Cations

Key words: cations, Kationen, CE, indirect detection, indirekte Detektion

Inorganic cations can be determined in uncoated capillaries with indirect UV detection. As the EOF migrates in the same direction as the cations short analysis times are possible. For the separation of ammonium and potassium it is necessary to add 18-crown-6 ether, which slows potassium down in relation to ammonium due to a selective komplexation of the crownether and potassium. The UV acitve co-ion of the electrolyte can be adapted due to the desired peak symmetry and the matrix. For the determination of fast cations like ammonium, potassium and sodium the electrolyte system based on imidazole is the most appropriate. For the determination of the slower cations an electrolyte based on aminopyridin or the cation buffer (Agilent) are available. These systems are equally suitable for the separation of aliphatic amines (see also chapter „Amine“). The optimization of the sensitivity can be achieved by increase of the injection.

Cation standard solution – 10 mg/l

  • Separation: CZE
  • Electrolyte: Aminopyridine
  • Capillary: fused silica, 50 µm ID, 64 cm in total
  • Injection: 10 s, 50 mbar
  • Detection: indirect UV, 260 nm
  • Description: The standard solution contains 10 mg/l ammonium, potassium, calcium, sodium, magnesium, strontium and barium each as well as 2 mg/l lithium.
Standardlösung 10 mg/l

Standard solution 10 mg/l

Download: Standardlösung10-pdf

Cation standard solution – 1 mg/l

  • Separation: CZE
  • Electrolyte: Aminopyridine
  • Capillary: fused silica, 50 µm ID, 64 cm in total
  • Injection: 10 s, 50 mbar
  • Detection: indirect UV, 260 nm
  • Description: The standard solution contains 1 mg/l ammonium, potassium, calcium, sodium, magnesium, strontium and barium each as well as 0,2 mg/l lithium.
Standardlösung 1mg/l

Standard solution 1mg/l

Download: Standardlösung-1.pdf

Cation standard solution – 1 mg/l with optimized Injection

  • Separation: CZE
  • Electrolyte: Aminopyridine
  • Capillary: fused silica, 50 µm ID, 64 cm in total
  • Injection: 30 s, 50 mbar
  • Detection: indirect UV, 260 nm
  • Description: The standard solution contains 1 mg/l ammonium, potassium, calcium, sodium, magnesium, strontium and barium each as well as 0,2 mg/l lithium. Due to the increase of the injection time the sensitivity is drastically improved.
Standardlösung 1 mg/l mit optimierter Injektion

Standard solution 1 mg/l with optimized Injection

Download: Standardlösung-1-optimiert.pdf

Cation standard solution – 10 mg/l

  • Separation: CZE
  • Electrolyte: Imidazole with 2 mM 18-crown-6
  • Capillary: fused silica, 50 µm ID, 64 cm in total
  • Injection: 10 s, 50 mbar
  • Detection: indirect UV, 215 nm
  • Description: The standard solution contains 20 mg/l cesium, 10 mg/l ammonium, potassium, calcium, sodium, magnesium, strontium and barium each as well as 2 mg/l lithium.
Standardlösung 10 mg/l mit Imidazol-Elektrolyt

Standard solution 10 mg/l,  Imidazole electrolyte

Download: Standardlösung10-Imidazol.pdf

Cations in tap water

  • Separation: CZE
  • Electrolyte: Imidazole with 2 mM 18-crown-6
  • Capillary: fused silica, 50 µm ID, 64 cm in totalt
  • Injection: 10 s, 50 mbar
  • Detection: indirect UV, 215 nm
  • Description: The tap water was diluted 1:2.
Kationen in Leitungswasser

Cations in tap water

Download: Kationen-in-Leitungswasser.pdf

Cations in juice

  • Separation: CZE
  • Electrolyte: Imidazole with 2 mM 18-crown-6>
  • Capillary: fused silica, 50 µm ID, 64 cm in total
  • Injection: 10 s, 50 mbar
  • Detection: indirect UV, 215 nm
  • Description: The juice was diluted 1:10.
Kationen in Saft

Cations in juice

Download: Kationen-in -Saft.pdf

Cations in fruits

  • Separation: CZE
  • Electrolyte: Imidazole with 2 mM 18-crown-6
  • Capillary: fused silica, 50 µm ID, 64 cm in total
  • Injection: 10 s, 50 mbar
  • Detection: indirect UV, 215 nm
  • Description: The determination of cations was done with a mango. The fruit was mashed and 250 mg of the pap were diluted in 10 ml pure water. This suspension was homogenized in an ultra sonic bath. The received solution was directly injected without filtration.
Kationen in Mango

Cations in mango

Download: Kationen-in-Mango.pdf

Cations in a soft drink

    • Separation: CZE
    • Electrolyte: Imidazole with 2 mM 18-crown-6
    • Capillary: fused silica, 50 µm ID, 64 cm in total
    • Injection: 10 s, 50 mbar
  • Detection: indirect UV, 215 nm
  • Description: The determination of cations was done in cola. It was diluted 1:10 before injection.
Kationen in einem Softgetränk (Cola)

Cations in a soft drink (Cola)

Download: Kationen-in-Cola.pdf

Cations in coffee

  • Separation: CZE
  • Electrolyte: Imidazole with 2 mM 18-crown-6
  • Capillary: fused silica, 50 µm ID, 64 cm in total
  • Injection: 10 s, 50 mbar
  • Detection: indirect UV, 215 nm
  • Description: The determination of cations was done in instant coffee. 10 mg of the powder were diluted 10 ml pure water before injection.
Kationen in aufgebrühtem Kaffee

Cations in coffee

Download: Kationen-in-Kaffee.pdf

Cation standard solution with calibration

  • Separation: CZE
  • Electrolyte: Cation Buffer, Agilent 5064-8203
  • Capillary: fused silica, 75 µm ID, 64 cm in total
  • Detection: indirekt UV, Sig. 350 nm, Ref. 215 nm
  • escription: The standard solution contains 5 mg/l ammonium, sodium and triethylamine, each. The pdf also shows the calibration curves found for the single ions.
Standardlösung je 5 mg/l

Standard solution, 5 mg/l.

Download: Kationen-TEA.pdf