Liofilchem® VP (NaOH) Reagent Droppers, 10 + 10 bottles x 2.5 mL

Liofilchem® VP (NaOH) Reagent Droppers are ready-to-use biochemical reagents designed for the Voges-Proskauer (VP) test, a classical qualitative assay used in microbiology laboratories to differentiate Enterobacteriaceae and other Gram-negative bacteria based on their ability to produce acetylmethylcarbinol (acetoin) during glucose fermentation.

The reagents are supplied in convenient dropper bottles, ensuring accurate dispensing, reproducible results, and reduced handling errors, making them ideal for routine diagnostics, teaching laboratories, and quality-controlled testing environments.

Intended Purpose

The VP test is used as an aid in bacterial identification, particularly to distinguish organisms that utilize the butanediol fermentation pathway. It is commonly applied alongside the Methyl Red (MR) test as part of the MR-VP biochemical testing scheme.

This test supports:

• Differentiation within Enterobacteriaceae
• Presumptive identification of fermentative pathways
• Routine microbiological diagnosis, requiring confirmation by additional tests

Kit Contents

Each kit contains:

• 10 dropper bottles of α-naphthol solution (2.5 mL each)
• 10 dropper bottles of sodium hydroxide solution (2.5 mL each)

Reagent Composition

• α-Naphthol: 5% (w/v) in ethyl alcohol
• Sodium Hydroxide (NaOH): 40% (w/v) in distilled water

Test Principle

Certain bacteria ferment glucose to produce acetylmethylcarbinol (acetoin) when grown in media such as MR-VP broth.

Upon addition of VP reagents:

1. α-Naphthol acts as a catalyst
2. NaOH provides alkaline conditions and oxygen exposure
3. Acetoin is oxidized to diacetyl
4. Diacetyl reacts with creatine present in the broth
5. A pink to bright red color develops, indicating a positive reaction

Test Procedure (Summary)

1. Inoculate MR-VP broth with a pure bacterial culture
2. Incubate at 35 ± 2 °C for 24–72 hours
3. Transfer 1–2 mL of broth to a clean test tube
4. Add:
   • 12 drops (0.6 mL) of α-naphthol
   • 4 drops (0.2 mL) of NaOH
5. Shake well to aerate
6. Observe color change within 20 minutes

Interpretation of Results

Quality Control

Each batch is performance-tested using reference strains:

Results meet established performance criteria.

Applications

• Clinical microbiology laboratories
• Hospital diagnostic laboratories
• Teaching and training laboratories
• Food and environmental microbiology
• Research laboratories performing biochemical identification

Storage & Stability

• Store at 2–8 °C, away from light
• Do not freeze
• Discard if cloudiness, discoloration, or contamination is observed
• Shelf life: 2 years from production

Limitations

• Allow at least 20 minutes before reporting a negative result
• Use pure cultures only
• Results must be interpreted in conjunction with other biochemical and clinical findings

Safety & Precautions

• For in vitro diagnostic use only
• For professional laboratory use
• Contains alkaline reagent (NaOH) – handle with care
• Consult Safety Data Sheet (SDS) before use
• Follow standard biosafety and laboratory precautions
• Do not mix reagents from different batches

Packaging Information

Liofilchem® VP (NaOH) Reagent Droppers provide a reliable, ready-to-use solution for Voges-Proskauer testing, enabling accurate differentiation of Enterobacteriaceae based on acetoin production. With validated performance, convenient dropper format, and IVD compliance, this kit is an essential component of routine biochemical identification workflows in microbiology laboratories.