Minimum effective betamethasone dosage on the neurological phenotype in patients with ataxia-telangiectasia: a multicenter observer-blind study.

BACKGROUND AND PURPOSE: Ataxia-telangiectasia (A-T) is a rare neurodegenerative disease, due to A-T mutated (ATM) gene mutations, which typically presents with signs of progressive neurological dysfunction, cerebellar ataxia and uncoordinated movements. A-T severely affects patients' quality of life. Successful treatment options are still not available. The aim of this multicenter study, performed with a blind evaluation procedure, was to define the minimal effective dosage of oral betamethasone, thus preventing the occurrence of side effects. METHODS: Nine A-T patients were enrolled to receive betamethasone at increasing dosages of 0.001, 0.005 and 0.01 mg/kg/day. Neurological assessment and the evaluation of quality of life were performed through the Scale for the Assessment and Rating of Ataxia and the Italian version of the Childhood Health Assessment Questionnaire (CHAQ) at each time-point. The drug safety profile was evaluated. Patients were categorized as responders, partial responders and non-responders. RESULTS: Four of nine patients had a benefit at a dose of 0.005 mg/kg/day of oral betamethasone. Using the higher dosage, only one additional patient had a positive response. Conversely, a daily dose of 0.001 mg/kg was ineffective. A correlation between the serum adrenocorticotropic hormone levels and the clinical response was observed. Five of 30 CHAQ items improved in four patients. CONCLUSIONS: These data suggest that a short-term betamethasone oral treatment, at a daily dosage of 0.005 mg/kg, is effective in some patients. Pre-existing risk factors for side effects should be taken into account before therapy.

Carbon nanotubes as nanovectors for intracellular delivery of laronidase in Mucopolysaccharidosis type I.

The immobilization of proteins on carbon nanotubes (CNTs) has been widely reported mainly for the preparation of sensors while the conjugation of enzymes for therapeutic purposes has scarcely been considered. Herein we report, to the best of our knowledge, the first example of intracellular delivery of a therapeutic enzyme by means of CNTs, retaining its activity. Mucopolysaccharidosis I is a rare genetic disease characterized by the deficiency or absence of the activity of the α-l-iduronidase (IDUA) enzyme. We evaluated the capacity of the recombinant form of the human IDUA enzyme, laronidase (Aldurazyme®), conjugated with CNTs to be internalized by fibroblasts from subjects affected with Mucopolysaccharidosis type I and the capacity of the enzyme to retain its activity after internalization. The enzyme was successfully delivered into the lysosomal space and the enzymatic activity of the conjugate was preserved after internalization up to 48 hours. This paves the way towards the use of such a kind of construct for therapeutic applications.

Results of an interlaboratory comparison of analytical methods for quantification of anhydrosugars and biosugars in atmospheric aerosol.

An interlaboratory comparison was performed to evaluate the analytical methods for quantification of anhydrosugars - levoglucosan, mannosan, galactosan - and biosugars - arabitol, glucose and mannitol - in atmospheric aerosol. The performance of 10 laboratories in Italy currently involved in such analyses was investigated on twenty-six PM (particulate matter) ambient filters, three synthetic PM filters and three aqueous standard solutions. An acceptable interlaboratory variability was found, determined as the mean relative standard deviation (RSD%) of the results from the participating laboratories, with the mean RSD% values ranging from 25% to 46% and decreasing with increasing sugar concentration. The investigated methods show good accuracy, evaluated as the percentage error (ε%) related to mean values, since method biases ranged within ±20% for most of the analytes measured in the different laboratories. The detailed investigation (ANOVA analysis at p < 0.05) of the contribution of each laboratory to the total variability and the measurement accuracy shows that comparable results are generated by the different methods, despite the great diversity in terms of extraction conditions, chromatographic separation - more recent LC (liquid chromatography) and EC (exchange chromatography) methods compared to more widespread GC (gas chromatography) - and detection systems, namely PAD (pulsed amperometric detection) or mass spectrometry.

Genetic epistasis between killer immunoglobulin-like receptors and human leukocyte antigens in Kawasaki disease susceptibility.

