Quality Control System: an understanding of analytical error; synthetic QC material; a set of QC rules; a process to follow if the rules signal. Quality Control (QC) Sera: reconstitution - staff trained; stability tested - post reconstitution and frozen. QC Rules: rules documented - basis of adoption; action to follow in case of failure documented; evidence of this procedure being used in place; are QC rules defined for both batch and continuous analysis - how is a 'run' defined for a continuous analytical process; means and standard deviations (SDs) of controls based on sufficient data points and reflects true state of system; evidence of staff training in the interpretation of QC rules; process documented; evidence of training of staff; evidence of regular review of Internal QC results. Patient-based QC Procedures in place: if delta check/anion gap/rerun of samples used, then a documented procedure to describe the process and evidence of it being in use; critical values - documented and evidence of use and documentation. Action on QC Rule Failure: documented process to follow with patient samples if control failure occurs; evidence that procedure has been followed in instances of control failure. External Quality Assessment (EQA) Program: Integration of Internal and External QC data.