Analysis of veterinary drug and pesticide residues in animal feed by high-resolution mass spectrometry: comparison between time-of-flight and Orbitrap.

The use of medium-high-resolution mass spectrometers (M-HRMS) provides many advantages in multi-residue analysis. A comparison between two mass spectrometers, medium-resolution (MRMS) time-of-flight (TOF) and high-resolution (HRMS) Orbitrap, has been carried out for the analysis of toxic compounds in animal feed. More than 300 compounds belonging to several classes of veterinary drugs (VDs) and pesticides have been determined in different animal feed samples using a generic extraction method. The use of a clean-up procedure has been evaluated in both instruments, and several validation parameters have been established, such as the matrix effect, linearity, recovery and sensitivity. Finally, both instruments have been used during the analysis of 18 different feed samples (including chicken, hen, rabbit and horse). Some VDs (sulfadiazine, trimethoprim, robenidine and monensin sodium) and one pesticide (chlorpyrifos) have been identified. In general, better results were obtained using the Orbitrap, such as sensitivity (1-12.5 µg kg(-1)) and recovery values (60-125%). Moreover, this analyser had several software tools, which reduced the time for data processing and were easy to use, performing quick screening for more than 450 compounds in less than 5 min. However, some disadvantages such as the high cost and a decrease in the number of detected compounds at low concentrations must be taken into account.

Identification of transformation products of pesticides and veterinary drugs in food and related matrices: use of retrospective analysis.

Retrospective analysis has been applied in different samples, including honey, meat, feed and nutraceutical products from ginkgo biloba, soya, royal jelly and green tea, with the aim of searching transformation products of pesticides and veterinary drugs, which were not included in an initial analysis. Generic extraction and analytical procedures based on high resolution mass spectrometry (Exactive-Orbitrap analyser was used) have been applied. All obtained data have been reprocessed and some compounds as anhydroerythromycin in honey and 3,5,6-trichloro-2-pyridinol in feed have been detected, demonstrating the applicability and the utility of the procedure. Advantages and disadvantages of retrospective approach have been highlighted.

Analysis of pesticide and veterinary drug residues in baby food by liquid chromatography coupled to Orbitrap high resolution mass spectrometry.

Pesticide and veterinary drug residues have been simultaneously determined in several baby foods as meat, fish and vegetable-based baby food. A generic extraction method without clean-up step was applied. Moreover, the use of a representative matrix for proper quantification of all target compounds was studied and the best results were obtained when vegetable-based baby food was used as representative matrix, allowing the reliable quantification of more than 300 compounds. The method was validated and good recoveries were obtained for most of compounds at concentrations higher than 50 µg kg(-1). Limits of detection (LOD) ranged from 0.5 to 50 µg kg(-1), whereas limits of quantification (LOQ) were established between 10 and 100 µg kg(-1). Limits of identification (LOIs) ranged from 0.5 to 50 µg kg(-1). This method was applied to the analysis of 46 different baby food samples and no positive samples were found.

Evaluation of the potential of GC-APCI-MS for the analysis of pesticide residues in fatty matrices.

A method based on gas chromatography-atmospheric pressure chemical ionization-mass spectrometry (GC-APCI-MS) has been developed for the analysis of pesticides in meat by using quadrupole-time of flight mass spectrometry (QTOF-MS). Ionization and MS conditions were studied for 71 compounds, although only 51 showed acceptable performance. The protonated form of the analytes was mainly found ([M + H]⁺), although some compounds generated the molecular ion (M⁺(•)). A fast and generic extraction procedure was applied in sample pretreatment. The analytical method was suitable for qualitative analysis, and it was also evaluated for quantitative analysis, obtaining adequate recovery and precision values for most of the studied analytes at two concentration levels (50 and 150 µg/kg). Several operational drawbacks were found with this instrument, such as slow stabilization and moderate sensitivity, although the fast switching between LC and GC allows the increase of its applicability.

Wide-scope analysis of pesticide and veterinary drug residues in meat matrices by high resolution MS: detection and identification using Exactive-Orbitrap.

