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      4造纸行业国家标准文库ASTM 标准汇总
      您的位置: 首页 -> 造纸行业国家标准文库 ->  ASTM 标准汇总 -> ASTM D4785–00a 水体低级典-131的测定

      ASTM D4785–00a 水体低级典-131的测定


      UY = fractional uncertainty in the chemical yield (recovery)
      of the iodine carrier,
      UO = any additional fractional uncertainty that has been
      determined or estimated, and
      Other terms are as defined in 14.1 and 14.2.
      14.4 Expanded Uncertainty (U):
      U~Bq/L! 5 KUC (5)
      where:
      K = coverage factor for the desired confidence interval
      (nomally K=2 for 95 % confidence interval).
      14.5 Calculate a priori minimum detectable radioactivity
      concentration (MDC) as follows:
      MDC ~Bq/L! 5
      ~4.65=Cb 1 2.71!
      E 3 t a 3 Va3 Y 3 e2lt (6)
      where:
      Cb = number of counts accumulated during the counting of
      the sample aliquant that are due to instrument background
      in the gamma-ray region of interest, and
      Other terms are as defined previously.
      NOTE 14—The counting times of the sample aliquant and of instrument
      background must be of equal length for Eq 3-6 to be valid. The values
      used for the terms in Eq 6 should be typical for the laboratory.
      15. Quality Control
      15.1 Prior to using this test method, a quality control (QC)
      program for the instrumentation (high-resolution gamma-ray
      spectrometer) shall be established when the system is calibrated.
      Quality control or tolerance charts shall be established.
      Control limits shall be established with corrective actions when
      control limits are exceeded.
      15.2 Before this test method is utilized for the analysis of
      samples, individuals performing this test method shall be
      qualified by analyses of samples spiked with iodine-131. The
      bias and precision of these measurements should be consistent
      with the data provided in Section 16.
      15.3 A QC source shall be counted daily or prior to use. The
      results shall be tabulated or plotted on control charts and
      evaluated in accordance with Practices D 3648.
      15.4 The counter background shall be determined periodically.
      The background data shall be maintained in a logbook or
      plotted on a trend chart, or both.
      15.5 Precision and bias can be assessed in the following
      manner: the precision of an individual measurement can be
      approximated by the total propagated uncertainty and bias can
      be assessed by the analysis of NIST-traceable spiked samples
      with known quantities of iodine-131.
      15.6 The project manager, as part of the external quality
      control program, shall submit blind quality control samples to
      the analysts along with routine samples. These external quality
      control samples, which usually include duplicate and blank
      samples, shall test sample collection and preparation as well as
      sample analysis whenever possible. In addition, analysts are
      expected to run internal quality control samples that will
      indicate whether the analytical method is in control. Both
      internal and external quality control samples need to be
      prepared in such a way to duplicate the chemical matrix of
      routine samples, insofar as this is practical. The quality control
      samples that are routinely used include blank samples, replicate
      samples, reference material, and spiked samples.
      16. Precision and Bias 7
      16.1 The collaborative test conducted of this test method
      included 6 laboratories each with one operator. Three activity
      levels between 0.74 Bq/L (20 pCi/L) and 149 Bq/L (4020
      pCi/L) were tested with three replicates per level. The determination
      of the precision and bias statements were made in
      accordance with Practice D 2777.
      16.2 These collaborative test data were obtained using
      reagent grade water.
      16.3 The overall precision S (T) and single-operator precision
      S (O) have been found to vary with level in a manner
      according to Fig. 2.
      16.4 The bias of this test method, based upon the collaborative
      test data, was found to vary with level according to Table
      1.
      17. Keywords
      17.1 iodine-131; ion exchange; low-level activity; radioactivity;
      water
      7 Supporting data are available from ASTM Headquarters. Request Research
      Report RR:D-19-1136.
      FIG. 2 S(T) and S(O) versus Concentration
      D 4785 – 00a
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