella Vulgaris to four elements simultaneously increases with time, mass of algae, and up to a temperature of about 20.0°C. The equilibrium points for binding three metals simultaneously are at pH=4.55, with 7 mg of algae, and after 2.0 hrs. in a 5 ml aliquot of the solution. In the four metal system, the optimum values are significantly higher while the binding capacity is reduced. The competition between metals for binding sites in the algal cells is governed by kinetic properties as related to the pH, mass of algae, time, and concentration of solution. The binding process is also dependent upon thermodynamics with respect to the temperature of the solution.     

Sustainable restoration: the contribution of algae

Abstract

The application of algae to the most meaningful fields of our life, such as food, environment and energy, finds a further confirmation in the extension of this application to cultural heritage protection. In this letter, we present the results of a preliminary study testing how a polysaccharide extracted from algal matrix can restore degraded paper giving back it mechanical strength and chemical structure.     

Discovery of New Cytotoxic Aplaminone Derivatives from the Sea Hare Aplysia kurodai and Elucidation of Their Accumulation from Local Sea Algae through the Food Chain

The shell-less herbivorous marine mollusk (sea hare) Aplysia kurodai is known to contain a variety of bioactive substances. While these compounds have been thought to originate from sea algae or their associated microbes, most of their origin and acquisition pathways are still unclear. Six new cytotoxic aplaminone derivatives, bromodopamine-terpenoid hybrid molecules, were isolated from A. kurodai. Among them, isoaplaminone had a reverse prenyl group at the C15 aliphatic chain, which is a rare structural feature from the viewpoint of terpenoid biosynthesis. Investigation for chemical components in A. kurodai and the sea algae collected at several different locations revealed that two major aplaminones were contained in the Laurencia complex species at specific sites. Our chemical and ecological studies provide new insights into the origin of marine alkaloid toxins and their dynamism through the food chain.     

Signal Substances and their Reception in the Sexual Cycle of Marine Brown Algae

Attraction and repulsion are responses to chemical stimuli which can be received and processed even by unicellular organisms without a morphologically defined nervous system. Chemical substances trigger off a chain of events which starts with a membrane-bound signal receptor and, after a sequence of regulatory and modulatory steps, ends in the modulation of a motor effector organ. Binding of the signal substances to the receptor produces conformational changes in which the receptor subunits are mutually dependent on one another, and also leads to chemical modification of the subunits and affects their molecular activity. These interactions, together with the characteristic type of movement, result in a physiological pattern of behavior which enables the flagellated sex cells (gametes) of marine brown algae to finally locate their partners. The simple but highly specific brown algae gamete systems have been investigated structurally and their biological activity analyzed. The signal substances are mainly highly unsaturated aliphatic or cyclic hydrocarbons with unsaturated side chains (general formula e. g. C₁₁H₁₄, C₁₁H₁₆, C₁₁H₁₈). These systems also serve as a simplifying model which helps in the understanding of complex ganglionic pathways in higher living organisms where the sense organs convey information from the surroundings to the central nervous system through nerve pathways. The information is then processed and answered, via efferent pathways, as movement.     

Speciation analysis of antimony in marine biota by HPLC-(UV)-HG-AFS: Extraction procedures and stability of antimony species

Speciation analysis of antimony in marine biota is not well documented, and no specific extraction procedure of antimony species from algae and mollusk samples can be found in the literature. This work presents a suitable methodology for the speciation of antimony in marine biota (algae and mollusk samples). The extraction efficiency of total antimony and the stability of Sb(III), Sb(V) and trimethylantimony(V) in different extraction media (water at 25 and 90 °C, methanol, EDTA and citric acid) were evaluated by analyzing the algae Macrosystis integrifolia (0.55 ± 0.04 μg Sb g⁻¹) and the mollusk Mytilus edulis (0.23 ± 0.01 μg Sb g⁻¹). The speciation analysis was performed by anion exchange liquid chromatography (post-column photo-oxidation) and hydride generation atomic fluorescence spectrometry as detection system (HPLC-(UV)-HG-AFS). Results demonstrated that, based on the extraction yield and the stability, EDTA proved to be the best extracting solution for the speciation analysis of antimony in these matrices. The selected procedure was applied to antimony speciation in different algae samples collected from the Chilean coast. Only the inorganic Sb(V) and Sb(III) species were detected in the extracts. In all analyzed algae the sum of total antimony extracted (determined in the extracts after digestion) and the antimony present in the residue was in good agreement with the total antimony concentration determined by HG-AFS. However, in some extracts the sum of antimony species detected was lower than the total extracted, revealing the presence of unknown antimony species, possibly retained on the column or not detected by HPLC-(UV)-HG-AFS. Further work must be carried out to elucidate the identity of these unknown species of antimony.     