Kawasaki disease (KD) is a pediatric acute multisystemic vasculitis complicated by development of coronary artery lesions. The breakthrough theory on KD etiopathogenesis points to pathogens/environmental factors triggered by northeastern wind coming from China. Natural Killer cells and T lymphocytes express the inhibitory/activating Killer Immunoglobulin-like Receptors (KIR) to elicit an immune response against pathogens by binding to human leukocyte antigens (HLA) class I epitopes. We first report on the role of KIR/HLA genetic epistasis in a sample of 100 Italian KD children. We genotyped KIR, HLA-A, HLA-B and HLA-C polymorphisms, and compared KD data with those from 270 Italian healthy donors. The HLA-A*11 ligand for KIR2DS2/2DS4/3DL2 was a KD susceptibility marker by itself (odds ratio (OR)=3.85, confidence interval (CI)=1.55-9.53, P=0.004). Although no epistasis between HLA-A*11 and KIR2DS2/S4 emerged, HLA-A*11 also engages KIR3DL2, a framework gene encoding for a pathogen sensor of CpG-oligodeoxynucleotides (CpG-ODN), and KD blood mononuclear cells are actually prone to pathogen CpG-ODN activation in the acute phase. Moreover, carriers of KIR2DS2/HLA-C1 and KIR2DL2/HLA-C1 were more frequent among KD, in keeping with data demonstrating the involvement of these HLA/KIR couples in autoimmune endothelial damage. The highest KD risk factor was observed among carriers of KIR2DL2 and two or more HLA ligands (OR=10.24, CI=1.87-56.28; P=0.007).

Data handling of GC/MS signals for characterization of PAH sources in Northern Italy aerosols.

The paper describes the characterization of polycyclic aromatic hydrocarbons (PAHs) in atmospheric aerosol samples using Gas Chromatography-Mass Spectrometry analysis. A data handling of GC/MS signals based on Experimental Autocovariance Function (EACVF) is described in order to directly characterize PAHs with a simple and reliable method suitable for processing large batches of samples. The method was successfully applied to 42 aerosol samples collected in different seasons (summer, fall and winter) in two locations in Northern Italy: Milan, a large urban area, and Oasi Le Bine, a rural site. The reliability of the EACVF results was verified by comparison with the values computed with the conventional GC/MS signal treatment and the data of independent studies. Two main emission sources were identified and described by PAH concentration profiles: the road traffic source (TR), characterized by high contributions of FLNT, PYR and CHR, and the residential combustion (COMB) mainly containing pyrogenic high molecular weight PAHs, i.e., CHR, BaP, BeP, BbF and BkF. In addition, some PAH diagnostic ratios were directly computed for the EACVF plot, to distinguish between traffic and combustion dominated emissions, i.e. the ratios CHR/BaP, PYR/BaP and PYR/BeP.

Liquid chromatography time-of-flight mass spectrometry evaluation of fungicides reactivity in free chlorine containing water samples.

Liquid chromatography (LC) combined with tandem mass spectrometry (MS/MS), based on the use of a hybrid quadrupole-time-of-flight mass analyzer, was used to investigate the reactivity of nine fungicides in free chlorine-containing water samples. Three of the selected compounds (fenhexamid, FEN; pyrimethanil, PYR; and cyprodinil, CYP) displayed a poor stability in presence of moderate chlorine levels; thus, the effects of different parameters on their half-lives (t(1/2)) were evaluated. Sample pH, bromide traces, and the water matrix affected their relative stabilities. Despite such variations, the three fungicides are degraded at significant rates not only in ultrapure, but also in surface water spiked with chlorine levels up to 2 µg ml(-1), and when mixed with chlorinated tap water, generating several transformation products (TPs). The time-course of precursor species and their TPs was followed in the LC-MS mode, using the information contained in accurate, full scan mass spectra (MS) to propose the empirical formulae of TPs. Thereafter, their ion product scan (MS/MS) spectra were considered to set their chemical structures; allowing, in some cases, to distinguish between isomeric TPs. The reaction pathway of FEN, the less stable fungicide, involved just an electrophilic substitution of hydrogen per chlorine, or bromine, and cleavage of the molecule to render an amide. PYR and CYP shared common reaction routes consisting of halogenation, hydroxylation, and condensation processes leading to complex mixtures of TPs, which were relatively stable to further transformations.

