Identification of new transformation products during enzymatic treatment of tetracycline and erythromycin antibiotics at laboratory scale by an on-line turbulent flow liquid-chromatography coupled to a high resolution mass spectrometer LTQ-Orbitrap

This work describes the formation of transformation products (TPs) by the enzymatic degradation at laboratory scale of two highly consumed antibiotics: tetracycline (Tc) and erythromycin (ERY). The analysis of the samples was carried out by a fast and simple method based on the novel configuration of the on-line turbulent flow system coupled to a hybrid linear ion trap – high resolution mass spectrometer. The method was optimized and validated for the complete analysis of ERY, Tc and their transformation products within 10 min without any other sample manipulation. Furthermore, the applicability of the on-line procedure was evaluated for 25 additional antibiotics, covering a wide range of chemical classes in different environmental waters with satisfactory quality parameters. Degradation rates obtained for Tc by laccase enzyme and ERY by EreB esterase enzyme without the presence of mediators were ∼78% and ∼50%, respectively. Concerning the identification of TPs, three suspected compounds for Tc and five of ERY have been proposed. In the case of Tc, the tentative molecular formulas with errors mass within 2 ppm have been based on the hypothesis of dehydroxylation, (bi)demethylation and oxidation of the rings A and C as major reactions. In contrast, the major TP detected for ERY has been identified as the “dehydration ERY-A”, with the same molecular formula of its parent compound. In addition, the evaluation of the antibiotic activity of the samples along the enzymatic treatments showed a decrease around 100% in both cases

Identification of metabolites and thermal transformation products of quinolones in raw cow milk by liquid chromatography coupled to high resolution mass spectrometry

The presence of residues of antibiotics, metabolites, and thermal transformation products (TPs), produced during thermal treatment to eliminate pathogenic microorganisms in milk, could represent a risk for people. Cow"s milk samples spiked with enrofloxacin (ENR), ciprofloxacin (CIP), difloxacin (DIF), and sarafloxacin (SAR) and milk samples from cows medicated with ENR were submitted to several thermal treatments. The milk samples were analyzed by liquid chromatography-mass spectrometry (LC-MS) to find and identify TPs and metabolites. In this work, 27 TPs of 4 quinolones and 24 metabolites of ENR were found. Some of these compounds had been reported previously, but others were characterized for the first time, including lactose-conjugated CIP, the formamidation reaction for CIP and SAR, and hydroxylation or ketone formation to produce three different isomers for all quinolones studied.

Heterogeneous products and tests for an appropriate aggregation level considering different qualities: evidence from fresh hake at Barcelona’s wholesale market

[cat] Aquest estudi destaca la importància de considerar un nivell d’agregació adequat en els anàlisis de demanda, ja que treballar utilitzant un nivell d’agregació inadequat pot donar lloc a estimacions esbiaixades. Aquest fet es mostra a través de l’anàlisi de diferents productes de lluç fresc comercialitzats a Mercabarna, el mercat majorista de Barcelona. La literatura sobre la demanda de peix tracta al lluç com un únic producte i espècie. No obstant això, en el mercat espanyol, es comercialitzen molts peixos com a lluç, els quals mostren comportaments molt diferents (des de béns inferiors fins a béns de luxe). Els resultats obtinguts, en concordança amb les observacions empíriques, demostren que l’anàlisi s’ha de realitzar amb un major grau de detall que a nivell d’espècie. Això qüestiona els resultats d’anteriors estudis de demanda i la majoria de les bases de dades, on l’observació del nivell d’agregació adequat dels productes no es té en compte.

Heterogeneous products and tests for an appropriate aggregation level considering different qualities: evidence from fresh hake at Barcelona’s wholesale market

[cat] Aquest estudi destaca la importància de considerar un nivell d’agregació adequat en els anàlisis de demanda, ja que treballar utilitzant un nivell d’agregació inadequat pot donar lloc a estimacions esbiaixades. Aquest fet es mostra a través de l’anàlisi de diferents productes de lluç fresc comercialitzats a Mercabarna, el mercat majorista de Barcelona. La literatura sobre la demanda de peix tracta al lluç com un únic producte i espècie. No obstant això, en el mercat espanyol, es comercialitzen molts peixos com a lluç, els quals mostren comportaments molt diferents (des de béns inferiors fins a béns de luxe). Els resultats obtinguts, en concordança amb les observacions empíriques, demostren que l’anàlisi s’ha de realitzar amb un major grau de detall que a nivell d’espècie. Això qüestiona els resultats d’anteriors estudis de demanda i la majoria de les bases de dades, on l’observació del nivell d’agregació adequat dels productes no es té en compte.

Identification of metabolites and thermal transformation products of quinolones in raw cow milk by liquid chromatography coupled to high resolution mass spectrometry.

The presence of residues of antibiotics, metabolites, and thermal transformation products (TPs), produced during thermal treatment to eliminate pathogenic microorganisms in milk, could represent a risk for people. Cow"s milk samples spiked with enrofloxacin (ENR), ciprofloxacin (CIP), difloxacin (DIF), and sarafloxacin (SAR) and milk samples from cows medicated with ENR were submitted to several thermal treatments. The milk samples were analyzed by liquid chromatography-mass spectrometry (LC-MS) to find and identify TPs and metabolites. In this work, 27 TPs of 4 quinolones and 24 metabolites of ENR were found. Some of these compounds had been reported previously, but others were characterized for the first time, including lactose-conjugated CIP, the formamidation reaction for CIP and SAR, and hydroxylation or ketone formation to produce three different isomers for all quinolones studied.

The impact of FTAs on MENA trade in agricultural and industrial products

This paper analyses the impact of Free Trade Agreements (FTAs) on Middle East and North African Countries (MENA) trade for the period 1994-2010. The analysis distinguishes between industrial and agricultural trade to take into account the different liberalisation schedules. An augmented gravity model is estimated using up-to-date panel data techniques to control for all time-invariant bilateral factors that influence bilateral trade as well as for the so-called multilateral resistance factors. We also control for the endogeneity of the agreements and test for self-selection bias due to the presence of zero trade in our sample. The main findings indicate that North-South-FTAs and South-South- FTAs have a differential impact in terms of increasing trade in MENA countries, with the former being more beneficial in terms of exports for MENA countries, but both showing greater global market integration. We also find that FTAs that include agricultural products, in which MENA countries have a clear comparative advantage, have more favourable effects for these countries than those only including industrial products. JEL code: F10, F15