scale analysis to micro scale imaging-ftir. State of the art and future perspectives.

Transcription

1 MP analysis by FTIR spectroscopy. From From macro macro scale analysis to micro scale imaging-ftir. State of the art and future perspectives. Alvise Vianello Vianello, Jes Vollertsen Aalborg University, Denmark

2 1 µm The size range and the analytical techniques for MP analysis 100 µm 10 µm 1000 µm Increasing uncertainty 5000 µm Optical microscopy µ ATR FTIR (single point analysis of particles on a filter) Increasing uncertainty Possibly down to a few μm (not proven) ATR FTIR (particles hand picked, analyzed on bench) Imaging μft IR using filters, windows, or slides IR Molecular Spectroscopy Macro Raman (particles hand Imaging μraman possible method, not well proven picked, analyzed on bench) NIR (pre sorting, bench analysis) Hy Spec. Imaging NIR (not well proven) TDU Pyr GC/MS; TED GC MS

3 Spectroscopic techniques for MP analisys Infrared (IR) molecular spectroscopy is the most used instrumental technique to identify polymers particles in environmental samples (28 studies Hidalgo Ruz et al., 2012) Wavenumber (cm 1) Electromagnetic spectrum 109 GAMMA RAYS 10 6 Most used IR spectroscopy! X RAYS ENERGY DECREASE WAVELENGHT INCREASE NEAR IR IR region 0,7µm ,95 NIR ULTRAVIOLET (UV) ,85 0,80 0, µm 0,80 0,55 0,60 0,50 Intensity Absorbance Absorbance 0,65 0,45 0,40 0,35 0, , ,30 0, ,25 0,20 0,20 0,15 0,30 0, ,10 0, ,05 0, Wavenumbers (cm-1) Raman 0,65 0, Wavelenght (µm) µm 0,70 0,55 RADAR, RADIO, TELEVISION WAVES 20 Micrometers ,75 0, FAR IR Wavenumbers (cm 1) 0, MICROWAVES 102 0, INFRARED (IR) MID IR 2,5µm 102 FT-IR 0, VISIBLE 1010 ENERGY INCREASE WAVELENGHT DECREASE Wavenumbers (cm-1) Raman shift (cm -1)

4 FT-IR spectroscopy FT-IR Vibrational spectroscopy which relies on the interaction (mostly absorption) of IR light with matter (sample). IR beam IR Active molecular specific bonds VIBRATIONS IR ABSORPTION (I0).. if there is a Δ in the molecular electric dipole moment Energy absorption IR vibrations are characteristic for each chemical bond, they "occupy" precise regions of the IR spectrum (specific wavenumbers ranges) Identification of a wide range of substances (organic and inorganic) IR Spectrum H2O FT-IR Spectrum 1,0 0,9 O H Stretching 0,8 0,7 Absorbance I<I0 (I) H O H Bending 0,6 0,5 0,4 0,3 0,2 0, Wavenumbers (cm-1)

5 Quick overview of the IR vibration normal modes Direction Symmetry Radial Latitudal Longitudal Symmetrical stretching Scissoring Wagging Antisymmetrical stretching Rocking Twisting Symmetric Antisymmetric

6 FT-IR spectrometer Michelson Interferometer Sample chamber Detector Light measured by detector Interferogram Data collection and management Mobile mirror Fourier Transform Mirror position (mm) Single beam 4.0 Interface Computer Single Beam 2.5 Beamsplitter Fixed mirror Sample Wavenumbers (cm-1) Background FTIR spectrum Source 0,95 PE 0,90 0,85 0,80 0,75 0,70 Absorbance 0,65 0,60 0,55 0,50 0,45 0,40 0,35 0,30 0,25 0,20 0,15 0,10 0, Wavenumbers (cm-1)

7 FT-IR for MP analysis MP identification according to their characteristic IR spectra (highly specific IR absorption, distinct band patterns in FT IR spectra) Sample preparation Dependent by the signal aquisition mode. A a clean up step is suggested to remove organic matter; sample must be dried (H 2 O absorbs in FT IR) FT IR analysis ATR (Macro/µ) Diffuse Reflection Trans Reflection Transmission ATR crystal Sample IR beam I 0 to detector I IR beam Diffuse component Sample I 0 IR beam Specular component to detector I Transmitted component Sample Gold coated slide I 0 IR beam Sample I Transmission window to detector LMPPs 5 1mm; SMPPs (1mm 300μm) SMPPs (300μm 5μm) MALMÖ, NOVEMBER 8 th 2017

8 Analysis of Large MP by ATR-FTIR spectroscopy FTIR analysis of pre sorted Large MP ( /300 µm particles) 0.20 FTIR Spectrometer + ATR Sample spectrum Ref. spectrum Spectrum analysis Abs Polypropylene: Match = % 0.20 Abs Spectrum collection Wavenumbers (cm-1) Advantages Good FT IR spectra from massive and rough samples Diamond ATR, no issues with silicates or hard materials Drawbacks Manual analysis (time consuming) Particle size limitation (500/300 μm)

