1.09293

KOVACS′ indole reagent

for detecting microbial indole in the identification of indole-positive and indole-negative microorganisms, suitable for microbiology

• Synonym(s): 4-(Dimethylamino)benzaldehyde solution, Indole reagent, Kovac′s reagent, Kovac′s reagent for indoles
• NACRES: NA.21
• UNSPSC Code: 41106212

Properties

• Quality Segment: 200
• form: liquid
• packaging: pkg of 100 mL
• technique(s): microbe id | specific enzyme detection: suitable
• color: yellow
• pH: <1 (20 °C in H₂O)
• transition temp: flash point 36 °C
• density: 0.92 g/cm³ at 20 °C
• application(s): microbiology
• storage temp.: 2-8°C
• suitability: Escherichia coli, enterovirulent E. coli (EEC) spp.

Description

General description

Kovac′s reagent is a biochemical reagent composed of n-Butanol, hydrochloric acid, and 4-dimethylaminobenzaldehyde. It is used for the detection of indole producing microorganisms. Tryptophan is abundant in trypticalle digested peptone. Some microorganisms can cleave tryptophan to give pyruvic acid, ammonia, and indole. Indole then reacts with 4-dimethylaminobenzaldehyde to form a dark red dye. As tryptophan also gives a color reaction with 4 dimethylaminobenzaldehyde, it must be separated from the indole. This is achieved by selectively extracting indole with butanol.

Application

Kovac′s Indole reagent is used for the detection of indole producing microorganisms in food and beverages, and environmental samples. This is suitable for the identification of E. coli.

Preparation Note

No metal containers. Keep the container tightly closed in a dry and well-ventilated place. Keep away from heat and sources of ignition

Analysis Note

Indole formation (Escherichia coli ATCC 25922 (WDCM 00013)): +
Indole formation (Proteus vulgaris ATCC 8427): +
Indole formation (Enterobacter aerogenes ATCC 13048): -
Tested in DEV-Tryptophan broth art. no. 1.10694. (after incubation 24 hrs.; 35 °C aerobic).

Other Notes

The reagent solution must be stored in the dark in the refrigerator, otherwise it may turn brown and cannot be used.

Safety Information

• pictograms: GHS02,GHS05,GHS07
• signalword: Danger
• hcodes: H226 - H290 - H302 - H314 - H317 - H335 - H336
• pcodes: P210 - P233 - P280 - P301 + P312 - P303 + P361 + P353 - P305 + P351 + P338
• Hazard Classifications: Acute Tox. 4 Oral - Eye Dam. 1 - Flam. Liq. 3 - Met. Corr. 1 - Skin Corr. 1 - Skin Sens. 1
• Storage Class: 3 - Flammable liquids
• wgk: WGK 1
• flash_point_f: 96.8 °F
• flash_point_c: 36 °C