Conferenza pubblica sulla Chimica Forense nell'ambito del ciclo di conferenze "Un Mare di Scienza" organizzato dalla Scuola di Scienze dell'Università degli Studi di Genova.
Dynamic light scattering measures the fluctuation changes in the intensity of scattered light to determine particle size and properties. It works by measuring the rate at which the intensity of scattered light fluctuates due to Brownian motion of particles. Larger particles diffuse more slowly than smaller particles, so intensity fluctuations are slower for large particles. The correlation function contains information about particle diffusion, with steeper curves indicating more monodisperse samples and more extended decay indicating greater polydispersity. Dynamic light scattering can determine particle size distribution, hydrodynamic radius, and diffusion coefficient.
The document discusses various concepts related to liquid chromatography including:
1. Distribution ratio and separation factor which are important parameters in liquid-liquid extraction.
2. Different types of chromatography techniques like normal phase, reverse phase, adsorption, ion-exchange, size exclusion chromatography.
3. Key aspects of liquid chromatography instrumentation like the pump, injector, column, detectors, and data system. Common detectors discussed are UV-Vis, fluorescence, conductivity etc.
MRI physics involves magnetic resonance imaging using protons' spin and magnetic properties. Protons precess at their Larmor frequency when placed in an external magnetic field. Radiofrequency pulses excite protons which absorb and emit energy, inducing a signal. Magnetic field gradients encode spatial information to generate images showing proton density and relaxation times, providing tissue contrast. Contrast depends on extrinsic parameters like pulse timing and intrinsic properties like T1 and T2 relaxation times.
Elemental CHNSO (CHNOS) analysis for determination of carbon, hydrogen, nitrogen, sulfur and oxygen content in petroleum products, biofuels, and more. CHNSO (CHNOS) elemental analyses from Intertek is available for a wide range of products and materials.
How to better understand SAR, interpret SAR products and realize the limitationsNopphawanTamkuan
This content shows how to better understand SAR (how to interpret SAR images and read SAR interferogram ). Moreover, capacities and limitations of SAR are discussed for each disaster emergency mapping (Flood, Landslide and Earthquake).
Dynamic light scattering measures the fluctuation changes in the intensity of scattered light to determine particle size and properties. It works by measuring the rate at which the intensity of scattered light fluctuates due to Brownian motion of particles. Larger particles diffuse more slowly than smaller particles, so intensity fluctuations are slower for large particles. The correlation function contains information about particle diffusion, with steeper curves indicating more monodisperse samples and more extended decay indicating greater polydispersity. Dynamic light scattering can determine particle size distribution, hydrodynamic radius, and diffusion coefficient.
The document discusses various concepts related to liquid chromatography including:
1. Distribution ratio and separation factor which are important parameters in liquid-liquid extraction.
2. Different types of chromatography techniques like normal phase, reverse phase, adsorption, ion-exchange, size exclusion chromatography.
3. Key aspects of liquid chromatography instrumentation like the pump, injector, column, detectors, and data system. Common detectors discussed are UV-Vis, fluorescence, conductivity etc.
MRI physics involves magnetic resonance imaging using protons' spin and magnetic properties. Protons precess at their Larmor frequency when placed in an external magnetic field. Radiofrequency pulses excite protons which absorb and emit energy, inducing a signal. Magnetic field gradients encode spatial information to generate images showing proton density and relaxation times, providing tissue contrast. Contrast depends on extrinsic parameters like pulse timing and intrinsic properties like T1 and T2 relaxation times.
Elemental CHNSO (CHNOS) analysis for determination of carbon, hydrogen, nitrogen, sulfur and oxygen content in petroleum products, biofuels, and more. CHNSO (CHNOS) elemental analyses from Intertek is available for a wide range of products and materials.
How to better understand SAR, interpret SAR products and realize the limitationsNopphawanTamkuan
This content shows how to better understand SAR (how to interpret SAR images and read SAR interferogram ). Moreover, capacities and limitations of SAR are discussed for each disaster emergency mapping (Flood, Landslide and Earthquake).
