Folyadékkromatográfiás hármas kvadrupol rendszerű tandem tömegspektrometriás (HPLC-MS/MS) módszerek az élelmiszervizsgálatokban: kihívások és előnyök = Challenges and advantages in food analysis based on high performance liquid chromatorgaphy triple quadrupole tandem mass spectrometry (HPLC-MS/MS)

Az Európai Unióban az Európai Bizottság 37/2010-es rendelete határozza meg az állatgyógyászati szerek maradékainak határértékét az állati eredetű élelmiszerekben. A reziduumok analízise legtöbbször folyadékkromatográfiás elválasztástechnikai megoldást igényel optikai vagy tömegspektrometriás detektálással. Az utóbbi detektálási mód mára széleskörűen elterjedt az élelmiszervizsgáló laboratóriumokban, és nagyfokú szelektivitásának köszönhetően viszonylag egyszerűen alkalmazható komplex minták mérésére. A folyadékkromatográfiás elválasztással kapcsolt tömegspektrometriás detektálás esetén gyakorlatilag a minta-előkészítést egyetlen szilárd-folyadék extrakcióra és azt követő hígításra vagy oldószercserére lehet leegyszerűsíteni, ha szűrő (screening) módszerként kívánjuk alkalmazni az eljárást. Megerősítő (konfirmációs) módszernek használva az említett kapcsolt technikát, a mintatisztítás (clean-up) nélküli eljárás már csak izotóphígításos módszerrel összekötve valósítható meg az esetek többségében. Ugyanis a viszonylagos egyszerűséggel szemben a folyadékkromatográfiás - tömegspektrometriás módszerek az interferencia nélküli mérés ellenére is alapos optimálást igényelnek mind a minta-előkészítésben, mind az azt követő műszeres analízisben, mert a célkomponensekkel ko-eluálódó és méréstechnikailag láthatatlan mátrixalkotók a meghatározások pontosságát nagymértekben befolyásolhatják. A mátrixhatások kompenzációjára mátrixból felvett, mátrix alapú kalibrációt vagy izotóphígításos módszert szoktak alkalmazni, de ezen eljárások se adnak mindig jó vagy egyáltalán elérhető megoldást, így az optikai detektálás olykor jobbnak bizonyul (pl.: tetraciklinek meghatározása). Az izotóphígításos módszerek egy különleges változata a „pontosan egyező dupla izotóphígításos módszer” (exact-matching double isotope dilution mass spectrometry), amelynek elsődleges helye van kontrolminták referencia értékeinek meghatározásában. In the Europea Union, maximum residue limits of pharmacologically active substances are determined by Commission Regulation (EU) No 37/2010. Residue analysis usually requires liquid chromatographic separation, coupled with optical or mass spectrometric detection. The latter detection method has become widespread by now in food testing laboratories and, because of its high selectivity, it can be used relatively easily for the measurement of complex samples. In the case of mass spectrometric detection coupled with liquid chromatographic separation, sample preparation can be reduced practically to a solid-liquid extraction, followed by a dilution or a solvent exchange, if the procedure is to be used as a screening method. When using the abovementioned coupled technique as a confirmation method, in most cases a procedure without clean-up can only be achieved by coupling with an isotope dilution method. This is so, because - despite their relative simplicity and despite being a measurement with no interference - liquid chromatographic-mass spectrometric methods require thorough optimization both in sample preparation and in the subsequent instrumental analysis, because the accuracy of the measurements could be greatly influenced by matrix components that are co-eluted with the target components but which are invisible to the measurement technique. To compensate for matrix effects, matrix-matched calibration or the isotope dilution method is usually used, but even these procedures do not always provide good or even available solutions, and so optical detection sometimes proves to be better (e.g. the determination of tetracyclines). A unique variation of the isotope dilution method is the exact-matching double isotope dilution mass spectrometry, which has a special place in the determination of the reference values of control samples

A LC-MS/MS confirmatory method for determination of chloramphenicol in real samples screened by competitive immunoassay

A new liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed to confirm chloramphenicol (CAP) residues in foods of animal origin and in urine samples, which were earlier found positive under the screening analysis, performed by competitive enzyme-linked immunoassay (ELISA) technique. The developed LC-MS/MS method was applied to four non-compliant samples from 2008 to 2012; giving concentrations of CAP residues from 1.18 to 3.68 μg kg−1. All samples, qualified positive by ELISA, were confirmed with the LC-MS/MS technique and found to be non-compliant. The effectiveness of the confirmatory method was proven by participating in a successful proficiency test in year 2010. Both LC-MS/MS and ELISA methods were validated according to the European Union 2002/657/EC decision. The decision limit of the confirmatory method was determined as 0.02 μg kg−1 for CAP in each validated matrix, while the detection capability of the screening test was 0.15 μg kg−1

