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Modelling and optimization of the electrokinetic chromatographic separation of mixtures of organic anions and cations using poly(diallydimethyl- ammonium chloride) and hexanesulfonate as mixed pseudostationary phases.

The separation of a series of aromatic carboxylic acids, sulfonates and opiates using electrokinetic chromatography employing a mixture of the soluble cationic polymer poly(diallydimethylammonium chloride) (PDDAC) and the amphiphilic anion hexanesulfonate as pseudostationary phases is described. In this system, the PDDAC pseudostationary phase interacts with the anionic analytes, whereas the hexanesulfonate pseudostationary phase interacts with the cationic analytes. A migration model has been derived which takes into account the ion-exchange (IE) interactions between the anions and the cationic PDDAC as well as the ion-pair (IP) interactions between the opiates and the hexanesulfonate. A further interaction between the combined PDDAC-hexanesulfonate complex and the more hydrophobic analytes is also evident and is accounted for in the model. Constants obtained by applying the model agreed well with the expected trends in IE affinities of the anions for PDDAC and also corresponded with the hydrophobic natures of the analytes. Optimization of the PDDAC and hexanesulfonate concentrations was performed using the normalized resolution product and minimum resolution product criteria. The minimum resolution product criterion proved to be most successful. An advantage of the described system is the improvement in peak shapes obtained after addition of hexanesulfonate to the electrolyte, resulting in increased plate numbers and better resolution. The system was very robust with mobilities varying by less than 2% over a period of days and on using different capillaries.

Alkanesulfonic Acids↗

Occupational skin diseases from epoxy compounds. Epoxy resin compounds, epoxy acrylates and 2,3-epoxypropyl trimethyl ammonium chloride.

Of a total of 3731 patients investigated between 1974 and 1990, 1844 (49.4%) had an occupational skin disease. Of them 142 (7.7%) had an occupational skin disease caused by epoxy compounds--135 patients (95%) had allergic contact dermatitis, five had irritant contact dermatitis, and two had contact urticaria. Apart from dermatoses, two patients had IgE-mediated asthma from exposure to DGEBA epoxy resins. Thus epoxy compounds are one of the main causes of occupational allergic contact dermatoses and can be considered potential causes of occupational asthma. The most frequent causes were epoxy resin compounds, which together induced 93% (132 cases) of all epoxy compound dermatoses. The three most common causative products were epoxy paints and their raw materials (31%, 41 cases), epoxy resin compounds used in electrical insulation (29%, 38 cases) and epoxy glues (18%, 24 cases). Fewer cases were caused by products containing epoxy acrylate and EPTMAC. The present study found that, in addition to contact allergy to DGEBA epoxy resins, contact allergy to epoxy hardeners, non-DGEBA resins and reactive diluents is common. Polyamine hardeners, most frequently MDA, DETA and TETA, rarely IPDA, tris-DMP, EDA, TMD and XDA, were the second commonest causes of contact allergy induced by epoxy resin compounds, after DGEBA epoxy resins. Cycloaliphatic epoxy resins and other non-DGEBA epoxy resins, including heterocyclic dimethyl hydantoin, phenol novolak and brominated epoxy resins, were the third commonest causes, and reactive diluents the fourth commonest cause of allergic dermatitis due to epoxy resin compounds. Most patients sensitized to reactive diluents were allergic to PGE, ortho-CGE, HDDGE and BDDGE, whereas fewer patients were sensitized to AGE, NPGDGE and BGE. Cross-sensitization between reactive diluents was common. Cardura E 10 and Epoxide 8 provoked no reactions. The present study also indicated that DGEBA epoxy resins with a high average MW ought to be regarded as potential sensitizers, and organic solvents probably promote sensitization to DGEBA, even if the amount of DGEBA is low in the causative products. When contact dermatitis induced by epoxy compounds is suspected, an accurate diagnosis is made with the use of detailed data on the patient's exposure and extensive patch testing, including tests with the patient's own products. No chemical can be used alone to screen for sensitization to all different contact allergens of epoxy compounds.(ABSTRACT TRUNCATED AT 400 WORDS)

Benzhydryl Compounds↗

A novel composite nanofiltration (NF) membrane prepared from graft copolymer of trimethylallyl ammonium chloride onto chitosan (GCTACC)/poly(acrylonitrile) (PAN) by epichlorohydrin cross-linking.

