ICP_Operations_Guide_2016

Water at pH of 7 Dilutions in water at pH 7 are not as common for most elements but may be required to prevent chemical reactions of some of the compounds containing the element. Please note that solutions at pH 7 may support biological growth and therefore the long-term stability should be questioned. Those elements that may have an advantage to being diluted in water at pH 7 are shaded in yellow to the right: Hydrofluoric Acid Matrices Hydrofluoric acid (HF) requires the use of HF- resistant introduction systems. These systems are more expensive than glass, have longer washout times, and give a larger measurement precision. However, there are times when the use of HF offers a major advantage over other reagents. Those elements where an HF matrix may be optimal are shaded in green below: 1. HF is used for Si 3 N 4 preparations and other nitrides. Sulfuric Acid Matrices Sulfuric acid (H 2 SO 4 below 100 ppm should be stored in borosilicate glass due to adsorption on plastic. 2. Trace levels of HCl or Cl - will form AgCl, which will photoreduce to Ag 0 . F denotes that the element can be diluted in H 2 SO 4 if complexed with F - . Cl denotes that the element can be diluted in H 2 SO 4 if complexed with Cl - . HF denotes that the element should have excess HF present when diluted with H 2 SO 4 . T denotes that the tartaric acid complex can be diluted in H 2 SO 4 . Phosphoric Acid Matrices Phosphoric acid (H 3 PO 4 1. Dilutions of Hg and Au in H 2 SO 4

) is commonly used in preparations and therefore added to standards in combination with other acids.

Elements that either benefit or comfortably tolerate the presence of H 2 SO 4

are shaded in orange below:

) is not commonly used in preparations since it attacks glass, quartz, porcelain, and Pt containers at

elevated temperatures (greater than 100 °C). However, the presence of 3 PO 4

will not adversely effect any of the elements at low

μg/mL levels and below.

* Visit inorganicventures.com/tech/icp-operations/ for additional information from this link