Absolute characterization of colloids by Field-Flow Fractionation.

The fundamental aspects of FFF techniques in their features of being absolute characterization techniques for colloids, particles,macromolecules and molecular assemblies, are reviewed. The different possible procedures for obtaining primary quantities for both monodisperse or quasi-monodisperse species and distributions of primary quantities for polydisperse species are described

Monte Carlo Model of non-Linear Chromatography

A stochastic approach to the nonlinear chromatography theory, based on the Monte Carlo simulation method, is presented. A computer program, acting as a "virtual chromatograph" and performing a discrete event simulation, is described. Such a program allows one to choose the column type, operating conditions, sample composition, injection method, mobile-phase dispersion model, and stationary-phase sorption-desorption kinetics. Nonlinearity is accounted for by continuously monitoring and updating both the column and the solute status and by moving individual molecules step by step along the column according to specific random modes. The program has been validated through a series of statistical tests and comparing the results with the well-known achievements of the classical stochastic theory. A first application is presented, referred to a real case benzene elution on a gas solid capillary column, where the Langmuir adsorption isotherm is assumed. The effect of both the sorption modes and the site capacity are investigated. Possible applications to investigate open problems in several fields of separation science are emphasized. In addition, several specific points such as the down-scaling of a real case and the correspondence of specific adsorption dynamics with the equilibrium Langmuir isotherm are described

VALIDATION OF AN ELECTROPHORETIC METHOD TO DETECT URINARY ALBUMIN IN CATS.

Urine samples were collected from 66 feline hospital admissions by cystocentesis or free catch, and analyzed (UPC, HRE). Within-assay imprecision for high (H), medium (M) and low (L) concentrations, between-assay imprecision, linearity/accuracy and percentage recovery were determined for albumin. Albumin was assessed by urine to creatinine ratio (UAC), percentage (ALB%) and mg/dl (ALB mg/dl). Cases were categorized: a) as chronic kidney disease with (CKDC) and without complications (CKD), feline lower urinary tract disease (FLUTD) or other, and b) as proteinuric (P), borderline proteinuric (BP), or not proteinuric (NP), and c) by type of sediment active (A) or not active (NA). Results: HRE within-assay CV was 2.58%(H), 5.31%(M), 3.42%(L), between-assay CV was 3.52%, recovery percentage was 97%, 93% and 109% for high, medium and low concentration, respectively, and linearity was high (r=0.99). Compared with UPC at different cut-off values, HRE showed higher specificity and PPV but lower sensitivity and NPV than dipstick to measure proteinuria. Dipsticks showed frequent false positives compared with HRE. Based on UPC, measures of albuminuria were higher in proteinurics than non-proteinurics, and ALB% correlated to UPC (r=0.35, R2=0.12, p<0.05) and UAC (r=0.41, R2=0.17, p<0.05). Samples with active sediment had higher ALB% than samples with inactive sediment. ALB% was not different between proteinuria groups (P, BP, NP). UPC, UAC, ALB mg/dl, ALB% were not different across pathologies, even if CKD had higher values. Conclusions: HRE is accurate and precise for measuring urinary albumin in cats. UPC, UAC and ALB% were correlated. Increases in filtered albumin and proteinuria indicate a greater glomerular involvement in renal disease

SPLITT cell separation of polydisperse suspended particles of environmental interest.

An analytical methodology for the dimensional characterization of SPM (Suspended Particle Matter) from natural waters, by using the SPLITT (Split-Flow Thin) cell separation technique is presented. The application of the SPLITT cells as continuous, two-way separative system for natural particle samples, has been studied focusing on the role of particle parameters, as density and shape, in the technique performance

CARATTERIZZAZIONE DIMENSIONALE ED ELEMENTALE DEL PARTICOLATO ATMOSFERICO MEDIANTE APPROCCIO INTEGRATO SDFFF/AAS/ICP-AES

L’inquinamento atmosferico è un fenomeno dinamico molto complesso determinato dalla presenza di sostanze indesiderate che, per qualità o quantità o lunga permanenza, compromettono la salubrità dell’aria, risultando pericolose per la salute dell’uomo e dannose per i materiali esposti. Il materiale particolato sospeso è una importante componente dell’atmosfera che viene studiata e controllata come indicatore di inquinamento, principalmente a causa dell’impatto negativo che ha sulla salute dell’uomo, dato che il materiale più fine di cui si compone, penetrando nelle vie respiratorie, può indurre alterazioni gravi delle mucose bronchiali, anche in virtù della sua capacità di veicolazione e di diffusione dei metalli pesanti ad esso associati, inquinanti prioritari conclamati. In questo contesto risulta interessante la caratterizzazione dimensionale ed elementale del particolato atmosferico per valutarne l’impatto ambientale. Si riportano qui alcuni risultati di uno studio di caratterizzazione dimensionale ed elementale di questa matrice ambientale, condotto attraverso un approccio metodologico di tecniche separative, la tecnica di Field Flow Fractionation (FFF), accoppiate con tecniche identificative di tipo spettroscopico (AAS e ICP-AES)1,2,3. La metodologia è applicata a campioni di PTS e PM10, prendendo in considerazione alcuni metalli di maggior interesse ambientale, quali Cd, Cr, Cu, Mn, Pb, Ni e Fe. Viene sottolineata la possibilità della metodologia sviluppata di fornire informazioni sul carico inquinante di metalli pesanti in funzione delle dimensioni delle particelle considerate, in maniera integrata

Suspected venous air embolism during urinary tract endoscopy in a standing horse

During cystoscopy, performed with air insufflation in a standing Argentinian gelding, the horse showed ataxia and fell to the ground with generalised muscular twitching and horizontal nystagmus, tachypnoea and tachyarrhythmia. General anaesthesia was induced. Arterial blood gas-analysis before induction of anaesthesia revealed an increased pH, decreased partial pressure of carbon dioxide and decreased partial pressure of oxygen. Venous air embolism was suspected