Determination of Cobalt in Urine by FI-ICP-AES with Online Preconcentration

Abstract

A method for the preconcentration and determination of cobalt in human urine samples was developed. The online preconcentration and determination were attained using inductively coupled plasma atomic emission spectromety (ICP-AES) coupled to a flow injection (FI) method. Cobalt was retained on an Amberlite XAD-7 resin as cobalt-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex at pH 9.5. Cobalt was removed from the microcolumn with perchloric acid. A sensitivity enhancement factor of 90 was obtained with respect to cobalt determination by ICP-AES without preconcentration. The value of detection limit for the preconcentration method proposed was 25 ng/L. The precision for 10 replicate determinations at the 5 mg/L (mean +/- SD, 5.1 +/- 0.14) Co level was 2.7% relative standard deviation, calculated from the peak heights obtained. The calibration graph preconcentration method for cobalt was linear with a correlation coefficient of 0.9994 from approximately 0.25 mg/L up to at least 100 mg/L. The method was successfully applied to the determination of cobalt in human urine samples.

Measurement of urinary cobalt as its complex with 2‐(5‐chloro‐2‐pyridylazo)‐5‐diethylaminophenol by liquid chromatography–tandem mass spectrometry for the purpose of anti‐doping control

“…28 Given the low concentration of naturally present cobalt in biological fluids, ICP-MS seems to be the method of choice as it does not require sample enrichment prior to analysis as would be the case for atomic absorption 29 or atomic emission spectroscopy. 30 Methods based on chromatography-mass spectrometry relying on derivatization of cobalt and subsequent extraction of its complex from biological matrix gained very little attention. 31,32 One of the reasons is the difficulty to select an appropriate internal standard as cobalt does not have stable isotopes apart from 59 Co. For instance, Aggarwal et al employed a stable isotope of nickel, 62 Ni, as internal standard for determination of cobalt in urine by gas chromatography-mass spectrometry upon formation of their volatile complexes with bis (trifluoroethyl)dithiocarbamate.…”

Rotational Isomerization about C−C Single Bond in a Novel ICT Probe Facilitates Naked‐Eye, Colorimetric and Ratiometric Detection of Cobalt in Aqueous Samples**

“…Consequently, considerable effort has been made to develop analytical methods for trace level detection of Co 2+ present in the samples collected from the environment. The different analytical strategies that have been adopted to detect cobalt (II) ions include AAS, [26] ICP‐AES, [27] and electrochemistry [28] . Regrettably, the aforesaid strategies require costly instruments [29] and arduous procedures and/or sample pretreatments [29] that make the process challenging for the on‐site detection of cobalt (II) ions.…”

Determination of ultra-trace cobalt in water samples by graphite furnace atomic absorption spectrometry after cloud point extraction using 2-(5-bromo-2-pyridylazo)-5-dimethylaminoaniline as the chelating agent

“…The determination of trace cobalt in natural waters and environmental samples is difficult due to its low concentrations and matrix effects. Although several methods for the determination of trace cobalt have been reported, such as graphite furnace atomic absorption spectrometry (GFAAS), [2][3][4] neutron activation analysis (NAA), 5,6 inductively coupled plasma-atomic emission spectrometry (ICP-AES), [7][8][9] and inductively coupled plasma-mass spectrometry (ICP-MS), 10,11 an analyte preconcentration and/or matrix separation step is required prior to most analytical techniques. The widely used techniques for separation and preconcentration of trace amounts of cobalt are liquidliquid extraction, 12 high performance chromatography 5 and solid-phase extraction with various adsorbents such as Amberlite XAD resins, 13,14 polymeric beads 15 and other sorbents.…”