1,721,012 research outputs found
Ochratoxin A detection in foods: state-of-the-art and analytical challenges
No full textOchratoxin A (OTA) can occur in a large variety
of commodities (cereals, beans, groundnuts, spices, dried
fruits, coffee, beer, wine) and, because of a carry-over effect,
in milk, pig blood, liver, and kidney, and poultry
meat from animals fed with contaminated feed. Because
of the persistence of OTA in the food chain, exposure to
the compound is a potential human health hazard. This
has prompted adoption of regulatory limits in several
countries which, in turn, implies the development of suitable
validated and official analytical methods and rapid
screening tests for cost-effective food control on a large
scale. Liquid chromatography with fluorescence detection
(LC–FLD), coupled with immunoaffinity column (IAC)
clean-up, is the most widely employed analytical technique.
LC coupled with electrospray-ionization mass spectrometry
(MS) has detection limits comparable with those of LC–
FLD and the selectivity of IAC can be achieved by tandem
(MS–MS) or sequential (MSn) detection. Synthetic
counterparts to natural antibodies in the form of molecularly
imprinted polymers seem a promising alternative to
IAC for sample preparation. New analytical approaches to
rapid, low-cost screening methods, for example those
based on biosensors and dip-stick-like kits, are a direction
in which innovation can be expected. Analytical methods
for evaluation of the occurrence of OTA in foods, human
exposure, and risk assessment are critically reviewed
Determination of ochratoxin A in pig tissue by liquid-liquid extraction/partition and high performance liquid chromatography
No full textA fast, simple, and sensitive HPLC–FD method
is described for determination of ochratoxin A (OTA) in
pig kidney and muscle; a small mass (<2.5 g) of sample
and a relatively small volume (<15 mL) of a non-halogenated
extraction solvent are required. Ochratoxin B,
systematically absent from all the samples investigated,
was used as internal standard. Liquid–liquid partition was
used for sample clean-up. Recoveries at the 1 ng g–1 level
were 86±15% and 74±8% for kidney and muscle, respectively,
and detection limits were 0.14 and 0.15 ng g–1.
Clean-up by solid-phase extraction (SPE) is required for
pig liver. A survey of the OTA content of tissues of pigs
slaughtered in southern Italy revealed that 52 out of
54 analysed samples were contaminated; the OTA concentration
in kidney ranged between 0.26 and 3.05 ng g–1.
The effect of measurement precision on compliance with
legal limits is also discussed
Determination of delorazepam in urine by solid phase microextraction coupled to high performance liquid chromatography
No full textAn SPME–HPLC–UV method for the determination of delorazepam, a representative benzodiazepine, in spiked
human urine samples was developed for the first time. The performances of two commercially available fibers, a
carbowax/templated resin (Carbowax/TPR-100) and a polydimethylsiloxane/divinylbenzene (PDMS/DVB), were
compared, indicating the latter as the most suitable for urine samples analysis. All the aspects influencing adsorption
(extraction time, pH, temperature, salt addition) and desorption (desorption and injection time, desorption solvent
mixture composition) of the analyte on the fiber have been investigated. In particular, short extraction times were
necessary to reach the equilibrium and very short desorption times were employed. The procedure required simple
sample pre-treatment and was able to detect 5 ng/ml in spiked urine, regardless of the complexity of the matrix.
© 2002 Elsevier Science B.V. All rights reserved
Solid-phase microextraction-high performance liquid chromatography and diode array detection for the determination of mycophenolic acid in cheese
No full textSPME, using a carbowax/templated resin fiber, interfaced with HPLC–UV/DAD has been optimized for the determination of the
mycotoxin mycophenolic acid (MPA) in cheese samples. All the parameters influencing the efficiency of the analyte extraction and
desorption have been carefully explored. The procedure has been applied to the analysis of blue-cheese samples such as Gorgonzola
and Danablu. Samples were subjected to a preliminary short sonication in bicarbonate buffer (0.2 M, pH 9.7); the subsequent
SPME was capable of a selective extraction of MPA, characterized by high recovery yields and detection limits of 50 and 100 ppb
for Danablu and Gorgonzola, respectively. The present method is faster and simpler than any other existing method for the
extraction of MPA from cheese and does not involve the use of toxic organic solvents
A Disposable Amperometric Biosensor for Measuring the Anticholinesterase Activity in Soil Extracts
No full textAllelic variation of gliadin-encoding genes in a collection of tetraploid wheat genotypes
