[Validity and usefulness of the RAE-CMBD studying patients hospitalised with influenza]. / Validez y utilidad del RAE-CMBD en el estudio de los pacientes hospitalizados con gripe.

OBJECTIVE: Understanding the hospital impact of influenza requires enriching epidemiological surveillance registries with other sources of information. The aim of this study was to determine the validity of the Hospital Care Activity Record - Minimum Basic Data Set (RAE-CMBD) in the analysis of the outcomes of patients hospitalised with this infection. METHODS: Observational and retrospective study of adults admitted with influenza in a tertiary hospital during the 2017/2018 and 2018/2019 seasons. We calculated the concordance of the RAE-CMBD with the influenza epidemiological surveillance registry (gold standard), as well as the main parameters of internal and external validity. Logistic regression models were used for risk adjustment of in-hospital mortality and length of stay. RESULTS: A total of 907 (97.74%) unique matches were achieved, with high inter-observer agreement (ƙ=0.828). The RAE-CMBD showed a 79.87% sensitivity, 99.72% specificity, 86.71% positive predictive value and 99.54% negative predictive value. The risk-adjusted mortality ratio of patients with influenza was lower than that of patients without influenza: 0.667 (0.53-0.82) vs. 1.008 (0.98-1.04) and the risk-adjusted length of stay ratio was higher: 1.15 (1.12-1.18) vs. 1.00 (0.996-1.001). CONCLUSIONS: The RAE-CMBD is a valid source of information for the study of the impact of influenza on hospital care. The lower risk-adjusted mortality of patients admitted with influenza compared to other inpatients seems to point to the effectiveness of the main clinical and organisational measures adopted.

Disección coronaria espontánea en España: un estudio sobre bases administrativas realizado a partir del Conjunto Mínimo Básico de Datos español / Spontaneous coronary artery dissection in Spain: a study using the minimum data set of the Spanish National Health System

Introducción y objetivos La disección coronaria espontánea (DCE) es una causa poco común de infarto agudo de miocardio (IAM). En este estudio se comparan la mortalidad y los reingresos hospitalarios de los pacientes con IAM-DCE e IAM de otras etiologías (IAM-NDCE). Métodos Se calcularon las razones de mortalidad hospitalaria y de reingresos a los 30 días estandarizadas por riesgo (RAMER y RARER respectivamente) utilizando el Conjunto Mínimo Básico de Datos del Sistema Nacional de Salud español (2016-2019). Resultados Se hallaron 806 eventos de IAM-DCE y 119.425 de IMA-NDCE. Los IAM-DCE se produjeron en pacientes más jóvenes y más frecuentemente mujeres que los IAM-NDCE. La mortalidad bruta fue menor (el 3 frente al 7,6%; p<0,001) y la RAMER, mayor (el 7,6±1,7 frente al 7,4±1,7%; p=0,019) en los IAM-DCE. Tras emparejamiento por puntuación de propensión (806 parejas), la mortalidad fue similar en ambos grupos (AdjOR=1,15; IC95%, 0,61-2,2; p=0,653). La tasa bruta de reingresos de los pacientes con IAM-DCE a 30 días fue similar (el 4,6 frente al 5%; p=0,67), mientras que la RARER fue menor (el 4,7±1 frente al 4,8±1%; p=0,015). Tras el emparejamiento por puntuación de propensión (715 parejas), la tasa de ingresos fue similar en ambos grupos (AdjOR=1,14; IC95%, 0,67-1,98; p=0,603). Conclusiones La mortalidad hospitalaria y los reingresos a los 30 días de los pacientes con IAM-DCE es similar a la de los IAM-NDCE cuando el riesgo se ajusta a las características basales de la población. Estos datos resaltan la necesidad de optimizar el manejo, tratamiento y seguimiento clínico de los pacientes con DCE (AU)