Dynamic Light Scattering (DLS) is a technique used to measure the size of particles in solution by analyzing how they scatter light over time due to Brownian motion. DLS can accurately measure translational diffusion coefficients of macromolecules to determine particle size and polydispersity. It is commonly used in biology to detect aggregates in protein solutions, determine sizes of proteins and complexes, and monitor ligand binding. Particle size is estimated from diffusion coefficients assuming a spherical shape, while polydispersity is measured from variability in diffusion among particles.
This document discusses the analysis and characterization of petroleum and petroleum products. It begins with an introduction to the constituents of petroleum and the fractional distillation process used to separate petroleum into fractions. It then describes several key tests used to analyze petroleum products, including tests to determine specific gravity, viscosity, aniline point, color, cloud point, pour point, and tests to detect water, acid/base content, ash, and metals. The document provides details on the principles and procedures for each test method. It concludes with discussions of petroleum fractionation and the typical composition of crude petroleum.
Side scan sonar was developed during WWII to detect submarines. It works by emitting acoustic signals from a towfish pulled behind a vessel to image the seafloor on both sides. Stronger returning signals appear darker on sonographs and are influenced by factors like target material, slope, and contrast. Side scan sonar is useful for mapping seafloor features and locating objects like shipwrecks. Limitations include effects from waves, currents, lack of contrast, and difficulties maintaining constant speed and towfish elevation.
This document provides an overview of GPS (Global Positioning System) including its history, components, signals, measurements, and applications. It discusses how GPS uses precise timing signals from satellites combined with trilateration to determine user locations on Earth. It also covers topics like reference frames, datums, orbit determination, and factors that influence satellite positioning.
Statistics is important in chemistry for collecting, analyzing, and presenting quantitative data. It is used in analytical chemistry to detect, identify, and measure unknown chemical compositions using instrumentation techniques. Statistical methods like descriptive statistics are used to summarize sample data using measures like the mean and standard deviation, while inferential statistics draw conclusions from data subject to random variation. Statistics plays a vital role in chemistry research by guiding data collection, interpretation, and presentation to properly characterize and summarize results. It is especially useful for drawing reliable conclusions in chemistry research.
THIS PRESENTAION CLEARLYEXPLINS ABOUT CONTRAST MEDIA ,T1 AND T2 AGENTS USED IN MRI IAMGING.
IT ALSO SHOWS RELAXIVITY AND ITS FORMULA AND CONTRAST ADMINISTRATION I.E,GADOLINIUM. AND CLASSIFICATION OF MRI CONTRAST AGENTS.
Relativity theory project & albert einstenSeergio Garcia
Albert Einstein was a German-born theoretical physicist who developed the theory of relativity, one of the pillars of modern physics. He was born in 1879 in Germany and died in 1955 in the United States. He is best known for his mass-energy equivalence formula E=mc2, which has been called the world's most famous equation. The document provides background on Einstein's life and work, and summarizes his theories of special relativity, which describes physics at high speeds, and general relativity, which proposes that gravity results from the curvature of spacetime.
Analytical class atomic absorption spectroscopy, P K MANIP.K. Mani
This document discusses atomic absorption spectroscopy and atomic emission spectroscopy. It begins by explaining the basic principles of how atomic absorption spectroscopy works, where atomic vapors are subjected to UV-VIS radiation which causes electron excitation. The extent of absorption is then used to quantitatively measure the concentration of atomic vapors. It then explains atomic emission spectroscopy, where a sample is excited by a flame, plasma or discharge, causing electron excitation and emission of radiation in the UV-VIS region. The wavelength and intensity of emission provides qualitative and quantitative information. Key concepts like oscillator strength, line widths, and sources of broadening like Doppler effect and collisions are then discussed. Details are provided about hollow cathode lamps and how they are used as light sources.
