Efficacy and safety of antiarrhythmic therapy in dogs with naturally acquired tachyarrhythmias treated with amiodarone or sotalol: a retrospective analysis of 64 cases

INTRODUCTION/OBJECTIVE

Studies on the use of amiodarone or sotalol are limited in dogs. Therefore, this study aimed to provide data on the efficacy and safety of these drugs in dogs with ventricular tachyarrhythmia (VT) and/or supraventricular tachyarrhythmia (SvT).

ANIMALS, MATERIALS, AND METHODS

Dogs with VT and/or SvT treated with amiodarone or sotalol as a first-line therapy were retrospectively evaluated. Signalment, clinical, diagnostic, therapeutic, and outcome data were retrieved. For VT, efficacy was demonstrated through a decrease of the Lown-Wolf grade to less than five or a reduction of at least 85% in the number of ventricular premature complexes observed on Holter monitoring. For SvT, efficacy was represented by cardioversion or a reduction in the mean heart rate on Holter monitoring ≤140 beats/min. Treatment-related side effects (TRSEs) were classified as clinically relevant and irrelevant. Statistical analysis was performed to compare data before and after antiarrhythmic prescription.

RESULTS

Sixty-four dogs were included. Amiodarone and sotalol were efficacious in treating both VT (85.7% and 90.0% of cases, respectively) and SvT (75% and 71.4% of cases, respectively). No significant differences were found when comparing their efficacy rates in dogs with VT and SvT (P=0.531 and 0.483, respectively). Clinically relevant TRSEs were rare with both amiodarone and sotalol (8.3% and 5% of cases, respectively), while clinically irrelevant TRSEs occurred more frequently with amiodarone (29.2%) than with sotalol (10%).

DISCUSSION

In dogs with tachyarrhythmias, amiodarone and sotalol are generally efficacious and safe, as clinically relevant TRSEs seem rare.

CONCLUSIONS

This study provides novel data on the effects of amiodarone and sotalol in dogs with tachyarrhythmias.

Prognostic role and characteristics of the indeterminate response in differentiated thyroid cancer: a systematic review

PURPOSE

The management of differentiated thyroid cancer (DTC) is actually based on a dynamic risk stratification based on classes of response to the therapy. Indeterminate response (IR) includes a heterogeneous group of patients with different characteristics, particularly different Tg and AbTg levels and/or imaging findings. The aim of systematic review (SR) is to evaluate the prognosis, diagnostic findings and other characteristics of patients in the IR class.

METHODS

A wide literature search in the Scopus, PubMed/MEDLINE and Web of Science databases was performed to find published articles on patients with DTC and IR after treatment. The quality assessment of studies was carried out using QUADAS-2 evaluation.

RESULTS

Eight articles were included in the systematic review. Six studies evaluated the prognosis and the prognostic factor in patients with IR, one study evaluated the role of 2-[18F]FDG PET-CT in the management of patients with IR and biochemical incomplete response and one study the risk factors for IR.

CONCLUSION

Patients with DTC and IR to therapy have a probability of disease relapse < 15%. Tg value could be a predictor of disease progression. The role of 2-[18F]FDG PET-CT needs to be further investigated.

Spread of Toxoplasma gondii among animals and humans in Northern Italy: A retrospective analysis in a One-Health framework

Toxoplasmosis occurs worldwide and is considered one of the most important food-borne parasitic zoonoses. The consumption of undercooked meat containing viable tissue cysts and ingestion of environmental oocyst are the most important sources of infection. The aim of this retrospective study was to evaluate the spread of Toxoplasma gondii in the province of Bologna (Emilia-Romagna region) in northern Italy, with a One Health approach, comparing seropositivity rates in different animal species and in humans over the last 19 and 4 years respectively. Analyses were performed on serological data collected over different periods at three separate locations: Istituto Zooprofilattico Sperimentale della Lombardia e della Emilia-Romagna (IZSLER); Veterinary University Hospital Clinical Pathology Service, Department of Veterinary Medical Sciences, University of Bologna; and Unit of Microbiology, St. Orsola Hospital, Bologna. Most relevant seropositivity rates observed in animals were 15.5% (wild boar), 25% (roe deer), 18.7% (goat), 29.9% (sheep), 9.7% (pigs), 42.9% and 21.8% in cat and dog, respectively. A comprehensive screening was conducted on a population of 36,814 individuals, revealing a prevalence of 20.4%. Among pregnant women, a frequence of 0.39% for active toxoplasmosis was observed. Despite certain limitations, this study provided valuable insights into the extensive distribution of this parasitic infection among diverse animal species and human populations in the province of Bologna. These findings underscore the importance of implementing consistent and proactive toxoplasmosis screening protocols during pregnancy, while emphasizing the critical need for adopting a One Health approach for effective control of this parasitic disease.

