Thermo Scientific picoSpin picoSpin-45 Frequently Asked Questions

Frequently Asked Questions

General Questions

Is the picoSpin-45 spectrometer really the world’s first miniature NMR spectrometer?

Haven’t desktop NMR machines been around for years?

In a proton NMR spectrum, lines are typically separated by a few parts per million (ppm).
To qualify as a true spectrometer, an NMR system must have resolution well below 1
ppm. The picoSpin-45’s resolution is better than 0.1 ppm, or 100 ppb (parts per billion).
Before the picoSpin-45, all commercial miniature NMR machines had resolution that was
too poor for them to qualify as spectrometers. They could be used to analyze NMR
relaxation times, but they were not spectrometers in the sense usually meant in NMR. So
yes, the picoSpin-45 really is the world’s first miniature NMR spectrometer.

How does it work?

The picoSpin-45 is, in most respects, a conventional Fourier-transform proton NMR
spectrometer. It has all of the usual NMR spectrometer components including a magnet,
shim coils, programmable pulse sequencer, RF transmitter, solenoid RF coil, low-noise
receiver and digital data acquisition system. What is different is just that everything is so
small. Instead of a large and expensive superconducting magnet, we use a fist-sized
room-temperature permanent magnet. The electronic circuits are all miniaturized using
techniques similar to those used in cell phones. The sample fluid is confined to a small
capillary with an inside diameter of about 0.3 mm.

How stable is the picoSpin-45? Can I use averaging to improve the signal-to-noise ratio?

The system is stabilized by a magnet temperature controller and by software techniques.
If the sample itself behaves in a time-independent way, any number of single shots can
be averaged together to improve SNR.

Can I look at flowing samples?

Yes, but spectroscopic resolution will suffer unless the sample is stationary during the
NMR data acquisition. For most applications, either the inlet port or the outlet port should
be closed during data acquisition, and there should be a small fluid volume between the
closed valve or plug and the port. Otherwise, thermal expansion of the fluid can cause
flow.

Why does the picoSpin-45 have a capillary cartridge?

When reasonable precautions are observed, problems with clogging and contamination
of the capillary can be avoided. However, accidents do occur, and when they do, it is a
great advantage to be able to replace the capillary in the field. Cartridge changes only
take a few minutes. The unit should be re-shimmed whenever the cartridge is changed.

1 of 4

What experiments can I do other than 1-D spectroscopy?

The picoSpin-45 contains a general-purpose programmable pulse sequencer with 20 ns
time resolution. The sequencer-controlled RF oscillator has 32-bit frequency resolution,
8-bit phase resolution and 8-bit attenuator resolution. The main-channel pulse program
can contain up to 1024 instructions. With these capabilities, essentially any proton NMR
experiment is possible, including spin-echo T

2

measurements and T1 inversion-recovery.
The first released version of the picoSpin software (Version 0.80) supports 1D
spectroscopy only.

Can I write my own pulse sequences?

When version 1.0 of the software is released, users will be able to write their own pulse
sequences and experiment scripts.

Sample Handling

How do I inject a sample?

The spectrometer has an inlet connector and an outlet connector on the front panel. The
fluid path between them is a capillary with an ID of about 0.3 mm and a total volume of
about 20 microliters. Our standard stainless steel 1/32” panel fittings are part numbers
VICI ZBU.5 for the outlet and VICI ZBUFR.5F for the inlet, available from VICI. The inlet
fitting has a replaceable 2-micron frit filter (VICI 2FR1-10, also available in other materials
and sizes).

You can connect to these fittings in many ways. If you would like to inject your sample
from a syringe, we suggest the VICI VISF.5FPK syringe port (PEEK). To close off the inlet
and outlet, you can use VICI ZP.5FPK plugs (PEEK). You can also connect 0.030” OD
microbore PTFE tubing (Cole-Parmer part EW-06417-11) to these fittings using a grooved
PEEK ferrule VICI ZGF.5PK-10. A #30 syringe needle can be used to inject fluids into this
PTFE tubing.

What materials are in contact with the sample fluid?

Our standard cartridges use microbore PTFE capillary and a short section of quartz glass
capillary at the location of the RF coil. The front panel fittings are stainless steel with a
stainless still frit filter on the inlet. PEEK ferrules are used to connect the microbore PTFE
capillary to the front panel fittings. Contact us to discuss other materials for special
applications.

How do I remove a sample?

Just flush the capillary with either a clean solvent or your next sample.

Chemical Applications

What kind of samples can I measure?

Any proton-containing liquid, not too viscous for injection into a 0.3 mm ID capillary, can
be used.

Will the signal I am looking for be strong enough to see?

Good question! It is always a good idea to estimate the signal-to-noise ratio (SNR) before
you get started with unfamiliar samples. The exact SNR depends on many things,

2 of 4