Quality Assurance – Environmental Chemistry

wastewaterParadigm’s quality assurance program is based on criteria determined by the USA Environmental Protection Agency (EPA), the NYS Department of Health Environmental Laboratory Approval Program (ELAP), and the NYS Department of Environmental Conservation (DEC).  Within New York State the Department of Health is the official certifying body for laboratories, and as such we follow their requirements for all certifiable analyses.

Paradigm is certified by the NYS Department of Health to perform analysis of Air & Emissions, Solid & Hazardous Waste, Potable Water, and Non-Potable Water.

As a certified environmental laboratory, Paradigm is subject to a biennial audit by the NYS Department of Health.  This audit is performed in-person by a team of trained DOH auditors, and covers all aspects of laboratory operations.  This includes sample receipt and processing, sample storage, sample analysis, instrument calibration and maintenance, standards and reagent preparation, and record keeping. Deficiencies are noted to the laboratory director in writing, and require documentation of corrective actions taken in response. Failure to correct deficiencies can lead to decertification.

The laboratory is also audited annually by the Quality Assurance Officer. The findings from this audit also require documentation of corrective actions, and the Quality Assurance Officer is responsible for conducting follow-up audits to verify the corrective actions are being implemented. Additionally, the Quality Assurance Officer conducts quarterly audits of projects that have been completed. Where errors are found that affect the reported results, the reports are revised and re-sent to the client with a letter documenting the error and correction.

Paradigm Environmental analyzes performance evaluation samples from the NYS Department of Health. Samples are received covering individual parameters and/or parameter groups within the certifying categories. Analytical results are reported and statistically evaluated against the pool of laboratory respondents. Results must fall within acceptance limits to maintain certification for an individual parameter or parameter group.

Good laboratory practices include the regular preparation and analysis of quality control samples.  In addition, each regulatory program has specific requirements regarding the frequency and type of QC required. A comprehensive description of the QC required for analysis can be found in our Quality Assurance Manual, The EPA and DOH Methods Manuals, and our standard operating procedures.

The basic elements of laboratory quality control include:
• Method Blanks
• Laboratory Control Samples
• Matrix Spikes
• Duplicates
• Surrogates
• References
• Quality Control Samples

Preparation blanks consist of laboratory pure water, or a clean solid matrix, which is subjected to any extractions, digestions or distillations required to prepare samples for analysis. The resulting blank sample is then analyzed along side environmental samples under identical conditions. Blanks measure the cleanliness of an analytical system. Blanks are analyzed at a minimum frequency of 1 per 20 environmental samples or with each analytical or preparation batch.

Laboratory control standard are laboratory pure water, which has been spiked with a known amount of the analyte(s) of interest. Reference checks measure the accuracy of an analytical procedure. Laboratory control standard are analyzed at a minimum frequency of 1 per 20 environmental samples.

Matrix spikes are duplicate environmental samples to which a known amount of the analyte(s) of interest have been added.  Matrix spikes serve to measure the ability of an analytical system to accurately recover the analyte(s) of interest from the sample matrix. Matrix interferences may be positive or negative, causing false high or low readings respectively. Matrix spikes are analyzed at a minimum frequency of 1 per 20 environmental samples.

Duplicate analyses measure the precision, or reproducibility, of an analytical system. Duplicates are created from identical portions of an environmental sample which has been split in the lab, and are analyzed at a minimum frequency of 1 per 20 environmental samples. Due to lack of measurable quantities, organics precision is often measured using duplicate matrix spikes.

Surrogates are spikes which are added to all environmental samples and quality control samples destined for organics analysis. They consist of organic compounds which are similar in nature to the analytes of interest, but are not expected to be found in the environment. Surrogates are added prior to sample preparation, and are used to measure the performance of the analytical system as well as any matrix interferences.

Reference samples are generally samples that are analyzed without being taken through the entire preparatory process.  These samples verify the instrument is properly calibrated and that the calibration remains consistent throughout the duration of the analytical process.

Quality control samples are purchased from independent vendors who certify their standards to NIST-traceable reference standards. These samples have been previously tested and they come with pre-determined acceptance limits. These quality control samples are taken through the entire preparatory and analytical process, and the derived values are compared to the manufacturer supplied acceptance limits. These samples are matrix specific and enable the laboratory to keep their analytical edge sharp.

Data concerning quality control is accumulated over time and used to statistically generate acceptance limits. QC recoveries which fall outside these limits, or outside EPA regulatory limits, indicate a problem with the analytical system or the sample matrix. Failure of the analytical system requires immediate suspension of analysis, corrective action, and re-analysis of any affected samples.

Matrix interferences are specific to a sample or group of samples, and are caused by the nature of the sample itself. Matrix interferences can in some cases be eliminated with additional preparatory procedures.  For those samples with unavoidable matrix interferences, the data is flagged as a warning to the user.