Testing Types
Antimicrobial Effectiveness Test (AET) USP 〈51〉

Antimicrobial Effectiveness Test (AET) USP 〈51〉

USP 〈51〉 preservative challenge testing to verify that antimicrobial preservative systems effectively control microbial contamination throughout a product's shelf life.

Terms and Conditions

I. Confidentiality:

PLS Analytical ("PLSA") maintains strict confidentiality with its clients.

Formal Confidentiality agreements may be initiated by the client or by PLS Analytical.

II. Financial Information

Payment in advance is required for clients whose credit has not been established with PLSA.
Payment terms are “NET 15 days from receipt of the results”. Buyer agrees to pay all costs, including, but not limited to attorney and accounting fees and other expenses of collection resulting from any default by buyer in any of the terms of this contract.
Purchase orders or valid credit card information are REQUIRED. Orders submitted without this information may cause delays in testing.
For third party billing a signed purchase order must be received from the party paying for the service.
A surcharge of 50% or greater will be added for EXPRESS service. Express is subject to prior approval and availability.
Pricing is designed for single samples. Project discounts may be available. Quotations will be provided free of charge.
A minimum billing of $25.00 will be charged on all samples including those samples cancelled at the customer's request.
Clients that request Raw Data will have a copy sent to them electronically (at no charge) along with their report. There may be a surcharge for copies of the raw data and report when requested after initial sending is completed.
Additional charges may be assessed (e.g. hazardous samples, composite fee).
Shipping costs will be charged to clients that would like containers, coolers or ice packs returned.
Liability of PLSA is limited to an amount no greater than the amount invoiced.

III. Sample Submission:

Fill out the Sample Submission Form COMPLETELY, including product name, lot number, test, methods, and the amount of samples sent. Incomplete information may cause a delay in providing services.
All results will be reported by the method supplied and/or identified. If a limit is not supplied, we will default to associated compendia limits, or “Report Results” when compendial limits are not available.
All samples should be labelled with company name, product name and lot number. Samples received without a lot number will be sent back to the client for proper labeling. Hazardous Substances must be appropriately labeled for the protection of office and laboratory personnel.
- Shipping carton exterior must be labeled as to the hazard enclosed; caustic, cytotoxic, antineoplastic, explosive, corrosive, toxic, or carcinogenic, etc.
- Safety Data Sheet (SDS) must be provided for all Hazardous samples.
- Additional charges may be applied.
- Please place Sample Submission Form, SDS and any other correspondence submitted, in an envelope and place at the top of the box or affixed to the outside of the box. Failure to use the PLSA Submission Form for Analytical Services may delay results.

IV. Retention and Disposal:

Samples are retained for a period of 30 days after completion of analysis.
Special PRIOR arrangements must be made to return or retain samples under other conditions.
Unless alternate arrangements have been made, raw data will be retained for 6 years after final report date.

IMPORTANT

Turnaround Times:
- In calculating turnaround times, pending all appropriate documentation is in order; if the sample is received before 10 am then the day the sample is received is Day 1 otherwise it will be on the next business day.
- Standard TAT is 10 Business days.
- Express Service is subject to prior approval, availability and surcharges.
- For International orders, please allow sufficient time for samples to clear customs.
Please pack samples appropriately to prevent breakage.
Because transportation of materials to our facilities can have significant impact on the moisture content of client sample materials, PLS Analytical will not accept client-provided Loss on Drying/Moisture content results. When required for testing, the Loss on Drying/Moisture Content will be performed at PLS Analytical and will be billed to clients at a flat rate. Please contact our Customer Service Team for current associated costs.
If growth is obtained during microbial enrichment testing, a gram stain will be performed and billed to the client. Please contact our Customer Service Team for current associated costs.
For Questions regarding the above information please contact our Client Services Department at 732-698-5050.

I confirm that I have read and accept the terms and conditions.

