F. J. Arrebola

Reduction of analysis time in gas chromatography. Application of low-pressure gas chromatography-tandem mass spectrometry to the determination of pesticide residues in vegetables

An alternative to conventional capillary gas chromatography (GC) is evaluated as a new approach to determine pesticide residues in vegetables. Low-pressure gas chromatography-tandem mass spectrometry (LP-GC-MS-MS) is proposed after a fast and simple extraction of the vegetable samples with dichloromethane and without clean up. The use of the above-mentioned GC technique reduced the total time required to determine 72 pesticides to less than half the present time (31 min), increasing the capability of a monitoring routine laboratory. The use of guard column and plug of carbofrit into the glass liner in combination with LP-GC was evaluated. The method was validated with limits of quantitation low enough to determine the pesticide residues at concentrations below the maximum residue levels stated by legislation. In order to assess its applicability to the analysis of real samples, 25 vegetable samples previously determined using conventional-capillary GC-MS-MS were analysed by LP-GC-MS-MS. The results obtained with the compared techniques showed differences lower than 0.01 mg kg(-1).

Determination of 81 multiclass pesticides in fresh foodstuffs by a single injection analysis using gas chromatography-chemical ionization and electron ionization tandem mass spectrometry

A new analytical method has been proposed to determine 81 multiclass pesticide residues in vegetables. It is based on a fast extraction of the pesticides with dichloromethane and a further analysis of the extract by gas chromatography–tandem mass spectrometry (GC–MS–MS). For that, a single injection of the extract is carried out using the optimum ionization mode (electron ionization (EI) or chemical ionization (CI)) for each pesticide. The presented method reduces the total time of analysis with respect to those which propose two different injections in order to analyze such number of pesticides, being more suitable for its usage in routine laboratories. The method was validated in order to be applied to real samples. Recoveries in cucumber at two different fortification levels were evaluated and ranged between 73% and 108% for all pesticides. The relative standard deviation (R.S.D.%) was lower than 22% in all cases. The calculated limits of detection (LOD) and quantification (LOQ) were lower than the maximum residue levels established by European legislations. Inter-day recoveries and precision were evaluated too. The method has been successfully applied to the analysis of approximately 4000 real samples from El

Pesticide Residue Analysis in Waters by Solid‐Phase Microextraction Coupled to Gas Chromatography‐Tandem Mass Spectrometry

ABSTRACT A new analytical method is proposed for determining 34 multi‐class pesticides in drinking and natural (ground, surface and sea) waters. The method combines the advantages of solid‐phase microextraction (SPME) and gas chromatography‐tandem mass spectrometry (GC‐MS‐MS). Polydimethylsiloxane (PDMS) and polydimethylsiloxane/divinylbenzene (PDMS/DVB) stationary phases were evaluated and the optimization of the main extraction parameters was carried out in order to improve sensitivity and selectivity. That is the case of the influence of agitation, adsorption and desorption times, desorption temperature, addition of electrolytes, and pH of the sample. Performance characteristics of the analytical method were evaluated in order to validate the proposed methodology. Quantification limits were lower than 35.5 ng L−1 in all cases and therefore, the method can be applied for determining the target pesticides in drinking waters at concentrations below the levels allowed by EU and US legislation (100 ng L−1). The calibration was performed between 50 and 500 ng L−1 using linear or polynomial mathematical functions. Recovery rates (between 80.7% and 110.0% in all cases), and precision (<15.2% in all cases, expressed as relative standard deviation) were studied too. The method was applied to the analysis of natural and drinking water samples from the south‐east of Spain, an intensive agricultural area. Pesticides most detected were endosulfan and lindane at concentrations that, in general, were lower than 100 ng L−1.

Screening Method for the Determination at Parts Per Trillion Levels of Pesticide Residues in Vegetables Combining Solid‐Phase Microextraction and Gas Chromatography‐Tandem Mass Spectrometry

