The practice of assigning retest dates is the recommended procedure in the US Food
                            and Drug Administration’s Guidance for Industry document to the pharmaceutical industry:
                            Q7A Good Manufacturing Practice Guidance for Active Pharmaceutical Ingredients (API’s)
                            and is standard pharmaceutical industry practice for reference standards.
                            
                            
                            Per the Q7A:
                            
                            
                            
                                “An API expiry or retest date should be based on an evaluation of data derived from
                                stability studies. Common practice is to use a retest date, not an expiration date.”
                                
                                
                                “Retest Date: The date when a material should be re-examined to ensure that it is
                                still suitable for use.”
                                
                                
                                “Expiry Date (or Expiration Date): The date placed on the container/labels of an
                                API designating the time during which the product is expected to remain within established
                                shelf life specifications if stored under defined conditions and after which it
                                should not be used.”
                            
                            
                            
                            Consistent with our accreditation to ISO Guide 34, expiration dates are assigned
                            to Cerilliant products based on stability studies:
                            
                            
                            
                                ISO Guide 34, Section 5.9.4, defines Expiration Dates as “An assessment of the stability
                                of the assigned property values of the reference material performed at periodic
                                intervals after characterization to confirm that all values are maintained from
                                production until its expiry date. Wherever appropriate, the reference material producer
                                shall provide an expiry date for the useable life to the reference materials produced,
                                based on initial and on-going stability studies in compliance with ISO Guide 35.”
                                
                                
                                ISO 17025 does not specifically speak to the assignment of expiration dates or retest
                                dates. It does speak to the calibration of equipment and the use of certified reference
                                standards as follows:
                            
                            
                            
                                
                                    - 
                                        Section 5.58 – “Whenever practicable, all equipment under the control of the laboratory
                                        and requiring Calibration shall be labeled, coded, or otherwise identified to indicate
                                        the status of calibration, including the date when last calibrated and the date
                                        or expiration criteria when recalibration is due.”
                                     
                                    - 
                                        Section 5.6.2.1.2 – “There are certain calibrations that currently cannot be strictly
                                        made in SI units. In these cases calibration shall provide confidence in measurements
                                        by establishing traceability to appropriate measurement standards such as: - the
                                        use of certified reference materials provided by a competent supplier to give a
                                        reliable physical or chemical characterization of a material…”
                                     
                                    - 
                                        Section 5.10.4.3 - “A calibration certificate (or calibration label) shall not contain
                                        any recommendation on the calibration interval except where this has been agreed
                                        with the customer. This requirement may be superseded by legal requirements.”