Reverse-Phase Ion-Pair Chromatography (HPLC) of Alkylbenzene Sulfonates
- L.A. Verkruyse (ARCO Oil & Gas Co.) | R.V. Lewis (ARCO Oil & Gas Co.) | K.O. Meyers (ARCO Oil & Gas Co.) | S.J. Salter (ARCO Oil & Gas Co.)
- Document ID
- Society of Petroleum Engineers
- SPE Oilfield and Geothermal Chemistry Symposium, 1-3 June, Denver, Colorado
- Publication Date
- Document Type
- Conference Paper
- 1983. Society of Petroleum Engineers
- 5.4.7 Chemical Flooding Methods (e.g., Polymer, Solvent, Nitrogen, Immiscible CO2, Surfactant, Vapex), 2.5.2 Fracturing Materials (Fluids, Proppant), 4.1.2 Separation and Treating, 4.1.5 Processing Equipment
- 0 in the last 30 days
- 109 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 8.50|
|SPE Non-Member Price:||USD 25.00|
A high-performance, liquid-chromatographic procedure is presented thatrapidly and quantitatively separates alkylbenzene sulfonates according to theiralkyl chain length and structure. The separation employs octadecylsilanizedsilica gel as a stationary phase and an aqueous acetonitrile solution oftetrabutyl ammonium chloride (TBAC) as the mobile phase. The TBAC acts as anion-pair reagent and suppresses the ionic nature of the reagent and suppressesthe ionic nature of the sulfonates. Separation is effected by gradients in TBACconcentration and mobile phase polarity. The concentration of each component isthen quantitatively measured by a UV detector. Gradient selection and samplematrix effects are discussed. Several examples are presented that demonstratethe utility of this analytical procedure.
Petroleum sulfonates that have broad equivalent weight distributions andsignificant amounts of polysulfonates may not be optimal for use inmicellar/polymer flooding.1 During the dynamics of such processes,these materials can fractionate1-4 by either adsorption orinterphase transport (phase behavio)5 driven mechanisms. Suchresults have led to the use of narrower distribution, better definedsurfactants, sometimes referred to as synthetics, although this distinction issomewhat vague. Many questions remain to be answered regarding the selection ofoptimal surfactants and surfactant-blend distributions. In order to performsuch studies, it is necessary to have available a quantitative, reliable, andhopefully simple analytical technique that will account for each of thesurfactant species independently. This paper presents such a technique,employing high performance liquid chromatography (HPLC). The technique reportedhere has proved useful in evaluating the purity of materials intended to bemonoisomeric, as well as analyzing components in surfactant blends. We discussthe procedure and show how this technique can be tailored to a particularsurfactant system. We present a variety of matrix systems for which thetechnique works well, as well as some for which it does not. The effects ofvarious parameters are shown, and examples are given that demonstrateapplications of the method.
High performance liquid chromatography is rapidly becoming a powerful toolin the analysis of surfactants used in micellar/polymer flooding. Theseparation of petroleum sulfonates according to their degree of sulfonation byanion-exchange chromatography is well documented in theliterature.1,6,7 However, these techniques do not offer sufficientselectivity to separate sulfonates differing only in alkyl chain length orpoint of attachment. Recently, reverse-phase ion-pair chromatography hasemerged as a versatile alternative to ion-exchange chromatography for theseparation of ionic species. In ion-pair chromatography the ionic nature of thesample is suppressed by association with an ion-pair reagent of oppositecharge. The resulting nonionic ion-pair partitions between the polar mobilephase and the nonpolar stationary phase.
Among the parameters controlling the retention of the ion-pair are pH,temperature, polarity of the mobile phase, lipophilicity of the stationaryphase, and the size, concentration and lipophilic nature of the counter-ion. Agradient in any of these parameters could be used to separate a mixture ofsulfonates with a wide range of molecular weights. In practice, gradients insolvent polarity and counter-ion concentration are the mostcommon.8,9
|File Size||496 KB||Number of Pages||10|