Introduction and objectives Spontaneous coronary artery dissection (SCAD) is a rare cause of acute myocardial infarction (AMI). We sought to compare the results on in-hospital mortality and 30-day readmission rates among patients with AMI-SCAD vs AMI due to other causes (AMI-non-SCAD). Methods Risk-standardized in-hospital mortality (rIMR) and risk-standardized 30-day readmission ratios (rRAR) were calculated using the minimum dataset of the Spanish National Health System (2016-2019). Results A total of 806 episodes of AMI-SCAD were compared with 119 425 episodes of AMI–non-SCAD. Patients with AMI-SCAD were younger and more frequently female than those with AMI–non-SCAD. Crude in-hospital mortality was lower (3% vs 7.6%; P<.001) and rIMR higher (7.6±1.7% vs 7.4±1.7%; P=.019) in AMI-SCAD. However, after propensity score adjustment (806 pairs), the mortality rate was similar in the 2 groups (AdjOR, 1.15; 95%CI, 0.61-2,2; P=.653). Crude 30-day readmission rates were also similar in the 2 groups (4.6% vs 5%, P=.67) whereas rRAR were lower (4.7±1% vs 4.8%±1%; P=.015) in patients with AMI-SCAD. Again, after propensity score adjustment (715 pairs) readmission rates were similar in the 2 groups (AdjOR, 1.14; 95%CI, 0.67–1.98; P=.603). Conclusions In-hospital mortality and readmission rates are similar in patients with AMI-SCAD and AMI–non-SCAD when adjusted for the differences in baseline characteristics. These findings underscore the need to optimize the management, treatment, and clinical follow-up of patients with SCAD (AU)

[What about the weekend effect? Impact of the day of admission on in-hospital mortality, length of stay and cost of hospitalization]. / ¿Qué hay del efecto fin de semana? Impacto del día de ingreso sobre la mortalidad intrahospitalaria, la duración de la estancia y el coste de la hospitalización.

INTRODUCTION: There is no agreement on the existence of the weekend effect in healthcare or, if it exists, on its possible causes. The objective of the study was to evaluate the differences in healthcare outcomes between patients admitted on weekdays or weekends in a high-complexity hospital. METHODS: Observational and retrospective study of patients admitted between 2016 and 2019 in a public hospital with more than 1300 beds. Hospitalization episodes were classified according to whether admission took place between Friday at 3:00 p.m. and the following Monday at 8:00 a.m. (weekend admission) or not (admission on weekdays). Mortality, length of stay and associated costs were compared, applying their respective risk-adjustment models. RESULTS: Of the total 169,495 hospitalization episodes analyzed, 48,201 (28.44%) corresponded to the weekend, presenting an older age (54.9 years vs. 53.9; P<.001), a higher crude mortality rate (5.22% vs. 4.59%; P<0.001), and a longer average length of stay (7.42 days vs. 6.74; P<.001), than those admitted on weekdays. The median crude cost of stay was lower (€731.25 vs. €850.88; P<0.001). No significant differences were found when applying the adjustment models, with a risk-adjusted mortality ratio of 1.03 (0.99-1.08) vs. 0.98 (0.95-1.01), risk-adjusted length of stay of 1.002 (0.98-1.005) vs. 0.999 (0.997-1.002) and risk-adjusted cost of stay of 0.928 (0.865-0.994) vs. 0.901 (0.843-0.962). CONCLUSION: The results of the study reveal that the assistance provided during the weekends does not imply worse health outcomes or increased costs. Comparing the impact between hospitals will require a future homogenization of temporal criteria and risk adjustment models.

[RECALMIN. Patient care in the internal medicine units of the Spanish national health system]. / RECALMIN. La atención al paciente en las unidades de Medicina Interna del Sistema Nacional de Salud.

