Documentation:APBI Teaching Lab Quality Assurance and Control

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What are Quality Assurance and Quality Control?

Quality Assurance

Quality assurance is the program designed by a researcher or lab that strives to ensure the final results reported by a lab are correct and accurate.

Practices for maintaining quality assurance

1.   Standard Operating Procedures (SOP’s) - Laboratory methods/equipment is clearly described in a document of standard operating procedures. Periodic review to update procedures is key to adapting your protocol.

2.   Training- Each researcher/technician is trained by a person that is proficient in the method prior to running analyses. This can also be done using a test.

3.   Reliable and Well-Maintained Equipment – Equipment is only operated by trained individuals, a log book is kept for each instrument to help keep track of deficiencies and problems, equipment is regularly calibrated according to manufacturers guides.

4.   Traceability - Analytical standards used are traceable to certified reference materials. Internal reference materials are checked as far as technically and economically practicable.

5.   Annual Review of QC results - The results of proficiency testing and QC results are annually evaluated for trends. Quality Control

Quality Control

Quality controls are the set of measures that must be included in each analysis to test that it is working properly.

Practices for maintaining quality control

1.   Blanks - A blank reagent (i.e. reagent with no sample) is analyzed with every set of samples that are extracted or digested. This reagent blank includes any and all reagents that are used in the analytical process and is carried through the entire process, including extraction and filtering or digestion.

2.   Lab Duplicates - At least ten percent (1 in 10) of samples are analyzed in duplicate. Duplicate values typically should fall within a specific range of each other for all samples, unless sample homogeneity is a problem – consult the literature for acceptable values based on the analysis you are completing.

3.   Field Duplicates – A duplicate sample is taken from the sample place at the same time of sampling. You can follow a similar rule to the lab duplicate rules.

4.   Split Samples – A sample split into two subsamples at the lab. One sample is analyzed at one lab, and one at another lab, then compared (not a common practice in soil research setting).

5.   Standard Reference Materials - At least one standard reference material is analyzed with each set of samples. Samples run with a standard reference material that falls outside the acceptable range are reanalyzed, including digestion or extraction if necessary.

6.   Spike Samples - Sample fortifications or spikes are used to verify the accuracy of tests requiring extensive sample manipulation (such as acid digestion), for non-standard sample types, and if target of interest may exist in barely detectable quantity.

7.   Standard Curves – When using a standard curve to determine sample concentration, obtaining an R2 of 0.98-1.00 is ideal, if lower samples and standards should be re-analyzed.

8.   Sample Exchange and Certification Programs – Labs can participate in a number of sample exchange and certification programs. For example, some labs participate in the International Plant Exchange for plant material, the North American Proficiency Testing Program for soils, water, plant material, and manure, the Agriculture Laboratory Proficiency Program for plant tissue, and the National Forage Testing Association for the analysis of moisture, crude protein and acid detergent fiber in feed.

Why do QA/QC Matter?

Quality assurance and control are important concepts in the process of data collection. Samples must be managed from the field, to transport, to storage, and analysis. Depending on the sample type and analysis to be performed, if certain protocols are not followed at all stages there can be important ramifications. By incorporating QA/QC controls into all steps of lab procedures, you can mitigate some of the negative consequences of not ensuring QA and QC and receiving inaccurate results including:

a.   Failure to provide proper remediation technologies, over/under fertilizer rates, seeding rates, or irrigation recommendations

b.   Increased analysis and sampling costs if more sampling is required

c.   Delaying correct results

d.   Increased cost in time, personnel effort, inputs, and other resources

e.   Poor outcomes in terms of experiment results, remediation success, crop yields, and delayed harvest.

Quality Management System

A quality management system can be used to improve and ensure the quality of results from your lab. These systems often involve:

Organization and supervision

It is important for supervisors and/or lab managers to establish a line of hierarchy to show who is responsible for various tasks and responsibilities, and the training required for each role. Often in smaller labs, the lab manager will be required to assist in helping all students/researchers maintain QA/QC for their projects. However, when possible, a QA/QC manager should be put in place.

Personnel and Training

A lab is only as good as it’s people. Therefore it is important to ensure that all personnel are competent, trained, and motivated for their tasks. All lab personnel should at minimum receive WHMIS training and detailed training on protocols that are specific to their work. Additional training is recommended on protocols that are higher risk and might involve dangerous chemicals or processes, on how to react in case of an emergency. Training certificates and dates should be recorded in a lab training management/safety binder. Regular competency assessment and proficiency testing should be conducted and documented. This can be done by direct observation of the personnel, records monitoring, and/or by analyzing the quality control or the external quality assessment results.


Purchasing the correct equipment for your analyses, correct installation, ensuring that it works correctly, conducting training, and regular maintenance are a crucial component to maintaining QA/QC in your lab. An inventory of equipment, manuals, and repair logs should be kept on all equipment. SOPs for equipment should be located nearby for easy reference.