Anti-infective prophylaxis for primary immunodeficiencies: what is done in Italian Primary Immunodeficiency Network centers (IPINet) and review of the literature.

Primary immunodeficiencies (PIDs) are rare diseases characterized by an increased susceptibility to infections. Early diagnosis and appropriate treatment are critical for reducing morbidity and mortality. Based on available data, the efficacy of antibiotic administration for the prophylaxis of infections remains uncertain, and recommendations supporting this practice are poor. The use of antimicrobial prophylaxis is mainly based on single institution-specific experience without controlled measurements of patient safety and quality health outcomes. To address this issue an Italian Network on Primary Immunodeficiencies (IPINet) has been set up in 1999 within the Italian Association of Pediatric Hematology and Oncology (AIEOP) to increase the awareness of these disorders among physicians. Further, diagnostic and treatment guideline recommendations have been established to standardize the best clinical assistance to all patients, including antibiotic prophylaxis, and for a national epidemiologic monitoring of PIDs. The aim of this review is not only to give a scientific update on the use of antimicrobial prophylaxis in selected congenital immunological disorders but also to draw a picture of this practice in the context of the Italian Primary Immunodeficiency Network (IPINet). Controlled multicenter studies are necessary to establish if, when and how you should start an efficacious antimicrobial prophylaxis.

Health-related quality of life in severe cryoglobulinaemic vasculitis and improvement after B-cell depleting therapy.

OBJECTIVES: To study the health-related quality of life (HRQOL) in severe cryoglobulinaemic vasculitis (CV) associated with hepatitis C virus infection (HCV) and to describe the effect of rituximab on HRQOL. METHODS: HRQOL was evaluated with the Medical Outcomes Study Short Form 36 (SF-36). Health Survey questionnaire was submitted to 15 patients with severe CV. SF-36 questionnaire was evaluated at baseline and after rituximab. Physical Health Composite Summary (PCS) and Mental Health Composite Summary (MCS) scores were calculated according to standard protocols, and normalised to healthy controls. SF-36 summary scores were compared with those of HCV positive patients without CV, and other vasculitis published in the literature. European Quality of Life-5 dimensions (EQ5D) scores were also derived. RESULTS: Physical and mental domain scores were all reduced if compared with those of the healthy population, with physical domains being greatly affected. HRQOL of CV was comparable with HRQOL reported for the other small vessel vasculitis. The development of CV in HCV positive patients worsened PCS rather than MCS score. Birmingham Vasculitis Activity Score (BVAS) did not correlate with HRQOL, while the presence of peripheral neuropathy was associated with a worse HRQOL. Early rituximab treatment improved both PCS and MCS scores, with long-term effects. CONCLUSIONS: PCS rather than MCS was affected in HCV positive patients when CV is present. Rituximab improved both physical and mental domains, thus supporting its use before antiviral therapy in severe HCV-related CV. The cost/benefits ratio of a sequential therapy may be supported.

A randomized controlled trial of rituximab for the treatment of severe cryoglobulinemic vasculitis.

OBJECTIVE: To conduct a long-term, prospective, randomized controlled trial evaluating rituximab (RTX) therapy for severe mixed cryoglobulinemia or cryoglobulinemic vasculitis (CV). METHODS: Fifty-nine patients with CV and related skin ulcers, active glomerulonephritis, or refractory peripheral neuropathy were enrolled. In CV patients who also had hepatitis C virus (HCV) infection, treatment of the HCV infection with antiviral agents had previously failed or was not indicated. Patients were randomized to the non-RTX group (to receive conventional treatment, consisting of 1 of the following 3: glucocorticoids; azathioprine or cyclophosphamide; or plasmapheresis) or the RTX group (to receive 2 infusions of 1 gm each, with a lowering of the glucocorticoid dosage when possible, and with a second course of RTX at relapse). Patients in the non-RTX group who did not respond to treatment could be switched to the RTX group. Study duration was 24 months. RESULTS: Survival of treatment at 12 months (i.e., the proportion of patients who continued taking their initial therapy), the primary end point, was statistically higher in the RTX group (64.3% versus 3.5% [P < 0.0001]), as well as at 3 months (92.9% versus 13.8% [P < 0.0001]), 6 months (71.4% versus 3.5% [P < 0.0001]), and 24 months (60.7% versus 3.5% [P < 0.0001]). The Birmingham Vasculitis Activity Score decreased only after treatment with RTX (from a mean ± SD of 11.9 ± 5.4 at baseline to 7.1 ± 5.7 at month 2; P < 0.001) up to month 24 (4.4 ± 4.6; P < 0.0001). RTX appeared to be superior therapy for all 3 target organ manifestations, and it was as effective as conventional therapy. The median duration of response to RTX was 18 months. Overall, RTX treatment was well tolerated. CONCLUSION: RTX monotherapy represents a very good option for severe CV and can be maintained over the long term in most patients.

