Re: Analytical lab performance on spike samples

[loesch@viper.eh.doe.gov (Robert M. Loesch)]

Jamie Mallon wrote:

>  New Thread!
>
>The internal dosimetry group at Sandia is in the process of developing a 
>procedure to document the review of lab results for spiked samples.  I have 
>reviewed the ANSI N13.30(draft 1994) guidance for performance criteria on QC 
>samples.  The ANSI standard identifies numerical criteria for the avg. bias of
>a group of spike samples.  This parameter alone is insufficient to evaluate
the 
>performance of an analytical lab.  Individual sample bias could swing wildly, 
>while the average bias is within the -0.25 to +0.50 criteria.
>
>We are thinking of looking at the standard deviation of the bias to provide a 
>measure of how the bias is behaving.  So the questions are:
>
        The -0.25 to +0.50 average bias criteria comes from secion 4.3.2 of the
        Dec. 20, 1994 draft of N13.30.  However section 4.3.3 also specifies 
        0.4 for relative precision.

>1. Is anyone aware of any formal guidance in this or a related area(e.g.
TLD's, 
>   radiochemistry)?
>
        One source certaining would be the contractual requirements that you 
        specify. Since you are a DOE facility, the procurement order requires
        that you ensure the quality of the service that is being provided, e.g.
        periodic spikes and blanks.
>
>2. Has anyone adopted 'rule of thumb' guidance for their own use?
>
        The Nevada Test Site performs quarterly QC checks of their TLD service
        laboratory using the same requirements as specified in the DOELAP 
        Standard.  Anything specified in N13.30 should be fair game for your
        QA of the vendor. I would start with the N13.30 requirements and layer 
        on top any additional contractural requirements and consider lowering 
        the testing levels (r/n activities) periodically to ones that are more
        realistic or typical of levels seen at the site.

>Thanks for the help.
>
>Jamie Mallon
>
>Environmental Dimensions Inc.
>Phone 505-844-8287
>Fax   505-844-0701
>Email JMallo@SAIX367.Sandia.gov

Bob Loesch
Member, N13.30 Working Group