Seafoods extracts

Manger, R.L. et al., Detection of sodium channel toxins directed cytotoxicity assays of purified cigua-toxins, brevetoxins, saxitoxins, and seafood extracts, J AOAC Int 78, 521, 1995. 

Manger, R.L., L.S. Leja, S.Y. Lee, J.M. Hungerford, Y. Hokama, R.W. Dickey, H.R. Granade, R.J. Lewis, T. Yasumoto, and M.M. WekeU (1995). Detection of sodium channel effectors directed cytotoxicity assays of purified ciguatoxins,brevetoxms, saxitoxin, and seafood extracts. J. AOAC Int. 78, 521-527. 

To cite a few examples, HPLC was coupled with SIA for the simultaneous determination of several heavy metals by means of nitro-PAPS (polyfiuoroalkyl phosphate esters) complexes [43]. An SIA—HPLC—atomic fluorescence spectrometry (AFS) system was proposed for As speciation in seafood extracts, implementing standard addition method for simultaneous quantification of four As species [44]. An SIA-HPLC with electrochemical detection was proposed using a homemade microcolumn SPE coupled to SIA in order to automate the sample cleanup, extraction and detection of sulfonamides [45]. 

Munoz O, Velez D, Montoro R (1999) Optimization of the solubilization, extraction and determination of inorganic arsenic [As(III) i- As(V)] in seafood products by acid digestion, solvent extraction and hydride generation atomic absorption spectrometry. Analyst 124 601-607. 

Seafood may naturally contain small amounts of various PAHs, absorbed from the sea water. The aquatic environment is contaminated with PAHs due to oil spills, incomplete combustion of fossil fuels, industrial and urban effluents, extraction from creosoted wharfs and pilings, as well as from biosynthesis by plants and marine microorganisms. 

The more classical approach to assess the presence of marine biotoxins in seafood is the in vivo mouse bioassay. It is based on the administration of suspicious extracted shellfish samples to mice, the evaluation of the lethal dose and the toxicity calculation according to reference dose response curves, established with reference material. It provides an indication about the overall toxicity of the sample, as it is not able to differentiate among individual toxins. This is a laborious and time-consuming procedure the accuracy is poor, it is nonspecific and generally not acceptably robust. Moreover, the mouse bioassay suffers from ethical implications and it is in conflict with the EU Directive 86/609 on the Protection of Laboratory Animals. Despite the drawbacks, this bioassay is still the method of reference for almost all types of marine toxins, and is the official method for PSP toxins. 

M. C. Yebra, A. Moreno-Cid and S. Cancela, Flow injection determination of copper and iron in seafoods by a continuous ultrasound-assisted extraction system coupled to FAAS, Int. J. Environ. Anal. Chem., 85(4-5), 2005, 315-323. 

A. Moreno-Cid and M. C. Yebra, Continuous ultrasound-assisted extraction coupled to a flow injection-flame atomic absorption spectrometric system for calcium determination in seafood samples. Anal. Bioanal. Chem., 379(1), 2004, 77-82. 

There have been few elemental speciation studies in the literature involving cation-exchange chromatography (CEC) coupled to ICP-MS. A cation-exchange column was used by Larsen et al. [57,69] for arsenic speciation in several seafood sample extracts. The chromatography was optimized for the separation of arsenocholine, trimethylarsinic, trimethylarsine oxide, inorganic As, and two unknown cationic arsenic compounds. A mobile phase of 20 mM pyridinium ion, at pH 2.65, was used to perform the separation (Fig. 10.10). 

Speciation analysis for Hg in seafood was reviewed by Cairo et al. [10]. The increased use of MW-assisted extraction techniques in speciation analysis has also been discussed with regard to GC-ICP-MS [11, 12]. 

Figure 18.2 presents an overall flow chart of extraction and separation procedures that can be used to isolate, separate, and measure lipid, water-soluble, and residue-associated As species in seafoods. 

N. Ybanez, D. Velez, W. Tejedor, R. Montoro, Optimisation of the extraction, clean up and determination of arsenobetaine in manufactured seafood products by coupling liquid chromatography with inductively coupled plasma atomic emission spectrometry, J. Anal. Atom. Spectrom., 10 (1995), 459-467. 

An As extraction efficiency lower than 100 percent in the analysis of seafood or other samples is not a rare finding (see Table 19.2) and several attempts have been made to clarify the reason for this fact. The first explanation is connected with the available analytical instrumentation. Typical sample preparation methods for water-soluble As species aim at generating analytes compatible with the widely used HPLC techniques, for example, with ion-exchange columns [2], Therefore, the hardly known lipid soluble As species that may predominate are usually not extracted and analyzed. This is obviously rather serious as the relevant samples are sometimes foods consumed in large quantities, for example, freshwater fish and mussels in inland countries [34, 112, 128]. This scientific gap in As speciation has just been identified and is being worked out. 

From a practical point of view, the latter loss in speciation is less of a problem. In as much as the toxicity of As(III) and As(V) cannot be differentiated in terms of food safety reasons, their pooled concentrations can be used to assess the overall risk and the analyst can focus on the much less known As species to determine their structure and toxicity. This approach was followed by Parks et al. [133], who addressed the availability of As species from matrix components in difficult-to-extract seafood samples. TMAH was used, a highly basic compound formerly rejected for As speciation because of its incompatibility with chromatography [122], to create a three-step sequential extraction technique. TMAH was... 

N. Parks, P. A. Gallagher, C. A. Schwegel, A. H. Ackerman, J. T. Creed, The liberation of arsenosugars from matrix components in difficult to extract seafood samples utilizing TMAOH/acetic acid sequentially in a two-stage extraction process, Poster presentation at the 2003 European Winter Conference on Plasma Spectrochemistry, Garmisch-Partenkirchen, 12-17 January 2003. 

Hot water extraction is not recommended for analyses investigating the speciation of arsenic in seafood, animal tissues, or bodily fluids focused on the detection of toxic methyl derivatives of arsenic(III) acid. These derivatives are intermediate products that exhibit low stability, particularly under in vitro conditions [93-97]. 

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