Analysis and measurement of silver nanoparticles in wastewater by single particle ICP-MS

- Sep 29, 2020-

"Nanosilver" is the abbreviation or common name of "silver nanoparticle". It refers to particles composed of silver atoms, and their particle size is usually in the range of 1-100nm. The antibacterial properties of the surface of silver materials have long been known, and the mechanism is located on the surface of the material. Silver atoms can be slowly oxidized by the oxygen in the environment to release free silver ions (Ag+), these silver ions bind to the sulfhydryl groups on the bacterial wall to block the respiratory chain of the bacteria and ultimately kill the bacteria attached to the surface of the material. The small size effect and surface effect of nano particles, as the particle size decreases, the ratio of the surface atomic number of nano silver to the internal atomic number increases rapidly, which ultimately leads to a significant increase in the release rate of silver ions and a more significant sterilization effect.

Various products using the antibacterial properties of nano silver, including textiles, cosmetics, medicines, etc., and other industrial products, are increasingly being developed and put into use. These nano-silver will eventually enter the environment and have an impact on the ecological environment and biological health.

The technical means to quickly detect and characterize nanoparticles in various environmental matrices is therefore extremely necessary, and PerkinElmer's single-particle ICP-MS technology can meet this challenge well.

This experiment takes you to understand the ability of single particle ICP-MS to measure nano-silver in different wastewater.


Water sample: It was taken from a sewage treatment plant near Montreal, Quebec, Canada.

Wastewater: Wastewater discharged into the river after final treatment by the sewage treatment plant, and collected after the secondary sedimentation tank.

Mixed solution: After biological treatment, it leaves the aeration tank and reaches the secondary settling tank to treat suspended solids and sediments. The wastewater is collected from the secondary aeration tank.

Alginate: A ppm-level polysaccharide that can be detected in wastewater and is composed of soluble organic carbon in wastewater. Alginate solution was used as a known control and substitute for comparing wastewater samples. Dissolve sodium alginate (Sigma-Aldrich, St. Louis, Missouri, USA) extracted from brown algae in deionized water to prepare an alginate solution with a concentration of 6 ppm, and shake for one hour.

Standard Ag ENPs coated with PVP with an average particle size of 67.8±7.6nm (determined by TEM, nanoComposix™ Inc., San Diego, California, USA), add 10mL to all samples to make the concentration 10ppb (5,000,000 particles /mL). The sample is diluted 10-1000 times with deionized water and sonicated for 5 minutes before testing. All samples are made in triplicate.

Use PerkinElmer NexION® 300D/350D ICP-MS for analysis, using SP-ICP-MS mode, under the Syngistix™ software nano analysis module

Experimental results

Figure 1 shows the particle size distribution of the standard 0.1ppb (50,000 particles/mL) Ag ENPs, which is equivalent to an average particle size of 66.1±0.1nm and a concentration of 52,302±2102 particles/mL. The consistency between the particle size test results and the TEM setting indicates that the alginate base does not affect the measurement accuracy.


In conclusion

Experiments prove that SP-ICP-MS has the ability to accurately test silver nanoparticles in three different types of wastewater samples. Although wastewater matrices are complex, they will not inhibit the ability of SP-ICP-MS to accurately measure particle size and nanoparticle concentration.