SRM 2669 - Arsenic Species in Frozen Human Urine

SRM 2669 is intended for method validation and quality assurance in the National Health and Nutrition Examination Survey (NHANES) and other similar assessment of human exposure to arsenic. In biennial NHANES conducted by the CDC, the exposure of U.S. population to arsenic is assessed by measuring arsenic species in urine. A toxic element and a known carcinogen, arsenic is present in the environment in many chemical forms or species. The toxicity of arsenic species varies widely. An accurate assessment of arsenic exposure must be based on the quantity as well as the speciation of arsenic.

With certified values for all seven species at key levels, SRM 2669 is the first reference material to contain primary arsenic species of dietary exposure and their metabolites in one material, which makes it most suited as a quality assurance material for arsenic exposure measurements. The reference material is the first to contain As(III) and As(V) species, the most toxic and most important for assessment of arsenic poisoning yet most difficult to stabilize. Because the matrix of the reference material is natural rather than processed (e.g., freeze dried), the product is better suited for the intended purpose of validating the accuracy of methods for urine analysis.

keywords: biological material , body fluid , urine , arsenic speciation , speciation analysis

Storage:
The SRM should be stored at –80 °C in the original unopened package. The certification does not apply to contents of previously opened pouches as the stability of  all species has not been investigated under such conditions.

Use:
SRM 2669 should be thawed at room temperature. The material should be used within 4 h after being thawed. Unused or remaining material should be discarded after the specified time. Once the pouches are cut open, each vial of the SRM should be homogenized by gently inverting the vial several times before a test portion is removed. To determine arsenic species in the SRM, particulates in the subsample should be removed. Recommended procedures for removal of particulates are: (1) extracting supernatant after centrifuging at 2 × 106 gn for 5 min, or (2) filtration using a 0.45 μm syringe filter. To determine the total arsenic in SRM 2669, the entire subsample, including particulates, should be used.