Fractional excretion of electrolytes and neutrophil gelatinase-associated lipocalin as early biomarkers of acute kidney injury in dogs with acute pancreatitis

OBJECTIVES

To determine if fractional excretion of urinary electrolytes and neutrophil gelatinase-associated lipocalin could detect different degrees of kidney injury in dogs with naturally occurring acute pancreatitis.

MATERIALS AND METHODS

We included dogs with acute pancreatitis. Dogs with a history of kidney disease, urinary tract infection, dogs which received potentially nephrotoxic drugs and dogs managed with haemodialysis were excluded. Acute kidney injury was diagnosed if there was an acute onset of clinical signs, haemato-chemical results compatible with acute kidney injury. Students or staff-owned dogs were selected to build the healthy group.

RESULTS

The study population was composed of 53 dogs: acute pancreatitis with AKI (n=15), acute pancreatitis alone (n=23), and healthy dogs (n=15). In dogs with acute pancreatitis and AKI, all the FEs of urine electrolytes were significantly higher than dogs with acute pancreatitis alone and healthy ones. Dogs with acute pancreatitis alone had higher uNGAL/uCr than healthy dogs (median 54 ng/mg vs. 0.1 ng/mg) and lower compared to AP-AKI patients (54 ng/mg vs 209 ng/mg). Some fractional excretion of electrolytes are increased acute kidney injury dogs, however their role in the early detection of renal injury in acute pancreatitis dogs remains doubtful. On the contrary, urinary neutrophil gelatinase-associated lipocalin had higher concentrations in dogs with acute pancreatitis with or without acute kidney injury compared to healthy controls, suggesting that it may be used as an early marker of renal tubular damage in acute pancreatitis dogs.

A large deletion in the Plasminogen gene is associated with ligneous membranitis in a Maltese dog

Ligneous membranitis/conjunctivitis (LM, OMIM 217090) is a hereditary disorder caused by a congenital plasminogen (PLG) deficiency. In veterinary medicine, LM (OMIA 002020‐9615) has rarely been reported in Golden Retrievers, Yorkshire Terriers, Doberman Pinschers and Scottish Terriers. In the latter breed, an A>T variation in an intron donor site of the PLG gene (PLG, c.1256+2T>A) has been found to be the sole causative molecular defect reported to date in dogs. Owing to the absence of plasmin enzymatic clearance which in turn depends on the lack of its proenzyme plasminogen, fibrin deposits tend to accumulate in viscous membranes on the eyes, triggering and sustaining an intense inflammatory response. A case of LM was diagnosed in a 7‐month‐old male Maltese dog. The dog was examined for severe recurrent conjunctivitis. A diagnosis of ligneous conjunctivitis was made by an ophthalmologist after a thorough eye examination and was confirmed by a complete lack of plasma activity of plasminogen. The main local signs were redness of the conjunctiva with persistent membranes having ligneous (wood‐like) membranes on the eyes. The disease was associated with a complex rearrangement involving the plasminogen gene loci, causing the complete deletion of exon 1. This study provides a spontaneous animal model for LM associated with complete plasminogen deficiency and provides a method for detecting affected or carrier dogs.

18F-FDG-PET/CT in laryngeal cancer: Comparison with conventional imaging and prognostic role

OBJECTIVE

The aim of this study was to investigate the diagnostic accuracy of staging ¹⁸F-FDG-PET/CT in laryngeal cancer, compare these results with conventional imaging (CI) and assess the value of ¹⁸F-FDG-PET/CT features to predict survival.

METHODS

Fifty-four patients with laryngeal squamous cell cancer and baseline ¹⁸F-FDG-PET/CT were retrospectively enrolled. The PET images were analyzed visually and semi-quantitatively by measuring several metabolic parameters. A combination of clinical follow-up/imaging follow-up and/or histopathology was taken as reference standard. Progression free survival (PFS) and disease specific survival (DSS) were computed using Kaplan-Meier curves.