Abstract A new analytical method is proposed for determining residues of 70 pesticides of different chemical families at parts per trillion levels in fresh vegetables. For that, only 4 g of the vegetable samples were quickly extracted with 10 ml of ethyl acetate. The method is based on a vanguard/rearguard strategy that reduces the average time required per sample when the method is applied to a high number of vegetable samples in a quality control laboratory. At the beginning, an aliquot of the extract is evaporated and re‐dissolved in a mixture water:acetone (9∶1 v/v). For screening purposes, the pesticides were extracted for only 10 min by direct immersion of a solid‐phase microextraction (SPME) fiber (65 µm polydimethylsiloxane‐divinylbenzene, PDMS‐DVB). The SPME device was automated and on‐line coupled to a gas chromatograph with an ion trap mass spectrometer (GC‐MS) operated in full scan mode for screening in less than 18 min those samples that potentially contain pesticides above 0.01 mg kg−1 (cut off value). After that, only those potentially non‐negative samples were reanalyzed by a sensitive quantifying/confirming method that re‐extract by SPME the pesticides in 55 min of absorption and determine them by GC with tandem MS (MS/MS). The method has been validated following EU guidelines and compared with a conventional extraction method based on the use of higher amounts of organic solvents. The limits of detection (LOD), confirmation (LOC) and quantitation (LOQ) as well as the calibration curves obtained allowed the determination of the target pesticides at concentrations clearly below the maximum residue levels (MRL) stated by EU being possible the determination of parts per trillion of the pesticides in ecological (green) vegetables. The method has been applied to the analysis of real samples and the results compared with those obtained by a conventional extraction method accredited by ENAC (Spanish Accreditation Body). The proposed method was also evaluated participating in a proficiency test with adequate results (z‐score among±2).

Artificial insemination in Payoya goats: factors affecting fertility

The present study was conducted to determine the effect of different factors on pregnancy rate after artificial insemination (AI) with refrigerated and frozen semen in Payoya goats reared under commercial farm conditions. A total of 820goats,belongingto10farms,wasused.Thetotalnumberofstudiedinseminationswas1384overa4-yearperiod.Factors considered in the study were year, farm, month of AI, age of the goat at AI, dose of progestagen, eCG dose, buck, type of semen (refrigerated or frozen), technician, number of goats to be inseminated (group size), incidences at AI (problems, no problems, trans-cervical insemination), distance from semen collection to farm, number of previous kidding, kidding-AI interval,andmilkproduction.Thevariablestudiedwasfertility,expressedassuccessfulkidding.Meanfertilitywas59%.Six (farm, age, group size, transcervical AI, number of kidding and milk production) of the 15 factors studied presented a significant(P <0.05)effectonfertilityafterAI.Ourresultsdemonstratedthatitisdifficulttocontrolallthecriticalaspectsof AI programs at the farm level. These factors should be controlled and the variations that could compromise the chance of beingpregnantmustbeknownbytechnicians.Thegoodfertilityresultsobtainedduringthenon-breedingseasonemphasise the implementation of this technique so as to improve the competitiveness of the dairy Payoya breed flocks.

Solid phase microextraction and gas chromatography coupled to magnetic sector high resolution mass spectrometry for the ultra-trace determination of contaminants in surface water

With the aim of monitoring water quality according to the regulations established by the European Union it would be necessary to implement analytical methodologies capable of simultaneously determining a broad range of organic pollutants at ultra-trace levels, allowing for increased sample throughput. In addition, the high number of samples to be analyzed requires a particular focus on setting up fully automated analytical methodologies. In view of that, this study is aimed at the development of a complete automated procedure for the ultra-trace determination of certain pesticides, polycyclic aromatic hydrocarbons (PAHs), brominated diphenyl ethers (BDEs) and polychlorinated biphenyls (PCBs) in surface waters. The proposed method is based on an on-line combination of solid phase microextraction (SPME) and gas chromatography coupled to double-focusing magnetic sector high resolution mass spectrometry (GC-HRMS). SPME as well as GC-HRMS conditions were optimized to achieve maximum extraction efficiency and sensitivity, which was reinforced by using multiple ion detection (MID) as acquisition mode. Using only 19mL of water and with minimum sample manipulation, the method allowed for the determination of 53 compounds exhibiting good linearity (R2>0.99), recoveries between 84 and 118% and relative standard deviation (RSD) values <20% for intra-day and inter-day precision. In addition, the method provides quantification limits (LOQs) between 0.1-50ngL-1, lower than the Environmental Quality Standards (EQS) fixed by Directive 2013/39/EC. Finally, the method was successfully applied to determine target contaminants in Almería surface water compartments, detecting dioxin-like PCBs, BDEs and some pesticides.

