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? Ultimately, your Data Quality Objectives (DQO) will determine what you expect from your selected environmental laboratory. Once you determine the types of services you will need, you can locate an appropriate lab using one of the ISO/IEC 17025:2005 registrars located in your area.

Guide for Obtaining Quality Laboratory Services

Choosing a laboratory based solely upon price, a telephone or web directory listing, advertising, convenient location to your site, or some limited past experience is a sure strategy for disaster. Selection of a laboratory must be made through use of objective criteria for evaluating a laboratory's competency and qualifications. The first criteria you should consider is require that the laboratory is ISO/IEC 17025:2005 accredited. You should then 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 You require. Next, perform a 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, and ultimately 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. It is your responsibility to determine if a laboratory is producing quality data that satisfies your DQOs, and performs the specific analyses required for your project to prevent the increased costs associated with re-sampling and re-analysis.

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. In order to select a laboratory you should request a review of their Quality Control (QC) sample and/or duplicate sample control limits, Proficiency Analysis Test (PAT) sample data, and, whenever possible, Measurement Uncertainty data for the analyte(s) and matrices you want to have analyzed.
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. It is always advisable to agree with the laboratory management on the level of QC you are expecting to be analyzed with your samples and to be reported with the analytical data. This demonstrates to the laboratory that you are serious about the quality of your data.

Corrective Actions and Customer Complaints

Every ISO/IEC 17025 accredited laboratory must have an implemented formal program for the documentation of Corrective Actions and addressing Customer Complaints. This is en excellent tool for evaluating how serious a laboratory is about data quality and customer satisfaction. Upon request, a laboratory should provide you information about the established program and also provide you general (statistical) information on Corrective Actions and Customer Complaints and how they are generally resolved. A high number of issues related to sample loss, samples expired in the laboratory, reporting falsely high or misidentified peaks, incorrect analytical method used, or not achieving turnaround time requirements should alert you to a potential lack in quality or dedication to customer needs. In such situations, choosing a different laboratory should be considered.

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 and that performance data such as PAT results and/or Measurement Uncertainty evaluations are available for your review. Never send samples to a laboratory, expecting that they will select the required method and have experience in performing that procedure; always verify they have the necessary capabilities before sending your samples.

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. Improperly preserved or temperature controlled samples may produce questionable results which must be qualified as such when reporting 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, for example, with analytical techniques that employ a single, non-specific instrument detector, reliance on a single chromatographic column, and/or the inability of the analytical method to properly deal with background sample matrix (interference). Laboratories that extensively use the more costly Mass Selective Detectors (MSD) for organic and metals analysis, are in a better position to provide positive identification of the analyte in question due to the nature of these detectors. A laboratory which advertises scientifically-sound and legally-defensible data would most likely perform a repeat analysis of an analyte detected at a concentration close to or above the Maximum Contaminant Limit (MCL) or action limit prior to reporting, although most laboratories charge extra for repeat analysis and will perform a true confirmation analysis only if requested. Therefore, your wishes should be clarified with the laboratory on how to deal with tentatively identified target analytes and the possible costs associated with repeat and confirmation analyses.
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 reports you receive from the laboratory should include:
  • Concentration units
  • Data (Results)
  • Definitions for all abbreviations used
  • Date sampled
  • Date of Sample Preparation
  • Date analyzed
  • Method used
  • Detection limits
  • Location or sample ID # (sample identification information)
  • Trip blank results (where appropriate, VOCs, EDB/DBCP, etc.)
  • Any special problems encountered during analyses (interferences, insufficient sample, etc.) and its affect on results
  • Identification of the persons who performed the analysis and approved the release of the data
Additional information such as Measurement Uncertainty, Case Narrative, or providing Quality Control results must be provided upon your request, but should be coordinated with the laboratory prior to submitting your samples.
The accuracy of the report is very important. If you notice frequent problems (such as improperly place 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

For a large number of procedures the time from when a sample is collected to when it is analyzed must not exceed a regulatory driven stipulated period. In order for the laboratory to ensure your samples are analyzed within the stipulated holding time you must provide the laboratory the date and time the sample was collected. If the holding time is exceeded, the results are questionable; the data will be qualified on the laboratory’s certificate of analysis and generally will not be accepted for regulatory purposes. The data, if used by the customer, must be qualified as exceeding the holding times when submitted to the regulatory agency.
Before you use a laboratory 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 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. To be sure you receive proper service, provide the laboratory with all Data Quality Objectives (DQOs) or the information required (e.g., sampling requirements, regulatory limit, methods required, method detection limit (MDL), limit of quantitation (LOQ), actions levels, etc.). Be certain to compare the laboratory’s published detection limits to the required regulatory limits. Ensure the advertised MDL and LOQ can be met for the matrix of your samples.