This document discusses various types of artifacts that can occur in MRI images and their causes and remedies. It covers technique-related artifacts such as chemical shift artifacts, Gibbs artifacts, aliasing artifacts, and magic angle artifacts. It also discusses patient-related artifacts like motion artifacts, metal artifacts, and flow artifacts. System-related artifacts discussed include shimming artifacts, gradient artifacts, and radiofrequency-related artifacts. For each type of artifact, the etiology, manifestation, and tips for remedying the artifact are provided. The document uses images to demonstrate examples of artifacts and their effects on MRI scans.
1. The document discusses using synchrotron radiation for x-ray spectroscopy techniques to study 3d transition metal oxides.
2. It introduces x-ray absorption spectroscopy (XAS) and resonant inelastic x-ray scattering (RIXS) as two techniques that can probe core electron excitations and provide information about materials' electronic and magnetic properties.
3. Synchrotron radiation facilities provide tunable x-ray energies, polarization control, and high photon fluxes needed for these resonant spectroscopy techniques to study transitions in transition metal oxides.
Gravimetric analysis is a quantitative analytical technique where the concentration of an analyte is determined by precipitating it from solution, isolating the precipitate, and weighing it. Some key aspects of gravimetric analysis are that the precipitate must be insoluble, of known composition, and pure to minimize errors from impurities. Conditions like precipitation temperature, reagent concentrations, and digestion can be adjusted to increase particle size and purity for accurate weighing and analysis.
This document provides an overview of magnetic resonance imaging (MRI). It discusses the timeline of MRI development, how an MRI machine works, MRI principles regarding proton spin and magnetic fields, T1- and T2-weighted images, and common indications, advantages, disadvantages, and contraindications of MRI. MRI utilizes proton spin and magnetic fields to generate detailed images of internal structures without using ionizing radiation.
1) Solvent extraction is a technique used to separate components in a mixture based on differences in solubility between two immiscible liquid phases.
2) It involves transferring a solute from one liquid phase to another, such as transferring a compound from an aqueous phase to an organic phase like benzene.
3) The amount of solute extracted into each phase can be calculated using the partition coefficient K, which is a ratio of concentrations in the two phases at equilibrium.
Steady-state free precession (SSFP) is a unique MRI sequence that uses both spin echo and gradient echo techniques. In SSFP, gradient echoes are acquired in each repetition time (TR) while maintaining coherence between excitations using balanced gradients. This results in a signal dependent on T1 and T2 properties. SSFP provides high signal-to-noise ratio and is used for cardiac imaging, flow imaging, T1/T2 mapping, and whole body imaging, but is sensitive to field inhomogeneities. Sensitivity encoding (SENSE) uses knowledge of multiple receiver coils' spatial sensitivities to unfold aliased signals and reduce scan time.
Dynamic light scattering, also known as photon correlation spectroscopy or quasi-elastic light scattering, is a technique that primarily measures the Brownian motion of macromolecules in solution that arises due to bombardment from solvent molecules, and relates this motion to the size
Its a theoretical content for Pharmacy graduates, post graduates in pharmacy and Doctor of Pharmacy And also M Sc Instrumentation, UG and PG of Ayurveda medical students, MS etc.
The document discusses the functions and working principles of an energy dispersive spectrometer (EDS). EDS can determine the chemical composition of materials down to the micron scale by detecting the characteristic x-rays emitted when the material is exposed to an electron beam. The EDS system includes an x-ray detector that converts x-ray energies into electrical signals and a multi-channel analyzer to separate the signals by energy into an elemental composition spectrum. Factors such as detector resolution, sample properties, and operating conditions can affect the accuracy of elemental quantification by EDS.
Dynamic Light Scattering (DLS) is a technique used to measure the size of particles in solution by analyzing how they scatter light over time due to Brownian motion. DLS can accurately measure translational diffusion coefficients of macromolecules to determine particle size and polydispersity. It is commonly used in biology to detect aggregates in protein solutions, determine sizes of proteins and complexes, and monitor ligand binding. Particle size is estimated from diffusion coefficients assuming a spherical shape, while polydispersity is measured from variability in diffusion among particles.
