Laboratory Sciences
How Do I Choose a Biological or Environmental Testing Laboratory? 
As a laboratory customer, how can you make sure that the results you receive will meet your data quality needs? 


Guide for Obtaining Quality Laboratory Services

Selection of a laboratory must be made through use of objective criteria for evaluating a laboratory's competency and qualifications.
1) Require that the laboratory is ISO/IEC 17025:2005 accredited.
2) Conduct a detailed review of the laboratory’s official ISO/IEC Scope of Accreditation to ensure the laboratory is accredited to perform all the analytical procedures that you need.
3) Review of their blind, round-robin Proficiency Analysis Test (PAT) program data to determine the history of the laboratory’s successful identification of the analytes you are interested in on blind PAT samples.
4) Conduct an on-site audit of the laboratory and its Quality System.
These measures will help you to select a laboratory that can provide you with the data quality required by your project and regulatory analysis.
Laboratory accreditation to ISO/IEC 17025:2005 alone does NOT guarantee quality data or the level of customer service you need. Laboratory accreditation makes information available about analytical data quality to the customer. This information can be used by you to help choose your laboratory. 
Things to consider when selecting a laboratory:

Accuracy and Precision of Data

Your sample data will be used to determine compliance with environmental law or as a foundation upon which to base a health-risk assessment, therefore, you will want your results to be as accurate and precise as possible. Each parameter, method, and laboratory has different precision and accuracy limits.
Once you have selected a laboratory you should check their performance by submitting Duplicate samples (ideally with samples which are expected to return positive target analyte results) as Blind samples. This will provide information on the laboratory’s accuracy and precision. 

Customer Complaints

Every ISO/IEC 17025 accredited laboratory must have an implemented formal program for addressing Customer Complaints. This is an excellent tool for evaluating how serious a laboratory is about data quality and customer satisfaction.

Approved Methods

Most biological and environmental monitoring programs require the use of approved analytical methods. Unfortunately these methods may vary from program to program and country to country. Make sure the laboratory meets requirements of the environmental regulatory program your samples must comply with and ensure that the approved analytical methods are formally implemented and routinely performed at the laboratory of your choice.

Sampling Instructions, Bottles and Preservatives

If requested, the laboratory should be able to provide you with written instructions or Customer Guides designating preservatives, sample containers, compatible parameters, and shipping conditions which can be collected in the same bottles, and holding times for samples.
Sample containers (glass, plastic, etc.) and/or volumes, along with preservatives, vary from parameter to parameter. You may want your laboratory to provide you with bottles and chemical preservatives that have been analyzed and certified by the laboratory to ensure the quality of your analytical data.
Requiring laboratory supplied sampling containers will ensure the correct sample container and preservative, and minimize associated errors.
Laboratories that will provide these services will make your job easier!

Proper Identification of Compounds

As all laboratories are run by humans, it is possible for a laboratory to misidentify and misreport compounds (analytes). The probability for errors in reporting an analyte is greater with analytical techniques that employ a single, non-specific instrument detector.
Laboratories that extensively use the more costly specific detector for organic and metals analysis, are in a better position to provide positive identification of the analyte. 
If you have doubts about any analytical results received from your laboratory, you should request verification or confirmation of the reported result. A continuing record of compound misidentification should prompt you to seek better service.

Reporting Data

The accuracy of the report is very important. If you notice frequent problems (such as improperly placed decimal points, calculation errors, or improper units), poor data handling is indicated. Notify your laboratory that this is not acceptable and perhaps consider changing laboratories if these errors continue and/or are not immediately corrected.

Turnaround Time on Samples

You may need your lab results back within a specific time. Be sure to address the sample analysis priority with the laboratory and ensure that the laboratory agrees to meet selected sample analysis priority. Most laboratories have the capability to provide rapid turnaround times, usually at an increased cost.

Holding Times Prior to Analysis

Before you use a laboratory the first time, ensure that the lab has established method/analyte specific sample holding times in their analytical procedures and that the lab has the capability to track sample holding times, such as a Laboratory Information Management System (LIMS). You should also ensure that the samples can be stored properly and that storage conditions are documented continuously.

Accreditation Status

Most environmental monitoring programs require the use of an accredited laboratory. Be sure to check that the laboratory is accredited for the tests (analytes and matrices) you need to be performed.
Many laboratories subcontract work to other laboratories when they cannot provide the complete service requested or when their workload exceeds their in-house capacity. It is acceptable for laboratories to subcontract analyses as long as the contract laboratory meets the required accreditation and quality control requirements.
Make sure the laboratory you choose informs you of their use of accredited contract laboratories prior to the submission of your samples for analysis.


Always check with the laboratories under consideration to determine their extent of experience in analysis of your particular sample matrix. This experience is helpful when dealing with samples containing complex matrices. You should ask for references and contact those references to obtain an opinion regarding the laboratory’s technical ability and its customer service.
Always visit the laboratory to evaluate the overall value of its product and to verify its marketing or technical claims. Take the time to review records and ensure they are clear, concise, easy to read, and most of all reasonable.

Detection Limits

The laboratory should be informed about your required detection limits to meet your project or regulatory requirements. Be certain to compare the laboratory’s published detection limits to the required regulatory limits. 


Price varies widely for environmental laboratory services. When requesting bids you must ensure they provide the needed services. There might be hidden costs (e.g., sample clean-up, standard addition, confirmation, or reporting of quality control results), so ensure you ask.
Keep in mind the lowest price may not save you any money if you are required to resample and pay the laboratory to retest because of questionable data or if the detection limits were not met. Conversely, the highest price may not necessarily provide the best value.
The important factors are quality and the ability of the laboratory to meet your needs on the first set of samples, not the price. You should never let the cost of analysis be the ultimate deciding factor in choosing your environmental laboratory.

Helpful References

Smith, R.K.: Guide to Environmental Analytical Methods, 5th Edition, Genium Publishing Corporation, Amsterdam, NY, March 2003.
Smith, R.K.: Handbook of Environmental Analysis, 4th Edition, Genium Publishing Corporation, Schenectady, NY, June 1999.
Smith, R.K.: Interpretation of Inorganic Data, 1st Edition, Genium Publishing Corporation, Amsterdam, NY, August 2001.
Smith, R.K.: Interpretation of Organic Data, 1st Edition, Genium Publishing Corporation, Canada, April 2000.
Smith, R.K.: Lectures on Wastewater Analysis & Interpretation, First Edition, Genium Publishing Corporation, Schenectady, NY, 1999.