Eluents methylamine

Conductivity detection in both of its modes of application is also suitable for the detection of primary, secondary, and tertiary alkylamines. This is shown in Fig. 3-139 using three methylamines which are separated on Vydac 400 IC 405 with isonicotinic acid as the eluent. Interferences are possible if the sample contains potassium, rubidium, and/or cesium in addition to amines. However, a small variation of the solvent content in the mobile phase which mainly affects the retention of alkylsubstituted cations, allows the optimization of the separation. In comparison to Fig. 3-140, the separation of the... 

Most of the monovalent anions exhibit only small changes in their relative retention on resins containing one, two, or three hydroxyethyl groups, compared to the tri-methylamine resins (Table 3.1). However, when a stronger eluent was used (phthalate,... 

Anion/R Tn methylamine 0,19 10 Suppressor-based 1C. Ideal for high-pH eluents NaOll. COj-/HCO,... 

Figure 4.28 Separation of methylamines together with common inorganic cations on lonPac CS18. Column dimensions 250 mm x2 mm i.d. column temperature 40°C eluent 4 mmol/L methanesulfonic acid (EG) flow rate 0.25 mL/min detection suppressed conductivity injection volume 5 pL ...

Figure 4.80 Gradient elution of methylamines together with the six standard inorganic cations. Separator column lonPac CS12A eluent H2SO4 gradient 8mmol/L isocratically for 4 min and then to 20mmol/L in 4min flow rate 1 mL/min detection suppressed conductivity injection volume 25 pL peaks 0.5 mg/L...

The extent to which exchange occurs and the speed with which equilibrium is reached depend very much on the nature of the solvent. For the majority of surfactants, 80% methanol is a good solvent for both the sorption (uptake) and elution (recovery) steps. However, the rate of elution can be markedly affected by the concentration of alcohol in the eluent (see the end of section 4.5.4). Methanol has the added advantage that it is easily removed by evaporation. Ethanol and propan-2-ol (isopropanol) are also satisfactory, and some variation in concentration can be tolerated. Not all surfactants are readily soluble in methanol, and in such cases other solvents such as acetone or chloroform may be added. An example is the di(hydrogenated tallow)methylamine used in some soften-in-the-wash detergent powders, which requires the addition of up to 50% chloroform. 

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