RESULTS

All primary tumors were clearly identified by CI, and 52/54 by ¹⁸F-FDG-PET/CT with a sensitivity of 96.3%. Cervical nodal metastases were detected in 40/54 patients at ¹⁸F-FDG-PET/CT and in 34/49 patients at CI. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy on a patient-based analysis for nodal disease were 100%, 85.7%, 94.6%, 100% and 95.9% at ¹⁸F-FDG-PET/CT, and 91.4%, 85.7%, 94.1%, 80%, 89.8% at CI. Diagnostic performances of PET/CT and CI were not significantly different on a patient-based, side-by-side and level-by-level analysis. ¹⁸F-FDG-PET/CT recognized distant metastases in 7 patients allowing to an upstaging. At a median follow-up of 27 months, relapse/progression of disease occurred in 31 patients and death occurred in 32. Metabolic tumor volume (MTV T), MTV total and total lesion glycolysis (TLG) showed to be independent prognostic factors for PFS.

CONCLUSIONS

Both CI and PET/CT had good diagnostic performances for the staging of laryngeal cancer; baseline metabolic features (MTV and TLG) showed an important prognostic value in assessing the rate of PFS.

Comparison of clinicopathological patterns of renal tubular damage in dogs with acute kidney injury caused by leptospirosis and other aetiologies

In humans, leptospiral acute kidney injury (AKI) is characterised by tubulointerstitial involvement and renal electrolyte losses, impacting clinical presentation and case management. The aim of this study was to evaluate urine chemistry findings in dogs with leptospirosis in order to identify characteristic patterns of tubular damage associated with this disease. Dogs with intrinsic AKI caused by leptospirosis and by other aetiologies were prospectively enrolled. Clinical and clinicopathological variables, including serum and urine chemistry, fractional excretion (FE%) of electrolytes, and urinary neutrophil gelatinase-associated lipocalin (NGAL), were evaluated in both groups and compared statistically. Dogs with leptospirosis (n = 38) had significantly higher serum creatinine concentration than dogs with AKI caused by other aetiologies (n = 37). Serum potassium and glucose concentrations were comparable between groups. Dogs with leptospiral AKI had significantly higher FE of potassium (median 100%, range 20-480 vs. median 68%, range 5-300; P = 0.048), as well as higher magnitude of glucosuria (urine glucose to creatinine ratio, median 0.64, range 0-26 vs. median 0.22, range 0-13; P =  0.023) and frequency of positive glucose dipstick reaction (59% vs. 18%; P =  0.002), than dogs with AKI of other aetiologies. Additional markers of tubular damage considered in this study, including FE of other electrolytes and urinary NGAL, did not differ between groups. In conclusion, when compared to other aetiologies of intrinsic AKI, canine leptospirosis was characterised by increased glucosuria and kaliuresis.

Symmetric dimethylarginine concentrations in dogs with hypothyroidism before and after treatement with levothyroxine

OBJECTIVES

To evaluate the serum symmetric dimethylarginine (SDMA) and serum creatinine concentrations in a population of hypothyroid dogs at the time of diagnosis and after treatment.

MATERIALS AND METHODS

Serum SDMA and serum creatinine were measured in serum samples of 24 healthy dogs and 24 hypothyroid dogs, at the time of diagnosis (T0) and after supplementation with levothyroxine (T1).

RESULTS

The mean SDMA concentrations (reference intervals [RI] <18 μg/dL and <14 μg/dL depending on the source) were 11.7 ± 3.5 μg/dL, 13.8 ± 3.1 μg/dL and 11.83 ± 2.87 μg/dL in healthy dogs, and in the hypothyroid dogs at T0 and T1, respectively. The SDMA concentrations were higher in the hypothyroid dogs at T0 in comparison with the healthy dogs. Of the hypothyroid dogs, 1 out of 24 had an SDMA concentration above 18 μg/dL and 12 out of 24 above 14 μg/dL at T0. At T1, none of the hypothyroid dogs had SDMA concentrations above 18 μg/dL and two of them had SDMA concentrations above 14 μg/dL. The serum creatinine concentration was higher in the hypothyroid dogs at T0 as compared to the healthy dogs. At T0, 8 out of 24 hypothyroid dogs had serum creatinine concentrations above the RI (>1.4 mg/dL). In all but one dog, serum creatinine normalised after treatment.

