2-Amino-4-nitrophenol

154.12

154.12

776533

202-767-9

G501UCI6T9

4664

2811

DTXSID6020062

Orange prisms from water|Yellow-brown leaflets containing water of crystallization|Yellow-brown to orange prisms

2922299090

92.1

1.26

2-amino-4-nitrophenol appears as orange prisms or yellow powder. No odor. (NTP, 1992)

1.5±0.1 g/cm3

145-147 °C

368.1±32.0 °C at 760 mmHg

100 °C

1.689

H2O: slightly soluble

Store in a tightly closed container. Store in a cool, dry, well-ventilated area away from incompatible substances.

3.5X10-5 mm Hg at 25 deg C (est)

Oral-rat LD50: 2400 mg/kg; Oral-Mouse LD50: 850 mg/kg

Open flame is flammable; heated to decompose toxic nitrogen oxide gas

Henry's Law constant = 2.2X10-12 atm-cu m/mole at 25 °C (est)

pKa1 = 3.1 /amine/; pKa2 = 7.6 /phenol/ at 25 °C

When heated to decomposition it emits toxic fumes of NOx.|Hydroxyl radical reaction rate constant = 7.0X10-12 cu cm/molecule-sec at 25 °C (est)

Insoluble in water.

Nitro, Nitroso, Nitrate, and Nitrite Compounds, Organic

Oxidation of this chemical may occur in the presence of air and violent decomposition may occur if it is allowed to dry out completely at elevated temperatures. It is stable when stored protected from light and under nitrogen for two weeks at temperatures up to 140° F, and storage under nitrogen for up to 24 weeks at room temperature (77° F) should produce no loss of stability. This chemical is incompatible with acids, acid chlorides, acid anhydrides, chloroformates and strong oxidizing agents. It is also incompatible with iron. (NTP, 1992)

2811

2

36/37/38-68-43-40-20/21/22

26-45-36/37/39-36

SJ6300000

Xi,Xn

The warehouse is ventilated, low temperature and dry; stored and transported separately from food materials

Irritant

Stable under normal temperatures and pressures.

P261-P305 + P351 + P338

H315-H319-H335

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

DHHS/NTP; Toxicology & Carcinogenesis Studies of 2-Amino-4-nitrophenol in F344/N Rats and B6C3F1 Mice (Gavage Studies) Technical Report Series No. 339 (1988) NIH Publication No. 88-2595

Flash point data for this chemical are not available. It is probably combustible. (NTP, 1992)

|Warning|H302 (98%): Harmful if swallowed [Warning Acute toxicity, oral]|P201, P202, P261, P264, P270, P271, P280, P281, P301+P312, P302+P352, P304+P312, P304+P340, P305+P351+P338, P308+P313, P312, P321, P322, P330, P332+P313, P337+P313, P362, P363, P403+P233, P405, and P501|Aggregated GHS information provided by 2196 companies from 15 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.|H302: Harmful if swallowed [Warning Acute toxicity, oral]|P261, P264, P270, P272, P280, P301+P312, P302+P352, P305+P351+P338, P321, P330, P333+P313, P337+P313, P363, and P501

Fires involving this material can be controlled with a dry chemical, carbon dioxide or Halon extinguisher. A water spray may also be used. (NTP, 1992)

Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]: As an immediate precautionary measure, isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids. SPILL: Increase, in the downwind direction, as necessary, the isolation distance shown above. FIRE: If tank, rail car or tank truck is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2016)

SMALL SPILLS AND LEAKAGE: Should a spill occur while you are handling this chemical, FIRST REMOVE ALL SOURCES OF IGNITION, then you should dampen the solid spill material with 60-70% ethanol and transfer the dampened material to a suitable container. Use absorbent paper dampened with 60-70% ethanol to pick up any remaining material. Seal the absorbent paper, and any of your clothes, which may be contaminated, in a vapor-tight plastic bag for eventual disposal. Solvent wash all contaminated surfaces with 60-70% ethanol followed by washing with a soap and water solution. Do not reenter the contaminated area until the Safety Officer (or other responsible person) has verified that the area has been properly cleaned. STORAGE PRECAUTIONS: You should protect this chemical from exposure to light. Keep the container tightly closed under an inert atmosphere, and store under refrigerated temperatures. (NTP, 1992)

