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Infrared (IR) Spectroscopy: Principle

March 6, 2019

incident light beam

Reflection

Matter

Transmission Absorption

Interaction between light and matter

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Infrared (IR) Spectroscopy: Principle

March 6, 2019

Infrared (IR) Spectroscopy: Principle

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Infrared light is transformed into vibrations

Symmetric stretching vibration

Anti-symmetric stretching vibration

Deformation vibration

Interaction between light and matter

March 6, 2019

15002000250030003500

Wavenumber cm-1

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Infrared light is transformed into vibrations

Example: water spectrum

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Infrared (IR) Spectroscopy: Principle

March 6, 2019

500750100012501500175020002500300035004000

Wavenumber cm-1

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Benzocaine

Polycarbonate

Caffeine

Talc

IR-Spectrum: A chemical fingerprint of the sample

Infrared (IR) Spectroscopy: Principle

IR-spectrum: Qualitative analysis

1. Identity check of a known substance

IR Spectroscopy: Analytical Value

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Analytical approach:

Comparison of the „spectral fingerprint“ of a sample with the spectrum of a reference material

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5001000150020002500300035004000

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IR-spectrum: Qualitative analysis

2. Identification of unknown substances

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Analytical approaches:

a. Assignment of bands to

functional groups

b. Search for similar spectral

fingerprint in spectral libraries

CH

C=O IR Spectroscopy: Analytical Value

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Concentration proportional to absorption

(Lambert-Beer‘s law)

1. Measurement of reference samples with

known composition.

2. Determination of a calibration function

between measured spectra and reference

data (concentration or sample properties)

3. Analysis of samples using the calibration

function

X

Analysis

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ance

Concentration

X

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Wavenumber

Calibration IR-spectrum: Quantitative analysis

IR Spectroscopy: Analytical Value

March 6, 2019

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ALPHA II Spectrometer System

A small

FT-IR-spectrometer

with a broad range of

applications

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QuickSnapTM sampling modules for different applications

An optimal spectrometer for every task

March 6, 2019

ALPHA II Design Follows Application

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Most robust and comfortable ATR:

• Pure diamond crystal: No limitation of spectral range

• ATR-crystal brazed in chemically inert ceramic

• High working distance and open accessibility for easy sampling

Analysis of a wide range of samples:

• Solids

• Pastes

• Liquids

The most often used spectrometer set-up: ALPHA II with Platinum ATR

ALPHA II

ATR: Attenuated Total Reflectance

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Measurement Technique: ATR: Attenuated Total Reflectance

Sample

ATR-crystal

Refractive index n1 > n2

n2

n1

Interaction of IR-light and sample is required to measure the IR-spectrum

Benefits ATR

• Defined penetration depth of IR-light into the sample surface

• No sample preparation required

Requirements on ATR-crystal

• IR-transparent

• High refractive index

• Robust

Powders

Granules

Films & shaped parts

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Liquids

Pastes

ALPHA II: Universally Applicable

ALPHA II: Applications

• Identity Verification

Incoming raw materials

Solids, liquids

Pure substances and mixtures

• Characterization and Identification

Unknown material, e.g.

Contaminants

Competition products

Hazards

Composition of mixtures (products)

• Quantification

Components in solution, pastes, (solids)

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ALPHA II: Identity Check of Incoming Goods

• Correct material?

• Compliant with quality requirements?

Comparison of IR-spectrum with references

NOT

OK

IR-Spectrum

Use for

product

Back to

Supplier NOT

OK

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ALPHA II: Identity Check of Incoming Goods

• Enter sample info and check preview spectrum

• Perform measurement

• Verify material by comparison against reference data

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ALPHA II: Identification of Unknown Material

• Spectrum identification by library search

BRUKER ATR-FTIR-Library COMPLETE

26.000 FTIR-Spectra

Substance classes: polymers, monomers, additives, plasticizer, fillers, building materials, cosmetics,

excipients, organic and inorganic chemicals, biochemicals, fibres, proteins, fatty acids, lipids, ingredients, natural products, silicon containing compounds, solvents, pesticides, pollutants, semiconductors, dyes, paints, coatings, food, food additives, minerals, lubricants, surfactants, kidney stones, pharmaceuticals, and drugs

High information content: CAS number, molecular formula, chemical structure, molecular weight for

pure chemical substances

March 6, 2019

6. März 2019

ALPHA II: Polymer Identification

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Recycling: Unknown plastic products measured by ATR

Polycarbonate

PVC

Polypropylene

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ALPHA II: Identification

• Forensics: Illegal drugs Trace evidence (fibers, …)

• Intuitive software user interface, dedicated work-flow for drug ID

• Mixture Analysis

• Extensive libraries

March 6, 2019

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ALPHA II: Identification

• Medical: Kidney stones

• Intuitive software user interface

• Extensive libraries with authentic kidney stone spectra

March 6, 2019

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ALPHA II The Contactless

• Reflection interface on front

• Measurement spot: 6mm

• Distance to sample: approx. 15mm

• Gold mirror for reference

• Option: integrated video camera

Useful for

• Large objects

• Metallic surfaces:

Cleanliness

Coatings

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Recycling:

Large plastic parts (electronic, automotive,…)

Contactless measurement (5 sec)

