VIMS Analytical Service Center for Nutrients

• QC... As Monitored at the Instrument
• QA... As Implemented by QA/QC Officer
• Information Reported to the Investigator

... As Monitored at the Instrument

The following Quality Control Criteria are the basic parameters monitored by the analyst at the bench. An Investigator may specify absolute limits or additional protocols as required for the project.

• Correlation - Calibration curve coefficient must exceed 0.999.
  
  
• Standard Reference Materials - Analyzed daily, matrix matched, mid-range concentration, must meet statistical control limit (internal) for lot.
  
  
• Intercept Correction - Employed to eliminate any standard matrix artifacts not applicable to samples.
  
  
• Precision - 10% Duplication - Randomly chosen, not linked to field duplication. Control limits derived from past data in similar concentration range and matrix, or specified by investigator.
  
  
• Accuracy - 10% Spiking - Recovery of known addition added directly to sample to verify the control of matrix interferences. Statistical control limited. Failure to meet criteria triggers interference screening and method modification.
  
  
• Baseline correction - Zero analyte response verified every 10 samples. Drift mathematically compensated.
  
  
• Sensitivity Correction - Calibration verified every 10 samples. 10% deviation triggers re-calibration. Drift below 10% mathematically corrected.

... As Implemented by QA/QC Officer

• Documentation of Sample Custody
  
  
• Establishment of control limits, and monitoring of each analytical run for compliance to validate accuracy and precision.
  
  
• Data report generation, with intent to review data in its final form.
  
  
• Verification of absolute mathematical relationships between fractional analyte components, and overall "reasonableness" of results.
  
  
• Preparation of Quality Control Summaries as require by individual Investigators,
  on a project basis.
  
  
• Maintenance of all records, electronic and hardcopy, for period defined by Investigator.

Data Report Format and Content

Data reports are available in hard copy or ASCII file format, and can be transfered to an Investigator on disk, or by FTP.

• Unless specified, concentrations of dissolved and particulate parameters are reported on a mg/L or micro-g/L basis. Sediments, scallops, and other solid matrices are reported as "% by weight" or mg/g (wet/dry basis, whichever is specified by the Investigator).
  
  
• The Data Report presents all replicates, means, and recovery percentages obtained. QC Results (Precision and Accuracy/Recovery) can be provided as a separate report as well. Method references can be provided for proposal development or publication.