MINIMUM PROTECTIVE CLOTHING: If Tyvek-type disposable protective clothing is not worn during handling of this chemical, wear disposable Tyvek-type sleeves taped to your gloves. RECOMMENDED RESPIRATOR: Where the neat test chemical is weighed and diluted, wear a NIOSH-approved half face respirator equipped with an organic vapor/acid gas cartridge (specific for organic vapors, HCl, acid gas and SO2) with a dust/mist filter. (NTP, 1992)

moderately toxic

IDENTIFICATION AND USE: 2-Amino-4-nitrophenol is an orange prismatic solid. It can also be found as a yellow brown leaflets or yellow prisms. It is soluble in ethanol, diethyl ether, acetic acid and warm benzene. It is soluble in acetone and water. This chemical is used in the production of mordant and acid dyes. It is also used as an antioxidant and light stabilizer in butyl rubbers, and as a catalyst in the production of hexadiene. It was also formerly used in hair dyes. HUMAN EXPOSURE AND TOXICITY: Individuals may be exposed to this chemical through inhalation and dermal contact where the material is used or produced. The general population may be exposed to this chemical via inhalation and dermal contact with consumer products containing 2-amino-4-nitrophenol. There is inadequate evidence fo the carcinogenicity of this chemical in humans. ANIMAL STUDIES: 2-Amino-4-nitrophenol produced allergic contact dermatitis in guinea pigs. There is limited evidence for the carcinogenicity of this compound in experimental animals. The chemical induced sister chromatid exchange and chromosomal aberrations in Chinese hamster ovary cells. Neither micronuclei, chromosomal aberrations or dominant lethal effects were induced in rodents exposed in vivo. 2-Amino-4-nitrophenol was mutagenic in Salmonella typhimurium strains TA98 and TA100 with metabolic activation. It was not mutagenic in Salmonella typhimurium strains TA1535 or TA1537.

LD50 Rat ip 246 mg/kg|LD50 Rat oral 2400 mg/kg|LD50 Mouse ip 143 mg/kg

During the 15-day studies, rats and mice received doses of 0, 313, 625, 1,250, 2,500, or 5,000 mg/kg. All rats that received 2,500 or 5,000 mg/kg and all female rats that received 1,250 mg/kg died before the end of the studies. Final mean body weights of chemically exposed rats surviving to the end of the studies were comparable to those of vehicle controls. Diarrhea was observed in all groups of exposed rats except those receiving 313 mg/kg. All mice that received 2,500 or 5,000 mg/kg, 2/5 males and all females that received 1,250 mg/kg, and 1/5 females that received 313 mg/kg died before the end of the studies. Final mean body weights of exposed mice surviving until the end of the studies were comparable to those of vehicle controls.|In 13-week studies, F344/N rats and B6C3F1 mice of each sex received 2-amino-4-nitrophenol at doses of 0, 62.5, 125, 250, 500, or 1,000 mg/kg. All rats that received 1,000 mg/kg and 2/10 males and 2/10 females that received 500 mg/kg died before the end of the studies. The final mean body weight of male rats that received 500 mg/kg was reduced 10% compared with that of vehicle controls; final mean body weights of all other surviving exposed rat groups were comparable to those of vehicle controls. Diarrhea and lethargy were observed for rats that received 500 or 1,000 mg/kg. All male mice and most females that received 1,000 mg/kg and 4/10 females that received 500 mg/kg died before the end of the studies. Final mean body weights of chemically exposed mice were comparable to those of vehicle controls. No compound-related clinical signs were observed in mice during the studies. Mineralization of the renal cortex and degeneration of the renal tubular epithelium were observed in male and female rats that received 1,000 mg/kg and in males that received 500 mg/kg. Degeneration and necrosis of the renal tubular epithelium was observed in 5/10 male and 3/10 female mice that received 1,000 mg/kg.|In the 2-year studies, rats and mice received 2-amino-4-nitrophenol at doses of 0, 125, or 250 mg/kg. Mean body weights of male rats that received 250 mg/kg were 8%-10% lower than those of vehicle controls throughout most of the 2-year study. Mean body weights of female rats were comparable to those of vehicle controls. Soft stools and occasional diarrhea were observed in chemically exposed rats starting 6 months after the beginning of the studies. Survival of male rats that received 250 mg/kg was markedly lower than that of vehicle controls after week 89 (final survival: vehicle control, 32/50; 125 mg/kg group, 24/50; 250 mg/kg group, 10/50). Survival of female rats was comparable among all groups (final survival: 25/50; 27/50; 31/50). Mean body weights of male and female mice that received 250 mg/kg were comparable to those of vehicle controls; the mean body weights of female mice that received 125 mg/kg were as much as 17% greater than that of vehicle controls. Survival of all mouse groups was comparable during the 2-year studies (final survival: male--28/50; 29/50; 23/50; female--28/50; 31/50; 30/50). ... Pigmentation of the small and large intestines was present in exposed rats but not in vehicle controls. Ulcers and erosive lesions of the digestive tract were observed in male rats that received 250 mg/kg and to a lesser extent in male rats that received 125 mg/kg. A carcinoma of the colon occurred in one male rat that received 250 mg/kg; no other neoplasms were observed in the gastrointestinal tract of rats. No pigmentation, ulcers, or erosive lesions were found in the digestive tract of mice. The severity of nephropathy was markedly greater in exposed male rats than in vehicle controls. Associated with the nephropathy were nonneoplastic lesions indicative of reduced renal function and secondary hyperparathyroidism, including parathyroid hyperplasia, mineralization of various organs, and fibrous osteodystrophy. Renal tubular cell hyperplasia (1/50; 4/48; 5/50) and renal cortical (tubular cell) adenomas (0/50; 1/48; 3/50) occurred in male rats. Renal cortical adenomas are infrequently observed in male F344/N rats (historical incidence, 0.5%). More preputial gland adenomas or carcinomas (combined) were observed in low dose male rats than in vehicle controls (3/50; 10/48; 3/50), whereas the incidences of clitoral gland neoplasms were decreased in dosed female rats (9/50; 6/50; 1/49). Hemangiomas or hemangiosarcomas (combined) occurred in male mice that received 2-amino-4-nitrophenol (0/50; 1/50; 5/50); each tumor was present at a different site. The historical control incidence is 11% at the study laboratory and 6% in 2-year NTP studies. ...Under the conditions of these 2-year gavage studies, there was some evidence of carcinogenic activity of 2-amino-4-nitrophenol for male F344/N rats, as shown by increased incidences of renal cortical (tubular cell) adenomas. The incidences of renal tubular cell hyperplasia were also increased in male rats exposed to 2-amino-4-nitrophenol. The survival of male rats that received 2-amino-4-nitrophenol was reduced compared with survival of vehicle control male rats. There was no evidence of carcinogenic activity of 2-amino-4-nitrophenol for female F344/N rats or for male or female B6C3F1 mice that received 125 or 250 mg/kg/day.|2-Amino-4-nitrophenol was mutagenic in Salmonella typhimurium strains TA98 and TA100 with metabolic activation. 2-Amino-4-nitrophenol was not mutagenic in strains TA 1535 or TA 1537. 2-Amino-4-nitrophenol was mutagenic in the mouse lymphoma L5178Y/TK+/- assay without metabolic activation. It was not tested with activation. 2-Amino-4-nitrophenol induced sister chromatid exchanges (SCEs) and chromosomal aberrations in Chinese hamster ovary cells in the presence and absence of metabolic activation.