This document discusses the analysis and characterization of petroleum and petroleum products. It begins with an introduction to the constituents of petroleum and the fractional distillation process used to separate petroleum into fractions. It then describes several key tests used to analyze petroleum products, including tests to determine specific gravity, viscosity, aniline point, color, cloud point, pour point, and tests to detect water, acid/base content, ash, and metals. The document provides details on the principles and procedures for each test method. It concludes with discussions of petroleum fractionation and the typical composition of crude petroleum.
Side scan sonar was developed during WWII to detect submarines. It works by emitting acoustic signals from a towfish pulled behind a vessel to image the seafloor on both sides. Stronger returning signals appear darker on sonographs and are influenced by factors like target material, slope, and contrast. Side scan sonar is useful for mapping seafloor features and locating objects like shipwrecks. Limitations include effects from waves, currents, lack of contrast, and difficulties maintaining constant speed and towfish elevation.
This document provides an overview of GPS (Global Positioning System) including its history, components, signals, measurements, and applications. It discusses how GPS uses precise timing signals from satellites combined with trilateration to determine user locations on Earth. It also covers topics like reference frames, datums, orbit determination, and factors that influence satellite positioning.
Statistics is important in chemistry for collecting, analyzing, and presenting quantitative data. It is used in analytical chemistry to detect, identify, and measure unknown chemical compositions using instrumentation techniques. Statistical methods like descriptive statistics are used to summarize sample data using measures like the mean and standard deviation, while inferential statistics draw conclusions from data subject to random variation. Statistics plays a vital role in chemistry research by guiding data collection, interpretation, and presentation to properly characterize and summarize results. It is especially useful for drawing reliable conclusions in chemistry research.
THIS PRESENTAION CLEARLYEXPLINS ABOUT CONTRAST MEDIA ,T1 AND T2 AGENTS USED IN MRI IAMGING.
IT ALSO SHOWS RELAXIVITY AND ITS FORMULA AND CONTRAST ADMINISTRATION I.E,GADOLINIUM. AND CLASSIFICATION OF MRI CONTRAST AGENTS.
Relativity theory project & albert einstenSeergio Garcia
Albert Einstein was a German-born theoretical physicist who developed the theory of relativity, one of the pillars of modern physics. He was born in 1879 in Germany and died in 1955 in the United States. He is best known for his mass-energy equivalence formula E=mc2, which has been called the world's most famous equation. The document provides background on Einstein's life and work, and summarizes his theories of special relativity, which describes physics at high speeds, and general relativity, which proposes that gravity results from the curvature of spacetime.
Analytical class atomic absorption spectroscopy, P K MANIP.K. Mani
This document discusses atomic absorption spectroscopy and atomic emission spectroscopy. It begins by explaining the basic principles of how atomic absorption spectroscopy works, where atomic vapors are subjected to UV-VIS radiation which causes electron excitation. The extent of absorption is then used to quantitatively measure the concentration of atomic vapors. It then explains atomic emission spectroscopy, where a sample is excited by a flame, plasma or discharge, causing electron excitation and emission of radiation in the UV-VIS region. The wavelength and intensity of emission provides qualitative and quantitative information. Key concepts like oscillator strength, line widths, and sources of broadening like Doppler effect and collisions are then discussed. Details are provided about hollow cathode lamps and how they are used as light sources.
This document discusses various types of artifacts that can occur in MRI images and their causes and remedies. It covers technique-related artifacts such as chemical shift artifacts, Gibbs artifacts, aliasing artifacts, and magic angle artifacts. It also discusses patient-related artifacts like motion artifacts, metal artifacts, and flow artifacts. System-related artifacts discussed include shimming artifacts, gradient artifacts, and radiofrequency-related artifacts. For each type of artifact, the etiology, manifestation, and tips for remedying the artifact are provided. The document uses images to demonstrate examples of artifacts and their effects on MRI scans.