Purchasing and inventory

Managing your inventory is critical in reducing costs and ensuring use before expiration are critical to reducing costs and providing accurate and timely reporting of laboratory results. The inventory should be kept up to date including information on reception, safe storage, and if necessary usage. Material Safety Data Sheets (MSDS) should be kept as part of this inventory. An online inventory may be used such as Quartzy or an excel document.

Documents and records

Documents provide written information about policies, processes, and testing procedures and should be stored in the laboratory quality manual for each laboratory. This manual should serve as a basis for writing the laboratory Standard Operating Procedures (SOPs) which need to be adapted to the laboratory’s role and capacity. The SOPs, QC/QA procedures, and other laboratory forms are all important components of the QA/AC program. An SOP should be written for all procedures in the laboratory, including sample collection, transport, storage, waste disposal, equipment use and maintenance, a summary of known sources of error in a lab and common mistakes, glassware/cleaning protocols, and SOP writing. Examples of records include: error logs, request forms, report forms, logbooks, quality control results, safety information, and critical communications. 

Process control

Process control refers to control of all activities involved in the operation of a laboratory. One of the most familiar process control measures is the use of internal QC to monitor the performance of analytical methods.

Information management

Written SOPs should be developed for all field and lab activities including: field data recording, data management, cleaning, and reporting, as well as for procedures and equipment.

Error report management

Common errors that should be logged and reviewed periodically to improve procedures and identify common issues include:

  • Sample identification error
  • Sample misplacement
  • Sample transport delayed or at the insufficient temperature
  • Contaminated sample
  • Performing an inappropriate test
  • Lack of QC/QA
  • Transcription and clerical errors

Errors can be identified through: observation from supervisor/mentor, checking sample list, QC/QA procedure results. When possible, immediate corrective action should be taken.  


Assessments can be completed to determine laboratory performance by comparing samples to known standards or to results from other laboratories. They can be conducted internally, through another lab, or through a third party lab assessment.

User assessments

The lab manager/supervisor should conduct periodic questionnaires, meetings, and observation periods to assess lab user needs and use feedback and information gathered to make improvements to the lab.

Process improvement

All these tools should be used together to improve the overall processes in the lab, as such, when changes are made, they should be documented in the SOP and implemented in the lab. These changes should be recorded and reflected in the SOPs and implemented in the lab.

Facilities and safety

The lab should develop guidelines for safety depending on the work being completed including but not limited to biological, radioactive, chemical, basic lab safety, basic safe operating procedures, and waste management.

Soil, Plant, and Water Sampling Recommended Guidelines


Recommendations for all types of sampling start with including a detailed sample label. The label will tell you all the pertinent information about your sample including: who they belong to, how to contact you, where your samples were taken, why your sample was taken, and the date. These are key to ensure:

  • All samples are accounted for
  • Samples that are lost can be returned
  • Samples have a unique identifier
  • Information pertaining to a particular sampling date or type are not lost. For example:
  1. Name
  2. Contact Information (phone number, email, and/or supervisors name)
  3. Unique sample identifier (For example: field location, GPS location, river/lake name etc. or a specific value that will be referenced in your lab sample database)
  4. Sample type and what kind of analysis will be completed. (For example: it may be important to put depth of soil, part of plant, location in river/lake etc. and biological, chemical, physical or more specific analysis that will be completed.
  5. Date

Click on the links below for more detailed sampling recommended guidelines:

Soil Sampling

Plant Sampling

Water Sampling


1.    UC Davis Analytical Lab. “QA/AC”. The Regents of the University of California, Davis campus, 2017-20.

2.    EPA. EPA Recommended Containers, Preservation Techniques, and holding times for water samples and analysis.

3.    Centre for Disease Control. 2019. Lab Manual. Chapter 13: Quality Control Assurance.

4.    WHO/CDC/CLSI. Laboratory Quality Management System Training Toolkit. 2009.

5.    NCCLS. Application of a quality management system model for laboratory services; Approved Guideline: Third Edition. NCCLS document GP26-A3. NCCLS. Wayne, Pennsylvania. 2004.

6.    ISO 15189:2007. Medical laboratories: requirements for quality and competence. Geneva, Switzerland: International Organization for Standardization; 2007

7.    NCBI. 2009. Guidelines for Using HIV Testing Technologies in Surveillance: Selection, Evaluation, and Implementation: 2009 Update. Chapter 6: Laboratory Quality Assurance and Safety.

8.    Hoskins, B. 2009. Recommended Soil Testing Procedures for the Northeastern United States. Chapter 1: Laboratory Quality Assurance Programs.

9.    Anatek Labs. 2019. Quality Assurance Plan.

10. Erocksson, U. 2016. Quality Assurance vs Quality Control.

11. Reisenauer, H. M. (ed.) 1978. Soil and Plant-Tissue Testing in California, Division of Agricultural Sciences, University of California, Bulletin 1879.