CLINICAL SIGNIFICANCE

The SDMA and serum creatinine concentrations were higher in hypothyroid dogs at diagnosis as compared to healthy dogs. Serum creatinine concentrations were increased in one-third of the hypothyroid dogs and in the majority of cases normalised after levothyroxine supplementation. SDMA concentrations were rarely above the upper limit of the RI when the higest (<18 μg/dL) cut-off was employed. The diagnostic accuracy of SDMA in dogs with thyroid dysfunction requires additional evaluation.

Effects of feeding low fishmeal diets with increasing soybean meal levels on growth, gut histology and plasma biochemistry of sea bass

The aquaculture industry depends upon the development of sustainable protein sources to replace fishmeal (FM) in aquafeeds and the products derived from soybeans are some of the most studied plant feedstuffs. A key area of investigation for continuing to improve modern aquafeeds includes the evaluation of varying proportions and combinations of plant ingredients to identify mixtures that are more efficiently utilized by the fish. This study investigated the effects of increasing soybean meal (SBM) by replacing a mix of plant ingredients in low FM (20%) diets on growth, blood biochemistry profile and gut histology on European sea bass. Five isonitrogenous and isolipidic experimental diets were formulated: four diets containing increasing SBM levels (0, 10, 20 and 30%; 0SBM, 10SBM, 20SBM and 30SBM, respectively) with a low content of FM (20%) and one control diet (0% SBM; 35% FM). Diets containing SBM brought to comparable performance and protein utilization, while 0SBM had negative impact on feed conversion rate and protein utilization. Blood parameters suggested an optimal nutritional status under all feeding treatments, even though slightly decreased values were reported at increasing dietary SBM. Histology examination did not show any changes indicative of soy-induced enteritis. We can conclude that for European sea bass: (i) different blends of plant protein did not affect feed intake despite the 20% FM dietary level; (ii) the inclusion of SBM maintains optimal growth and feed utilization in low FM diets; (iii) blood biochemistry profile showed a good nutritional status under all feeding regimes; (iv) no evidence of soy-induced enteritis was reported in any group fed low FM diets. For formulation of practical diets in on-growing of European sea bass, SBM up to 30% can be successfully incorporated into feeds containing low FM inclusion.

Feasibility of the echocardiographic subcostal view in newborn foals: two-dimensional and Doppler aortic findings

BACKGROUND

In dogs, due to better alignment with the aortic outflow, the subcostal (SC) transducer site provides greater Doppler-derived velocities than those obtained from the left parasternal view. The feasibility of this imaging approach has never been described in equine echocardiography.

OBJECTIVES

The objective of this study was to evaluate the feasibility of the SC view in newborn foals and compare aortic two-dimensional and Doppler-derived velocity measurements with those of standard parasternal long-axis (LAX) views.

STUDY DESIGN

A prospective observational study.

METHODS

Twenty-three newborn healthy Standardbred and Warmblood foals, aged from 7 h to 6 days, underwent transthoracic two-dimensional (2DE), M-mode and Doppler echocardiography that was performed in lateral recumbency. Right and left parasternal long-axis (R-LAX, L-LAX) and SC views were obtained to perform 2DE and Doppler assessments of the aortic valve (AoV). Aortic diameter at the sinus of Valsalva (AoS D) was measured from R-LAX and SC images. Aortic maximal velocity (AoV Vel_max ), velocity time integral (AoV VTI) and pressure gradient (AoV PG) were obtained by pulsed wave Doppler spectra from SC and L-LAX views.

RESULTS

The SC view was feasible in all foals. No significant difference was found in AoS D between different views (P = 0.06), and no significant correlation was detected for bodyweight (BW). AoV Vel_max , VTI and PG obtained from the SC view were greater than from the L-LAX view (P<0.0001, P = 0.0001 and P<0.0001 respectively), especially in foals with lower BW.

MAIN LIMITATIONS

The order of the transducer site was not randomised among foals, and the observer was not blinded during offline measurement.

CONCLUSIONS

The SC view can be easily obtained in recumbent newborn foals and provides optimal alignment with aortic outflow, leading to more reliable Doppler flow velocity than the conventional L-LAX view. Further investigations of the potential use of this view in Doppler estimation of aortic outflow and cardiac assessment of sick foals are recommended.