1. The document discusses using synchrotron radiation for x-ray spectroscopy techniques to study 3d transition metal oxides.
2. It introduces x-ray absorption spectroscopy (XAS) and resonant inelastic x-ray scattering (RIXS) as two techniques that can probe core electron excitations and provide information about materials' electronic and magnetic properties.
3. Synchrotron radiation facilities provide tunable x-ray energies, polarization control, and high photon fluxes needed for these resonant spectroscopy techniques to study transitions in transition metal oxides.
Gravimetric analysis is a quantitative analytical technique where the concentration of an analyte is determined by precipitating it from solution, isolating the precipitate, and weighing it. Some key aspects of gravimetric analysis are that the precipitate must be insoluble, of known composition, and pure to minimize errors from impurities. Conditions like precipitation temperature, reagent concentrations, and digestion can be adjusted to increase particle size and purity for accurate weighing and analysis.
This document provides an overview of magnetic resonance imaging (MRI). It discusses the timeline of MRI development, how an MRI machine works, MRI principles regarding proton spin and magnetic fields, T1- and T2-weighted images, and common indications, advantages, disadvantages, and contraindications of MRI. MRI utilizes proton spin and magnetic fields to generate detailed images of internal structures without using ionizing radiation.
1) Solvent extraction is a technique used to separate components in a mixture based on differences in solubility between two immiscible liquid phases.
2) It involves transferring a solute from one liquid phase to another, such as transferring a compound from an aqueous phase to an organic phase like benzene.
3) The amount of solute extracted into each phase can be calculated using the partition coefficient K, which is a ratio of concentrations in the two phases at equilibrium.
Steady-state free precession (SSFP) is a unique MRI sequence that uses both spin echo and gradient echo techniques. In SSFP, gradient echoes are acquired in each repetition time (TR) while maintaining coherence between excitations using balanced gradients. This results in a signal dependent on T1 and T2 properties. SSFP provides high signal-to-noise ratio and is used for cardiac imaging, flow imaging, T1/T2 mapping, and whole body imaging, but is sensitive to field inhomogeneities. Sensitivity encoding (SENSE) uses knowledge of multiple receiver coils' spatial sensitivities to unfold aliased signals and reduce scan time.
Dynamic light scattering, also known as photon correlation spectroscopy or quasi-elastic light scattering, is a technique that primarily measures the Brownian motion of macromolecules in solution that arises due to bombardment from solvent molecules, and relates this motion to the size
Its a theoretical content for Pharmacy graduates, post graduates in pharmacy and Doctor of Pharmacy And also M Sc Instrumentation, UG and PG of Ayurveda medical students, MS etc.
The document discusses the functions and working principles of an energy dispersive spectrometer (EDS). EDS can determine the chemical composition of materials down to the micron scale by detecting the characteristic x-rays emitted when the material is exposed to an electron beam. The EDS system includes an x-ray detector that converts x-ray energies into electrical signals and a multi-channel analyzer to separate the signals by energy into an elemental composition spectrum. Factors such as detector resolution, sample properties, and operating conditions can affect the accuracy of elemental quantification by EDS.
Controllo dell’incertezza dichiarata mediante l’utilizzo di ptRiccardo Narizzano
nella presentazione, dopo una breve descrizione dello z-score, viene discusso e illustrato come come verificare la attendibilità dell'incertezza dichiarata mediante l'utilizzo dei dati provenienti dai circuiti interlaboratorio
Statistica e probabilità in chimica: le regole del giocoRiccardo Narizzano
Statistica e probabilità in chimica: le regole del gioco
L’utilizzo di strumenti statistici da applicare ai risultati di misure occupa una parte sempre più rilevante dell’attività del chimico. Il diffondersi di questi strumenti sempre più evoluti non è però sempre accompagnato da una adeguata comprensione del loro significato. In letteratura sono comparsi recentemente testi interessanti, seppur pochi, di statistica applicata alle scienze chimiche, tuttavia la teoria generale in queste pubblicazioni non è sufficientemente approfondita. La statistica generale di base è ancora oggi riportata solamente in testi altamente specializzati, con un formalismo di non immediata lettura, oppure in testi generali in cui le applicazioni sono sostanzialmente di tipo demografico.