Automatic identification of polymer type from reflection spectrum

ALPHA II: Polymer Identification

Polymer classes in ID method

ABS Polyester

ASA PP/EPDM

PC+ABS EPDM

PC+PBT PE

PBT+PC SMC

PBT PMMA

PET PPE+SB

PC PPE+PPO

SAN PPE+PA

PA 6 PVC

PA 66 PS

TPU HIPS(SB)

PUR-RIM PUR-WS

SRIM POM

PP SMA

10001100120013001400150016001700

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ALPHA II: Quantification of Pharmaceutical Ingredients

• IR-spectroscopy allows quantification of individual components in pharmaceuticals

• Example: Methadone in water

Concentration: 0 to 12%

Correlation: 0.999

Sigma: 0.18

Methadone

12 %

10 %

8 %

5 %

1 %

Lambert-Beer‘s Law:

Spectral Intensity Concentration

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• ALPHA II multi reflection ATR:

Quantification of components in liquids and ointments at concentrations of ≥1%

• ALPHA II single reflection ATR:

Analysis of components down to concentrations of about 3%

ALPHA II: Quantification of Pharmaceutical Ingredients

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Quantification: Oil in Waste Water

Example: Quantification of oil in waste water on off-shore oil platforms

Background:

• On off-shore platforms large amounts of waste water are accumulated.

• To assure an environmentally safe waste dump the total hydrocarbon content in waste water has to be determined

Measurement approach:

• ALPHA II based method allows fast screening of waste water samples

• Hydrocarbons are extracted from waste water

• Extract is measured in transmission cell

March 6, 2019

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Quality control: Quantification of Oil in Waste Water on Off-Shore Oil Platforms

Spectra of extracted oil in chloroform

26502700275028002850290029503000

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Result of cross validation. Predicted ppm values vs. true ones

Application Note #82

March 6, 2019

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Quantification: FAME in Diesel

ASTM 7371:

System configuration:

• ALPHA II

• ZnSe ATR 6-reflectance

• PLS calibration (Quant 2)

DIN EN 14078:

System configuration:

• ALPHA II with universal sampling module

• Flow-through liquid cell (ZnSe-window; 100µm)

• Lambert-Beer-quantification

March 6, 2019

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FAME Analyze-Kit

• Flow-through liquid cell

• Wizard functionality

• Autosampler control

• Calibration

• Dedicated template

Quantification: FAME in Diesel

0.0%

0.5%

1%

2%

3%

5%

7%

10%

15%

20%

PLS Calibration

• Concentrations: 0.0 to 20.0 %

• R2 = 1.0000

• RMSECV = ≤ 0.02 %

• Measurements of higher concentrations in dilutions

March 6, 2019

Soil Analysis: Purpose

Qualitative Analysis:

• Soil functional attributes, e.g. fertility

Quantitative Analysis:

• Chemical parameters

e.g. organic carbon, total nitrogene, sand

• Physical parameters,

e.g. pH, cations exchange capacity (CEC)

Important for:

• Fertilizer management

• Greenhouse gas management

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Soil Analysis: Methods

Conventional:

• Sample preparation: extraction

• Methods: wet chemistry, photometric, colorimetric, hydrometric, AAS, MS, GC

Complex techniques, expensive, time consuming, low accuracy

Benefits of IR-spectroscopy in comparison with conventional soil analysis (Shepherd, Walsh, Encyclopaedia of Soil Science 2004)

• Repeatability and speed (high throughput)

• Easy sample preparation (direct measurement of dried, sieved & ground soil)

• Better precision and accuracy than actual reference measurements

• Parallel analysis of several soil properties from a single robust measurement

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Soil Analysis: IR-Solutions

ALPHA II:

• Compact & cost effective IR-spectrometer

• Manual DRIFT measurement of single samples

• Use in small or mobile laboratories

HTS-XT:

• Sensitive IR-system for diffuse reflection (DRIFT)

measurements on 24 or 96 well microplates

• Automated data acquisition, evaluation and

documentation

• High throughput capability

• Use in (central) laboratories

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500100015002000250030003500

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ance U

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Sample PP LDPE

1 93 % 0 %

2 83 % 10 %

3 73 % 20 %

4 63 % 30 %

5 93 % 40 %

6 0 % 93 %

Quantification: Polyethylen in Polypropylen-Blend

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Quantification: Polyethylen in Polypropylen-Blend

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Polypropylene Polyethylene

Concentration: 0 to 93% Correlation coefficient: 0.999 Sigma: 1.65

Concentration: 0 to 93% Correlation coefficient: 0.999 Sigma: 1.88

March 6, 2019

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Quantification: Wine Parameters

• ALPHA II temperature controlled • Starter calibration • Wizard Autosampler control Quantification

March 6, 2019

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ALPHA-T Gas Measurements

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• 7cm gas cell

• Volume: 6 ml

• Pressure resistance : up to 4 bar

• Swagelok connections

• Static & flow-through operation

• Thermal isolated stainless steel cell

• Heatable up to 200°C with integrated temperature controller

• Long pathlength: 4.8m

• Volume: 0.5l

• Pressure range: Vacuum to 3.5bar

• Temperature range: room temperature to 200°C

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ALPHA II - Mobile Application -

• Integrated touch panel • Transport case • Power pack • Wlan • Tripod

In the field use Mobile laboratories

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Glove box Inert atmosphere for

reactive samples

March 6, 2019

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