A multiresidue and multiclass method for the simultaneous determination of more than 350 compounds including pesticides, biopesticides and veterinary drugs in different meat matrices (beef, pork and chicken) by ultra-high performance liquid chromatography coupled to Orbitrap MS has been developed. In the present study, the determination of fragments was accomplished as an essential tool for a reliable identification of compounds using high resolution MS. To obtain these fragments, different strategies have been carried out in order to ensure an appropriate fragment assignment and identification. The analytical method is suitable for qualitative analysis, and it was also evaluated for quantitative analysis. Generic extraction conditions were optimized, obtaining adequate recovery and precision values for most of the studied analytes (>290). The limits of detection ranged from 2 to 16 µg kg(-1). Limits of quantification were 10 µg kg(-1) with the exception of few compounds with a higher value (50 or 100 µg kg(-1)). Limits of identification were also established, and they ranged from 2 to 150 µg kg(-1). This method was applied to the analysis of 18 meat samples and some veterinary drugs as enrofloxacin and sulfadiazine were detected and further identified/quantified (with triple quadrupole) in two different samples at 33 µg kg(-1) and trace levels, respectively. No pesticides were detected in the analyzed samples.

Erythrocyte deformability and aggregation in homozygous sickle cell disease.

Rheological properties of homozygous sickle cell anaemia (SCA) show marked heterogeneity, which may be explained in part by the concomitance of alpha genotypes or beta haplotypes, along with hydroxurea (HU) treatment. To further clarify this issue, in 11 homozygous patients with SCA in the steady state and in 16 healthy controls, we analysed erythrocyte deformability (ED) in a Rheodyn SSD by means of the Elongation Index (EI) at 12, 30 and 60 Pa, and erythrocyte aggregation at stasis (EA0) and at 3 sec-1 (EA1) in a Myrenne aggregometer along with fibrinogen, biochemical and haematological parameters. When compared with controls, homozygous (SS) patients showed a lower EI at all the shear stresses tested (p < 0.01) and higher EA0 (p < 0.014), but not higher EA1 (p = 0.076). Fibrinogen did not show statistical differences (p = 0.642). In the Spearman's correlation IE60 correlated inversely with Hb S (p < 0.05) and directly with MCV, MCH and Hb F levels (p < 0.01). EA0 correlated inversely with MCV, MCH, Hb F (p < 0.01) and directly with Hb S (p < 0.05). HU treatment improved EI and EA0, but not EA1. This paradoxical behaviour of HU on erythrocyte aggregation merits further research to be clarified.

Analysis of veterinary drug residues in cheese by ultra-high-performance LC coupled to triple quadrupole MS/MS.

A simple, reliable, and fast multiresidue method has been developed for the determination of 17 veterinary drugs belonging to several families (macrolides, sulfonamides, and anthelmintics) in cheese at trace levels. Ultra-high-performance LC coupled to MS/MS has been used for the analysis of these compounds in less than 9 min. Veterinary drug residues have been extracted from cheese samples using a QuEChERS (quick, easy, cheap, effective, rugged, and safe)-based extraction procedure without applying any further clean-up step. Matrix-matched calibration was used for quantification and recoveries were calculated at three concentration levels (10, 50, and 100 µg/kg). The obtained values ranged from 70 to 110% for the selected compounds except for tylosin and josamycin at 100 µg/kg (111.7 and 112.7%, respectively). Intra- and interday precision were also evaluated and RSDs were lower than 25% in all the cases. LOQs ranged from 0.3 µg/kg (for thiabendazole, oxfendazole, mebendazole, josamycin, and fenbendazole) to 10.5 µg/kg (abamectin), whereas decision limit and detection capability ranged from 2.3 (thiabendazole) to 11.3 (abamectin) and 4.2 (thiabendazole) to 14.3 µg/kg (abamectin), respectively. Finally, 13 samples were analyzed and traces of thiabendazole were detected in two different cheeses.

Comprehensive qualitative and quantitative determination of pesticides and veterinary drugs in honey using liquid chromatography-Orbitrap high resolution mass spectrometry.

A database has been created for the simultaneous analysis of more than 350 pesticides and veterinary drugs (including antibiotics) using ultra-high performance liquid chromatography coupled to high resolution Orbitrap mass spectrometry (UHPLC-Orbitrap-MS). This is a comprehensive exact mass database built using the Exactive-Orbitrap analyzer. The developed database includes exact masses of the target ions and retention time data, and allows the automatic search of the included compounds. Generic chromatographic and MS conditions have been applied. The presented database is suitable for qualitative analysis, and it was also evaluated for quantitative purposes in routine analysis, after the optimization and validation of a generic extraction method in honey samples. Adequate recovery and precision values for most of the studied analytes were obtained and the limits of detection (LOD) ranged from 1 to 50 µg kg(-1). For pesticides, LODs were always lower than the MRLs established by European Union in honey, except for a few compounds. This method was applied to the analysis of 26 real honey samples and some pesticides (azoxystrobin, coumaphos, dimethoate and thiacloprid) were detected in 4 samples. Azoxystrobin and coumaphos were determined in two different samples (organic honey) at 1.5 µg kg(-1) and 5.1 µg kg(-1). Veterinary drugs were not detected in the analyzed samples.

