Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:3:p7
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 3 (pt 7/9)
Character Range: 732506–735657

and independently quantified by virtue of, e.g. chromatographic separation or production of different mass ions in a GC/MS system.
Surrogates provide a means of checking that no gross errors have occurred at any stage of the procedure and which may cause significant analyte losses.

Surrogate spikes are only appropriate for organic analyses, for example, chromatographic methods. Where they are used, they should be added to all samples being analysed and are added to the analysis portion before extraction. Surrogate spike compounds may be deuterated, alkylated or halogenated analogues, or structural isomers of analyte compounds. Surrogate compounds used in analytical methods, normally three per method, should be chosen to monitor the variable method performance of the entire target analyte list.

    3.3.7         Internal standards (where appropriate)
Use of internal standards is highly recommended for chromatographic analysis of organics and some inorganic analyses, to check the consistency of the analytical step (e.g. injection volumes, detector response and retention times for chromatographic systems). Internal standards provide a reference against which quantitative data may be corrected for sample-specific variation in instrumental response (for organics analysis only).

For organics analysis, internal standards are normally synthetic deuterated compounds (isotopic analogues) of target compounds. Internal standards are added to each final extract solution after all extraction, clean-up and concentration steps. The addition is a constant amount of one or more compounds with qualities like those listed for surrogates, i.e. a similar instrumental response to that of the target compounds, etc.

Adjustments for variations in injection volume and instrument sensitivity are made by quantifying against the ratio of:

(peak height or area for analyte) : (peak height or area for the referenced internal standard) X (a response factor determined from a preceding calibration standard)

Methods should define specific QC criteria for internal standard response and procedures for analyte quantification where response is observed outside of predefined limits.

3.4              Documentation of validation and QC procedures
All method validation steps (including raw data and data validation assessment) should be recorded and retained while the method is in use. Results of validation procedures should be retained to enable monitoring of method reliability, confidence intervals for analysis results and trends in precision and accuracy over time, or with variation of equipment, source of calibration or analyst.

After completion of analysis of each sample process batch, all documentation relating to the samples and their analysis (including raw data and supporting QC data) should be retained for at least three years (NATA 2011, Section 4.13) so that all relevant information may be easily retrieved. This helps establish chain-of-custody of the sample and traceability of all data, and enables reviewing the analysis during an audit or investigation of a questionable result.

This data retention requirement applies