Tab. 1

Gradient elution program in liquid chromatography"

Tab. 2

Results of determination for sodium carboxylates by two-phase titration with bromocresol green as indicator"

Tab. 3

Fatty acid content determined by acid-base titration"

Tab. 4

Effects of the volume ratio of chloroform/isopropanol on the results of content of C14 carboxylate determined by two-phase titration with bromocresol green as indicator"

Tab. 5

Effects of the volume ratio of chloroform/isopropanol on the results of content of C12 carboxylate determined by two-phase titration with bromocresol green as indicator"

Tab. 6

Determination of active matter content in the samples of fatty alcohol PO-EO ether sulfate"

Fig. 1

Liquid chromatograms of four samples using elution program 1 in Table 1. Purified APEC, 2 mg/mL （a）; fatty alcohol PO-EO ether （nonionic raw material）, 2 mg/mL （b）; the mixture of 1.6 mg/mL purified APEC and 0.4 mg/mL nonionic raw material （c）; sodium glycollate, 2 mg/mL （d）"

Fig. 2

Liquid chromatograms of three samples, using elution program 2 in Table 1: Sodium glycollate, 0.1 mg/mL （a）; purified APEC, 1 mg/mL （b）; the mixture of 0.05 mg/mL sodium glycollate and 0.95 mg/mL purified APEC （c）"

Fig. 3

Mass spectrum of fatty alcohol （PO） m-（EO） n ether （nonionic raw material） （M≈2 200）"

Fig. 4

IR spectra of purified APEC and sodium glycollate"

Fig. 5

Calibration curves for determination of the active matter content in samples of fatty alcohol PO-EO sulfate （APES）, sodium C14 carboxylate and APEC by colorimetric method"

Fig. 6

Effects of storage time for the two-phase extraction system on the absorbance of chloroform phase in colorimetric method （30 ℃）"

Fig. 7

Calibration curve of the system of APEC standard sample mixed with nonionic raw material"

Fig. 8

Correlation between the theoretical conversion and that determined by the colorimetric method for the model products by mixing APEC standard sample with nonionic raw material"

Fig. 9

Appearance of APEC sample synthesized by carboxymethylation （a）; appearance of the aqueous mixtures of pure APEC and nonionic raw material （the mass fraction of nonionic raw material is shown） with the total concentration being 0.5%, taken at room temperature （b）"

Tab. 7

Recovery of the APEC samples measured by colorimetry"