Sample Submission Form

Submitter Information

Date

Company Name / Address

Contact Name

Billing

Send Invoice To

If differentSame as Report

Name and email for invoicing

Order References

PO Number*

Quote Number*

Turn Around Time

StandardRush

Express, needed byInclude Raw Data

Controlled substance

Yes No

Microbiology sample suitability

YesNo

Analytical sample: method verification required

YesNo

Special Instructions

Fill The Sample Columns

SAMPLE NAME	LOT # (ONE LOT PER LINE)	METHOD (MUST BE PROVIDED)	TEST REQUESTED (MUST BE PROVIDED)	SPECIFICATION (MUST BE PROVIDED)	QUANTITY

Required for Testing to Begin Customer Initials and Date

Overview

What are Antimicrobial Preservatives?

Antimicrobial preservatives are added to pharmaceutical products to inhibit microbial growth and maintain microbiological integrity throughout storage and use. At PLS Analytical, preservative assessments help manufacturers evaluate whether formulations provide effective protection against microbial contamination across a range of pharmaceutical dosage forms.

What is Antimicrobial Effectiveness Testing (AET) USP <51>?

PLS Analytical performs Antimicrobial Preservative Effectiveness Testing (AET) in accordance with USP <51> to evaluate the ability of preservative systems to control bacterial, yeast, and mold growth following a defined microbial challenge. These studies support formulation development, preservative optimization, product qualification, stability programs, and regulatory submissions by demonstrating that preservative performance meets compendial acceptance criteria.

Why it Matters

An effective preservative system is essential for maintaining product quality throughout its intended shelf life and use. Inadequate antimicrobial protection can increase the risk of microbial contamination, product degradation, batch rejection, and regulatory findings.

PLS Analytical delivers scientifically rigorous AET programs aligned with USP <51> and global regulatory expectations, helping manufacturers verify preservative performance, strengthen contamination control strategies, and generate reliable data for quality systems and regulatory submissions.

Testing Services

Evaluate preservative performance under real microbial challenge conditions

PLS Analytical performs USP 〈51〉 Antimicrobial Effectiveness Testing using compendial challenge organisms and controlled microbiological procedures to assess preservative performance across a wide range of pharmaceutical and healthcare products.

USP 〈51〉 Preservative Challenge Testing

USP 〈51〉 Preservative Challenge Testing evaluates the ability of preservative systems to reduce or inhibit microbial growth following exposure to defined challenge organisms. Scientifically robust data supports multidose pharmaceutical products, aqueous formulations, preservative-containing dosage forms, and regulatory compliance.

Formulation Development & Preservative Optimization

Formulation development and preservative optimization evaluate the effectiveness of preservative systems across formulation variations. Scientifically robust data supports new product development, reformulation programs, preservative optimization, product lifecycle improvements, and formulation decision-making.

Stability & Lifecycle Monitoring Studies

Stability and lifecycle monitoring studies evaluate preservative effectiveness throughout product shelf life under defined storage conditions. Scientifically robust data supports stability programs, shelf-life verification, lifecycle management, and regulatory submissions by confirming continued antimicrobial protection over time.

Advantages

Built for reliable, regulatory-ready results

Antimicrobial Effectiveness Testing provides critical evidence that preservative systems remain effective throughout product use and storage, supporting quality, compliance, and patient safety.

Product Protection

AET confirms that preservative systems can control microbial contamination introduced during manufacturing, storage, or repeated product use, helping maintain product quality and safety throughout the intended shelf life.

Reliable Preservative Performance Data

Testing generates quantitative microbiological data that demonstrates the effectiveness of preservative systems under defined challenge conditions. Results support formulation decisions, quality reviews, and regulatory documentation.

Early Identification of Formulation Risks

Challenge testing can identify preservative weaknesses before commercialization, allowing corrective action during development rather than after market release. This helps reduce reformulation efforts, investigations, and compliance risks.

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