OBJECTIVES: To perform a situation analysis of the care provided by internal medicine units (IMUs) in Spain and to develop, based on this analysis, proposals for improving the quality of care in these units. MATERIAL AND METHODS: A descriptive, cross-sectional study of the IMUs of general acute care hospitals of the Spanish National Health System (SNHS), with data referring to 2013. The study variables were collected via an ad hoc questionnaire. RESULTS: Of the total 260hospitals identified in the SNHS, 142responses were obtained from 139hospitals throughout Spain, which represents 53.5% of the IMUs in the SNHS. The mean number of internists per IMU was 14±8, with a mean rate of 7.2±3.3 internists per 100,000 inhabitants. In 2013, the average number of hospital discharges from the IMU was 2,987±2,066, and those discharged by internists was 232±107. Sixty-one percent of the IMUs had implemented an interconsultation unit, and 41% had implemented a systematic care program for complex chronic patients. Thirty-three percent of the IMUs conducted multidisciplinary rounds, and 60% of these IMUs planned the discharge. CONCLUSIONS: The 2013 RECALMIN survey revealed a number of important aspects of the organisation, structure and management of IMUs. The remarkable variability in the indicators of structure, activity and management probably reflect significant differences in efficiency and productivity, which therefore provide significant room for improvement.

Effects of organic modifier and temperature on the enantiomeric separation of several azole drugs using supercritical fluid chromatography and the Chiralpak AD column.

The effects of organic modifier and temperature on the enantioseparation of 10 triazoles and eight imidazoles, using supercritical fluid chromatography with the Chiralpak AD column, have been investigated in this work. For this purpose four different organic modifiers (methanol, ethanol, 2-propanol and acetonitrile) were evaluated. Only in the case of two compounds could the enantiomeric separation not be achieved with any of the modifiers tested; the rest of compounds were baseline or partially resolved with at least one of the modifiers. The alcohol-type modifiers provided the best results in terms of retention time and resolution. In general, retention increased in the order methanol < ethanol < 2-propanol; moreover it was possible to establish a relationship between the retention and the number of aromatic rings and dioxolane groups in the molecule, that is, the higher the number is, the higher the retention time. From the study of the temperature effect, the enthalpy-entropy compensation was demonstrated for all the compounds, except for bifonazole using methanol and miconazole using acetonitrile. This suggested that both analytes are enantiomerically resolved through different mechanisms.

Liquid chromatography coupled to ion trap-tandem mass spectrometry to evaluate juvenile hormone III levels in bee hemolymph from Nosema spp. infected colonies.

It has been described a fast, simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to measure juvenile hormone III (JH III), which was used to study of the effects of Nosema spp. infection on JH III levels in bee hemolymph. Honey bee hemolymph was extracted by centrifugation and mixed with a solution of phenylthiourea in methanol. This mixture was then centrifuged and the supernatant removed and evaporated to dryness. The residue was reconstituted in methanol containing the internal standard (methoprene) and injected onto an LC-MS/MS (ion-trap) system coupled to electrospray ionization (ESI) in positive mode. Chromatography was performed on a Synergi Hydro-RP column (4 µm, 30 mm × 4.60 mm i.d.) using a mobile phase of 20 mM ammonium formate and methanol in binary gradient elution mode. The method was fully validated and it was found to be selective, linear from 15 to 14,562 pg/µL, precise and accurate, with %RSD values below 5%. The limits of detection and quantification were: LOD, 6 pg/µL; LOQ, 15 pg/µL. Finally, the proposed LC-MS/MS method was used to analyze JH III levels in the hemolymph of worker honey bees (Apis mellifera iberiensis) experimentally infected with different Nosema spp. (Nosema apis, Spanish and Dutch Nosema ceranae strains). The highest concentrations of JH III were detected in hemolymph from bees infected with Spanish N. ceranae.

Supercritical fluid extraction of free amino acids from broccoli leaves.