太湖水体中藻蓝蛋白的紫外-可见吸收光谱特征分析

以藻蓝蛋白标准品和室内培养的铜绿微囊藻、鱼腥藻为参照,于2011年春、夏、秋三季在太湖采集75个水样,分析太湖水体中藻蓝蛋白的紫外-可见吸收光谱特征,及其与标准品、单一藻种光谱特征的区别和联系。结果表明：太湖水体中藻蓝蛋白的吸收光谱形态可根据500～700 nm的吸收峰个数划分为无峰型、单峰型和双峰型三类。无峰型光谱在500～700 nm间变化平缓,620 nm附近无藻蓝蛋白的特征吸收峰出现。根据300～450 nm的吸收差异,无峰型可划分为无峰Ⅰ和无峰Ⅱ两个亚类。峰型Ⅰ仅在260 nm附近出现吸收峰,250～800 nm的谱型更接近于有色可溶性有机物(CDOM);峰型Ⅱ在260和330 nm处均有吸收峰出现。单峰型光谱在620 nm的藻蓝蛋白特征吸收峰明显,受藻种差异和提取纯度的影响,其在250～300,300～450和500～700 nm的吸收峰出现位置和峰值比与标准品、单一藻种不同。双峰型光谱在620和670 nm附近各具一个吸收峰,同时在350～450 nm出现吸收肩,兼具藻蓝蛋白和叶绿素复合蛋白的吸收特征。     

青岛海藻重元素富集特性的SR-XRF分析及对海洋环境监测的应用

利用同步辐射X射线荧光 (SR XRF)定性和定量地分析了采自中国青岛海滨的 9种海藻 1 4个样品重元素的富集特性 ,发现不同种海藻重元素的富集特性有很大的差异。海蒿子对As和Sr,鸭毛藻对Br,海带对Ⅰ具有超富集能力。Mn/Fe峰强比的变化 ,是元素间拮抗的结果 ,与海水环境相关。测量了标样植物南极苔藓的检出限。定量地分析和比较了在青岛同一海滨分别于 1 985年和 1 999年采集的 5种海藻样品的XRF谱。1 999年采集的海藻的Fe ,Zn ,As,Br和Pb等元素含量明显上升 ,特别是海蒿子中的As和刺石松中的Pb分别增加了 1 55 %和 1 2 0 % ,结果说明了 1 4年来青岛海洋环境污染加重的趋势。     

Halogenated Sesquiterpenes from the Marine Red Alga Laurencia saitoi (Rhodomelaceae)

Four new halogenated sesquiterpenes, 10‐bromo‐3‐chloro‐2,7‐epoxychamigr‐9‐en‐8α‐ol ( 1 ), 2,10β‐dibromochamigra‐2,7‐dien‐9α‐ol ( 2 ), (9S)‐2‐bromo‐3‐chloro‐6,9‐epoxybisabola‐7(14),10‐diene ( 3 ), and (9R)‐2‐bromo‐3‐chloro‐6,9‐epoxybisabola‐7(14),10‐diene ( 4 ), were characterized from the marine red alga Laurencia saitoi. In addition, two known halosesquiterpenes, 2,10‐dibromo‐3‐chlorochamigr‐7‐en‐9α‐ol ( 5 ) and isolaurenisol ( 6 ), were also isolated and identified. Their structures were established on the basis of extensive analysis of spectroscopic data.