Selenium in urine

Figure 5. Wavelength profile data for the determination of selenium in urine (A) (left) as observed, (B) (right) background-corrected profiles,...

Aggarwal SK, Kinter M, Herold DA. 1992. Determination of selenium in urine by isotope dilution gas chromatography-mass spectrometry using 4-nitro-o-phenylenediamine, 3,5-dibromo-o-phenylenediamine, and 4-trifluoromethyl-o-phenylenediamine as derivatizing reagents. Anal Biochem 202(2) 367-374. 

Schierling, P., Oefele, Ch. and Schaller, K.H. (1982). Determination of arsenic and selenium in urine samples with the hydride AAS technique, ArztI. Lab., 21-27. 

The direct GF-AAS-determination of selenium in urine is still under debate (Hoenig, 1991). Acid digestion is therefore recommended prior to hydride generation AAS or fluoromet-ric determinations. 

The determination of selenium in urine, at least at first glance, appeared to be somewhat less problematic, as the atomic absorption was separated in time from the molecular structures, as is depicted in Figure 8.30 (a). However, the molecular structures did not all appear at the same point in time, indicating that more than one gaseous molecule might be involved. 

Gammelgaard, B., and Joens, O. (1999). Determination of selenium in urine by inductively coupled plasma mass spectrometry Interferences and optimization./A a/./If. Spectrom. 14(5), 867. 

Nam, S.-H., Masamba,W. R. L., and Montaser, A. (1994). Helium inductively coupled plasma-mass spectrometry Studies of matrix effects and the determination of arsenic and selenium in urine. Spectrochim.Acta, Part B 49(12/714), 1325. 

Hasunuma, R., T. Ogawa, Y. Fujise, and Y. Kawanashi. 1993. Analysis of selenium metabolites in urine samples of minke whales (Balaenoptera acutorostrata) using ion exchange chromatography. Comp. Biochem. Physiol. 104C 87-89. 

Lester et al. [24] have described a robotic system for the analysis of arsenic and selenium in human urine samples which demonstrates how robotics has been used to integrate sample preparations and instrument analysis of a biological matrix for trace elements. The robot is used to control the ashing, digestion, sample injection and operation of a hydride system and atomic absorption instrument, including the instrument calibration. The system, which routinely analyses both As and Se at ppb levels, is estimated to require only... 

An analytical technique has been developed for the determination of selenium species in urine to identify selenium containing compounds by combining electrospray MS/MS with ICP-MS after preparative solid phase extraction and final reversed phase HPLC separation.69... 

In environmental and clinical samples, IPC-ICP-MS may be used for selenium speciation [40-42]. Selenite, selenate, and trimethylselenomium were separated by Yang and Jiang [40], using a mobile phase containing 3% methanol and 5 mM PIC-A ion-pairing reagent. An ultrasonic nebulizer was used for improved sample transport, yielding detection limits of 22-74 pg Se for the three species, respectively. Selenite was found to be the most abundant species in urine and unidentified peaks were attributed to selenoaminoacids. 

B. Gammelgaard, L. Bendahl, U. Sidenius, O. Jons, Selenium speciation in urine by ion-pairing chromatography with perfluorinated carboxylic acids and ICP-MS detection, J. Anal. Atom. Spectrom., 17 (2002), 570-575. 

K. L. Yang, S. J. Jiang, Determination of selenium-compounds in urine samples by liquid chromatography-inductively coupled plasma-mass spectrometry with an ultrasonic nebuliser, Anal. Chim. Acta, 307 (1995), 109-115. 

J. Marchante-Gayon, I. Feldmann, C. Thomas, N. Jakubowski, Speciation of selenium in human urine by HPLC-ICP-MS with a collision and reaction cell, J. Anal. Atom. Spectrom., 16 (2001), 457-463. 

Selenium forms a volatile derivative, piazselenol, which can be subjected to GC analysis (Scheme 5.39). Young and Christian [612] treated selenium with 2,3-diaminonaph-thalene at pH 2.0 and extracted the resulting piazselenol into -hexane. With the use of an ECD, down to 5 10-I° g of selenium could be detected. The procedure, applied to the analysis of selenium in human blood, urine and river water, led to results equivalent to those obtained by neutron activation analysis. Similarly, Nakashima and Toei [613] performed the reaction of selenium (as selenious acid) with 4-chloro-o-phenylenediamine at pH 1 and extracted the derivative into toluene. They reported a detection limit of 0.04 jug. Shimoishi [614] analysed the content of selenium in metallic tellurium by this method. The sample was dissolved in aqua regia, followed by reaction with 4-nitro-o-phenylenediamine and extraction into toluene. Down to 10 ng of selenium could be determined using only a few milligrams of sample. Common ions did not interfere even when present in a large excess. Selenium in marine water was determined after the same derivatization step [615],... 

Hydride generation atomic absorption spectrometry and electrothermal atomisation atomic absorption spectrometry may also be employed for the measurement of selenium in biological samples. A comparison was made (MacPherson et al., 1988) of these methods with the fluorimetric method described here and all three methods were found to give accurate, reproducible results when samples of plasma and urine with certified selenium contents were analysed. 

Pan, R, Tyson, J.R, and Uden, P.C. Simultaneous speciation of arsenic and selenium in human urine by high-performance liquid chromatography inductively coupled plasma mass spectrometry. J. Anal. Atom. Spectrom. 2007, 22, 931-937. 

OSHA PEL TWA 0.01 mg(As)/m3 Cancer Hazard TWA 0.2 mg(Se)/m3 ACGIH TLV TWA 0.01 mg/m Confirmed Human Carcinogen BEL 35 n (As)/L inorganic arsenic and methylated metabolites in urine TWA 0.2 mg(Se)/m3 DFG MAK DFG TRK 0.2 mg/m calculated as arsenic in that portion of dust that can possibly be inhaled 0.1 mg(Se)/m3 NIOSH REL CL 2 ng(As)/m3 SAFETY PROFILE Confirmed human carcinogen. When heated to decomposition it emits fumes of As and Se. Incompatible with oxidizing materials. When heated to decomposition it emits highly toxic fumes of Se and arsenic. See ARSENIC COMPOUNDS and SELENIUM COMPOUNDS. 

HPLC/ICPMS is a powerful analytical technique and is now the most commonly used method for determining selenium urinary metabolites [215]. Over the last 10 years, most of the reports of selenium species in urine have used HPLC/ICPMS, sometimes together with molecular MS techniques. In this period, a total of 16 selenium species (see below) have been reported in urine, most of them novel human metabolites and some of them completely new compounds. 

These 16 compounds identified in urine mostly by HPLC/ICPMS include the compound 102 plus 15 other selenium metabolites (Table 18). For many of these, the assignments have been made on very little evidence and require confirmation before the compounds can be accepted as typical urine metabolites [216, 217]. Some, such as methylselenol, have already been retracted by their discoverers. Selenosugar 95 is now firmly established as a major urinary metabolite when selenium is administered, and it is also a constituent of natural urine. There have also been reports of selenosugar 94 and selenosugar 96 as minor constituents. Selenite appears to be a common minor metabolite in normal urine. 

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