Post-5 Ma rock deformation on Alonnisos (Greece) constrains the propagation of the North Anatolian Fault

The localization of the North Anatolian Fault in the northern Aegean Sea (North Aegean Trough) is an intriguing example of continental transform fault propagation. Understanding this process critically depends on the quantification of strike-slip displacement and the superposition of normal and strike-slip faulting in the region, which is the aim of this study. In particular, we unravel and quantify normal and dextral faulting along the Alonnisos fault system, at the south-western margin of the North Aegean Trough (Sporades Basin). We present detailed structural data collected from Messinian strata of Alonnisos to infer the amount of post-5 Ma tilting and shortening on the island, and relate them to normal and dextral faulting along the Alonnisos fault system through simple analytical half-space models of dislocations. The Messinian rocks of Alonnisos record significant (13.5°) tilting and gentle folding close to the termination zone of the main fault segment. The tilting of the Messinian rocks was related to footwall uplift during normal faulting (in the order of 6–7 km vertical displacement) along the Alonnisos fault system, which implies that the deepening of the Sporades Basin occurred post-5 Ma. The post-Messinian folding accommodated ∼1 km shortening along the footwall termination zone of the Alonnisos fault and was related to 3–4 km dextral slip, possibly during the last 100–200 kyr. This is the first clear indication of major dextral displacement along the Alonnisos fault system. Our results support interpretations of currently distributed dextral strain in the North Aegean in response to the propagation of the North Anatolian Fault. However, similarities with the evolution of the Sea of Marmara might suggest that dextral shear could yet become fully localized in the NAT

Post-5 Ma rock deformation on Alonnisos (Greece) constrains the propagation of the North Anatolian Fault

The localization of the North Anatolian Fault in the northern Aegean Sea (North Aegean Trough) is an intriguing example of continental transform fault propagation. Understanding this process critically depends on the quantification of strike-slip displacement and the superposition of normal and strike-slip faulting in the region, which is the aim of this study. In particular, we unravel and quantify normal and dextral faulting along the Alonnisos fault system, at the south-western margin of the North Aegean Trough (Sporades Basin). We present detailed structural data collected from Messinian strata of Alonnisos to infer the amount of post-5 Ma tilting and shortening on the island, and relate them to normal and dextral faulting along the Alonnisos fault system through simple analytical half-space models of dislocations. The Messinian rocks of Alonnisos record significant (13.5°) tilting and gentle folding close to the termination zone of the main fault segment. The tilting of the Messinian rocks was related to footwall uplift during normal faulting (in the order of 6–7 km vertical displacement) along the Alonnisos fault system, which implies that the deepening of the Sporades Basin occurred post-5 Ma. The post-Messinian folding accommodated ∼1 km shortening along the footwall termination zone of the Alonnisos fault and was related to 3–4 km dextral slip, possibly during the last 100–200 kyr. This is the first clear indication of major dextral displacement along the Alonnisos fault system. Our results support interpretations of currently distributed dextral strain in the North Aegean in response to the propagation of the North Anatolian Fault. However, similarities with the evolution of the Sea of Marmara might suggest that dextral shear could yet become fully localized in the NAT

Increased total scavenger capacity in rats fed corticosterone and cortisol on lipid-rich diet.

Background: In our earlier studies both corticosterone and cortisol had antioxidant effect in vitro.Objectives: Our aim was to clarify whether corticosterone and cortisol oral administration results in beneficial antioxidant changes in Sprague-Dawley adult male rats in vivo.Methods: Experimental animals were fed a lipid rich diet and treated with corticosterone or cortisol in the drinking fluid. Control group was fed only lipid rich diet with untreated drinking water. The untreated group was fed a normal diet with untreated water. Total scavenger capacity (TSC) was measured before and after 4 weeks of treatment in blood samples using a chemiluminometric assay.Results: Both corticosterone and cortisol treatment caused increased TSC. The control group and the untreated group showed no significant changes in TSC. Conclusion: Our results support the hypothesis that corticosterone and cortisol administration can improve the antioxidant status not only in vitro but also in vivo