Preliminary classification criteria for the cryoglobulinaemic vasculitis.

BACKGROUND: To develop preliminary classification criteria for the cryoglobulinaemic syndrome or cryoglobulinaemic vasculitis (CV). METHODS: Study part I developed a questionnaire for CV to be included in the formal, second part (study part II). Positivity of serum cryoglobulins was defined by experts as an essential condition for CV classification. In study part II, a core set of classification items (questionnaire, clinical and laboratory items, as agreed) was tested in three groups of patients and controls-that is, group A (new patients with the CV), group B (controls with serum cryoglobulins but lacking CV) and group C (controls without serum cryoglobulins but with features which can be observed in CV). RESULTS: In study part I (188 cases, 284 controls), a positive response to at least two of three selected questions showed a sensitivity of 81.9% and a specificity of 83.5% for CV. This questionnaire was employed and validated in study part II, which included 272 patients in group A and 228 controls in group B. The final classification criteria for CV, by pooling data from group A and group B, required the positivity of questionnaire plus clinical, questionnaire plus laboratory, or clinical plus laboratory items, or all the three, providing a sensitivity of 88.5% and a specificity of 93.6% for CV. By comparing data in group A versus group C (425 controls), the same classification criteria showed a sensitivity 88.5% and a specificity 97.0% for CV. CONCLUSION: Classification criteria for CV were developed, and now need validation.

Multi-residual GC-MS determination of personal care products in waters using solid-phase microextraction.

A multi-residual method is described for the simultaneous determination of 23 personal care products (PCPs), which display a wide range of physicochemical properties, present at trace levels in water samples. A one-step procedure was developed based on solid-phase microextraction (SPME) coupled with GC-MS analysis. A chemometric approach consisting of an experimental design (design of experiments) was applied to systematically investigate how four operating parameters--extraction temperature and time and desorption temperature and time--affect extraction recovery of PCPs in water. The optimum SPME procedure operating conditions, those yielding the highest extraction recovery for all the compounds, were determined; they correspond to an extraction time of 90 min and temperature of 80 °C and a desorption time of 11 min and temperature of 260 °C. Under these optimized conditions, the SPME procedure shows good analytical performance characterized by high reproducibility (RSD% intra-day accuracy varying in the 0.01-1.3% range) as well as good linearity and low detection limits (LODs lower than 2 ppb for most of the investigated PCPs).

Distribution of n-alkanes in the Northern Italy aerosols: data handling of GC-MS signals for homologous series characterization.