Full text linkWheat is one of the main crops bred worldwide. Durum wheat, specifically, is a key element of the Mediterranean diet, representing an élite crop grown in Italy. Durum wheat nutritional and technological values are largely due to the grain protein content (GPC), a complex genetic trait strongly affected by environmental factors and management practices. In the last decades, several breeding programs have been focused on improving GPC by both traditional and innovative approaches. Among seed storage proteins, prolamins, including both gliadins and glutenins, represent the major component. These two classes of proteins are indeed responsible of gluten formation and confer the extensibility and elasticity to the dough. Besides being of crucial importance for both technological properties and rheological characteristics, prolamins, and especially gliadins, have been found to be major triggers for human health, as involved in a number of wheat consumption-related conditions, such as the celiac disease, non-celiac gluten sensitivity, defined as the onset of a variety of manifestations related to wheat, rye and barley ingestion, and wheat allergies, both due to wheat ingestion or inhalation (of flour or pollen). The identification of loci responsible for the gliadin expression, and particularly of polymorphism in the aforementioned genes, which could result in a lower immunogenic/toxic potential, could be of great importance in breeding programs. For this purpose, we screened a collection of tetraploid wheat genotypes for allelic variants of annotated gliadin genes in the durum wheat genome, in order to identify genetic resources available to breeders to improve wheat nutritional and technological properties. Phylogenetic analysis among different species of Triticum genus and an in silico expression data analysis may also be useful in the exploitation of the complex scenario of gliadin–glutenin interaction and gluten role in the adverse reactions due to wheat consumption
Cromatografia a scambio ionico per la determinazione di acido micofenolico in estratti fungini
No full textDetermination of ochratoxin A in meat products by higt-permormance liquid chromatography coupled to electrospray ionisation sequential mass spectrometry
No full textA method based on liquid chromatography with electrospray ionisation ion trap mass spectrometry,
for the determination of ochratoxin A (OTA) in meat products using ochratoxin B (OTB) as an
internal standard, is described. Fragmentation patterns of OTA and OTB were studied by sequential
mass spectrometry. Trace determination was then accomplished by consecutive reaction monitoring
(CRM) of a fragment obtained by MS3 experiments. This led to a better signal-to-noise ratio
and to a higher specificity of the technique. The response to OTA was linear over at least one concentration
decade with a limit of detection of 0.6 ng/g. The method was applied to pig tissue samples
naturally contaminated by OTA
Evaluation of the thermal history of bovine milk from the lactosylation of whey proteins: an investigation by liquid chromatography–electrospray ionization mass spectrometry
No full textReversed-phase high-performance liquid chromatography
coupled to electrospray ionization mass spectrometry
(RP-HPLC–ESI-MS) has been used for analysis of the
native and lactosylated forms of the main whey proteins, á-
lactalbumin and â-lactoglobulins A and B, in commercial
bovine milk samples after different thermal treatment (pasteurisation
and ultra high-temperature, UHT, treatment), of
different lipid content, and of different brands, to find markers
of the thermal history of the milk. A new quantification
strategy was developed, based on peak-area integration after
multiple ion current extraction and considering all the ions
detectable in the multi-charge ESI mass spectrum for each
type of protein. Validation of the procedure for native forms
was first accomplished by calibration with model solutions.
Linearity was always good. Sensitivity was different for á-
lactalbumin and â-lactoglobulins; the signal was stronger for
the latter with only a slight difference between variants A and
B of â-lactoglobulins. Application of the quantification
approach to pasteurised and UHT milk samples showed that
the distributions of the three proteins and of their three main
forms (native, and mono and bi-lactosylated) in whey extracts
can be used as statistically robust discriminatory properties for
recognition of commercial thermal treatment of milk
Reliable Detection of Milk Allergens in Food Using a High-Resolution, Stand-Alone Mass Spectrometer
No full textReliable methods are needed for detection of
allergenic milk proteins in complex food matrixes.
The feasibility of an LC/high-resolution MS method
for the analysis of milk proteins in a thermally
processed model food (incurred cookies) and in
white wine spiked, respectively, with milk powder
and caseinate is described. Detection of milk
proteins was based on the identification of unique
peptides in the tryptic digests of cookie/wine
extracts using an RP-HPLC separation coupled to
an ExactiveTM nonhybrid mass spectrometer using
Orbitrap technology. The extremely high mass
accuracy and resolution provided by the Orbitrap
analyzer allowed a fast preliminary identification of
four previously proposed peptide markers of
caseins using only accurate values of the m/z of
their ions. No interference was observed, despite
the complexity of the analyzed matrixes. Moreover,
the availability of a high- energy, collisionally
activated dissociation cell integrated in the mass
spectrometer enabled acquisition of peptide
MS/MS-like spectra through post-source
fragmentation. Confirmation of peptide marker
identity could then be achieved by a comparison
between experimental and predicted product ions.
The described method shows the great potential of
Orbitrap MS as a reliable technique in the field of
protein allergen detection once the peptide
markers are identified
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