A novel composite nanofiltration (NF) membrane was prepared by over-coating the PAN ultrafiltration (UF) membrane with a GCTACC thin layer. The effects of membrane preparation techniques and operating conditions on the performance of the composite membrane were studied. The results indicate that a composite NF membrane from 1.0wt% GCTACC casting solution, vaporized for 2h at 50 degrees C, cross-linked for 20h at 50 degrees C and pH approximately 12 with ethanol/epichlorohydrin (50/0.45 wt/wt) had optimum performance. The resultant GCTACC/PAN composite membrane was positively charged. Scanning electron microscopy showed its asymmetric and composite features. At 25 degrees C and 30L/h of cycling flow, the permeability of pure water through this membrane is 6.3L/hm(2)MPa. At 25 degrees C, 1.2MPa and 30L/h of cycling flow, the rejection of 1000mg/L MgCl(2), CaCl(2), MgSO(4), Na(2)SO(4), and NaCl solutions is 0.976, 0.972, 0.897, 0.65, and 0.407, respectively, with fluxes of 6.8, 6.12, 6.12, 5.57, and 5.51L/hm(2), respectively. The order of rejection of different salts follows the decreasing order of MgCl(2), CaCl(2), MgSO(4), NaCl, KCl, Na(2)SO(4), and K(2)SO(4), which reveals the characteristics of the positively charged NF membrane. In addition, the curve for the streaming potential also illustrates the positively charged characteristics of this membrane, with a pressure osmotic coefficient of 11.7mVMPa(-1).

Acrylonitrile↗

Effects of polydiallyldimethyl ammonium chloride coagulant on formation of chlorinated by products in drinking water.

The objectives of this research work was to evaluate the reduction of THM precursors by cationic p-DADMAC and determine the correlations between the chlorine demand and trihalomethane formation in the presence of electrolyte solutions and ambient light. The chlorine demand was found to be significantly reduced provided that the H2SO4 electrolyte was fed to the sample solutions. The amount of CHCl3 formation was also decreased when the Na2SO4 electrolyte was introduced in spite of the levels of light intensity. The p-DADMAC can not only effectively remove the turbidity but also reduce the formation of CHCl3. The optimum dosage of p-DADMAC for reducing the turbidity, TOC and CHCl3 in the humic acid and source water samples was determined and depended upon the nature of organics.

Allyl Compounds↗

The action of tetraethyl-ammonium chloride on the response of the rat anococcygeus muscle to motor and inhibitory nerve stimulation and to some drugs.

1 Tetraethylammonium chloride (TEA) 0.125 mM to 20 mM potentiates the response of the anococcygeus muscle to field stimulation of the motor adrenergic nerves without affecting the response to noradrenaline suggesting a pre-synaptic origin of potentiation. The potentiation is greatest at low, submaximal, frequencies (2 Hz) of stimulation and only slight at the higher frequency of 20 Hz. This difference is due to the restraint imposed on the demonstration of potentiation by maximal or near maximal motor responses since reduction of the mechanical response at 20 Hz by either phentolamine (post-synaptic block) or guanethidine (pre-synaptic block) resulted in a great increase in potentiation of the response at this frequency. 2 TEA in concentrations up to 1 mM similarly potentites the response to inhibitory nerve stimulation and again the greatest effect is at low frequencies. Higher concentrations (5-20 mM) progressively depress the inhibitory response. It is suggested that TEA may specifically antagonize the post-synaptic action of the inhibitory transmitter and that at higher concentrations of TEA this effect dominates the pre-synaptic action in increasing transmitter release. 3 TEA has no effect on the motor response to tyramine. 4 TEA (5-20 mM) causes a maintained rise in muscle tone. Part of this is abolished by phentolamine but part is resistant. A similar muscle stimulant action of TEA is observed in muscles from rats previously treated with 6-hydroxydopamine in which indirect sympathomimetic drugs and field stimulation could no longer produce a motor response. These results suggest that part of the motor effect of TEA is due to an increased spontaneous release of noradrenaline and part to a direct action on the muscle. 5 TEA 0.125 mM to 20 mM antagonize the stimulant action of carbachol. Dose-response curves show a parallel shift to the right with no change in the maximum response suggesting a competitive atropine-like action. Such an effect has previously been reported in amphibian tissue but not so far as we can determine in mammalian preparations. 6 The possible mode of action of TEA is discussed.

Animals↗