In 1993, the Council of Geoscience (CGS) was established in South Africa and mandated to compile geosciences data and place it in the public domain in order to improve natural resource management. Acting as a repository for all African countries, it was determined that they would enable informed and scientifically based decisions to be made about the use of the earth’s resources.
As an analytical services provider, CGS examines anion concentrations in water as well as leachable anion concentrations in rock and soil samples. Often they encounter complex samples containing both high and low concentrations that complicate the analytical process. Discrete photometry analysis techniques were considered a reasonable solution. Because the tests are performed targeting a particular analyte such as nitrate (NO3) using specific reagents, all other interfering compounds will be ignored. In other words, each test will only measure for a specific known analyte.
Chloride and Sulfate Analysis
Some of their environmental or mine water samples contain both high concentrations of chloride (Cl) and sulfate (SO4) in addition to very low concentrations of NO3 and phosphate (PO4). In the past, it was impossible to test these samples in the same analytical run without repeated dilutions and without continuous damage to the instrument from high acid or metal matrix concentrations.
CGS improved their anion analysis by purchasing a discrete photometric analyzer (Thermo Scientific Gallery Plus discrete analyzer). They routinely performed tests for the following two analytical series:
- Fl, CL, NO2, NO3, PO4, and SO4
- Conductivity, pH, and alkalinity
Now they have the additional capability to examine hexavalent chromium (Cr(VI)), ammonia, and cyanide. With an ongoing demand for fast, accurate analysis, their new instrument can handle high throughput with minimal maintenance. Optimization of the specific concentration range for each individual analyte is possible allowing completion of all the required tests in one analytical run. With this unit, up to 350 tests can be completed in one hour, whereas in the past, less than 50 samples were analyzed in a standard overnight run. This uncovered a new world of capabilities for better and faster environmental analyses, water quality monitoring, mine water evaluations, and geochemical and hydrological mapping applications. Read more in Faster and Better Analysis of Complex Samples in a Geochemical Laboratory (link to the case study).
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Wastewater Nitrate Analysis
In wastewater, there are multiple ways to measure NO3. The standard at the moment is the cadmium reduction (Cd-reduction) test which exposes users to a highly toxic substance when handling the Cd column and the column itself can be easily damaged with the introduction of an oily substance. A rapid, non-toxic alternative using nitrite-nitrate enzymatic reduction has U.S. EPA approval in process (353.X). This method provides highly specific measurements and a flexible detection range. Another alternative method utilizes vanadium as reductant for total oxidized nitrogen (TON). In comparison studies, there was no difference seen in the results from using Cd-reduction or the TON assay method when examining various types of wastewater.
- Case Study: Efficiency and flexibility in water analysis (downloadable PDF)
- Application Note 7139, Automated Total Oxidized Nitrogen Method Using Vanadium as Reductant with Correlation to Cadmium and Hydrazine Reductant Methods in Sea, Natural, and Waste Waters (downloadable PDF)
Also, do visit our online Environmental Community pages, a wonderful resource totally dedicated to our Food and Beverage customers and featuring the latest on-demand webinars, videos, application notes, and much more.
Are complex samples complicating your wastewater analysis and is automated photometric determination of interest to your laboratory? If so, we would like to hear about your experience.