scholarly journals Biomonitoring of total mercury in urine: method validation and sample stability

Biomonitoring ◽  
2018 ◽  
Vol 5 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Sam De Craemer ◽  
Willy Baeyens ◽  
Martine Leermakers
Keyword(s):  
Total Mercury ◽  
Matrix Effects ◽  
Detection Limits ◽  
Storage Conditions ◽  
Dental Amalgam ◽  
Measured Concentration ◽  
Measurement Variability ◽  
Sample Stability ◽  
Lower Detection ◽  
Mercury In Urine

Abstract Biomonitoring of mercury (Hg) in urine can provide valuable information on environmental exposure to inorganic and elemental Hg. However, this requires a method with a sufficiently low detection limit, and in addition, sample stability during storage needs to be addressed. We adapted a method described in the literature to obtain lower detection limits by decreasing dilution and optimizing the amount of reagents used, while also investigating matrix effects, within- and between measurement variability, and accuracy. We tested Hg stability in urine under different storage conditions and using different stabilizers suggested in the literature. A five-fold dilution of the urine sample with addition of optimized amounts of BrCl gave the best results regarding detection limits, which could be further improved by using a gold amalgamation preconcentration step (Autrap). Application of the method in a biomonitoring study allowed detection of Hg in 95% of the samples without Au trap, and resulted in mercury levels that were comparable to similar populations and influenced by expected variables (age, dental amalgam). Regardless of the sample storage conditions of urine samples in polypropylene bottles, Hg decreased during the first days of storage, then slowly regained or exceeded the originally measured concentration. From these experiments, it appears that storage of the samples frozen at -20°C for several weeks prior to analysis, without the addition of additives is the preferred method.

Modified determination of total and inorganic mercury in urine by cold vapor atomic absorption sectrometry.

1976 ◽  
Vol 22 (10) ◽  
pp. 1719-1723 ◽  
Author(s):  
D Littlejohn ◽  
G S Fell ◽  
J M Ottaway
Keyword(s):  
Total Mercury ◽  
Chemical Reduction ◽  
Inorganic Mercury ◽  
Elemental Mercury ◽  
Mercury Vapor ◽  
Storage Conditions ◽  
Single Beam ◽  
A Value ◽  
Cold Vapor Atomic Absorption ◽  
Mercury In Urine

Abstract In this procedure a single-beam spectrophotometer is used without background correction. By the method of Magos [Analyst (London) 96, 847 (1971)] mercury in undigested urine is complexed to L-cysteine in acid solution. At high pH and in the presence of stannous ions, mercury ions are reduced to elemental mercury. The mercury vapor is partitioned above the reagent solution in a specially designed chemical reduction apparatus similar in principle to that used by Kubasik et al. [Clin. Chem. 18, 1326 (1972)]. The vapor is then flushed by air through an "absorption" cell, where the absorption of the mercury line at 253.7 nm is measured. The value obtained for inorganic mercury subtracted from that for total mercury gives a value for organic mercury. CV's for the inorganic mercury procedure at 40 and 5 mug/liter concentrations were 3.1% and 7.5%, respectively. The detection limit is 0.82 mug/liter. The CV for the total-mercury procedure (20 mug/liter) was 2.6%. Mean analytical recoveries of organic and inorganic mercury were 96.5% and 101%, respectively. We investigated storage conditions for urine and compared results by the present technique with those by activation analysis. Our method is a convenient way to screen individuals who have been exposed to a mercury hazard.

In-depth Analysis of the Impurities in GaN

1996 ◽  
Vol 1 ◽  
Author(s):  
A. P. Kovarsky ◽  
V. S. Strykanov
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Dynamic Range ◽  
Detection Limits ◽  
Background Level ◽  
Epitaxial Films ◽  
Depth Analysis ◽  
Lower Detection ◽  
Minimum Detection Level ◽  
Ion Yields ◽  
Secondary Ion

GaN epitaxial films were analyzed by Secondary Ion Mass Spectrometry (SIMS). Standard implanted samples were used to determine the appropriate analytical conditions for analysis of impurities. The dose and energy of implantation for selected elements (Mg, Al, Si, Zn, Cd, H, C and O) were chosen so the maximum impurity concentration was not more than 1020 atoms/cm3. The optimum analysis conditions were ascertained from the standards for each element, and the detection limits were deduced from the background levels of the implantation profiles. We demonstate that lower detection limits of 1015 atoms/cm3 with a dynamic range 103 − 105 are possible. Zn and Cd have low ion yields, so the minimum detection level for these elements is the background level of the detector. The detection limits of the other elements are determined by the contamination of an initial GaN matrix.

Detection Limits of AC-Coupled Inverse Raman Spectroscopy

1980 ◽  
Vol 34 (2) ◽  
pp. 144-146 ◽  
Author(s):  
Jeanne P. Haushalter ◽  
G. Patrick Ritz ◽  
David J. Wallan ◽  
Kathy Dien ◽  
Michael D. Morris
Keyword(s):  
Raman Spectroscopy ◽  
Detection Limits ◽  
Nitrate Ion ◽  
Lower Detection

ac-coupled inverse Raman spectroscopy is shown to yield detection limits comparable to those obtained by spontaneous Raman spectroscopy. For an aqueous nitrate ion, inverse Raman limits are about 2.5 times higher than those reported for conventional measurements with similar laser powers and measurement times. Proposed improvements in instrumentation may lower detection limits another 10 times with no change in laser powers or measurement times.

