Effect of salt additives on partition of nonionic solutes in aqueous PEG–sodium sulfate two-phase system

Abstract

Partition of 12 nonionic organic compounds in aqueous PEG-8000-Na(2)SO(4) two-phase system was examined. Effects of four salt additives (NaCl, NaSCN, NaClO(4), and NaH(2)PO(4)) in the concentration range from 0.027 up to ca. 1.9 M on binodal curve of PEG-sulfate two-phase system and solute partitioning were explored. It was found that different salt additives at the relatively high concentrations display different effects on both phase separation and partition of various nonionic solutes. Analysis of the results indicates that the PEG-Na(2)SO(4) ATPS with the up to 0.215 M NaCl concentration may be viewed as similar to the ATPS without NaCl in terms of the Collander equation's predictive ability of the partitioning behavior of nonionic compounds. All ATPS with each of the salt additive used at the concentration of 0.027 M may be viewed as similar to each other as the Collander equation holds for partition coefficients of nonionic solutes in these ATPS. Collander equation is valid also for the compounds examined in the ATPS with additives of NaSCN and NaClO(4) at the concentrations up to 0.215 M. The observed similarity between these ATPS might be explained by the similar effects of these two salts on the water structure. At concentrations of the salt additives exceeding the aforementioned values, different effects of salt additives on partitioning of various nonionic solutes are displayed. In order to explain these effects of salt additives it is necessary to examine the intensities of different solute-solvent interactions in these ATPS within the framework of the so-called Linear Solvation Energy Relationship (LSER) model.

High‐throughput process development of purification alternatives for the protein avidin

“…The fit coefficients are given in Table 1. In accordance with literature, the addition of 3% NaCl led to a shift of the binodal curve to lower concentrations 35,37,38 whereas using lower PEG molecular weight caused the opposite effect. 39,40 A significant difference between binodal curves of PEG600/phosphate and PEG600/(NH 4 Þ 2 SO 4 at pH 7 including the addition of NaCl to a mass fraction of 3% was not determined (see Figures 1a,g and 2c).…”

A green method for extracting molybdenum (VI) from aqueous solution with aqueous two-phase system without any extractant

“…The APTS have been widely used in extracting and separating bioactive substance [10][11][12], organic small molecule [13][14][15] and metal cations [16][17][18][19]. However, only a few outcomes have been reported in the extraction and separation of metal anion by ATPS.…”

Effect of sodium chloride on solute–solvent interactions in aqueous polyethylene glycol–sodium sulfate two-phase systems

“…Analysis of partition coefficients determined in this study for various organic compounds and proteins listed in Tables 1 and 2 shows that the so-called Collander solvent regression equation (see, e.g., in [18][19][20]) holds for all compounds (including proteins) in the PEG-8000-Na 2 SO 4 -0.215 M NaCl and PEG-10000-Na 2 SO 4 -0.215 M NaCl ATPSs and the same NaCl-free ATPSs [19] as shown in Fig. 1 Comparison of the partition coefficients of organic compounds and proteins in PEG-8000-Na 2 SO 4 -NaCl ATPS with those for the same compounds in the NaCl free PEG-8000-Na 2 SO 4 ATPS reported previously [16,18,19], illustrated graphically in Fig. 2 shows that the Collander solvent regression relationship holds for organic compounds but not for proteins.…”

“…The mechanism of effects of relatively small amounts of NaCl in the ATPS containing large amount of phaseforming salt remains unclear. We reported [16][17][18] previously that different salt additives (NaCl, NaH 2 PO 4 , NaClO 4 , NaSCN) at the concentrations from 0.027 M up to ca. 1.9 M affect partition behavior of small organic compounds in PEG-sodium sulfate ATPS according to the salt effects on the water structure.…”