Anionic Surfactant (LAS) Analysis

Five types of anionic surfactants that are subject to measurement in Japanese Drinking Water Quality Standards (sodium decylbenzenesulfonate, sodium undecylbenzenesulfonate, sodium dodecylbenzenesulfonate, sodium tridecylbenzenesulfonate, and sodium tetradecylbenzenesulfonate, their phenyl group is bonded to a carbon other than the terminal of a linear-chain alkyl group). You can use them for calibration curve creation.
In addition, Fujifilm Wako also offers a mixture standard solution in which the above five anionic surfactants are mixed at 1 mg/mL each (methanol solution).

Mixture standard solution

LAS (C₁₀-C₁₄), in which a phenyl group is bonded to carbons other than the terminal of the linear alkyl chain, are mixed. And the concentration values of each LAS are specified. It can be used for the notification test method of the Japanese Drinking Water Quality Standards.

• [HPLC Chromatogram]
• [Composition information]

  Peak No.	Anionic Surfactant
  C10	Sodium Decylbenzenesulfonate
  C11	Sodium Undecylbenzenesulfonate
  C12	Sodium Dodecylbenzenesulfonate
  C13	Sodium Tridecylbenzenesulfonate
  C14	Sodium Tetradecylbenzenesulfonate

• [HPLC conditions]

  Column	Wakopak® Navi C18-5 4.6 mm x 250 mm
  Column temperature	40℃
  Eluent	0.1 mol/L NaClO4 in CH3CN/H2O= 65/35
  Flow rate	1.0 mL/min.
  Detection	UV 225 nm

Single Standard Solution

Fujifilm Wako provides internal standard solutions that can be used for LC/MS analysis of anionic surfactants. Sodium 4-Dodecylbenzenesulfonate-¹³C₆ Standard Solution has physical properties close to those of C₁₂-LAS, which is subject to various regulations in Japan, and can be used as an internal standard.

Internal standard solution

Recovery test of sodium alkylbenzenesulfonate (C₁₀-C₁₄) in water samples using Presep^®-C C18 and Presep^®-Agri

(Compliant with the Japanese Drinking Water Quality Standards (enforced on April 1, 2004))

Wakopak^® Wakosil-Ⅱ

LC/MS/MS analysis example of LAS (C₁₀-C₁₄) using the Japanese Drinking Water Quality Standards notification method (HPLC column: Wakopak^® Wakosil-Ⅱ 3C8RS)

LC/MS/MS Chromatogram

Analysis conditions

Shimadzu LC/MS-8040

Column：	Wakopak® Wakosil-Ⅱ 3C18RS 2.0×150 mm
Column temperature：	40℃
Eluent：	A) H2O, B) CH3CN
Gradient：	Time (min.) B conc. (%) 0-30 60
Flow rate：	0.3 mL/min.

[MS]

Ionization: ESI
Mode: MRM

LC/MS/MS analysis example of LAS (C₁₀-C₁₄) using the Japanese Drinking Water Quality Standards notification method (HPLC column: Wakopak^® Wakosil-Ⅱ 3C18HG)

LC/MS/MS Chromatogram

LAS	Monitoring Ions (m/z)		Mode	LAS	Monitoring Ions (m/z)		Mode	LAS	Monitoring Ions (m/z)		Mode
	Precursor	Products			Precursor	Products			Precursor	Products
C10-LAS	297	183	-	C12-LAS	325	183	-	C14-LAS	353	183	-
C11-LAS	311	183	-	C13-LAS	339	183	-	13C12-LAS	331	176	-

Analysis conditions

[Instrument]

Shimadzu LC/MS-8040

[HPLC]

Column：	Wakopak® Wakosil-Ⅱ 3C18HG 2.0×150 mm
Column temperature：	40℃
Eluent：	A) 0.1 vol% HCOOH in H2O, B) 0.1 vol% HCOOH in CH3CN
Gradient：	Time (min.) B conc. (%) 0-30 75
Flow rate：	0.3 mL/min.

[MS]

Ionization: ESI
Mode: MRM

Wakopak^® Wakosil^® AS-Aqua

Linear alkylbenzene sulfonic acid (LAS) exists as a mixture of isomers, and many peaks are detected when use ODS columns.
Wakopak^® Wakosil^® AS-Aqua separates isomers as a single peak for each carbon length of LAS, which improves detection sensitivity, simplifies quantitative calculations, and shortens analysis time. Also, since the linear alkylbenzene sulfonic acids (LAS) and branched alkylbenzene sulfonic acids are separated, they can be distinguished. Furthermore, there is no significant difference in the measured values compared to a general ODS column, and more accurate measurements can be performed even in the low-concentration condition.

Comparison of ODS Columns and Wakopak^® Wakosil^® AS-Aqua for Anionic Surfactant Analysis

[HPLC]

Eluent	CH3CN/H2O=65/35 (v/v)+ 12.3 g/1,000 mL NaClO4 added
Flow rate	1.0 mL/min. (Wakopak® Navi C18-5), 0.7 min. (Wakopak® Wakosil® AS-Aqua)
Detection	FL Ex. 221 nm, Em. 284 nm
Injection volume	10 µL
Sample	Anionic Surfactants Mixture Standard Solution (C10-C14 each 10 mg/mL Methanol Solution)

Column: Wakopak^® Navi C18-5 4.6 mmx250 mm (ODS column)

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Column: Wakopak^® Wakosil^® AS-Aqua*

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* Wakopak^® Wakosil^® AS-Aqua can recognize and separate both linear and branched alkylbenzene sulfonic acids.

Separation of anionic surfactants mixture standard solution and toluene

Depending on the pretreatment method, toluene may be mixed in the extracted sample.

When using Wakopak^® Wakosil^® AS-Aqua, toluene and anionic surfactants are eluted separately, allowing analysis without interference from the toluene peak.

• 
• [HPLC]

  Column	: Wakopak® Wakosil® AS-Aqua 4.6 mm x 250 mm
  Column temperature	: 40℃
  Eluent	: CH3CN/H2O = 65/35 (v/v) + 12.3 g/1,000 mL NaClO4 added
  Flow rate	: 0.7 mL/min.
  Detection	: (Upper) FL Ex. 221 nm. Em. 284 nm (Lower) UV 225 nm
  Injection volume	: 10 μL
  Sample	: Anionic Surfactants Mixture Standard Solution 　(C10-C14 each 10 mg/mL Methanol Solution)+Toluene (1 μL/mL) added