Technical information

QUALITY

1. Isotopic Enrichment

The residual proton content of the solvent is determined by proton NMR by comparison of the integral of a reference sample signal with the integral of a residual proton signal. The isotopic enrichment is defined as atome per cent deuterium (D) content in the molecule.

	(D) atoms
Atom % deuterium (D) =	------------ x 100
	(H+D) atoms

2. Chemical Purity

EURISO-TOP's Standard deuterated solvents are evaluated after packaging on a 400 MHz FT NMR instrument and by gas chromatography. We warrant a chemical purity higher than 99.9%.

3. Water Content

To avoid water contamination, each batch of EURISO-TOP is routinely tested for chemical and isotopic purity after initial purification, before packaging, and after packaging. High field proton NMR data is acquired for each solvent we manufacture, and certain solvents are tested for purity by GC/MS for contaminants which could not be observed by proton NMR. Our quality control department tests for water content in our solvents are carried out by using the Karl Fisher titration method.

4. Storage

Chloroform-d, Methylene Chloride-d2 and Tetrachloroethane-d2 are not stabilised and are thus very sensitive to ultra-violet waves and oxidation. Their storage under refrigeration at less than +4°C (39.2°F) guarantees a longer shelf life. Before use, the vial should be left to warm to room temperature before opening under an anhydrous, inert atmosphere.
Tetramethylsilane (TMS) is a very volatile compound (bp=26°C). To minimise its loss it is packaged in a penicillin vial sealed with a Teflon faced septum. It is not necessary to keep it in a refrigerator.

5. Toxicity

All the hazard solvents of this range are labelled according to the hazard symbols and rules of advising in use.
Therefore, these solvents should be handled only by trained staff familiar with their potential hazards. They have similar properties to those of the non-isotope labelled counter parts. Appropriate precautions should be taken all times during their use and disposal. The products offered by EURISO-TOP are for laboratory research use only. Use in any other way than laboratory applications is the sole responsibility of the researcher.

CHOICE OF SOLVENT

This choice depends on several criteria:

solubility of the sample,
position of the peak of residual proton,
consequence on the chemical shift of the solute due to interactions with solvent molecules,
temperature of experiment,
polarity of solvent.

HANDLING

All deuterated solvents must be handled in a strict anhydrous and inert atmosphere (dry nitrogen or argon) in order to minimise the absorption of moisture.
This absorption leads not only to an increase in the HDO concentration and the resultant signal in 1H NMR spectrum, but also to exchange of the easily labile protons (especially heteroatom-linked ones). Solvent vials must be immediately re-closed after use and the solvent removed from an ampoule transferred into a dry vial.
Very hygroscopic solvents (Deuterium oxide and Dimethylsulfoxide d6) are packed in ampoules or in " penicillin " vials equipped with a septum (Teflon faced for DMSO). Solvent is withdrawn with a syringe. It is recommended to flush into the vial an amount of dry nitrogen equivalent to the amount of solvents to be withdrawn.

SAMPLE CONCENTRATION

The signal of the protons of the dissolved substance should be greater than the signal of the residual proton of the solvent used. So the quantity of the product depends on the isotopic enrichment of the solvent and the applied field in the NMR spectrometer.

TUBE PREPARATION

In order to ensure optimum measurements, we advise the user to work with unused NMR Tubes. Before use, the NMR tube must be perfectly cleaned (within and without) and dried. To avoid contamination with residual water absorbed into the inner wall of the NMR tube, we recommend to keep 1ml or more of Deuterium oxide in the tube over-night, to decant and wash it with acetone d6 or Methyl alcohol d4 and to store it in a " dessicator " saturated with Deuterium oxide.
To clean the outer wall of the NMR tube use a soft piece of tissue.

SAMPLE PREPARATION

The sample is dissolved in approximately 0.5ml of deuterated solvent and slightly heated if necessary.Insoluble substances are eliminated with a suitable filter cartridge before the introduction of the solution into the NMR tube.
Paramagnetic oxygen dissolved in solvents produces a reduction of the relaxation times and a line broadening.To avoid this phenomenon, the sample may be purged by degassing techniques (distillation, bubbling of dry inert gas, sealing of the sample tube under vacuum...).

REFERENCE MATERIAL

The position of the peak of the solvents can change with the temperature and the pH of the solution. In certain cases, it is not recommended to use it for calibration. The reference material for the 1H and 13C NMR is Tetramethylsilane (TMS).
TMS is not soluble in heavy water, so the internal reference for this solvent is: (2,2,3,3-d4) Trimethyl-3 propionic acid, sodium salt (d4-TMSP).