La carenza di una letteratura appropriata, unitamente ad un percorso formativo generalmente non idoneo, ha portato alla mancanza di un adeguato bagaglio culturale nel campo della statistica applicata alla chimica. Il corso si propone di illustrare e discutere i concetti generali di base, riportandoli alla realtà dell’attività del chimico, per consentire ai professionisti di colmare queste lacune e padroneggiare in maniera consapevole gli strumenti statistici indispensabili.
Il corso prevede una introduzione alla statistica descrittiva e inferenziale, tra gli argomenti affrontati saranno presentati in maniera logica e consequenziale i concetti di z-score, deviazione standard della media, t di student e intervallo di confidenza a una e a due code. Alla luce degli argomenti trattati verrà quindi rivolta particolare attenzione ai concetti di validazione dei metodi chimici, all’utilizzo dei circuiti interlaboratorio, ai differenti approcci alla stima dell’incertezza di misura e ai test di significatività.
Introduzione ai differenti approcci alla stima dell'incertezza di misura Nari...Riccardo Narizzano
This document discusses different approaches to estimating measurement uncertainty:
- The modelling approach uses a mathematical model of the measurement procedure and combines individual uncertainty contributions.
- The single laboratory validation approach uses quality control samples and duplicate analyses to estimate intermediate precision and uncertainty from bias.
- The interlaboratory validation approach uses reproducibility data from proficiency tests to directly estimate uncertainty, which may over or underestimate the laboratory's performance. The document recommends using a combination of these approaches as needed.
L'impatto sull'ambiente delle nostre abitudini quotidiane: gli Inquinanti Eme...Riccardo Narizzano
Gli inquinanti di interesse emergente, comunemente chiamati inquinanti emergenti, pongono la comunità scientifica di fronte a nuove ed importanti sfide per la tutela della salute pubblica e dell’intero ecosistema. Essi sono una grandissima famiglia di molecole comprendenti farmaci ed ormoni ad uso umano e veterinario, prodotti per la cura personale, stupefacenti, pesticidi e molecole di utilizzo industriale come i composti perfluorurati, clorurati e bromurati. Il problema relativo a farmaci, ormoni e prodotti per la cura personale è il più complesso sia dal punto di vista scientifico sia sociale. I dati scientifici riguardanti gli effetti sia sull'uomo sia sull'intero ecosistema di una esposizione cronica a bassi dosaggi di miscele di questi composti, sebbene ancora non definitivi, forniscono un quadro chiaro, inequivocabile e troppo spesso inquietante. La conferenza sarà focalizzata soprattutto sulla presenza e sull'impatto che farmaci e i prodotti per la cura personale stanno avendo sull'ambiente e le possibili ricadute sull'uomo. Verranno illustrati i dati della più recente letteratura scientifica internazionale ed il trend del consumo di farmaci mondiale, inoltre saranno analizzati il significato e l’attendibilità dei dati analitici relativi ai composti in tracce.
2. Il contenuto della presentazione può non riflettere necessariamente
la posizione ufficiale di ARPAL
3. Premessa
Cosa è la chimica forense
Ricostruzioni di scene del crimine: Caso Incendi
I passi fondamentali di una analisi chimica e l’importanza del quesito corretto
Applicazioni:
Lo sversamento di prodotti petroliferi
Casi non standard
Inquinamento ambientale da stupefacenti: Epidemiologia Forense
Accademia Ligure di Scienze e Lettere, 6 aprile 2017 Riccardo Narizzano
5. L’effetto CSI
• Il Sistema giudiziario e l’opinione pubblica sono portati ad apettarsi il
tipo di scienza forense mostrato da CSI
• Sfortunatamente, il 40% di quella scienza non esiste
6. Cosa è la chimica forense?
• La chimica forense è l’applicazione di principi scientifici e di analisi
chimiche volta alla risoluzione di questioni legali.