The extraction of free amino acids (AAs) from broccoli leaves using supercritical fluid extraction (SFE) with CO(2) modified with methanol, is presented in this work. The effect of the different variables was studied, showing the percentage of methanol a strong influence on the extraction. The best results in terms of extraction yield were obtained at 250 bar, 70°C, 35% methanol as organic modifier, a flow rate of 2 mL/min, and 5 min and 30 min as static and dynamic extraction times, respectively. The extraction yield obtained with the SFE method was comparable to that obtained employing conventional solvent extraction with methanol-water (70:30) and minor than using water, but the relative proportion of the AAs in the extracts was very different. For example, the use of SFE allowed the enrichment in proline and glutamine of the extracts. The selected conditions were applied to obtain SFE extracts of broccoli leaves from different varieties (Naxos, Nubia, Marathon, Parthenon and Viola). The highest levels of AAs were found in the SFE extracts from the Nubia variety.

Determination of tylosins A, B, C and D in bee larvae by liquid chromatography coupled to ion trap-tandem mass spectrometry.

A LC-MS/MS method has been developed to simultaneously quantify tylosins A, B, C and D in bee larvae, compounds currently used to treat one of the most lethal diseases affecting honey bees around the world, American Foulbrood (AFB). The influence of different aqueous media, temperature and light exposure on the stability of these four compounds was studied. The analytes were extracted from bee larvae with methanol and chromatographic separation was achieved on a Luna C(18) (150 × 4.6 mm i.d.) using a ternary gradient composed of a diluted formic acid, methanol and acetonitrile mobile phase. To facilitate sampling, bee larvae were initially dried at 60°C for 4h and afterwards, they were diluted to avoid problems of pressure. MSD-Ion Trap detection was employed with electrospray ionization (ESI). The calibration curves were linear over a wide range of concentrations and the method was validated as sensitive, precise and accurate within the limits of quantification (LOQ, 1.4-4.0 ng/g). The validated method was successfully employed to study bee larvae in field tests of bee hives treated with two formulations containing tylosin. In both cases it was evident that the minimal inhibitory concentration (MIC) had been reached.

Study of the enantiomeric separation of an acetamide intermediate by using supercritical fluid chromatography and several polysaccharide based chiral stationary phases.

Four chiral stationary phases, based on the phenylcarbamate derivatives of amylose or cellulose: Chiralcel OD-H, Chiralpak AD, Lux Cellulose-2 and Lux Amylose-2, were evaluated for the enantiomeric separation of an acetamide chiral intermediate, the (4S-trans)-4-(ethylamino)-4-(N-acetamide)-5,6-dihydro-(6S)-methyl-4H-thieno-[2,3-b]thiopyran-7,7-dioxide, using SFC. The effect of the different modifiers and temperatures, on the separation, was also studied. The chiral separation could not be achieved using the Chiralpak AD column, nevertheless the other columns provided excellent results with analysis times close to 6 min and resolutions higher than 2. The highest enantioresolutions and retentions were obtained with the Lux Cellulose-2 column and 2-propanol as organic modifier. The isoelution temperatures were estimated from the van't Hoff plots, and in all the cases they were above the temperature range studied which means that the enantiomeric separation was enthalpy driven.

Trace-metal distribution of cigarette ashes as marker of tobacco brands.

The trace-metal distribution of cigarette ashes offers a potential interest from the point of view of forensics and criminology dealing with the determination and classification of tobacco brands. There is a vast bibliography related to the determination of different metals in tobacco leaves. Nevertheless, none of them are directly linked to this matter. Therefore, in this work we present a methodology to assess the viability of discriminating between different tobacco brands by analysing the ashes after smoking. This methodology encompasses the data analysis by atomic techniques (inductively coupled plasma) and further data analysis by principal component analysis and partial least squares-discriminant analysis. The metal distribution (Zn, B, Mn, Fe, Mg, Cu, Ti, Al, Sr, Ca, Ba, Na, Li, and K) of cigarette ashes of different tobacco brands was determined in 149 samples obtained from local stores, representing the most common brands of cigarettes readily available to consumers in Spain. Further analysis of the data with PCA denoted significant differences between different brands of tobacco in their metallic content. In that sense, blond tobaccos were found to contain different patterns in metallic content than black tobaccos. Intrinsic differences were found between different brands, being possible to study the relationship between each brand and its metallic concentration and compare this relationship with other brands. Moreover the possibility of developing classification models to be able to discriminate between different brands was also introduced.