2-Amino-4-nitrophenol's production and subsequent use in the production of mordant and acid dyes(1) and hair dyes(2) may result in its release to the environment through various waste streams.

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 120(SRC), determined from a log Kow of 1.26(2) and a regression-derived equation(3), indicates that 2-amino-4-nitrophenol is expected to have high mobility in soil(SRC). The pKa of the phenol group on 2-amino-4-nitrophenol is 7.6(4), indicating that this compound will partially exist in the anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(5). Volatilization of 2-amino-4-nitrophenol from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 2.2X10-12 atm-cu m/mole(SRC), using a fragment constant estimation method(6). 2-Amino-4-nitrophenol is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 3.5X10-5 mm Hg(SRC), determined from a fragment constant method(7). Incomplete data are available regarding the biodegradation of 2-amino-4-nitrophenol in water; however, Nocardia v. was not able to use this compound as a carbon source under aerobic conditions(8).|AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 120(SRC), determined from a log Kow of 1.26(2) and a regression-derived equation(3), indicates that 2-amino-4-nitrophenol is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(3) based upon an estimated Henry's Law constant of 2.2X10-12 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). According to a classification scheme(5), an estimated BCF of 3.6(SRC), from its log Kow(2) and a regression-derived equation(6), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Incomplete data are available regarding the biodegradation of 2-amino-4-nitrophenol in water; however, Nocardia v. was not able to use this compound as a carbon source under aerobic conditions(7).|ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 2-amino-4-nitrophenol, which has an estimated vapor pressure of 3.5X10-5 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase 2-amino-4-nitrophenol is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 2.3 days(SRC), calculated from its rate constant of 7.0X10-12 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). 2-Amino-4-nitrophenol may also react with nitrate radicals in the atmosphere(4). Particulate-phase 2-amino-4-nitrophenol may be removed from the air by wet or dry deposition(SRC). Ultraviolet spectra of 2-amino-4-nitrophenol show maxima at 308 and 370 nm(5), indicating that this compound absorbs light at environmental wavelengths; therefore it may be susceptible to direct photolysis by sunlight(SRC).

