How a preservative concentration is justified, and where the 28-day convention comes from

Published 26 October 2026 · REVIVE LAB UAE Research Desk · 5 min read
The pharmacopoeial antimicrobial effectiveness test inoculates the product with defined bacteria and fungi — typically strains of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans and Aspergillus brasiliensis — at a known count and measures survival at intervals over 28 days. The product passes if the counts fall by specified amounts and do not rise again. A concentration of benzyl alcohol is acceptable because it passes this test. The 28-day beyond-use convention that pharmacy standards apply to opened multiple-dose containers derives from the duration of the test, not from a property of any particular vial.

What the test does

Each organism is added separately to the product at roughly a million per millilitre. Samples are plated at set days and the surviving count compared with the start. For injectable products the bacterial count must fall by at least a thousandfold within the first week and show no increase thereafter; fungi must not increase. The organisms are chosen to represent the kinds of contaminant a container might receive.

It is a performance test, so the same agent at a lower concentration could fail it.

What passing means

That the product inhibits growth of the challenge organisms under the test conditions for its duration. Bacteriostatic means exactly that: organisms introduced do not multiply. It does not mean the product sterilises what is added to it, and it says nothing about spores, viruses or endotoxin.

The 28 days of the test became the default service life assigned to opened multiple-dose containers in compounding standards, unless a manufacturer states otherwise.

The boundary

This page describes a pharmacopoeial test and a regulatory convention derived from it. It does not state how long any solution should be kept or used; REVIVE LAB UAE provides no such guidance.

Bacteriostatic water is supplied by REVIVE LAB UAE as a diluent for lyophilised research peptides, for laboratory research use only. It is not for human or veterinary use, and no dosing, administration or protocol guidance is provided.

What it costs

FormatStrengthPriceAvailability
Bacteriostatic Water3 mL × 2AED 99In stock

Delivery is AED 40 flat and free on orders over AED 700. Payment is cash on delivery anywhere in the UAE, or USDT (TRC20) in advance, which takes 5% off the order total.

Frequently asked

What the test does?

Each organism is added separately to the product at roughly a million per millilitre. Samples are plated at set days and the surviving count compared with the start. For injectable products the bacterial count must fall by at least a thousandfold within the first week and show no increase thereafter; fungi must not increase. The organisms are chosen to represent the kinds of contaminant a container might receive.

Does REVIVE LAB UAE provide dosing guidance?

No. REVIVE LAB UAE supplies research materials and provides no dosing, administration or protocol guidance of any kind. Every product is sold for laboratory research use only and is not for human or veterinary consumption.

How fast is delivery in the UAE?

Stock is held in Dubai. An order confirmed before 4 PM Dubai time is dispatched the same working day, reaching Dubai and Abu Dhabi the same day and the remaining emirates within 24 hours. Delivery is AED 40 flat and free over AED 700.

Bacteriostatic Water — in stock, dispatched from Dubai
HPLC-verified, lot certificate on every carton, 24-hour delivery nationwide. Browse the catalogue → All peptides UAE

Related reading

Supplied for laboratory research use only. Not for human or veterinary consumption. REVIVE LAB UAE provides no dosing, administration or protocol guidance.