Human Urine

This Certified Reference Material (CRM) is intended for use in the quality assurance of the analysis of arsenic species and other selected trace elements in urine. One unit of NIES CRM No.18 Human Urine consists of two bottles, each bottle containing freeze-dried urine corresponding to approximately 10 ml. It was produced and is distributed by The National Institute for Environmental Studies (NIES), Ibaraki, Japan.

The starting material for this CRM was a composite stock of urine collected from non-occupationally-exposed Japanese males. The urine stock was filtered through membrane filters (5 μm and 0.45 μm).

Portions (10.00±0.05 g) of the filtered urine were dispensed into 950 glass bottles. The urine was then freeze-dried. Each bottle was sealed with a Teflon-lined silicone cap with aluminum closures.

The homogeneity of this CRM was assessed by measuring the concentration of Na, Mg, P, K, Ca, Zn and As by ICP atomic emission spectrometry and ICP mass spectrometry, in four 1 ml-subsamples from each of 6 randomly selected bottles after pressurized HNO3 digestion. No significant between-bottle variation was detected for these elements.

Certified Values were determined for the concentrations of total arsenic, dimethylarsenic acid, arsenobetaine, selenium and zinc, based on the collaborative inter-laboratory analysis. Certified Values are listed in Table 1. Means of the acceptable mean values from the collaborating laboratories were assigned as Certified Values with twice the standard deviation of the mean representing the uncertainty ranges. The Certified Values are valid only for freshly reconstituted material.

Reference Values were given for the concentrations of lead and copper, based on IDMS determination in a single laboratory (NIES), and they are listed in Table 2. The Reference Values are valid only for freshly reconstituted material.

Table 1, Certified Values

Constituent	Unit	Content*1	Method*2
Total arsenic	mg/L	0.137±0.011	a,b,c,d,e,f
Arsenobetaine	mg/L as As	0.069±0.012	g,h
Dimethylarsinic acid	mg/L as As	0.036±0.009	g,i
Total selenium	mg/L	0.059±0.005	d,e,f,j
Total zinc	mg/L	0.62±0.05	f,k,l

Content*1

The freeze-dried urine powder to be reconstituted with 9.57 g of purified water. Specific gravity of the reconstituted urine is 1.015 (23℃).

Method*2

a:	Inductively coupled plasma mass spectrometry (ICP-MS)
b:	ICP high resolution mass spectrometry (ICP-HRMS)
c:	Microwave induced nitrogen plasma mass spectrometry (MIP-MS)
d:	Electrothermal atomic absorption spectrometry (ETAAS)
e:	Hydride generation AAS (HGAAS)
f:	Instrumental neutron activation analysis (INAA)
g:	High performance liquid chlomatography-ICP-MS detection (HPLC-ICP-MS)
h:	HPLC-MIP-MS
i:	HPLC-HG-ICP-MS
j:	Fluorimetry
k:	ICP atomic emission spectrometry (ICP-AES)
l:	Isotope dilution ICP-MS (ID-ICP-MS)

Table 2, Reference Values

Constituent	Unit	Content*1
Total copper	mg/L	0.010
Total lead	mg/L	0.0011

Content*1

The freeze-dried urine powder to be reconstituted with 9.57 g of purified water. Specific gravity of the reconstituted urine is 1.015 (23℃).

Add 9.57 g of purified water to each bottle. Gently swirl the bottle to completely dissolve the freeze-dried material. Do not shake vigorously: it will result in foaming.

This CRM is not sterilized. Use appropriate procedures for health protection when handing.

Unreconstituted NIES CRM No.18 Human Urine is assumed to be stable under the appropriate storage conditions specified above. NIES will monitor the stability of this CRM and if any signs of instability are detected, users will be notified.

Note that the Certified and Reference Values are valid only for freshly reconstituted material. However, NIES assumes, but does not guarantee, that a reconstituted sample is stable for up to 1 month when it is stored at 4℃ in the dark.