---
title: Barritt’s A reagent
description: "Barritt’s A reagent consists of alpha-naphthol in ethanol. It is used with [Barritt’s B](https://vumicro.com/docs/barritts-b-reagent/) reagent (40% KOH) to detect the presence of [2,3-butanediol](https://vumicro.com/docs/voges-proskauer-test/) (so-called \"neutral fermentation products\") produced from glucose in [MRVP broth](https://vumicro.com/docs/mrvp-broth/). After inoculating MRVP broth and incubating overnight,…"
url: "https://vumicro.com/docs/barritts-a-reagent/"
updated: "2022-06-17"
category: Reference Library / Reagents, Chemicals, Stains
---

# Barritt’s A reagent

Barritt’s A reagent consists of alpha-naphthol in ethanol. It is used with [Barritt’s B](https://vumicro.com/docs/barritts-b-reagent/) reagent (40% KOH) to detect the presence of [2,3-butanediol](https://vumicro.com/docs/voges-proskauer-test/) (so-called "neutral fermentation products") produced from glucose in [MRVP broth](https://vumicro.com/docs/mrvp-broth/).

After inoculating MRVP broth and incubating overnight, five drops of each reagent are added to the culture. Barritt’s A should be added first. This is followed by addition of five drips of [Barritt's B](https://vumicro.com/docs/barritts-b-reagent/). Development of a red color indicates the presence of 2,3-butanediol.

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