Eluents for running LC-ICP MS

The mobile phase contains water and organic solvent(DMF, acetonitrile, ethanol, n-propanol). the concentration of water from 5-40% that will make the eluents ''hydrophilic'' or afford the hydrophilic interaction.
DMF

1.      Dimethylformamide(DMF)

Due to the contribution of the two possible resonance structures of an amide, the bond order of the carbonyl C=O bond is reduced, while that of the carbon-nitrogen bond is increased. Thus the infrared spectrum of DMF shows a lower C=O stretching frequency at 1675 cm^−1[3] than an unsubstituted C=O bond. Also, because of the partial double bond character, the rotation about the C-N axis is slow at room temperature, making the two methyl groups inequivalent on the NMR time scale, giving rise to two singlets of 3 protons each at δ 2.97 and 2.88,^[3] instead of one singlet of 6 protons in the proton NMR spectrum.

N,N-Dimethylformamide (DMF) is miscible with water in all proportions

The vapour pressure at 20°C is 3.5hPa^[5] A Henry's law constant of 7.47×10⁻⁵ hPa·m³/mol can be deduced from an experimentally determined equilibrium constant at 25 °C.The partition coefficient logPOW is measured to –0.85.^[7] Since the density of DMF (0.95 g/cm³ at 20 °C^[4]) is very similar to that of water, significant flotation or stratification in surface waters in case of accidental losses is not expected.

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