Eicosyl sodium sulfate

The compression or decompression of bovine serum albumin monolayers spread on an aqueous substrate at a pH near the isoelectric point can effect surface tension. The surface pressure changes depend on the distance between the position of the surface pressure measuring device and the compression barrier. This effect is minimal at a pH above or below the isoelectric point and undetected for small molecules (myristic acid and eicosyl sodium sulfate) even when the substrate contains substituted alkyl amines. A theory is proposed which attributes the above observation to surface drag viscosity or the dragging of a substantial amount of substrate with the BSA monolayer. This assertion has been experimentally confirmed by measuring the amount of water dragged per monolayer using the technique of surface distillation. 

Additional experiments were conducted on eicosyl sodium sulfate monolayers spread over 0.1N 2-amino-2-methyl-l-propanol (pH = 9.65, 24.5°C) and 0.1N 2-amino-l-butanol (pH 8.5, 24.5°C). In all cases of compression or decompression, the measured surface pressures were independent of the distance between the measuring device and the compression barrier. 

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