The paper describes the characterization of n-alkane homologous series present in PM samples performed by gas chromatography-mass spectrometry analysis. The PM samples were collected in three locations in northern Italy: Milan, a large urban area, Oasi Bine, a rural site far from big city centers, and Alpe San Colombano, a remote, high altitude site in the Alps. They represent different particle sizes (PM(1), PM(2.5), PM(10)) and seasons (summer, fall, and winter). The analyzed samples were characterized in terms of PM total mass, total concentration of C(20)-C(32) n-alkanes and carbon preference index, CPI, to quantify the relative abundance of odd versus even n-alkanes. As alternative to the conventional method based on peak integration, a chemometric approach based on autocovariance function (EACVF) computation was found reliable to characterize the homologous series. In particular two parameters have proven useful chemical markers for tracking the biogenic and anthropogenic origins of n-alkanes: CPI(EACVF) and series %, estimating the % n-alkanes abundance relative to total alkane concentration. The investigated samples display a large variation in the n-alkanes relative abundance: the lowest values (series % = 1-14%) were found in summer and the highest (series % = 24-48%) in winter. In addition, a considerable seasonal variation of CPI(EACVF) values can be identified for all the sampling sites: the CPI(EACVF) values are close to 1 (CPI(EACVF) = 0.8-1.2) in the cold seasons, revealing a strong contribution from anthropogenic emissions, while spreader values (CPI(EACVF) = 0.9-3) were found in the warm season, that is, reflecting a variable contribution from biogenic sources in combination with anthropogenic emissions.

Enantiomeric resolution of biomarkers in space analysis: Chemical derivatization and signal processing for gas chromatography-mass spectrometry analysis of chiral amino acids.

The work compares two GC-MS methods for enantioselective separation of amino acids as suitable candidate for stereochemical analysis of chiral amino acids on board spacecrafts in space exploration missions of solar system body environments. Different derivatization reagents are used: a mixture of alkyl chloroformate-alcohol-pyridine to obtain the alkyl alkoxy carbonyl esters and a mixture of perfluorinated alcohols and anhydrides to form perfluoroacyl perfluoroalkyl esters. 20 proteinogenic amino acids were derivatized with the two procedures and submitted to GC-MS analysis on a Chirasil-l-Val stationary phase. The results were then compared in terms of the enantiomeric separation achieved and intensity of MS response. The combination of methyl chloroformate (MCF) and heptafluoro-1-butanol (HFB) allows separation of 14 enantiomeric pairs, five of which display a resolution (R(s)>or=1.2) supposed to be sufficient to quantify the enantiomeric excess. Three mixtures of trifluoroacetic (TFAA) and heptafluorobutyric (HFBA) anhydrides were combined with the corresponding perfluorinated alcohols - TFE (2,2,2-trifluoro-1-ethanol) and HFB (2,2,3,3,4,4,4-heptafluoro-1-butanol) - to give three different reagents (TFAA-TFE, TFAA-HFB, HFBA-HFB): the derivatives obtained show separation of the same number of proteinogenic amino acids (14 of 20) at a temperature lower than column bleeding limit (200 degrees C) and 8 of them give a separation with R(s)>or=1.2. Linearity study and limit of detection (X(LOD)) computation show that both methods are suitable for quantitative determination of several amino acid diastereomers at trace level (X(LOD) approximately 0.5nmol as derivatized quantity). Both the procedures were coupled with automatic data handling to increase their suitability for space analysis: the simplified data treatment is especially helpful to handle the low quality data recovered from space experiments and labor and time are saved, as imposed by the space experiments requiring a rapid delivery of the results. To achieve this aim, a chemometric approach based on the computation of the Autocovariance Function (ACVF) was applied to extract information on the enantiomeric pairs present in the sample and the enantioseparation achieved on the chiral column.

Reduced memory B cells in patients with hyper IgE syndrome.

Dominant-negative mutations in STAT-3 have recently been found in the majority of patients with sporadic or autosomal-dominant hyper IgE syndrome (HIES). Since STAT-3 plays a role in B cell development and differentiation, we analyzed memory B cells in 20 patients with HIES, 17 of which had STAT-3 mutations. All but four patients had reduced non-switched and/or class-switched memory B cells. No reduction in these B cell populations was found in 16 atopic dermatitis patients with IgE levels above 1000 KU/L. There was no correlation between the reduction of memory B cells and the ability to produce specific antibodies. Moreover, there was no correlation between the percentage of memory B cells and the infection history. Analysis of memory B cells can be useful in distinguishing patients with suspected HIES from patients with atopic disease, but probably fails to identify patients who are at high risk of infection.

A prospective study on children with initial diagnosis of transient hypogammaglobulinemia of infancy: results from the Italian Primary Immunodeficiency Network.

