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SEMI C1-0705 © SEMI 1978, 2005 8 Table 2 Data Reporting Requ irements for Trace Metals, Trace Anions, and Moisture Sample A Result A Sample B Result B Average Average of Result A and B Spike The amount of spike equivalen…

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SEMI C1-0705 © SEMI 1978, 2005 7
5.35 Sulfate Standard Solution — Dissolve 0.148 g of anhydrous sodium sulfate, Na
2
SO
4
, in water and dilute with
water to 100 mL. Then dilute 10 mL of this solution with water to 1000 mL (1.0 mL = 0.010 mg of sulfate (SO
4
)
ion).
5.36 Thymolphthalein Indicator Solution — Dissolve 0.10 g of thymolphthalein in 100 mL of 95% EtOH (ethanol)
reagent alcohol.
6 Method Validation
6.1 Method Validation — Analytical methods for trace metals, trace anions, moisture and assays require that
performance parameters be assessed and compared to the standard and guideline requirements. The accuracy,
precision of the measurement and interferences should be reviewed and reported with each method.
6.1.1 Accuracy for Trace Metals, Trace Anions, and Moisture
6.1.1.1 Method accuracy is a figure of merit that compares the data generated from the determined concentration of
a sample to its “known” concentration. In some cases, a traceable standard may not be available and a “best
available standard” may be substituted.
6.1.1.2 Determine the accuracy of a test method by utilizing a standard reference material as a sample and analyze it
using the proposed test method. Report the test method accuracy as percent (%) bias:
100 x
X
XX
bias %
value"true"
value"true""found"
6.1.1.3 If no suitable traceable standard exists for the “true value,” describe the procedures used to qualify the “best
available standard.”
6.1.1.4 Spiked recovery determinations are used to make a limited assessment of accuracy. Method validation is
based on the analysis of a minimum of two samples and a minimum of two spiked samples (Figure 1).
Initial
Product
Sample
A
Sample B
Spiked
Sample C
Spiked
Sample D
Result A Result B Result C Result D
NOTE: Samples A, B, C, and D are originally from the same initial product.
Figure 2
Data Collection Structure
6.1.2 Measurement of Precision
6.1.2.1 Typically a repeatability and reproducibility study is done, where samples are analyzed over a period of
multiple days.
6.1.2.2 Measures of method precision incorporate all applicable method variability sources (such as sample
preparation, calibration, and instrumental performance) into their definitions. An assessment of method precision
for trace metals, trace anions, and moisture is detailed in Tables 2 and 4.
SEMI C1-0705 © SEMI 1978, 2005 8
Table 2 Data Reporting Requirements for Trace Metals, Trace Anions, and
Moisture
Sample A Result A
Sample B Result B
Average Average of Result A and B
Spike The amount of spike equivalent to 50% of the specified value for
trace impurity, and it should be added to the sample prior to any
sample preparation (ex., sample dilution, evaporation, etc.)
Spike Sample C Result C
Spike Sample D Result D
Recovery 1 Result C – Average
% Recovery 1 (Recovery 1 / Spike) × (100)
Recovery 2 Result D – Average
% Recovery 2 (Recovery 2 / Spike) × (100)
Average % Recovery (% Recovery 1 + % Recovery 2) / 2
% Recovery Range Max. % Recovery - Min. % Recovery
Result Standard Deviation When applicable, report the Std. Dev. of multiple measurements
for each Result
Relative Standard Deviation When applicable, report the Relative Std. Dev. of multiple
measurements for each Result
6.1.2.3 Measurement Repeatability targets how well measurements can be repeated and should be reported as
percent (%) relative standard deviation (Tables 2 and 4).
6.1.3 Interference Checks
6.1.3.1 List all interferences that were examined during the course of method validation. Also note any known
potential interferences.
6.1.4 Data Reporting Requirements
6.1.4.1 Table 2 along with Figure 1 illustrates the minimal data structure and analysis required to support method
validation for trace metals, trace anions, and moisture. Table 3 is used for assays.
Table 3 Data Reporting Requirements for Assays
Specification Width W = upper spec. limit – lower spec. limit
If no upper spec. limit is stated for an assay of an ultrapure product,
use 100%.
Pooled Standard Deviation


N
i
i
N
i
ii
pp
n
sn
ss
1
1
2
2
1
1
where N1 groups of current or historical n
i
2 assays taken on the i
th
sample have their standard deviations pooled and
2
i
s is the standard
deviation of the data in the i
th
group squared.
Degrees of Freedom

N
i
i
ndf
1
1
where degrees of freedom 4
SEMI C1-0705 © SEMI 1978, 2005 9
90% Upper Confidence
Limit
n
s
t
p
df 10.0,
UCL%90
where n is the total number of assay measurements taken on the
sample in question and t is a t-statistic with the associated degrees of
freedom and 10% of the distribution to its right
6.1.4.2 In cases for trace metals, trace anions, and moisture where more samples are measured, statistical quantities
analogous to those in Table 2 should be constructed. For methods where automatic consecutive measurements can
be obtained from the instrument, Results A, B, C, and D should be the mean of five or more instrumental
measurements.
6.1.5 Summary of Criteria for Success — The success of the criteria for each figure of merit depends on the
specification, the matrix of the analyte, and levels of detection required. For trace metals, trace anions and moisture,
method success criteria are found in Table 4. For assays the 90% upper confidence limit can not exceed 30% of the
specification’s width.
Table 4 Method Success Criteria for Trace Metals, Trace Anions and Moisture
Figure of Merit Criteria for Successful Method
Accuracy
Spiked Recovery Study
75-125% Spiked Recovery for each spiked sample.
Method Precision
Spiked Recovery Study
% Recovery Range less than or equal to 35%.
Measurement Precision Maximum RSD = 20% of the concentration of each spiked
sample where:
100x
Sample Spiked of Conc.
ResultStd.Dev.
RSD
Method Detection Limit As per SEMI C10: Guide for Determination of Method
Detection Limits; Method Detection Limits cannot exceed the
specification.
Interference Checks
If interferences were examined or potential interferences
exist, list them.
6.1.6 Applicability to Existing Specifications — The current implementation of Method Validation only applies to
new or revised specifications. Any prior method validated by SEMI to support a given specification still remains
applicable to that specification.
6.1.7 Example: Trace Metals, Trace Anions and Moisture — Suppose that repeat measurements from four samples;
A, B, C and D were available as follows:
Sample A: 0.19, 0.21, 0.25, 0.15, 0.23
Sample B: 0.31, 0.21, 0.17, 0.22, 0.26
Spiked Sample C: 0.83, 0.62, 0.76, 0.79, 0.80
Spiked Sample D: 0.77, 0.87, 0.69, 0.83, 0.84
NOTE 2: Table 5 illustrates the calculations required as per Table 2.