Evaluation of the delta neutrophil index from an automated blood cell analyser in septic dogs

Immature granulocytes (IG) are a marker of severe inflammatory states in human beings and animals, and have been linked to a diagnosis of sepsis and poor prognosis. The delta neutrophil index (DNI), automatically calculated by a haematological analyser, provides an estimate of circulating IG. In particular, an increased DNI value has been associated with the severity of sepsis, and mortality, in critically ill human beings. The aims of this study were to determine the DNI reference interval (RI) in healthy dogs, and to evaluate its diagnostic and prognostic significance in dogs with sepsis. A total of 118 dogs with sepsis undergoing a complete blood cell count (CBC) at the time of hospital admission were included retrospectively. Dogs with sepsis were compared to 20 dogs with primary immune-mediated haemolytic anaemia (IMHA) and 99 healthy controls. The DNI RI was set from 0 to 9.2%. The DNI was significantly higher in dogs with sepsis compared to dogs with IMHA and healthy dogs (P<0.001), and significantly higher in dogs with septic shock compared to septic dogs without circulatory failure (P<0.03). No differences were detected between survivors (78/118) and non-survivors (40/118). Septic dogs with a DNI above the RI had significantly higher frequencies of IG and toxic neutrophil changes on manual blood smear evaluation (P=0.03 and P<0.001, respectively). The DNI had a fair performance in identifying dogs with sepsis in this population and predicted septic shock. Larger prospective studies are needed to validate DNI measurement in dogs and to test its clinical utility.

Accuracy of a Flash Glucose Monitoring System in Diabetic Dogs

Background

A novel flash glucose monitoring system (FGMS) (FreeStyle Libre, Abbott, UK) was recently developed for humans. It continuously measures the interstitial glucose (IG) concentrations for 14 days.

Objectives

To assess the clinical and analytical accuracy of the FGMS in diabetic dogs.

Animals

Ten client‐owned diabetic dogs on insulin treatment.

Methods

Prospective and observational study. The FGMS was placed on the neck for up to 14 days. During the 1st–2nd, 6–7th, and 13–14th days from application, the IG measurements were compared with the plasma (EDTA) glucose (PG) concentrations analyzed by a reference hexokinase based method.

Results

The application and the use of the FGMS were apparently painless, easy, and well tolerated by all dogs. Mild erythema at the site of the application was found in 5/10 dogs at the end of the wearing period. A good correlation between IG and PG concentrations (rho = 0.94; P < .001) was found. The FGMS was 93, 99, and 99% accurate at low, normal, and high blood glucose concentrations. Mean ± standard deviation difference from the reference method was 2.3 ± 46.8 mg/dL.

Conclusion and clinical importance

The FGMS is easy to use and is accurate for IG glucose measurement in diabetic dogs.

Investigation of the presence of canine adenovirus (CAdV) in owned dogs in Northern Italy

The use of a modified live canine adenovirus (CAdV) vaccine has greatly reduced the incidence of infectious canine hepatitis (ICH) in dogs. Nevertheless, cases of CAdV type 1 and 2 (CAdV-1 and CAdV-2) infection have been recently reported posing questions about the epidemiological situation of CAdV in dogs. In order to assess the presence of CAdV, samples from 51 dogs presented at a Veterinary Teaching Hospital in Bologna, Italy, for reasons unrelated with CAdV infection, were tested with a polymerase chain reaction (PCR) assay for CAdV. Thirty dogs (58.8%) were PCR positive for CAdV-2 infection and four of them (7.8%) were positive for CAdV-1. Sequence analysis performed on the obtained PCR products suggests that a genetically stable CAdV-1 strain and different CAdV-2 strains circulate in the canine population examined and that coinfections are relatively frequent.

