ARSINE

Substance

Arsine
(Arsenic hydride, arsenic trihydride, hydrogen arsenide)
CAS 7784-42-1

Formula

AsH₃

Physical Properties

Colorless gas
bp -62 °C, mp -117 °C
Slightly soluble in water (0.07 g/100 mL at 20 °C)

Odor

Garlic-like odor detectable at 0.5 to 1 ppm

Vapor Density

2.7 (air = 1.0)

Vapor Pressure

>760 mmHg at 20 °C

Flash Point

< -62 °C

Autoignition Temperature

Not established. Decomposes at 232 to 300 °C to form elemental arsenic and hydrogen.

Toxicity Data

LC_LO inhal (rat) 94 ppm (300 mg/m³; 15 min)

PEL (OSHA) 0.05 ppm (0.2 mg/m³)

TLV-TWA (ACGIH) 0.05 ppm (0.16 mg/m³)

Major Hazards

Extremely toxic gas that destroys red blood cells and can cause widespread organ injury and death.

Toxicity

The acute toxicity of arsine by inhalation is extremely high. This substance is a powerful systemic toxin with a strong affinity for the hemoglobin in the blood, causing hemolysis. Acute inhalation of arsine can cause the breakdown of red blood cells and hemoglobin, impairment of kidney function, damage to the liver and heart, electroencephalogram abnormality, hemolytic anemia, and death due to kidney or heart failure. Symptoms may be delayed for several hours, particularly if very low concentrations have been inhaled. Symptoms of exposure to arsine may include headache, malaise, weakness, dizziness, breathing difficulty, abdominal pain, nausea, vomiting, jaundice, dark red (bloody) urine followed by absence of urination, pulmonary edema, and coma. Exposure to a concentration of 5 to 10 ppm in air for several minutes may be hazardous to human health. The minimum amount of arsine detectable by odor is about 0.5 ppm; since the permissible exposure limit is 0.05 ppm, arsine does not have adequate warning properties to avoid overexposure.

In cases where the amount of inhaled arsine is insufficient to produce acute effects, or where small quantities are inhaled over prolonged periods, destruction of red blood cells will occur. The only symptoms noted may be general tiredness, pallor, breathlessness on exertion, and palpitations as would be expected with severe secondary anemia. The carcinogenicity of arsine in humans has not been established; however, arsenic and certain inorganic arsenic compounds are recognized human carcinogens.

Flammability and Explosibility

Arsine is flammable in air, having a lower explosion limit (LEL) of 5.8%. The upper limit has not been determined. Combustion products (arsenic trioxide and water) are less toxic than arsine itself. In the event of an arsine fire, stop the flow of gas if possible without risk of harmful exposure and let the fire burn itself out.

Reactivity and Incompatibility

Arsine is a strong reducing agent and reacts violently with oxidizing agents such as fluorine, chlorine, nitric acid, and nitrogen trichloride.

Storage and Handling

Because of its high acute toxicity, arsine should be handled using the "basic prudent practices" of Chapter 5.C, supplemented by the additional practices for work with compounds of high toxicity (Chapter 5.D), flammability (Chapter 5.F), and for work with compressed gases (Chapter 5.H). In particular, cylinders of arsine should be stored and used in a continuously ventilated gas cabinet or fume hood. Local fire codes should be reviewed for limitations on quantity and storage requirements. Carbon steel, stainless steel, Monel®, and Hastelloy®C are preferred materials for handling arsine; brass and aluminum should be avoided. Kel-F® and Teflon® are preferred gasket materials; Viton® and Nylon® are acceptable.

Accidents

In the event of a release of arsine, the area should be evacuated immediately. Regard anyone exposed to arsine as having inhaled a potentially toxic dose. Rescue of an affected individual requires appropriate respiratory protection. Remove exposed individuals to an uncontaminated area and seek immediate emergency medical help. Keep victim warm, quiet, and at rest; provide assisted respiration if breathing has stopped.

To respond to a release, use appropriate protective equipment and clothing. Positive pressure air-supplied respiratory protection is required. Close cylinder valve and ventilate area. Remove cylinder to a fume hood or remote area if it cannot be shut off.

Emergency response and rescue procedures should be in place before beginning work with arsine. Local rescue assistance may be needed and should be prearranged.

Disposal

Excess arsine should be returned to the manufacturer, according to your institution's waste disposal guidelines.

Viton® is a registered trademark of DuPont Dow Elastomers.

The information in this LCSS has been compiled by a committee of the National Research Council from literature sources and Material Safety Data Sheets and is believed to be accurate as of July 1994. This summary is intended for use by trained laboratory personnel in conjunction with the NRC report Prudent Practices in the Laboratory: Handling and Disposal of Chemicals. This LCSS presents a concise summary of safety information that should be adequate for most laboratory uses of the title substance, but in some cases it may be advisable to consult more comprehensive references. This information should not be used as a guide to the nonlaboratory use of this chemical.

Source: National Academy of Sciences.