scholarly journals Determination of shelf life and activation energy for tumor necrosis factor-alpha in cerebrospinal fluid samples

1996 ◽  
Vol 42 (5) ◽  
pp. 670-674 ◽  
Author(s):  
M Cruz Ruiz ◽  
F Recio Quijano ◽  
L F López Cortés ◽  
M Hebles Duvison ◽  
R Vázquez Rubio
Keyword(s):  
Cerebrospinal Fluid ◽  
Shelf Life ◽  
Storage Conditions ◽  
Tnf Alpha ◽  
Necrosis Factor Alpha ◽  
Accelerated Stability ◽  
Sample Stability ◽  
Factor Alpha ◽  
Stability Time ◽  
Necrosis Factor

Abstract The cytokine rumor necrosis factor-alpha (TNF-alpha) plays a prominent role in the inflammatory response and has been quantified in several kinds of body fluids. A safe method for keeping samples under the best storage conditions for later studies is clearly needed. We estimated TNF-alpha shelf life by using an accelerated stability testing protocol based on the Arrhenius equation. We investigated two kinds of samples: cerebrospinal fluid (CSF) normal pool (from patients without meningitis) and CSF pathological pool (from patients with pyogenic meningitis). Results of the stress protocol indicated that storing both normal and pathological CSF samples at -70 degrees C would maintain sample stability-i.e., retain at least 90% of the original TNF-alpha content-for approximately 5 years. At -20 degrees C and 4 degrees C, the projected stability time at which the same recovery would be obtained was 190 and 90 days, respectively.

scholarly journals Leachate seepage from landfill: a source of groundwater mercury contamination in South Africa

Water SA ◽  
2019 ◽  
Vol 45 (2 April) ◽  
Author(s):  
V Nevondo ◽  
T Malehase ◽  
AP Daso ◽  
OJ Okonkwo
Keyword(s):  
Solid Waste ◽  
Total Mercury ◽  
Atomic Absorption Spectrophotometry ◽  
Dental Amalgam ◽  
Consumer Products ◽  
Limpopo Province ◽  
Mercury Contamination ◽  
Fluorescent Light ◽  
Groundwater Samples ◽  
Landfill Sites

Mercury has been used for many centuries in the production of consumer products such as thermometers, electrical switches, fluorescent light bulbs, batteries, biocides and pesticides, cosmetics and dental amalgam filling, among others. After use, these mercury-containing consumer products form part of the municipal solid waste (MSW). As a result of an unseparated solid waste collection system, mercury-containing wastes tend to end up in landfills where mercury and other pollutants can leach out of products into landfill leachates. The present study, therefore, was conducted with the aim of determining the total mercury (THg) concentrations in leachate and sediment samples collected from 4 selected landfill sites (3 sites in Gauteng Province – Soshanguve, Hatherly, Onderstepoort and 1 site in Limpopo Province – Thohoyandou). Groundwater samples were collected from the monitoring boreholes at the four selected landfill sites in the summer and winter periods. An acid digestion method was employed for sample preparation and this was followed by analysis using cold vapour atomic absorption spectrophotometry (CVAAS). The concentration range of total mercury in the Thohoyandou leachate, sediment and groundwater samples was 0.12–2.07 μg/L, 0.03–0.48 μg/g and 0.09–2.12 μg/L, respectively. In Soshanguve, the concentration range of total mercury in leachate, sediment and groundwater samples was 0.10–1.20 μg/L, 0.04–0.62 μg/g and nd –1.66 μg/L respectively, Hatherly concentration range was 0.42–1.31 μg/L and 0.06–0.78 μg/g in leachate and sediment, respectively and in Onderstepoort the concentration range was 0.12–2.41 μg/L, 0.03–0.50 μg/g and 0.05–2.44 μg/L, in leachate, sediment and groundwater, respectively. The findings from this study suggest that there is a likelihood of groundwater pollution by mercury from landfill leachate seepage, particularly for landfills that are not lined with a geomembrane. 

The Design and Some Emission Characteristics of an Economical dc Arc Plasmajet Excitation Source for Solution Analysis

1970 ◽  
Vol 24 (2) ◽  
pp. 197-205 ◽  
Author(s):  
S. E. Valente ◽  
W. G. Schrenk
Keyword(s):  
Gas Flow ◽  
Matrix Effects ◽  
Detection Limits ◽  
Inert Gas ◽  
Excitation Source ◽  
Analytical Response ◽  
Gas Consumption ◽  
Moderate Sensitivity ◽  
Dc Arc ◽  
Better Than

The de-arc plasmajet has been applied to a large number of emission problems since its introduction in 1959 because it offers reduced matrix effects, stability, and moderate sensitivity. However, its use has been significantly limited due to operating costs associated with its high inert gas flow rates. A new excitation source, based on the principle of the plasma jet, has been developed that can operate at a much lower cost. The source operates from a conventional dc-arc power supply and uses commercially available electrodes. Total inert gas consumption is less than 2.5 liters/min. Stability of the source is better than 1% and reproducibility is approximately 4%. An excitation temperature of 5800 K was calculated from the relative intensities of several vanadium lines. The source can be operated continuously for several hours at a time. Design and some characteristics of the arc are presented. Detection limits are given for 12 elements. Six of the elements (Ca, Cr, Fe, Li, Ni, and Y) have detection limits below 10 ng/ml. Analytical response for the elements studied is linear over a wide concentration range. A calibration curve for Ca is presented which is linear over more than four orders of magnitude.

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