The rate constant for the vapor-phase reaction of 2-amino-4-nitrophenol with photochemically-produced hydroxyl radicals has been estimated as 7.0X10-12 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 2.3 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). 2-Amino-4-nitrophenol may also react with nitrate radicals in the atmosphere(2). 2-Amino-4-nitrophenol is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(3). Ultraviolet spectra of 2-amino-4-nitrophenol show maxima at 308 and 370 nm(4), indicating that this compound absorbs light at environmental wavelengths; therefore it may be susceptible to direct photolysis by sunlight(SRC).

An estimated BCF of 3.6 was calculated for 2-amino-4-nitrophenol (SRC), using a log Kow of 1.26(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low.

The Koc of 2-amino-4-nitrophenol is estimated as 120(SRC), using a log Kow of 1.26(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that 2-amino-4-nitrophenol is expected to have high mobility in soil. The pKa of the phenol group on 2-amino-4-nitrophenol is 7.6(4), indicating that this compound will partially exist in the anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(5). However, anilines are expected to bind strongly to humus or organic matter in soils due to the high reactivity of the aromatic amino group(6,7), suggesting that mobility may be much lower in some soils(SRC).

The Henry's Law constant for 2-amino-4-nitrophenol is estimated as 2.2X10-12 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that 2-amino-4-nitrophenol is expected to be essentially nonvolatile from water surfaces(2). 2-amino-4-nitrophenol's Henry's Law constant indicates that volatilization from moist soil surfaces may not occur(SRC). 2-Amino-4-nitrophenol is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 3.5X10-5 mm Hg(SRC), determined from a fragment constant method(3).

NIOSH (NOES Survey 1981-1983) has statistically estimated that 20,256 workers (17,049 of these were female) were potentially exposed to 2-amino-4-nitrophenol in the US(1). Occupational exposure to 2-amino-4-nitrophenol may occur through inhalation and dermal contact with this compound at workplaces where it is produced or used. The general population may be exposed to 2-amino-4-nitrophenol via inhalation and dermal contact with hair dye and other consumer products containing 2-amino-4-nitrophenol(SRC).

Percutaneous absorption through the skin of Sprague-Dawley rats of each sex was examined following application of two hair dye formulations: formulation 1 contained 1.54% 14C-2-amino-4-nitrophenol; formulation 2 contained 0.77% 14C-2-amino-4-nitrophenol, 1,4-diaminobenzene (1,4-phenylenediamine), 2,4-diaminoanisole, oleic acid and isopropanol and was mixed with equal amt of a 6% hydrogen peroxide soln. After 1 and 5 days, 0.21 and 0.36% of the radiolabel administered in formulation 1 and 1.12 and 1.67% of that administered in formulation 2 had been absorbed (calculated as combined radiolabel in urine, feces, expired air and carcass, without treated skin area). Absorbed material was excreted predominantly in the urine within 24 hr after the initial application ... .|Five days after oral administration by gavage of 2 mL (14)C-2-amino-4-nitrophenol (0.2% in saline), 68.3% + 9.4 (SD) of the radiolabel had been excreted in the urine and 25.4% + 6.9% in the feces. Within 3 hr, about 4% of the radiolabel was eliminated in the bile. Following subcutaneous injection of the same dose, 89% of the dose was eliminated after 1 day, predominantly in the urine ... (/It was/ noted that metabolites were not identified in the urine, bile or feces in either study.)|Percutaneous absorption of (14)C-2-amino-4-nitrophenol (specific radioactivity 10 mCi/mmol (65 uCi/mg); purity, 98%) was studied in vitro by partitioning between excised human abdominal skin preparations and water. 2-Amino-4-nitrophenol appeared to bind to skin components ... .

A liquid chromatography-tandem mass spectrometry (LC-MS-MS) analysis of biological fluids (blood, urine, gastric content, and bile) collected at autopsy in a case of suspected 2,4-dinitrophenol (DNP) fatal poisoning allowed the determination of DNP and its known metabolites (2-amino-4-nitrophenol and nitro-4-aminophenol). The tentative identification of three conjugated metabolites (DNP glucuronide, DNP sulfate, and 2-amino-4-nitrophenol glucuronide) could be made on the basis of their pseudomolecular ion, isotopic and fragmentation patterns, and retention characteristics. Another DNP metabolite reported in the literature, 2,4-diaminophenol, was not detected in the samples. Postmortem blood concentrations were 48.4 mg/L for DNP and 1.2 mg/L for 2-amino-4-nitrophenol. ...|YIELDS 2,4-DIAMINOPHENOL PROBABLY IN RATS. /FROM TABLE/|2-Amino-4-nitrophenol was the predominant metabolite formed enzymatically by nitroreduction following oral administration of 2,4-dinitrophenol (22.5 mg/kg bw) to ICR mice.