Development and validation of a liquid chromatography-fluorescence-mass spectrometry method to measure glyphosate and aminomethylphosphonic acid in rat plasma.

A simple and fast method has been developed and validated to measure glyphosate (GLYP) and aminomethylphosphonic acid (AMPA) in rat plasma based on reversed-phase high performance liquid chromatography (RP-HPLC) coupled to fluorescence (FLD) and electrospray ionization mass spectrometry (ESI-MS) detection. After protein precipitation with acetonitrile, GLYP and AMPA were derivatized with 9-fluorenylmethylchloroformate (FMOC-Cl) and then separated on a C(12) column (250mm×4.60mm i.d.) using a gradient of an ammonium formate (20mM, pH 8.5) and acetonitrile mobile phase. Selected ion monitoring (SIM) mode of the MS was used to obtain maximum sensitivity when quantifying GLYP and AMPA. The validation shows the method to be consistent and reliable, with an intra- and inter-day precision for GLYP and AMPA>9% for both detectors. For both compounds the accuracy ranged from 2.1% to 7.8% for the intra-day readings, and from 4.1% to 8.6% for the inter-day values. The efficacy of GLYP extraction ranged from 87% to 93% and it was between 76% and 88% for AMPA. Moreover, the limits of quantification (LOQ) for GLYP and AMPA were 5 and 10ng/mL, respectively with FLD, and 0.4 and 2ng/mL with ESI-MS. The method was successfully applied to simultaneously measure both compounds in rat plasma samples several days after oral administration of glyphosate.

Application of enzymatic probe sonication extraction for the determination of selected veterinary antibiotics and their main metabolites in fish and mussel samples.

A new method based on enzymatic probe sonication extraction prior to high-performance liquid chromatography (HPLC) has been developed for the determination of 11 antibiotics (drugs) and the main metabolites of five of them in fish tissue and mussel samples. The analytes belong to four different classes of antibiotics (sulfonamides, tetracyclines, penicillins and amphenicols). The analysed compounds were sulfadiazine (SDI) and N(4)-acetylsulfadiazine (NDI) metabolite, sulfamethazine (SMZ) and N(4)-acetylsulfamethazine (NMZ), sulfamerazine (SMR) and N(4)-acetylsulfamerazine (NMR), sulfamethoxazole (SMX), trimetroprim (TMP), amoxicillin (AMX) and its main metabolite amoxicilloic acid (AMA), ampicillin (AMP) and its main metabolite ampicilloic acid (APA), chloramphenicol (CLF), thiamphenicol (TIF), oxytetracycline (OXT) and chlortetracycline (CLT). The main factors affecting the extraction efficiency (type of enzyme, type and volume of extractant, ultrasounds power and extraction time) were optimised in tissue of hake (Merluccius merluccius), anchovy (Engraulis encrasicolus), mussel (Mytilus sp.) and wedge sole (Solea solea). The extraction was carried out using an extraction time of 5 min with 5 mL of water and subsequent clean-up with dichloromethane. High-performance liquid chromatography (HPLC) with diode array (DAD) and fluorescence (FLD) detectors was used for the determination of the antibiotics. The separation of the analysed compounds was conducted by means of a Phenomenex Gemini C(18) (150 mm x 4.6 mm I.D., particle size 5 microm) analytical column with LiChroCART LiChrospher C(18) (4 mm x 4 mm, particle size 5 microm) guard-column. Analysed drugs were determined using formic acid 0.1% (v/v) in water and acetonitrile in gradient elution mode as mobile phase. The proposed method was also evaluated by a laboratory assay consisting of the determination of the targeted analytes in samples of Cyprinus carpio which had previously administered the antibiotics.