Prognostic factors for survival in dogs with pituitary-dependent hypercortisolism treated with trilostane

Pituitary-dependent hypercortisolism (PDH) is one of the most frequent endocrinopathies in dogs, but prognostic factors are largely unknown. The aim of this retrospective case series study was to determine the prognostic value of different clinical and clinicopathological variables evaluated in dogs newly diagnosed with PDH that were subsequently treated with trilostane. Medical records from one referral centre were evaluated. Eighty-five dogs with PDH were included. The median survival time was 852 days (range 2-3210 days); 60/85 (70 per cent) and 25/85 (29 per cent) dogs survived more than one and three years, respectively. In multivariable model analysis the length of survival of older dogs (HR 1.24, 95% CI 1.09 to 1.40) and dogs with higher serum phosphate concentrations (HR 1.35, 95% CI 1.01 to 1.81) was shorter. Serum phosphate concentrations were above the reference range in 37/85 (44 per cent) of animals. Clinical signs, liver enzymes, serum cortisol concentrations of the endocrine tests, proteinuria, systolic hypertension, the presence of concomitant disorders, and the frequency of trilostane administration were not associated with survival time. Hyperphosphataemia is a common finding in dogs with newly diagnosed PDH and represents a negative prognostic factor.

Reversible pulmonary hypertension in a cat

A 13-year-old, neutered female domestic shorthair cat was presented for sudden respiratory distress following palliative radiotherapy and the combined administration of a single dose of carboplatin for the treatment of recurrent fibrosarcoma. Clinical and radiographic findings were suggestive of pleural effusion. Echocardiography revealed marked right-sided cardiac enlargement associated with tricuspid regurgitation and Doppler evidence of pulmonary hypertension. After 25 days of treatment for congestive heart failure and suspected pulmonary thromboembolism, clinical signs and echocardiographic and Doppler evidence of right-sided cardiac enlargement and pulmonary hypertension had completely resolved. To the best of the authors' knowledge, this is the first report of reversible pulmonary hypertension, likely secondary to pulmonary thromboembolism, in a cat.

Gas chromatography–mass spectrometry analysis of amino acid enantiomers as methyl chloroformate derivatives: Application to space analysis

This work describes a GC-MS method for enantioselective separation of amino acids. The method is based on a derivatization reaction which employs a mixture of alkyl chloroformate-alcohol-pyridine, as reagents to obtain the N(O,S)-alkyl alkoxy carbonyl esters of amino acids. Various reaction parameters are investigated and optimized to achieve a reproducible derivatization procedure suitable for separation of amino acid enantiomers on Chirasil-L-Val chiral stationary phase. In particular, the following topics are investigated for 20 proteinogenic amino acids: (i) the proper reagent and reaction conditions to obtain the highest derivative yield; (ii) the amino acid reactivity and the MS properties of the obtained derivatives; (iii) the linearity and sensitivity of the analytical method; (iv) the retention behavior of the derivatives and their enantiomeric separation on the Chirasil-L-Val chiral stationary phase. By combining the resolution power of the Chirasil-L-Val column and the high selectivity of the SIM MS detection mode, the described procedure enables the enantiomeric separation and quantification of 16 enantiomeric pairs of amino acids. The procedure is simple and fast and reproducible. It displays a wide linearity range at ppb detection limits for quantitative determinations: these properties make this derivatization method a suitable candidate for amino acid GC-MS analysis on board of the spacecrafts in space exploration missions of solar system body environments.

Development of an SdFFF–ETAAS hyphenated technique for dimensional and elemental characterization of colloids

Direct hyphenation of electrothermal atomic-absorption spectroscopy (ETAAS) to sedimentation field-flow fractionation (SdFFF) has been developed to enable elemental characterization of submicron particles as a function of size. This hyphenation is particularly suitable for characterizing colloidal particles of environmental interest, for example water-borne particles. The interface is an automatic capillary injection device (CID) which enables direct introduction of large and variable volumes of colloidal particle suspensions into a hot graphite furnace, thus preconcentrating the colloidal particles on the furnace walls. The method was validated by determination of Fe in certified submicron Fe2O3. The procedure was set up by first optimizing the SdFFF fractionation under programmed field conditions, thus enabling optimum fractionation of particle size. The ETAAS procedure was then tested to determine whether it could be used for direct analysis of Fe2O3 slurries without the need for a mineralization step. CID coupled to ETAAS was subsequently exploited for its ability to enhance the sensitivity, because of the increased injection volume. Statistical tests and data handling were conducted to prove the suitability of the ETAAS-CID module. Finally, off-line and on-line ETAAS-CID-SdFFF hyphenation were investigated. These experiments emphasized the advantages of the on-line coupling, because it enables synchronized sampling, enrichment, and elemental analysis of the flowing eluate. The benefits of the proposed hyphenation are the high specificity of analytical detection, increased sensitivity, reduction of analysis time, and minimum sample handling and contamination.