Offspring sex ratio in sheep, cattle, goats and pigs: influence of season and lunar phase at conception

Abstract This study assessed the relationship between season and lunar phase at conception on offspring sex ratio of four livestock species (sheep, cattle, goats and pigs). The sex of 66,830 lambs (1995–2015); 25,546 calves (2011–2015); 5671 kids (2002–2007) and 1916 piglets was recorded. Moon phases were categorized as either new moon, crescent moon, full moon or decrescent moon. Sex ratio, expressed as proportion of males (males/males + females), was tested against the expected value of 1:1. In sheep, offspring sex ratio and lunar phase were not correlated; season had a significant (p = 0.002) effect on offspring sex ratio. The proportion of males born of spring and winter matings was significantly higher than it was among offspring born of summer (p < 0.05) or autumn (p < 0.01) conceptions. Offspring sex ratios in spring (p < 0.05), autumn (p < 0.01) and winter (p < 0.05) differed significantly from the expected. In cattle, moon phase and season did not affect the offspring sex ratio; however, the interaction effect was highly significant (p = 0.001). The overall piglet sex ratio (0.522), and the sex ratios among piglets conceived during a crescent moon and those conceived in summer differed significantly (p < 0.05) from 1:1. Research including additional factors such as hormonal treatments prior to insemination, food availability, weather and maternal and paternal factors might provide the underlying reasons for the effects of season and moon phase on offspring sex ratio in some livestock species.

Management and meteorological factors affect fertility after artificial insemination in Murciano-Granadina goats

Over 6 years, 2004 artificial inseminations (AI) were documented from 13 goat farms. We quantified the effect on fertility rate of management factors (farm, year, month, timing and order of insemination, dose of progestagen, prostaglandin, equine chorionic gonadotrophin and prostaglandin doses, age, technician, problems at AI, body condition and buck) and meteorological conditions at AI (mean, maximum and minimum temperatures, mean relative humidity, mean solar radiation, and total rainfall). Meteorological variables were converted to categorical variables to quartiles and deciles. Overall fertility was 56%. Each of the management factors had a significant (P < 0.05) effect on fertility. Non-pregnant goats differed significantly in most of the meteorological variables. Successful inseminations were associated with significantly (P < 0.001) higher mean, maximum and minimum temperatures, and solar radiation, and lower relative humidity, and rainfall, than were failed inseminations. Fertility rates of the highest and lowest deciles were significantly different for each of the meteorological variables. Inseminations performed when meteorological values were in the highest decile of mean (62%), maximum (61%) and minimum temperature (60%), and solar radiation (59%), and the lowest of relative humidity (61%) and rainfall (57%) had a significantly (P < 0.0001) higher proportion of does that became pregnant than when meteorological values were within the opposite decile (47%; 34%; 55%; 46%; 45%, and 43%, respectively). In conclusion, management and meteorological factors affected the success of AI in goats. Although technical factors can be controlled, it remains to be determined whether scheduling the dates of insemination based on forecasted temperatures can improve the success of AI.

Effects of season and artificial photoperiod on semen and seminal plasma characteristics in bucks of two goat breeds maintained in a semen collection center

Aim: This study quantified the effects of season and photoperiodic treatment on semen and seminal plasma (SP) characteristics in 12 bucks of two Spanish goat breeds (Murciano-Granadina, and Payoya) for the past 1 year. Materials and Methods: A total of 6 bucks (three of each breed) were exposed to the natural day length and the other six males (three of each breed) were exposed to alternating conditions of 2 months of long days (16 h light) and 2 months of short days (8 h light). Weekly concentrations of glutamic oxaloacetic transaminase/aspartate aminotransferase (GOT/AST), lactate dehydrogenase (LDH), potassium, testosterone, and protein in SP were measured. Reaction time and scrotal circumference were recorded, and plasma testosterone concentrations were measured before semen collection. Results: Sperm volume, LDH, and potassium concentration in SP, and reaction time did not differ significantly between breeds, seasons, and photoperiodic treatment. Sperm concentrations were higher (p<0.001) in spring and summer than they were in autumn and winter. Mean percentage of positive hypo-osmotic swelling test sperm was the highest in summer and under the artificial photoperiod (p<0.01). GOT/AST concentrations differed (p<0.01) between breeds and seasons. Breed, season, and photoperiod had significant (p<0.001) effects on protein and testosterone levels in SP. Plasma testosterone concentrations were highest in summer (p<0.001), and differed significantly (p<0.01) between breeds. Scrotal perimeter differed significantly (p<0.001) between breeds and photoperiod. Conclusion: Recognition of those seasonal and breed-specific differences in the performance of bucks should help to improve the management of individual semen samples for use in artificial insemination programs.