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.

Checklist for Selecting an Environmental Laboratory

  • Is the laboratory accredited to perform the methods you require?
  • Verify their accreditation status by requesting a copy of their ISO/IEC 17025:2005 certificate of accreditation and a copy of their official Scope of Accreditation, listing all the methods the laboratory is accredited to perform.
  • In addition to, not in lieu of accreditation, is the laboratory registered to any other internationally recognized and accepted standard of quality or environmental management (ISO 9001:2008 QMS or ISO 14001:2004 EMS)?
  • When did the laboratory undergo their last ISO/IEC 17025:2005 on-site accreditation audit?
  • Schedule an appointment to visit the laboratory, review their files and if possible audit the laboratory.
  • How well did the lab perform on their last audit?
  • How many non-conformances to the ISO/IEC 17025:2005 standard were identified during the on-site audit?
  • How did the laboratory address all of the identified non-conformances?
  • How many Proficiency Analysis Tests (PAT) is the laboratory participating in?
  • Does the laboratory participate in PATs for the target analytes and matrices you are planning to submit sample for?
  • How did the laboratory do on the latest round of PAT samples?
  • How close were results reported in a PAT round to the PAT true value?
  • Does the laboratory take adequate measures to determine cause(s) of PAT round non-compliance?
  • What is the laboratory’s overall performance on PAT rounds for the last year, two years or three years?
  • Does the lab have a history of repeat failures on PAT rounds for a specific reference analyte?
  • Are there any outstanding enforcement actions against this lab and if so, do they affect your project?
  • Does the laboratory follow the approved reference methods? If not, to what extent do deviations influence the accuracy and precision of reported data?
  • Review the laboratory’s official ISO/IEC 17025:2005 Scope of Accreditation, current version of their Quality Manual, and applicable Standard Operating Procedures (SOPs) and Work Instructions (WI).
  • Can the lab meet the required holding times prior to analysis?
  • What is their history on meeting holding times?
  • What sample priority turnaround times does the laboratory offer?
  • Do they meet your project's requirements?
  • What is the probability that your project will be "bumped" for higher priority projects or samples?
  • Talk to the Laboratory Director, explain your Data Quality Objectives (DQO) and expectations and get answers before you submit your samples.
  • Review the laboratory’s published data on their Limit of Quantitation (LOQ), Method Detection Limit (MDL), and Measurement Uncertainty (MU) to ensure the laboratory can meet your DQOs and achieve the appropriate detection levels for your project.
  • Does the laboratory regularly achieve the desired accuracy and precision of data needed for your project?
  • Request to review the laboratory’s control limits and other quality control data.
  • How are analytical data reported? Does the laboratory identify and correct quality control failures appropriately?
  • Does the laboratory offer electronic reporting of data?
  • Request a sample report(s) to ensure it meets your requirements.
  • What is the experience/qualification level of the laboratory's current staff?
  • Review the qualifications of key employees.
  • Request to review the laboratory’s training records.
  • If possible, interview various staff to determine level of technical competence
  • Ask the laboratory to supply references, and check with the references to get their opinion of the data quality and customer service the laboratory provides.
  • Compare analytical method prices to other ISO/IEC 17025:2005 accredited laboratories.
  • Does the laboratory charge more for a given method? What is the level of quality control samples routinely run by the laboratory along with customer samples?
  • Does the lab routinely perform confirmation analysis? If not, do they charge extra for confirmation analysis?
  • Ask the lab about any "extra" charges you may incur, and remember, that resampling usually ends up costing you, and not the laboratory, more.