Transient hypogammaglobulinemia of infancy (THI) is a heterogeneous disorder characterized by reduced serum IgG levels in early infancy. A putative diagnosis is initially made after exclusion of other causes of hypogammaglobulinemia while a definitive diagnosis of THI can only be made a posteriori in patients with normalization of IgG levels. The aim of this study is to characterize clinical and immunological features of children with an initial diagnosis of THI in correlation to natural outcome, and to assess predictive laboratory parameters of clinical evolution for this disorder. We prospectively analysed clinical and immunological characteristics of 77 THI children at initial diagnosis and of 57 patients at follow-up. Memory B cell subsets and in vitro immunoglobulin production were evaluated. Seventy patients (91 percent) showed clinical symptoms. Patients suffered from infections (91 percent), allergies (47 percent) and autoimmune disease (4 percent). During follow-up 41/57 children (72 percent) normalized IgG values, mostly within 24 months of age (p less than 0.001), allowing the diagnosis of THI. The 16 children who did not normalize their IgG levels showed a higher frequency of severe infections and autoimmune disease (p less than 0.01). Moreover, they expressed a reduced frequency of IgM and switched memory B cells (p less than 0.01) and an inability to produce IgG in vitro (p less than 0.02). We conclude that most patients with an initial diagnosis of THI spontaneously recover within 24 months of age and have a benign clinical course, while a subgroup of children with undefined hypogammaglobulinemia share a clinical and immunological profile with other primary immunodeficiencies. Early recognition of children with hypogammaglobulinemia during infancy who are likely to suffer from permanent immunodeficiencies later in life would allow prompt and appropriate laboratory and clinical interventions.

Risk factors for Sjögren's syndrome: a case-control study.

OBJECTIVE: The aim of this study was to investigate potential risk factors for Sjögren's syndrome (SS) by means of a multi-centre case-control study, focusing in particular on familial and environmental risk factors. 140 female SS patients and 109 female controls with orthopaedic problems were consecutively enrolled in seven university hospitals in Italy. METHODS: Information regarding the patient's lifestyle, her medical, menstrual and pregnancy history, and any family history of autoimmune diseases (AD) was obtained through a detailed structured questionnaire. The odds ratio (OR) and 95% confidence interval (95%CI) were calculated using unconditional logistic regression, adjusting for age and family size. The probability of first-degree relatives developing an autoimmune disease was also investigated. RESULTS: A positive family history of AD was significantly associated with SS. Subjects with a first-degree relative (FDR) with AD showed a seven-fold increase in the risk for SS compared to controls (OR=7.4, 95%CI 2.8-20.1); the strength of this association increased with the number of relatives affected. Similarly, the FDR of SS patients had a higher risk of AD in comparison to subjects without FDR affected by SS. Women with one or more pregnancies had an increased risk of SS (OR=2.1, 95%CI 1.0-4.3). CONCLUSION: This study suggests that a family history of AD is associated with SS.

Molecular analysis of the pre-BCR complex in a large cohort of patients affected by autosomal-recessive agammaglobulinemia.

Autosomal-recessive agammaglobulinemia is a rare and heterogeneous disorder, characterized by early-onset infections, profound hypogammaglobulinemia of all immunoglobulin isotypes and absence of circulating B lymphocytes. To investigate the molecular basis of the disease, 23 patients with early-onset disease and no mutations in Bruton tyrosine kinase, the gene responsible for X-linked agammaglobulinemia, were selected and analyzed by direct sequencing of candidate genes. Two novel mutations in the mu heavy chain (muHC) gene (IGHM) were identified in three patients belonging to two unrelated families. A fourth patient carries a previously described G>A nucleotide substitution at the -1 position of an alternative splice site in IGHM; here, we demonstrate that this mutation is indeed responsible for aberrant splicing. Comparison of bone marrow cytofluorimetric profiles in two patients carrying different mutations in the IGHM gene suggests a genotype-phenotype correlation with the stage at which B-cell development is blocked. Several new single nucleotide polymorphisms (SNPs) both in the muHC and in the lambda5-like/VpreB-coding genes were identified. Two unrelated patients carry compound heterozygous variations in the VpreB1 gene that may be involved in disease ethiology.

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.

GC-MS analysis of amino acid enantiomers as their N(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.