• L’uso di tecniche chimiche per identificare e quantificare tracce di
sostanze note o sconosciute e per tracciare la loro origine ai fini di una
indagine legale.
La chimica forense esiste quindi laddove scienza e legge si sovrappongono
La chimica forense è soprattutto chimica analitica applicata si e ciò che la
distingue come una disciplina a sé stante è la scienza del confronto
7. Il quesito forense non è lo stesso del quesito legale
Il quesito forense, per esempio, è: “questa polvere bianca contiene uno
stupefacente? Se sì, quanto?”
Risposta: “il campione contiene 6.2 ± 0.3 g di cocaina”
Il quesito legale è invece “l’imputato è colpevole di possesso di
stupefacenti?”
Il chimico forense fornisce dati che possono contribuire a
rispondere al quesito legale, ma costituiscono solo un elemento
della risposta complessiva.
8. La chimica analitica fornisce dati qualitativi e quantitativi necessari alla domanda
forense, ad esempio:
• Da dove potrebbe venire questa fibra?
• Questo pezzo di plastica può provenire da questo sacchetto?
• Per appiccare questo incendio è stato utilizzato del gasolio?
• Questo frammento proviene da quella macchina?
• Questa polvere bianca contiene degli stupefacenti?
• La quantità della molecola trovata in campioni postmortem permette di determinare
le cause del decesso?
9. Quando il chimico forense lavora su un reperto, generalmente è chiamato a
svolgere tre compiti:
I. identificazione. (Analisi qualitative e/o quantitative)
II. classificazione. (Colore, morfologia….)
III. Individuazione di una possibile origine.
Evidenza
scientifica
Questo non significa che l’evidenza sia inutile, semplicemente esiste una limitazione
su ciò che può essere detto con un certo grado di affidabilità (confidenza).
inclusiva esclusiva
10. Ricostruzione della Scena del Crimine
Incendi: Ricerca degli Inneschi
Un innesco può lasciare infiniti tipi di tracce, legate al tipo di innesco ed alla fantasia dell’incendiario.
Conviene fotografare e raccogliere qualsiasi materiale anche se all’apparenza insignificante.
Analisi GC/MS del campione di terriccio raccolto sulla
verticale dei reperti metallici.
13. Scienza e tribunali hanno il compito di ottenere informazioni da evidenze
pertinenti con il caso in questione
Scienza
Metodo scientifico
Sistema
accusatorio
Argomenti presentati
da opposte fazioni
(accusa e difesa)
L’evidenza scientifica e le testimonianze possono supportare o confutare le diverse tesi
Tutto quello che uno scienziato può e dovrebbe fare è
produrre la migliore scienza possibile seguita dalla più chiara
presentazione possibile
15. Campione analitico
Estrazione
Purificazione
Analisi Chimica
Non esiste il solvente universale
R
O
OH
R
N
R'
R''
Solventi Polari
(composti polari a
medio-basso PM
Acidi, Basi)
Solventi Apolari
(composti apolari)
Eliminare i composti interferenti
con la molecola di interesse.
Non sempre è possibile.
Sono necessarie informazioni
precise sulla molecola di
interesse.
Analisi Chimica: I passi fondamentali
16.
17. Chimica forense nei casi di sversamento di prodotti petroliferi
Composizione del Petrolio Greggio
Il greggio è una miscela complessa
formata da diverse migliaia di
molecole differenti la cui
composizione varia in funzione del
luogo di estrazione, fino anche al
singolo pozzo.
Qualunque procedimento legale conseguente ad uno sversamento di greggio in ambiente deve
essere supportato da robuste evidenze scientifiche che colleghino l’inquinamento alla possibile
sorgente
18. BIOMARKERS composti in tracce derivanti dalle foreste che hanno originato il greggio. Sono anche chiamati
“fossili molecolari” dato che la loro struttura molecolare ricorda quella della loro origine biologica.
