120 / 620
Linearity
To determine linearity, chloride calibration standards were injected in triplicate over
seven concentration levels covering the range of 50–1000 mg/L. To establish stability of the
analytical curve, three independent experiments were conducted using independently prepared
standards. The calibration results show that the detection is linear over the concentration range,
with a coefficient of determination >0.9999. Calibration errors at each level of the calibration
curve were >5%. Check standards at the lowest point and midpoint of the analytical range were
checked daily throughout the batch run. The system was recalibrated when the percent error of
the check standards was >5%.
Error, % = calculated concentration – actual concentration actual concentration × 100
Accuracy
Accuracy was determined by fortifying the placebo samples (prior to sample preparation)
at 50 and 100% of the typical level of Chloride found in a powdered infant formula. These
recovery experiments were performed over multiple days on two different instruments. In
addition, NIST SRM 1849a was analyzed during the course of this validation. Table 2 contains
recovery results for Chloride on the five placebo samples respectively.
The percent chloride recovered ranged from a low of 92.2% to a high of 107%. The
percent relative standard deviations (RSD) ranged from a low of 0.44% to a high of 3.99%. The
overall mean recovery is 99.7% with a RSD of 4.1%. With the exception of two recovery value
at 92.2%, and 107%, all data meets the criteria specified in the SMPR (95-105% recovery).
Results on NIST SRM 1849a can be found in Table 3 & 4. The mean value of
7707mg/Kg (n = 32), falls within the certified range of 5950-8011mg/Kg. The RSD obtained
from all results is 2.05%. This is within the limits set in the SMPR.
Precision
Repeatability was evaluated on all 12 fortified AOAC SLV test material matrices
including the NIST SRM 1849a using multiple instruments. Samples and standards were
prepared freshly every day over six days and analyzed in triplicate to calculate the intermediate
and overall reproducibility. Precision data for all samples can be found in Tables 5.
Chloride concentration ranged from 4031 to 25673 mg/Kg. Overall precision was < 6% for all
samples. Percent relative standard deviations ranged from a low of 1.80% to a high of 5.58 %.
Reproducibility
Reproducibility was determined in the precision experiments conducted over multiple days and
involving different lots of reagents made fresh each analysis day. In addition, two instruments
were used during this validation study.
Chlor-03 SLV
FOR ERP USE ONLY
DO NOT DISTRIBUTE