This Standard Reference Material (SRM) is intended for use as a primary calibration standard for the quantitative determination of arsenobetaine (AB). A unit of SRM 3033 consists of two 5 mL sealed borosilicate glass amber ampoules of water solution prepared gravimetrically to contain a known mass fraction of AB. Certified Mass Fraction Value of AB (as As): 19.06 mg/kg ± 0.27 mg/kg k = 2.18
A NIST certified value  is a value for which NIST has the highest confidence in its accuracy in that all known or suspected sources of bias have been investigated or taken into account . The AB value is calculated by subtracting the mass fraction of arsenic impurities from the mass fraction of total arsenic as detailed below. The expanded uncertainty, U, is calculated as U = kuc, where uc represents, at the level of one standard deviation, the combined effects of the between-method and the within-method components of uncertainty. The coverage factor, k, corresponds to an approximately 95 % level of confidence. The certified value is metrologically traceable to the derived SI unit for mass fraction, expressed as milligrams per kilogram. 美国NIST临床检验材料
The NIST measurements of total arsenic were made using inductively coupled plasma optical emission spectrometry (ICP-OES) and instrumental neutron activation analysis (INAA). These measurements were combined as the weighted means of the individual sets of measurements, estimated using a Gaussian random effects model  and the DerSimonian-Laird procedure [4-5]. The associated measurement uncertainty was evaluated by the application of the parametric statistical bootstrap, consistent with the ISO/JCGM Guide and its Supplement 1 [6-8]. The NIST measurements of arsenic impurities were made using ion chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS) and liquid chromatography inductively coupled plasma mass spectrometry (LC-ICP-MS).
When possible, these measurements were combined using the same approach as used for the total arsenic measurements. When arsenic impurity measurement values were observed to be below detection limits, the nonparametric Kaplan-Meier method for computing summary statistics of censored data  was utilized. 砷代甜菜碱标准溶液SRM 3033
本标准参考物质（SRM）旨在用作砷代苯胺（AB）定量测定的主要校准标准。SRM 3033的一个单元由两个5 mL密封的硼硅酸盐玻璃琥珀色安瓿水溶液组成，该安瓿通过重量法制备，含有已知质量分数的AB。AB的认证质量分数值（as）：19.06 mg/kg±0.27 mg/kg k=2.18