Resistenti all’invecchiamento
Differiscono in concentrazione da sorgente a sorgente. Ogni greggio presenta specifici rapporti di
concentrazione dei diversi biomarkers (impronta digitale).
19. μ è il valore medio tra i due DR consideratiL’insieme dei DR in un greggio
costituisce la sua impronta
digitale Criterio di concordanza: Diff. Relativa < 14% (RSD 5%)
Il confronto tra la composizione dell’inquinamento e quello della possibile sorgente viene
effettuato tramite la comparazione delle impronte digitali dei due prodotti. Le impronte digitali
vengono ottenute calcolando i rapporti di concentrazione di specifici composti (biomarkers e
Idrocarburi Policiclici Aromatici)
Rapporti diagnostici (DR): sono
calcolati dividendo tra loro le
concentrazioni di due biomarkers
Differenza relativa (RD): per ogni
rapporto diagnostico viene calcolata tra
l’inquinamento e la possibile origine
27. 24 25 26 27 28 29 30 31 32 33
time (min)
Fendimetrazina
N
O
H
bupropione caffeinaCl
N
O
H
O
N
N N
N
O
Estratto acido
Estratto CHCl3
Composizione Maggioritaria Finale
Analisi GC/MS
29. Problema: ricovero al PS di minore dopo consumo di yogurt da bere alla fragola
Indicazione PS:
Possibile contaminazione volontaria da benzodiazepine
Evidenze: tappo con foro da ago
Ipotesi:
Contaminazione volontaria da farmaco contenente benzodiazepina in forma liquida.
Categoria farmacologica reperibile mediante prescrizione medica: Rintracciabilità
dell’eventuale possessore elevata per farmaci di minor utilizzo
Un buco nello yogurt
30. Formule di struttura di alcune benzodiazepine di uso comune e
nome commerciale del principio attivo-farmaco
Diazepam
(Valium,
Tranquirit)
Lorazepam
(Tavor)
Flunitrazepam
(Roipnol,
Darkene)
Nordazepam
(Madar)
Lormetazepam
(Minias)
N
N
O
Cl
N
H
N
O
Cl
OH
Cl
N
N
O
Cl
OH
Cl
N
H
N
O
ClN
H
N
O
O2N
F
31. CHCl3 H2O (soluzione satura di NaCl) + OH-
Estrazione selettiva di benzodiazepine da matrice yogurt
Separazione Liquido Liquido
N
N
O
R4
R2
R3
R1
N
N
O
R4
R2
R3
R1
H
Ultrasuoni
Raffreddamento
Elettroliti (NaCl)
fase organica
Matrice yogurt: pH tipico ~ 4.2
GC/MS
32. 22.0 22.2 22.4 22.6 22.8 23.0
time (min)
SIM
Full Scan
lorazepam
N
HN
Cl
O
HO
Cl
Yogurt contaminato
Yogurt “riferimento”
Analisi GC/MS
5 10 15 20 25 30 35 40 45 50 55
time (min)
33. Problema: ricovero al PS di minore dopo consumo granita all’anice
Indicazione PS: Nessuna
Evidenze: bicchiere contenente granita “fuso”
La granita è stata preparata con l’ultima bottiglia della
fornitura aperta per l’occasione
Il giallo della granita blu
Dati Preliminari:
Analisi solventi negativa
Il bicchiere rimane molle anche dopo parecchie ore, anzi il processo di rammollimento aumenta
nel tempo
Cannuccia e cucchiaio contenute nel bicchiere che non presentano fenomeni di rammollimento
36. Risultati delle indagini strutturali
O
Struttura molecolare bicchiere:
Polistirene
n
Struttura molecolare cannuccia:
Polipropilene
Struttura molecolare Anetolo
Struttura molecolare stirene
n