Hydrofluoric acid

And other hydrogen fluoride releasing chemicals

Hydrofluoric acid (HF) is a clear, colorless, inorganic acid that is used in research and industry for its ability to etch glass, metal and silicon compounds.  It is also an essential tool for semiconductor and electronic fabrication and mineral processing.  Despite its useful properties, exposure to HF poses severe health risks.  This can result in tissue necrosis and amputations, imbalances of sodium and magnesium levels in the body, and can ultimately be fatal.  Best management practices must be reviewed and continually employed while working with this chemical.

Bottle of hydrofluoric acidOther fluorine-containing compounds can pose similar health hazards resulting in HF exposure. 

These chemicals include but are not limited to:

Buffered Oxide Etchant (BOE) – comprised of HF and a buffering agent like ammonium fluoride
Fluoroboric acid (HBF4)Chemical symbol for Hydrogen fluoride pyridine complex
Hydrogen fluoride pyridine
Kroll’s Reagent (Solution containing HF and HNO3)
Lithium hexafluorophosphate (LiPF6)  

 

What Makes HF So Dangerous?

Unlike other inorganic acids like hydrochloric (HCl), sulfuric (H2SO4), nitric (HNO3), or phosphoric (H3PO4) acid, hydrofluoric (HF) acid is highly lipophilic and readily penetrates through the skin into deeper tissue.

Once absorbed, the fluoride ion – which has an extremely strong affinity for cations – combines with the calcium (Ca2+) and magnesium (Mg2+) in the blood to form insoluble salts.  This, in turn, reduces the amount of calcium and magnesium leading to hypocalcemia and hypomagnesemia.  This electrolyte imbalance can result in cardiac arrhythmia and cardiac arrest.

Depending on the concentration of acid that one is exposed to, symptoms of exposure which include pain, discoloration or discomfort can vary significantly.  Solutions < 7% HF may take several hours before onset of symptoms, resulting in delayed presentation, deeper penetration of the undissociated HF, and a more severe burn.  Solutions of 12% HF may take up to one hour to produce symptoms.  HF solutions > 14.5% immediately produce symptoms including redness, swelling, and blistering.    

 

Requirements for Working with HF and HF-releasers

HF Exposure Emergency Response 

ALL HYDROFLUORIC ACID EXPOSURES ARE 911 EMERGENCIES!  

TRANSPORT TO A HOSPITAL VIA AMBULANCE IS REQUIRED WITHOUT EXCEPTION!

In order to prevent cross contamination, the victim should perform the following actions on themselves.  If assistance is required, the colleague must be extremely careful not to contaminate themselves in the process.  Any person assisting should use HF-protective gloves (thick neoprene or nitrile), goggles, and any other necessary PPE. Do not use latex gloves; they do not provide an effective HF barrier.

Hydrofluoric Acid Resources