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QA/QC

The Analytical Laboratory's policies and procedures related to quality control/quality assurance are available in its QA/QC Manual (PDF).  Click here to view the Lab's Quality Policy Statement.

The goal of the Analytical Laboratory QA/QC Program is to guarantee the generation of precise and accurate analytical data.

Quality assurance involves the planned and systematic actions necessary to provide confidence in each analytical result. The QA/QC Program has two components: Quality Assurance (QA) - the system used to verify that the entire analytical process is operating within acceptable limits and Quality Control (QC) - the mechanisms established to measure non-conforming method performance.

QA Procedures

STANDARD OPERATING PROCEDURES (SOPs) - Each laboratory method is clearly described in standard operating procedures. These methods are periodically reviewed for updates.

TRAINING - Tests are performed by trained staff members. Each staff member must meet performance criteria before performing a test.

RELIABLE AND WELL-MAINTAINED EQUIPMENT - Each instrument is operated by trained staff members. Maintenance logbooks are kept for each instrument. The instruments are calibrated according to manufacturer guidelines and in accordance to the relevant SOPs. Balances, pipettes and other measuring devices are calibrated frequently.

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

ANNUAL REVIEW OF QC RESULTS - The results of proficiency testing and QC results are annually evaluated for trends. A system of control charts is used to determine if the system is in a state of statistical control and examine the relative variability of repetitive data. Control charts are also used with reference materials and spiked samples to assess the accuracy of measurements.

QC Samples

BLANKS - A reagent blank 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.

DUPLICATES - At least ten percent of samples are analyzed in duplicate. The first, last and every tenth sample are run in duplicate. Duplicate values typically should fall within 8% of each other for all samples unless sample homogeneity is a problem. This information is included in the report.

STANDARD REFERENCE MATERIALS - At least one standard reference material is analyzed with each set of samples. The values for the standard reference materials are included in the final report. Samples run with a standard reference material that falls outside the acceptable range are reanalyzed, including digestion or extraction if necessary.

SPIKE SAMPLES - Sample fortifications or spikes are used to verify accuracy of tests requiring extensive sample manipulation (such as acid digestion) or for non-standard sample types.

SAMPLE EXCHANGE AND CERTIFICATION PROGRAMS - The Analytical Laboratory participates in a number of sample exchange and certification programs. The Laboratory participates in the International Plant Exchange for plant material and the North American Proficiency Testing Program for soils, water and plant material and manure. The Laboratory participates in the Agriculture Laboratory Proficiency Program for plant tissue.  The Laboratory is certified by the National Forage Testing Association for the analysis of moisture, crude protein and acid detergent fiber in feed.