Evolution of Magnetic Resonance: The Impact on Portable and Process NMR/MRI

Michael J. McCarthyDepartment of Food Science & Technology

NMR and MRIStrengths- Chemical identification- Structure determination- Medical imaging- Microscopy imaging- Noninvasive- High speed…

Current Limitations: Not suitable for industrial environmentNot portableLow sensitivity

Strawberry Milk Chocolate Milk 4 Averages

Chocolate Milk 20 Averages

http://www.bruker-biospin.com/nmr_magnets_us2.html?&L=0&print=

Goals of our NMR work• Address current limitations and enable process

NMR/MRI spectrometers for in-line control– Compatible with operation in an industrial

environment• Small side streams• Larger installations for 100 % inspection

– Rapid measurements of• Composition / quality attributes• Structure / Particle size, Rheological

properties– Compatible with fluid food processing

• Clean in place chemical• Liquid and particulate suspensions

Enabling process NMR/MRI• Engineered materials

– Novel magnets• Aspect AI• ABQMR Inc.

• Miniaturization – NeSSI compatible– Microfabricated components– Dynamic nuclear polarization

• Measurement information processing– Artificial intelligence, neural networks,

chemometric methods

2 T MRI system

Magnet Design Options• Higher magnetic field (~1.0 T)

– Advantages• Signal-to-noise! (high speed)

– Disadvantages• Cost• Weight

– Imaging/nonimaging options• Low magnetic field strength (~0.05 to 0.2 T)

– Advantages• Cost• Easier to integrate

– Disadvantages• Signal-to-noise ratio (limits speed)

– Imaging and/or nonimaging

1 Tesla; ~0.4 sec scan

0.1 T; 8 hour scan

Range of Permanent Magnet Designs

WWW.ASEPECT-MR.COM

1.0 Tesla Permanent MagnetSize: 700x700x600 mmBore Size: 96x240x240 mm~1200 lbs

0.96 Tesla5 cm3

685 g21 nanoliters

Permanent Magnet Shimming

• Shimming – to make the field uniform• Approach for permanent magnets

– Incorporate into design of magnet– Passive shim (use small additional units of metal)– Active shim (coils + current)

• Alternate approach for very small samples– Incorporate into design of magnet– Move sample around in field to find “best” spot

High Field System – Industrial System 1.0 Tesla

No external field

Industrial grade

Large volume

1 Tesla Field Strength

High performance

Imaging

Spectroscopy Photos courtesy of ASPeCT Magnet Technologies Ltd.www.aspect-mr.com

2. FSE1. Turbo Flash

Example: Seed Detection

Tomato concentrate viscosity to ketchup viscosity

1 (6 ounce) can tomato paste with garlic1/2 cup light corn syrup1/4 cup white vinegar1/4 cup white balsamic vinegar 1/4 cup water1 tablespoon sugar1 teaspoon salt1/4 teaspoon onion powder

Measure tomato concentrate rheology

Correlation of Ketchup Bostwick using in-line viscosity measurements of 12 Brix Tomato Concentrate

Tomato Concentrate (Viscosity/density)(-1/5)

Tom

ato

ketc

hup

Bos

twic

k (c

m)

McCarthy and McCarthy, in press, Relationship between in-line Viscosity and Bostwick Measurement during Ketchup Production, J. Food Science

Portable low-field magnetSingle-sided design

10.2 cm diameter5.0 cm high3.0 kilogramsProton frequency 5.2 MHzMeasurement at 20 mm depth into melon(alternate designs yield up to 50 mm depth)

Photo courtesy of ABQMR, Inc

550 600 650 700 750 8008.5

9

9.5

10

10.5

11

11.5

12

12.5

13

Spin spin relaxation time, ms

Deg

rees

Brix

Personal size watermelon

data1 linear

Brix =-0.015 X +21

Single-side magnet vendors• ACT

– http://www.act-aachen.com/• Magritek

– www.magritek.com• Spin Track NMR

– http://www.process-nmr.com• Bruker

– http://www.brukeroptics.com/profilerssnmr.html

• ABQMR – www.abqmr.com

0.05 T System to measure T2Magnet

Electronics

Speed: 4 fruit per minute for relaxation time measurementAccuracy: 75 to 80% compared to manual inspection

System built by Quantum Magnetics Corporation

A range of small commercial spectrometers• Spincore• TecMag LapNMR• Resonance Systems SpinTrack• Magritek LapSpec• And others

Miniaturizationmicro-NMR Incorporate DNP

Low field NMR SpectraBenchtop/portable spectroscopy

Labscale system for metabolomics measurements

Microscale rheology

Spectroscopy at 0.96 Tesla (~41 MHz)

• 0.24 ppm line width (9.9±0.4 Hz) spectrum of water single shot (S/N = 61)

• Lower plot is a single-shot spectrum of pure ethanol (SNR of highest peak is 45)

Challenge with Permanent MagnetsSpectroscopy

• Field is a function of temperature– Absolute value– Uniformity of the value

• SmCo 300 ppm/K (12300 Hz/K)– Temperature during

acquisition with induce broadening

– 2.1 Hz/s (for McDowell/Fukushima magnet) in a well controlled laboratory

• Solutions?– Move sample around

in the field to find the homogeneous spot

– Improve thermal insulation

– Temperature control– Field frequency lock

• Second channel

– Shim coils

Permanent Magnet based imaging

• Field is a function of temperature

• Acquisition time is short (~0.1 to 1 s)– Imaging has a shorter

acquisition time than for spectroscopy

• On our Aspect system– Good quality images

from 42.8 to 44 MHz• (old lab with poor

temperature control)

– Frequency drift results in the image being slightly displaced in the image field of view

• Easy to adjust the image for this effect

Polarization Transfer

Electron polarization

Nuclear polarization

DNP 110x to 200x Signal Enhancement

x100

Advanced in-line sensors for sorting fruit

Paste Production

WholePeel Pack

Byproducts

Sunburn

Good

Magnetic Resonance Imaging

Rot

Using a Partial Least Squares-Discriminant Analysis applied to MRI data it is predicted that yields for theprocess can be increased by approximately 10%

Summary• Novel permanent magnet

designs extend applications of NMR/MRI from laboratory to the production line.

• Microfabricated components are NeSSI scale compatible.

• Permits quantitative quality standards and process control.

Issues needing to be addressed• Spectroscopy

– Signal/Noise– Changes in field strength and homogeneity are F(T)

– Impacts peak position– Impacts peak shape

• Imaging– Process integration (e.g. combining an MRI, a

rheometer as part of a process line)• Single-side magnets

– Temperature induced field changes– Speed of measurement

Acknowledgements• Rebecca Milczarek• Boaz Zion• Paul Chen• Sandra Garcia• Songi Han• Jeffrey Walton• Eiichi Fukushima,

ABQMR, Inc.

• Uri Rapoport, ASPECT Magnet Technologies Ltd. www.aspect-mr.com

• USDA• USDA-BARD• CDFA• Citrus Research Board• Avocado Commission• ConAgra Foods• Paramount Citrus

Association• CPAC