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Accuracy
- a. Analyze the NIST SRM 1849a over six days using multiple instruments and
compare results to the reported NIST-certified value.
b. Determine spike recovery from unfortified products (i.e., placebos). Spike each selected
sample at 50 and 100% of the amounts found in the unfortified products and analyze in duplicate
on each of three days. Use the overall mean of the unspiked unfortified samples for calculating
recoveries.
Reference sample
- NIST Standard Reference Material 1849a Infant/Adult Nutritional Formula,
or equivalent. SRM 1849a is a milk-based, hybrid infant/adult nutritional powder. One unit of
SRM 1849a contains 10 packets each containing approximately 10 g of material. The reference
value of NIST SRM 1849a for chlorine is 7010 mg/kg.
Sample calculation (Conversion of mg/L to mg/Kg):
For the conversion of mg/L concentration (obtained from Chromatogram) to mg of
Chloride/Kg of Sample, mg/L concentration obtained was divided by 73.5 and multiplied by
1000 to get mg/Kg.
Explanation of factor 73.5:
1.47g of sample dissolved in 20 mL water is equivalent to 73.5g in 1L and the Chloride
concentration obtained from chromatogram is in x mg/L, thus x mg of Chloride in 73.5g of
sample. For all the samples this factor was used with assumption that RTF samples have similar
concentration as that of reconstituted powders.
Validation Results
Separation and Detection
Ultra centrifugal filter devices were used to filter the sample and remove the fats and
proteins from the sample. Following the filtration, Chloride was separated from some common
anions using a Dionex IonPac AS15 column and detected by suppressed conductivity. Figure 1
shows the Chromatogram of a 2.5µL injection of the SRM 1849a sample. The retention time for
Chloride is 15.45 min.
Specificity
Specificity was determined by analyzing five placebo samples supplied with the SPIFAN
test material kit. All placebo analyses show low concentrations of Chloride compared to fortified
samples except the Infant elemental formula which showed the same concentration of Chloride
in the Placebo and the fortified product.
Chlor-03 SLV
FOR ERP USE ONLY
DO NOT DISTRIBUTE