Rheological red blood cell behaviour in minor α-thalassaemia carriers.

Although several studies have been published regarding rheological behaviour of red blood cells in beta and delta-beta thalassaemia traits, little information about erythrocyte deformability in alpha-thalassaemia carriers is available. We aimed to determine erythrocyte deformability in heterozygous (silent, -α/αα) and homozygous (minor alpha-thalassaemia, -α/-α) carriers of the alpha-thalassaemia trait for the alpha 3.7 deletion, the most common in our geographical area. We evaluated erythrocyte deformability by means of the elongation index (EI) in a Rheodyn SSD at 12, 30 and 60 Pa, along with basic haematological cell count, erythrocyte indices, reticulocytes, plasma lipids and iron metabolism parameters in 36 (18 women, 18 men) alpha-thalassaemia carriers (17 heterozygous, 19 homozygous) and 36 healthy subjects (23 women, 13 men). The molecular diagnosis of the alpha 3.7 deletion was evaluated by a PCR-based method. Alpha-thalassaemia carriers presented higher red blood cell counts, RDW-CV (p < 0.001) and lower haemoglobin, MCV, MCH and MCHC (p < 0.001) than controls. EI was statistically lower at 12, 30 and 60 Pa in cases than in controls (p = 0.001, p = 0.002, p = 0.010, respectively). No differences in either elongation indices or haematimetric values were observed when comparing silent heterozygous and minor homozygous alpha-thalassaemia carriers (p > 0.05). Pearson's bivariate correlation showed that EI60 correlated positively with haemoglobin and MCV, MCH, MCHC (p < 0.01), but negatively with ferritin (p< 0.05) and RDW-CV (p< 0.01). In the multivariate regression analysis, MCV (p = 0.001) and haemoglobin (p < 0.001) predicted EI60, with this model accounting for around 43% of variation in EI60 (R2 = 0.427). Alpha-thalassaemia carriers phenotypically showed mild microcytosis and hypochromia, irrespectively of them being silent heterozygous or minor homozygous alpha-thalassaemia carriers, which is associated with decreased erythrocyte deformability.

Multi-mycotoxin analysis in eggs using a QuEChERS-based extraction procedure and ultra-high-pressure liquid chromatography coupled to triple quadrupole mass spectrometry.

A reliable and rapid method has been developed for the determination of 10 mycotoxins (beauvericin, enniatin A, A1, B1, citrinin, aflatoxin B1, B2, G1, G2 and ochratoxin A) in eggs at trace levels. Ultra-high-pressure liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) has been used for the analysis of these compounds in less than 7 min. Mycotoxins have been extracted from egg samples using a QuEChERS-based extraction procedure (Quick, Easy, Cheap, Effective, Rugged and Safe) without applying any further clean-up step. Extraction, chromatographic and detection conditions were optimised in order to increase sample throughput and sensitivity. Matrix-matched calibration was used for quantification. Blank samples were fortified at 10, 25, 50 and 100 µg kg(-1), and recoveries ranged from 70% to 110%, except for ochratoxin A and aflatoxin G1 at 10 µg kg(-1), and aflatoxin G2 at 50 µg kg(-1). Relative standard deviations were lower than 25% in all the cases. Limits of detection ranged from 0.5 µg kg(-1) (for aflatoxins B1, B2 and G1) to 5 µg kg(-1) (for enniatin A, citrinin and ochratoxin A) and limits of quantification ranged from 1 µg kg(-1) (for aflatoxins B1, B2 and G1) to 10 µg kg(-1) (for enniatin A, citrinin and ochratoxin A). Seven samples were analyzed and aflatoxins B1, B2, G1, G2, and beauvericin were detected at trace levels.

Development and validation of an ultra-high performance liquid chromatography-tandem mass-spectrometry (UHPLC-MS/MS) method for the simultaneous determination of neurotransmitters in rat brain samples.

