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Detergents (anionic surfactants, MBAS) Test Kits

Detergents (anionic surfactants, MBAS) Test Kits

What are Detergents?
A detergent is a surfactant, or mixture of surfactants, with cleaning properties designed to remove dirt from surfaces. In conventional terms it is a synthetic soap usually diluted in water. Surfactant molecules are characterized by their hydrophilic head and their longer hydrophobic tail. Surfactants are classified by the charge on the hydrophilic head. If it has a positive charge, it is called a cationic surfactant, a negative charge is called an anionic surfactant, and if the head has no charge, it is called a nonionic surfactant. Surfactant cleansing action is via a structure called a micelle which is formed when the hydrophobic tails attach to dirt or grease particles while the hydrophilic heads point out. Micelles lift the dirt off-of the surface. The most common kind of surfactant used in detergents are anionic surfactants.

Why Test for Detergents?
Municipalities often monitor stormwater for detergents (anionic surfactants) as a part of an illicit discharge field investigation program. Households and businesses can release detergents into the environment which can pollute natural bodies of water. Detergents are also measured in pharmaceutical operations to ensure that there are no residuals present following equipment cleaning processes.

About Our Test Kits
CHEMetrics is proud to have our CHEMets® detergents test kit listed in the EPA’s Illicit Discharge Determination Elimination manual. The kits utilize the Methlyene Blue Active Substances (MBAS) method to provide measurements in ppm (mg/L) of linear alkylbenzene sulfonate (LAS). The procedure features a unique extraction and sampling technique that eliminates several steps required in other test procedures and provides increased sensitivity.

CHEMetrics offers a visual (K-9400) CHEMets test kit that can measure detergents visually at a range of 0-3 ppm LAS. This test kit turns a blue color in relation to the concentration of anionic surfactants. R-9400 is the refill pack for this product.

If you require more precision we recommend the instrumental (I-2017) Vacu-vials kit®, which comes with a Single-Analyte Photometer (SAM) that measures at a range of 0-2.50 ppm LAS. R-9423 is the refill pack for the instrumental SAM Photometer.

Please note that the shelf-life of R-9400 is 5 months and R-9423 is 8 months. We recommend stocking quantities accordingly.

Click on a catalog number in the tables below for more information or to purchase a test kit.

Visual Kits

Range MDL Method Kit Catalog No. Refill Catalog No.
0-3 ppm 0.125 ppm Methylene Blue K-9400 R-9400

Instrumental Kits

Range Method Kit Catalog No.
0-2.50 ppm Methylene Blue I-2017


The Methylene Blue Method

References: USEPA Methods for Chemical Analysis of Water and Wastes, Method 425.1 (1983). APHA Standard Methods, 23rd ed., Method 5540 C-2000. ASTM D 2330-02 , Methylene Blue Active Substances.

The methylene blue active substances (MBAS) method is used in a 3-minute procedure to measure anionic detergents in the 0-3 ppm (mg/L) range. The procedure features a unique extraction/sampling technique that eliminates several steps required in other test procedures and provides increased sensitivity. Anionic detergents react with methylene blue to form a blue-colored complex that is extracted into an immiscible organic solvent. Results are expressed in ppm (mg/L) as linear alkylbenzene sulfonate (LAS), equivalent weight 325.