Low CRM recovery issue

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Anathan Johnson
Anathan Johnson's picture
Low CRM recovery issue

I've been analysing Cd in blood and urine sample by diluting sample with the mixture of 0.05% Triton-X, 0.5% nitric acid (distilled 2 times), and 2% methanol. The dilution factor for blood and urine is 40 and 10 respectively.I used blood and urine CRM, bought from UTAK, to control the accurate of the analysis. I've lately encountered a problem with recovery of the CRM. The recovery vary between 78 - 80% now while it used to be around 90%.The CRM was stored between 2 - 8 Celsius degree.