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Alternaria
Published in Dongyou Liu, Laboratory Models for Foodborne Infections, 2017
Alicia Rodríguez, Andrea Patriarca, Mar Rodríguez, María Jesús Andrade, Juan José Córdoba
For the evaluation of mycotoxin production by Alternaria, analytical methods based on chromatography are often used for their extraction and detection from the food matrices (Figure 30.1). Usually, a solvent extraction from solid foods with organic solvents, such as dichloromethane, methanol, acetonitrile, or ethyl acetate, is required, although an acidic extraction or a further acidification step is preferable to increase the recovery for TeA.33 Cleanup procedures are necessary when a complex matrix is involved. Successive steps of solvent partitioning, solid phase extraction (SPE) columns, or solid phase microextraction are common cleanup techniques used in most food matrices.24
History and Sources of Essential Oil Research
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
In static HS analysis, the liquid or solid sample is placed into a vial, which is heated to a predetermined temperature after sealing. After the sample has reached equilibrium with its vapor (in equilibrium, the distribution of the analytes between the two phases depends on their partition coefficients at the preselected temperature, the time, and the pressure), an aliquot of the vapor phase can be withdrawn with a gas-tight syringe and subjected to gas chromatographic analysis. A simple method for the HS investigation of herbs and spices was described by Chialva et al. (1982), using a blender equipped with a special gas-tight valve. After grinding the herb and until thermodynamic equilibrium is reached, the HS sample can be withdrawn through the valve and injected into a gas chromatograph. Eight of the obtained capillary gas chromatograms are depicted in the paper of Chialva and compared with those of the respective essential oils exhibiting significant higher amounts of the more volatile oil constituents. However, one of the major problems with static HS analyses is the need for sample enrichment with regard to trace components. Therefore, a concentration step such as cryogenic trapping, liquid absorption, or adsorption on a suitable solid has to be inserted for volatiles occurring only in small amounts. A versatile and often-used technique in the last decade is solid-phase microextraction (SPME) for sampling volatiles, which will be discussed in more detail in a separate paragraph. Since different other trapping procedures are a fundamental prerequisite for dynamic HS methods, they will be considered in the succeeding text. A comprehensive treatment of the theoretical basis of static HS analysis including numerous applications has been published by Kolb and Ettre (1997, 2006).
Clinical Detection of Exposure to Chemical Warfare Agents *
Published in Brian J. Lukey, James A. Romano, Salem Harry, Chemical Warfare Agents, 2019
Benedict R. Capacio, J. Richard Smith, Robert C. diTargiani, M. Ross Pennington, Richard K. Gordon, Julian R. Haigh, John R. Barr, Brian J. Lukey, Daniel Noort
Specific biomarkers of lewisite exposure are currently based on a very limited number of in vitro experiments (Jakubowski et al., 1993; Wooten et al., 2002) and animal studies (Fidder et al., 2000; Logan et al., 1999). Wooten et al. (2002) developed a solid phase microextraction (SPME) headspace sampling method for urine samples followed by GC-MS analysis. It is the most sensitive method reported to date with an LOD of 7.4 pg/mL. Animal experiments have been limited in both number and scope. In one study of four animals, guinea pigs were given a subcutaneous dose of lewisite (0.5 mg/kg). Urine samples were analyzed for CVAA using both GC-MS and GC coupled with an atomic emission spectrometer set for elemental arsenic (Logan et al., 1999). The excretion profile indicated a very rapid elimination of CVAA in the urine. The mean concentrations detected were 3.5 μg/mL, 250 ng/mL, and 50 ng/mL for the 0 to 8 hour, 8 to16 hour, and 16 to 24 hour samples, respectively. Trace level concentrations (0 to10 ng/mL) of CVAA were detected in the urine of the 24 to 32 h and 32 to 40 h samples. The second animal study also used a subcutaneous dose of lewisite (0.25 mg/kg) given to four guinea pigs (Fidder et al., 2000). Using GC-MS, CVAA was observed in urine samples up to 12 h following exposure. In this same experiment, blood from the animals was also analyzed using CVAA for GC-MS. The amount of measured CVAA was the sum of CVAA that was displaced from hemoglobin along with free CVAA in the blood. The assay was able to detect the analyte at 10 days after the exposure, although the concentration was only 10% of that found at 24 h after exposure. Following the incubation of human blood with radiolabeled lewisite, Fidder et al. (2000) found that 90% of the radioactivity was associated with the RBCs, and 25% to 50% was found with the globin. Due to the reactive nature of CVAA, derivatization using a thiol compound has generally been applied as part of the sample preparation process (see Figure 20.6).