Overview of pesticide residues in stored pollen and their potential effect on bee colony (Apis mellifera) losses in Spain.

In the last decade, an increase in honey bee (Apis mellifera L.) colony losses has been reported in several countries. The causes of this decline are still not clear. This study was set out to evaluate the pesticide residues in stored pollen from honey bee colonies and their possible impact on honey bee losses in Spain. In total, 1,021 professional apiaries were randomly selected. All pollen samples were subjected to multiresidue analysis by gas chromatography-mass spectrometry (MS) and liquid chromatography-MS; moreover, specific methods were applied for neonicotinoids and fipronil. A palynological analysis also was carried out to confirm the type of foraging crop. Pesticide residues were detected in 42% of samples collected in spring, and only in 31% of samples collected in autumn. Fluvalinate and chlorfenvinphos were the most frequently detected pesticides in the analyzed samples. Fipronil was detected in 3.7% of all the spring samples but never in autumn samples, and neonicotinoid residues were not detected. More than 47.8% of stored pollen samples belonged to wild vegetation, and sunflower (Heliantus spp.) pollen was only detected in 10.4% of the samples. A direct relation between pesticide residues found in stored pollen samples and colony losses was not evident accordingly to the obtained results. Further studies are necessary to determine the possible role of the most frequent and abundant pesticides (such as acaricides) and the synergism among them and with other pathogens more prevalent in Spain.

Profile and relative concentrations of fatty acids in corn and soybean seeds from transgenic and isogenic crops.

In this work 44 fatty acids, which were analyzed as methyl esters by GC/MS in scan mode, have been determined in genetically modified corn and soybean seeds. Their relative concentrations have been compared with those of isogenic lines grown in the same conditions. Studied compounds comprised saturated and unsaturated fatty acids, including cis/trans isomers and minor fatty acids. A classical soxhlet extraction and an accelerated solvent extraction have been assayed to extract the fatty compounds from seeds and the GC separation has been carried out on a biscyanopropylpolysiloxane chromatographic column. Soxhlet extraction was selected as the most convenient and applied to compare the samples. Specific compounds, which could denote the origin of the crop have not been observed, but for some sample pairs, significant differences have been found in relation to the percentage of certain acids; the highest differences for major acids were 4.1% in corn and 4.8% in soybean. The concentrations of long chain acids such as 24:0, 26:0 and 28:0 were higher in some isogenic lines whereas the concentrations of short chain acids such as 6:0, 8:0, 9:0, 10:0 and 12:0 were higher in their transgenic counterparts.

Toxicokinetics of glyphosate and its metabolite aminomethyl phosphonic acid in rats.

The toxicokinetics of glyphosate after single 100 mgkg(-1) intravenous (i.v.) and 400 mgkg(-1) oral doses were studied in rats. Serial blood samples were obtained after i.v. and oral administration. Plasma concentrations of glyphosate and its metabolite amiomethyl phosphonic acid (AMPA) were determined by HPLC method. After i.v. and oral administration, plasma concentration-time curves were best described by a two-compartment open model. For glyphosate, the elimination half-lives (T(1/2beta)) from plasma were 9.99 h after i.v. and 14.38 h after oral administration. The total plasma clearance was not influenced by dose concentration or route and reached a value of 0.995 l h(-1)kg(-1). After i.v. administration, the apparent volume of distribution in the second compartment (V(2)) and volume of distribution at steady state (V(ss)) were 2.39 and 2.99 l kg(-1), respectively, suggesting a considerable diffusion of the herbicide into tissues. After oral administration, glyphosate was partially and slowly absorbed with a T(max) of 5.16 h. The oral bioavailability of glyphosate was found to be 23.21%. Glyphosate was converted to AMPA. The metabolite AMPA represented 6.49% of the parent drug plasma concentrations. The maximum plasma concentrations of glyphosate and AMPA were 4.62 and 0.416 microg ml(-1), respectively. The maximum plasma concentration of AMPA was achieved at 2.42 h. For AMPA, the elimination half-life (T(1/2beta)) was 15.08 h after oral administration of glyphosate parent compound.