9 Analysis of Small MP by FTIR spectroscopy: µft-ir μft-ir Analysis of MP directly on filter/ IR slide/ir windows IR Microscope FTIR Spectrometer Cassegrain objective Single point μft-ir Analysis Microscopic inspection of the sample (filter, petri dish, etc.) Analysis of selected single particles by FTIR choosing the right beam size (µatr; Reflection; Transmission) µftir spectrum from a single MCT detector µft-ir-imaging analysis Analysis of the spatial distribution of the component materials in a sample FTIR imaging systems contain multi element detectors, producing IR images (each pixel contains an IR spectrum)

10 Source globar Interferometer IR Objective scheme Detector Reflection Cassegrain Objective Single MCT detector Linear array detector µft-ir Mirrors Sample Mirrors Transmission FPA detector Cassegrain Condenser MALMÖ, NOVEMBER 8 th 2017

11 µft-ir-imaging spectroscopy for Small MP analysis µft-ir-imaging Powerful and versatile analytical technique for spectrochemical imaging Analysis of the spatial distribution of the component materials in a sample FTIR imaging systems contain multi element detectors, producing IR images (each pixel contains an IR spectrum) at relative hi speed. The array detector allows to collect up to 16,000 pixels/spectra simultaneously and has therefore enabled the FT IR microscopy to become also an imaging technique. Visible Image IR Image Filtered IR Image

12 µft-ir-imaging spectroscopy for MP analysis (Linear array vs Focal Plane array detectors) Linear array 2 linear arrays of 16 MCT detectors Slower than FPA High spatial resolution ( 10 µm) Spectral range cm-1 FPA detector (32x32 up to 128x128 MCT detectors) Faster than Linear Array Best spatial resolution ( 5 µm or more) Spectral range cm-1 Focal Plane array

13 FPA-µFT-IR-Imaging spectroscopy for Small MP analysis Visible Image IR Map 70 Row = 146 Col = 111 %T Spectral range Image filter FTIR spectrum (PBT) Wavenumbers (cm-1)

14 FPA-µFT-IR-Imaging spectroscopy for Small MP analysis Powerful and versatile analytical technique for spectrochemical imaging Sample (10 mm diameter) scan velocity up to 4,5h (128x128 FPA) 2 3 scans per day Huge amount of data (Many GB!) to process Multiple issues in data handling and managing Most of FT IR imaging softwares are not reliable for the MP analysis A lot of clicking Inaccurate analysis!

15 FPA-µFT-IR-Imaging spectroscopy for MP analysis: First example of automatic pipeline (AWI) Data aquisition from FPA µft IR Imaging FTIR Data processing by Opus Macro Image analysis (Python Script) Open source/freeware software MP identification, quantification and image analyis (particle size distribution) Based on a commercial FTIR software Primpke et al., 2017

16 A dedicated MP analysis software First steps in developing a dedicated software for FPA Imaging data analysis MPHunter Software written by Jes Vollertsen using RAD Studio (Embarcadero Delphi IDE) RAD Studio: an object oriented programming environment allowing easy construction of user friendly interfaces preserving fast computational speed.dmd (Agilent) and.dx (Bruker) file conversion to MPHunter software file format (.spe) Managing of FPA data from different FPA detectors (e.g. 64x64 and 128x128) Friendly User Interface (FT IR software like ) Extremely light application around 5 MB! MALMÖ, NOVEMBER 8 th 2017

17 How does it works? Load a pre converted mosaic Load reference spectra from a library (file.txt) Select one or more ref. spectra (we hope to use it with many ref. spectra ) Load the filters (to use afterwards) Select the spectral range (up to 4 ranges at the same time here just cm 1) Heat map Control Panel Ranges Ref. Library Filters

18 How does it works? Pearson s Correlation Coefficient analysis Removing noise using filters Mark particles as MP Measure dimensions Save MP Display the found MP

19 ...To summarize... FTIR is the most promising analytical technique for MP analysis (ID, quantification) Macro ATR FTIR is suitable for Large MP analysis, giving reliable results, but it is manual and time consuming Other IR techniques (like Hy Spec NIR and Macro Raman) has to be tested to automatize Large MP analysis Imaging μft IR is the most suitable technique for Small MP analysis, avoiding manual pre sorting A full automatization (or semi automatization) of the data analysis is important to increase the accuracy and precison of the analysis AWI automatic pipeline is the first example of fully automatized MP data analysis (very important step) AAU MPHunter is another example of semi automated software for MP analysis, user friendly and customizable A better automatization is required to make MPHunter more reliable and eventually get rid of the clicking nightmare Interface MPHunter with AWI Automatic Pipeline for MP analysis, creating a freeware program for MP data analysis MALMÖ, NOVEMBER 8 th 2017

20 Thank you MALMÖ, NOVEMBER 8 th 2017