A simple method for the simultaneous determination of glutamate, γ-aminobutyric acid (GABA), choline, acetylcholine, dopamine, 5-hydroxyindole-3-acetic (5-HIAA), serotonin, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) was developed by using ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). These compounds are analysed in a single chromatographic run in less than 8 min, adding heptafluorobutyric acid (HFBA) in the mobile phase to improve the separation of the selected neurotransmitters. The analytes were detected using electrospray ionization (ESI)-MS/MS in positive mode with multiple reaction monitoring (MRM). Good linearity was obtained (R² > 0.98) and the intra and inter-day precision of the method (expressed as relative standard deviation) were lower than 26%. Limits of quantification were lower than 2.440 µg/g of brain in all the cases, allowing the sensitive determination of these compounds in rat brain extracts. Therefore, the method was successfully applied for the quantitative determination of neurotransmitters in several rat brain regions (prefrontal cortex, striatum, nucleus accumbens and amygdala), detecting glutamate, GABA and choline at concentrations higher than 1000 µg/g, 30 µg/g and 100 µg/g respectively, whereas the other compounds were found at lower concentrations.

Erythrocyte deformability in anaemic patients with reticulocytosis determined by means of ektacytometry techniques.

It is not clearly established whether reticulocyte deformability is lower than that of the mature erythrocytes, as most of studies published on this matter have evaluated this rheological parameter by means of micropipette techniques, which are unsuitable for routine measurements. Information is scarce as regards the evaluation of reticulocyte deformability by means of ektacytometry techniques, routinely used in clinical laboratories. We aimed to evaluate erythrocyte deformability (ED), with ektacytometry, in samples of 44 anaemic patients with peripheral reticulocytosis (reticulocytes: (260+/-150)x10(3)/microl) and in 60 healthy non-anaemic volunteers with a normal reticulocyte count (reticulocytes: (60+/-20)x10(3)/microl). We also determined other factors that may influence ED, such as erythrocyte indices (MCV, MCH, MCHC), glucose, total cholesterol and triglycerides. ED was evaluated determining the elongation indices (EI) at 12, 30 and 60 Pa, by means of the Rheodyn SSD. At the three shear stresses tested, patients showed statistically lower EI than controls, higher reticulocyte count, lower cholesterol levels and higher MCHC (P<0.001, respectively). A statistically significant negative correlation (P<0.01) was found between the reticulocyte count and the EI at 12, 30 and 60 Pa (r=-0.643, r=-0.678 and r=-0.692, respectively), and between the EI and the MCHC (correlation coefficients: -0.743, -0.741 and -0.738; P<0.01). As the differences in ED could be attributed partly to alterations in erythrocyte indices and plasma lipid levels, a linear regression analysis was performed, showing that EI is independently associated with the reticulocyte count. Our results suggest that reticulocytes are responsible for the decreased ED observed in anaemic patients with peripheral reticulocytosis, when this hemorheological parameter is evaluated by means of ektacytometry techniques.

Rheological behaviour of red blood cells in beta and deltabeta thalassemia trait.

In major and intermediate thalassemia a decrease in erythrocyte deformability and increased erythrocyte aggregability has been described, but few studies have dealt with the question of rheological red blood cell behaviour in minor beta and deltabeta thalassemia carriers, mostly in deltabeta, because it is a less common entity. To ascertain whether there are differences in red blood cell behaviour between minor thalassemia and controls and between both types of thalassemia trait beta and deltabeta, we determined erythrocyte deformability and aggregability in 30 beta and 30 deltabeta trait carriers diagnosed both with conventional methods and globin gene analysis, and in 40 age- and sex-matched controls. Erythrocyte deformability determined by means of the Rheodyn SSD showed a statistically significant lower Elongation Index (EI) at all the shear stresses tested in both thalassemic groups compared with controls (p<0.001). Minor beta thalassemia carriers showed lower EI than deltabeta carriers (p<0.001). Erythrocyte aggregability measured with the Myrenne aggregometer was significantly lower in both thalassemic groups than in controls (p<0.001), although no significant differences could be observed between both thalassemic groups. The rheological alterations found in thalassemia carriers are in part due to microcytosis, hypochromia and the morphological changes that characterize this kind of anaemia. The less altered deformability found in deltabeta carriers, is in agreement with the fact that it deals with a more benign trait.