Total Organic Carbon (TOC) Determination
Total organic carbon measures the amount of organic contamination in a sample, which is critical to human safety and success. Organic contamination reduces ion exchange capacity and causes harmful biological growth, making treated water unsafe for us. Total organic carbon concentration in liquid and solid samples is one of the most important screening parameters in water and environmental analysis. Whether it is water quality assessment, waste treatment or cleaning validation, there is always a need to assess organic contamination.
BOC Sciences has accumulated many years of experience in wet chemical analysis. Our chemists are able to provide fast and simple determination of total organic carbon in liquids and solids. Whether you want to determine TOC in ultrapure water, drinking water, surface water, seawater, wastewater, soil eluate, soils, sediments or solid waste, we always have the perfect solution for your application.
Application of Our TOC Determination Services
- Water Treatment
Measuring the TOC of treated water is critical, as it helps ensure that the processes used to remove contamination from these facilities are working properly.
- Wastewater
Analyzing the TOC in incoming wastewater helps to plan and streamline the wastewater treatment process. In addition, TOC can be used to determine biological oxygen demand (BOD) and chemical oxygen demand (COD).
- Environmental Solids Matrix
TOC analysis plays a critical role in environmental analysis. TOC is not limited to water analysis, but can also be tested for solid samples such as soil, sludge or mud.
Our TOC Determination Process
Total organic carbon (TOC) - all covalently bonded carbon atoms in the organic molecule
Total Inorganic Carbon (TIC) - carbonates, bicarbonates and dissolved carbon dioxide
The TOC measurement is actually calculated by subtracting the TIC value from the TC of the sample. At BOC Sciences, we use wet chemistry to acidify the sample to produce carbon dioxide and measure it as TIC, and then oxidize and measure the remaining non-purifiable organic carbon (NPOC). The whole process is divided into three stages:
- Acidification
- Oxidation
- Detection and quantification
Total Organic Carbon Measurement
- Sample Preparation
Prior to processing, we first homogenize the sample, i.e., we mix or break the sample so that it is representative of the whole sample when it is measured. Depending on the sample, we choose different homogenization techniques.
- Dissolution of TIC
In order to measure the organic carbon content of a sample, the inorganic sources of carbon in the form of carbonates and bicarbonates salts and minerals must be removed from the sample. This is usually done by treating the sample with non-oxidative acids such as H2SO4 and HCl.
- Quantitative Analysis of TOC
- Pretreatment
After pre-treating the sample with inorganic acid to dissolve any inorganic material in the sample, a known amount of potassium dichromate (K2Cr2O7) in concentrated sulfuric acid is added to the sample following the Walkey-Black procedure.
- Quantification of TOC
After the samples are treated and all organic carbon is digested, we employ a titration method to oxidize the excess dichromate in the samples. The amount of TOC in the sample can be determined by comparing the excess that is titrated to the amount that was originally added to the original solution. Finally, we can do stoichiometric calculations to determine the amount of dichromate that oxidizes the organic carbon in the sample, thereby calculating the TOC.
We offer a variety of quantification methods including manual, potentiometric , and titration, depending on the customer's choice :
- Manual titration
In manual titration, we use some common indicators such as ferrous ammonium sulfate. The titrant is added until equilibrium is reached. The sign that equilibrium has been reached is the color change catalyzed by the indicator.
- Potentiometric titration
The conductance of a sample can be measured by potentiometric titration by inserting a platinum electrode into the sample. When the sample reaches the endpoint, the conductance will be essentially zero.
- Capture of CO2
In addition to the titration method, we offer another effective strategy for quantification. Oxidized organic carbon can be evolved to CO2, CO2 can therefore be captured on an absorbent material such as ascarite or other abrasive absorbents, whose mass change as absorbed CO2 can be measured, or the absorbed CO2 can be desorbed and quantified.