GC-MS analysis of amino acid enantiomers as theirN(O,S)-perfluoroacyl perfluoroalkyl esters: Application to space analysis

The target of the in-situ research of optical activity in extraterrestrial samples stimulated an extended investigation of a GC-MS method based on the derivatization of amino acids by using a mixture of perfluorinated alcohols and perfluorinated anhydrides. Amino acids are converted to their N(O,S)-perfluoroacyl perfluoroalkyl esters in a single-step procedure, using different combinations of the derivatization reagents trifluoroacetic anhydride (TFAA)-2,2,2-trifluoro-1-ethanol (TFE), TFAA-2,2,3,3,4,4,4-heptafluoro-1-butanol (HFB), and heptafluorobutyric anhydride (HFBA)-HFB. The derivatives obtained are analyzed using two different chiral columns: Chirasil-L-Val and gamma-cyclodextrin (Rt-gamma-DEXsa) stationary phases which show different and complementary enantiomeric selectivity. The mass spectra of the derivatives are studied, and mass fragmentation patterns are proposed: significant fragment ions can be identified to detect amino acid derivatives. The obtained results are compared in terms of the enantiomeric separation achieved and mass spectrometric response. Linearity studies and the measurement of the limit of detection (LOD) show that the proposed method is suitable for a quantitative determination of enantiomers of several amino acids. The use of the programmed temperature vaporiser (PTV) technique for the injection of the untreated reaction mixture is a promising method for avoiding manual treatment of the sample and decreasing the LOD.

In situ analysis of the Martian soil by gas chromatography: Decoding of complex chromatograms of organic molecules of exobiological interest

Gas chromatography-mass spectrometry (GC-MS) will be used in future space exploration missions, in order to seek organic molecules at the surface of Mars, and especially potential chemical indicators of life. Carboxylic acids are among the most expected organic species at the surface of Mars, and they could be numerous in the analysed samples. For this reason, a chemometric method was applied to support the interpretation of chromatograms of carboxylic acid mixtures. The method is based on AutoCovariance Function (ACVF) in order to extract information on the sample--number and chemical structure of the components--and on separation performance. The procedure was applied to standard samples containing targeted compounds which are among the most expected to be present in the Martian soil: n-alkanoic and benzene dicarboxylic acids. ACVF was computed on the obtained chromatograms and plotted versus retention time: peaks of the ACVF plot can be related to specific molecular structures and are diagnostic for chemical identification of compounds.

Analysis of complex mixtures recovered from space missions statistical approach to the study of Titan atmosphere analogues (tholins)

To study Titan, the largest moon of Saturn, laboratory simulation experiments have been performed to obtain analogues of Titan's aerosols (named tholins) using different energy sources. Tholins, which have been demonstrated to represent aerosols in Titan's haze layers, are a complex mixture, resulting from the chemical evolution of several hydrocarbons and nitriles. Their chromatographic analysis yields complex chromatograms, which require the use of mathematical procedures to extract from them all the information they contain. Two different chemometric approaches (the Fourier analysis approach and the statistical model of peak overlapping) have been successfully applied to pyrolysis-GC-MS chromatogram of a tholin sample. Fundamental information on the mixture's chemical composition (number of components, m) and on the separation system performance (separation efficiency, sigma) can be easily estimated: the excellent correspondence between the data calculated by the two independent procedures proves the reliability of the statistical approaches in characterizing a tholin chromatogram. Moreover, the plot of autocorrelation function contains, in a simplified form, all the information on the retention pattern: retention recursivities can be easily singled out and related to specific molecular structure variations. Therefore, the autocorrelation function (ACF) plot constitutes a simplified fingerprint of the pyrolysis products of tholins, which can be used as a powerful tool to characterize a tholin sample.

Continuous split-flow thin cell and gravitational field-flow fractionation of wheat starch particles

The combined employment of the SPLITT (split-flow thin) cell--a relatively new system for fast, continuous binary separation--and of gravitational field-flow fractionation (GrFFF)--a fractionation technique suitable for micron particle size distribution determination--was investigated for starch separation and characterization. Emphasis is placed on the main advantages of both techniques: operating under gentle earth gravity field, low cost and ease of maintenance. The reproducibility of GrFFF is demonstrated. Both the SPLITT separation and GrFFF fractionation results were checked by optical microscopy. Application examples of typical starch fractionation experiments are reported and discussed.