It had an elimination half-time from the plasma /of ICR mice/ of 46 hr ... .

Two hair dye components, carcinogenic 4-nitro-2-aminophenol and 5-nitro-2-aminophenol, induced Cu(II)-dependent DNA cleavage frequently at thymine and guanine residues in DNA fragments obtained from the c-Ha-ras-1 protooncogene. When the p53 tumor suppressor gene was used, 4-nitro-2-aminophenol caused Cu(II)-dependent piperidine-labile sites at poly G sequences. In the presence of Cu(II), both components increased 8-oxo-7,8-dihydro-2'-deoxyguanosine formation in DNA. The inhibitory effects of catalase and bathocuproine on DNA damage suggest the involvement of H2O2 and Cu(I). It is speculated that nitro-2-aminophenols undergo Cu(II)-mediated autoxidation to generate active oxygen species causing DNA damage which leads to their carcinogenesis.

SYMPTOMS: Symptoms of exposure to this chemical may include irritation of the skin and eyes. ACUTE/CHRONIC HAZARDS: This chemical is toxic by ingestion. It may be harmful by inhalation or skin absorption. It is an irritant of the skin, eyes and upper respiratory tract. When heated to decomposition it emits irritating gases and toxic fumes of carbon monoxide, carbon dioxide and nitrogen oxides. (NTP, 1992)

EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop. SKIN: IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. Gently wash all affected skin areas thoroughly with soap and water. IMMEDIATELY call a hospital or poison control center even if no symptoms (such as redness or irritation) develop. IMMEDIATELY transport the victim to a hospital for treatment after washing the affected areas. INHALATION: IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. IMMEDIATELY call a physician and be prepared to transport the victim to a hospital even if no symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop. Provide proper respiratory protection to rescuers entering an unknown atmosphere. Whenever possible, Self-Contained Breathing Apparatus (SCBA) should be used; if not available, use a level of protection greater than or equal to that advised under Protective Clothing. INGESTION: DO NOT INDUCE VOMITING. Phenols are very toxic poisons AND corrosive and irritating, so that inducing vomiting may make medical problems worse. IMMEDIATELY call a hospital or poison control center and locate activated charcoal, egg whites, or milk in case the medical advisor recommends administering one of them. If advice from a physician is not readily available and the victim is conscious and not convulsing, give the victim a glass of activated charcoal slurry in water or, if this is not available, a glass of milk, or beaten egg whites and IMMEDIATELY transport victim to a hospital. If the victim is convulsing or unconscious, do not give anything by mouth, assure that the victim's airway is open and lay the victim on his/her side with the head lower than the body. DO NOT INDUCE VOMITING. IMMEDIATELY transport the victim to a hospital. OTHER: Since this chemical is a known or suspected carcinogen you should contact a physician for advice regarding the possible long term health effects and potential recommendation for medical monitoring. Recommendations from the physician will depend upon the specific compound, its chemical, physical and toxicity properties, the exposure level, length of exposure, and the route of exposure. (NTP, 1992)

2-amino-4-nitrophenol

2-Amino-4-nitrophenol is available commercially with the following specifications: Purity, 96% (min); ash, 0.1% (max); iron, 100 ppm (mg/kg) (max); lead, 5 ppm (mg/kg) (max); arsenic, 2 ppm (mg/kg) (max). It is available in research quantities at purities from 90->99%.

Phenol, 2-amino-4-nitro-: ACTIVE|Cosmetic Ingredient Review Expert Panel ... concluded that 2-amino-4-nitrophenol ... were safe as hair dye ingredients in the current practices of use and concentration

A liquid chromatography-tandem mass spectrometry (LC-MS-MS) analysis of biological fluids (blood, urine, gastric content, and bile) collected at autopsy in a case of suspected 2,4-dinitrophenol (DNP) fatal poisoning allowed the determination of DNP and its known metabolites (2-amino-4-nitrophenol and nitro-4-aminophenol). The tentative identification of three conjugated metabolites (DNP glucuronide, DNP sulfate, and 2-amino-4-nitrophenol glucuronide) could be made on the basis of their pseudomolecular ion, isotopic and fragmentation patterns, and retention characteristics. Another DNP metabolite reported in the literature, 2,4-diaminophenol, was not detected in the samples. Postmortem blood concentrations were 48.4 mg/L for DNP and 1.2 mg/L for 2-amino-4-nitrophenol. ...