Evaluation of blood BTEX levels in fuel stations workers using vortex-assisted dispersive liquid-liquid microextraction based on deep eutectic solvent followed by gas chromatography flame-ionization detector
Published in Toxin Reviews, 2023
Mari Ataee, Toraj Ahmadi Jouybari, Hawre Lateef Ahmed, Hadi Ahmadi Jouybari, Meghdad Pirsaheb, Nazir Fattahi
Sample preparation play an important role in purifying matrix interference and enrichment of target analytes prior to HPLC analysis. Therefore, an efficient and effective extraction step is necessary to obtain the highest accuracy in the determination of small amounts of BTEX compounds in blood samples. Liquid–liquid extraction (LLE) (Yu et al. 2022), solid phase extraction (SPE) (Raza et al. 2018), solid-phase microextraction (SPME) (Fustinoni et al. 1999), liquid-phase microextraction (LPME) (Sarafraz-Yazdi et al. 2008), and dispersive liquid–liquid microextraction (DLLME) (Assadi et al. 2010) are widely used in the extraction of BTEX in various samples. Recently, the synthesis of green, environmentally friendly, and inexpensive solvents called deep eutectic solvents (DESs) have attracted much attention in the field of green chemistry. DES includes hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD), which are bound by hydrogen bonding at suitable temperatures and specific proportions (Malaeke et al. 2018, Ahmadi-Jouibari et al. 2021, Fattahi et al. 2022a). A simple synthesis process and good biocompatibility are other advantages of DES compared to ionic liquids and toxic organic solvents. Until now, these solvents have been used for the extraction and preconcentration of various organic and inorganic compounds (Ataee et al. 2020, Nemati et al. 2022).
Identification of odor biomarkers in irradiation injury urine based on headspace SPME-GC-MS
Published in International Journal of Radiation Biology, 2021
Xin Wu, Tong Zhu, Hongbing Zhang, Lu Lu, Xin He, Changxiao Liu, Sai-jun Fan
Urine is stable, easy to collect and noninvasive, and it is widely used in clinical practice. However, due to low concentrations and various interferences including water, the analysis of VOCs is restricted, so it is very important to enrich the sample. Solid phase microextraction (SPME) has high extraction efficiency, a high pre-concentration factor and is easily automated (Ghorbani et al. 2019; Jalili et al. 2020). These advantages make it very popular, especially in combination with gas chromatography-mass spectrometry (GC-MS) with high resolution and high sensitivity, which greatly promotes the analysis of VOCs in urine. Nowadays, metabolomics based on SPME-GC-MS has been used for urine VOCs analysis of many diseases, such as cancer, autism and gastrointestinal diseases (Cozzolino et al. 2014; Gundamaraju et al. 2017; Deev et al. 2020).
Liquid chromatography coupled to mass spectrometry for metabolite profiling in the field of drug discovery
Published in Expert Opinion on Drug Discovery, 2019
Javier Saurina, Sonia Sentellas
As a further step, extraction techniques can be applied to recover the desired metabolites without unwanted interferences. Liquid extraction with organic solvents and hydro-organic mixtures has been widely used, in which the affinity of drug metabolites towards the extraction solvents is the basis to obtain high recoveries. Solid phase extraction (SPE) offers great analytical possibilities in metabolite profiling because of its versatility. A great variety of (ad/ab)sorbents are commercially available which can be chosen depending on the characteristics of metabolites and matrices. In this regard, the same kind of mechanisms taking place in the chromatographic separation (see below) can be exploited here for cleanup and preconcentration purposes. As a miniaturized version, solid phase microextraction (SPME), based on the retention and concentration of analytes on absorbent fibers of a wide range of materials, have also been introduced for the treatment of biological samples [28].