Use of supercritical fluid extraction and gas chromatography-mass spectrometry to obtain amino acid profiles from several genetically modified varieties of maize and soybean.

A method using supercritical fluid extraction (SFE) and gas chromatography-mass spectrometry (GC/MS) for obtaining the amino acid profiles of genetically modified maize and soybean is proposed. SFE is carried out in a homemade modular system where amino acids are extracted with carbon dioxide modified with 35% of methanol, in conditions optimized by a central composite design. Once extracted, the amino acids are determined by GC/MS. The method has been applied to three samples of maize derived from MON810, other from NK 603 and a Roundup ready soybean sample. The profiles are compared with those obtained from their corresponding isogenic non-transgenic varieties. Although differences are directly observed in some cases by visual comparison of the chromatograms, the application of ANOVA shows more significant differences. In general terms, isogenic varieties seem to have higher content of several amino acids.

Trace analysis of fumagillin in honey by liquid chromatography-diode array-electrospray ionization mass spectrometry.

In this work a new liquid chromatography with diode array detection and electrospray ionization mass spectrometry (LC-DAD-ESI-MS) method has been developed for the determination of fumagillin residues in honey. This procedure involves a solid-phase extraction on polymeric cartridges for the isolation of fumagillin from diluted honey. Chromatographic separation of fumagillin was performed in isocratic mode, on a C(18) column (150 mm x 4.60mm i.d., 5 microm), the mobile phase consisted of a mixture of ammonium formate 20mM in water and acetonitrile (61/39, v/v), at 35 degrees C and the flow rate was set at 1.0 mL/min. Average analyte recoveries, influenced by the botanical origin were from 88 to 96% in replica sets of fortified honey samples. The detection limits of the LC-DAD-ESI-MS method were between 24 and 1 microg/kg for clear honeys (rosemary) and between 45 and 4 microg/kg for dark honeys (heather). The developed method has been applied to the analysis of fumagillin residues in honey samples collected from veterinary treated beehives, infected by Nosema ceranae and fed with the technical product at different doses.

Sample preparation methods to analyze fipronil in honey by gas chromatography with electron-capture and mass spectrometric detection.

Several sample preparation methods have been assayed to analyze residues of fipronil in honey. After diluting the honey, liquid-liquid extraction (LLE) with organic solvents, and solid-phase extraction (SPE) on commercial cartridges or Florisil-packed column have been tested at three concentration levels: 0.01, 0.1 and 1 mg/kg. LLE with n-hexane or SPE on a Florisil column resulted to be the most suitable procedures to analyze fipronil at trace concentrations. Fipronil was quantified by gas chromatography (GC) with electron-capture detection (ECD) or mass spectrometric (MS) detection after conventional or matrix-matched calibration. The detection limit of fipronil in honey samples was below 1 microg/kg. The degradation of fipronil in honey has also been studied, being identified three minor degradation products in the extracts.

Comparative study of sample preparation procedures to determine fipronil in pollen by gas chromatography with mass spectrometric and electron-capture detection.

Several sample preparation methods have been assayed to analyze residues of fipronil in pollen at trace concentrations. Extraction with organic solvents, solid-phase extraction on either commercial cartridges or a Florisil-packed column and a matrix solid-phase dispersion, also with Florisil as a dispersing agent, have been tested. Determination of fipronil in the extracts has been carried out by GC with electron-capture and mass spectrometric detection. An extraction with acetonitrile followed by a clean-up on ODS or polymeric cartridges was the most suitable procedure to obtain acceptable recoveries and relatively simple chromatograms. The matrix-effects observed in the quantification can be corrected with a matrix-matched calibration.