TOC (Total Organic Carbon) is the quantity of carbon present in an organic compound. It has evolved into a key indicator of approximate amounts of organic contamination and may thus be used to predict water quality. In many circumstances, a Total Organic Carbon analyzer is utilized to check the Analyzer's lack of change in organic content continually.

What Is Total Organic Carbon (TOC) Analysis?

Total Organic Carbon Analysis is a technique for determining the quality of water. Water purity is crucial in many industries, including pharmaceutical, industrial, power generating, and water supply. Bacteria or other inorganic substances in the environment can suggest filtration, storage, or system failure.

Contamination can also cause issues such as damage to industrial systems or a decrease in product quality, threatening profitability and consumer health. Furthermore, knowing the purity of water protects users, suppliers, and the environment by allowing water to be utilized, provided, and disposed of in the safest, most cost-effective, and ecologically friendly manner possible.

The following can be measured by TOC analysis: 

      TC - Total carbon,

      IC - Inorganic carbon,

      TOC - Total organic carbon,

      POC - Purgeable organic carbon and

      NPOC - Nonpurgeable organic carbon.

TOC has evolved into a key metric for monitoring the total quantities of organic chemicals present. This is despite the lack of a direct quantitative association between total organic carbon and the overall concentration of organic compounds present, and it demonstrates the need for having an easy-to-measure, broad indicator of the approximate degree of organic contamination.

It also illustrates the allure of a parameter with a name that sounds more essential than it is! The TOC is frequently employed as an ongoing monitor of change or lack of change in organic content.

Working Principle Of TOC Analyzer

A TOC analyzer can be used to determine total organic carbon. This operates by oxidizing the organic component into a quantifiable state. When organic carbon is oxidized, carbon dioxide is produced, which may then be measured and turned into a TOC measurement. TOC analysis entails calculating this measurement and subtracting the 'inorganic carbon,' which is the concentration of dissolved carbon dioxide and carbonic salts.

Components Of TOC Analysis

TOC analysis consists of three steps: sampling, oxidation, and detection. To meet regulatory requirements, it is advised that the sample system have automatic sampling, acidification, and sparging for TOC analysis, automatic dilution capabilities, and auto-calibration using a single stock standard.

The organic carbons must be oxidized to estimate the degree of TOC. There are numerous oxidation technologies available on the market today.

Among the methods for converting TC to CO2 are:

Thermal Oxidation

The sample will be combusted in a reactor using this oxidation process. A maximum temperature of around 1,000°C is usually obtained, which does not allow for the complete oxidation of all carbon components. At these temperatures, a catalyst, such as copper oxide or platinum, must be utilized. The catalytic combustion process can normally handle TOC concentrations of up to 4,000 mg/l. To achieve higher ranges, the sample is frequently diluted with demin water.

Photochemical Oxidation (Uv-Persulfate Method)

The oxidation of TOC is done using UV light and a digesting reagent, sodium persulphate, and an NDIR detector are used to detect the CO2 generated. Because particles are difficult to oxidize entirely, this approach is best suited for determining TOC in clean water (drinking water, condensate, boiler feed water).

Wet Chemical Oxidation

The water sample is oxidized using strong chemicals as oxidants like ozone, which are slightly hazardous to health and the environment. The acids and bases produced by ozone oxidation are utilized to change the pH of the sample along the pH scale. The oxidation potential of such approaches, however, is relative, because particles and more complicated carbon molecules can only be partially digested or not at all. These practices are not recommended by current occupational safety and environmental protection requirements. According to studies, combining Persulfate with heat and UV light resulted in a more accurate and faster analysis.

Reasons To Measure Total Organic Carbon (TOC)

High-quality water is a critical element used throughout the pharmaceutical manufacturing process. Assuring the purity of the water aids in the elimination of the impact that bacteria and other organic substances may have on product quality.

When organic substances react with other elements, they form molecules that can be detrimental to products and the environment once the water is drained. TOC analysis, in addition to water purity standards, can give validation of the cleaning processes used by corporations to maintain drug-manufacturing equipment.

While organic matter is not always harmful, excessive amounts in water can have a substantial influence on ecosystems and cause equipment damage if left unregulated and untreated.

1) Avoid Environmental Consequences Organics in rivers or streams can be hazardous to the ecosystem even if the molecules themselves are not immediately toxic. Organic waste, by reducing oxygen levels in the water, can cause fish suffocation and have a wide range of negative effects on water ecosystems. 

2) Ensure Compliance With Regulations —

Organic compounds are precursors to disinfection by-products (DBP), which are rigorously controlled in the drinking water sector. Measuring TOC allows you to execute the best treatment to reduce DBP generation and meet regulatory standards. Industries and governments that fail to monitor TOC correctly may fail to comply with laws and regulations, paying costs or fines. There are further financial ramifications for breaching discharge permit restrictions.

3) Business Efficiency & Integrity — Organic compounds in products negatively impact flavor, odor, appearance, and customer impressions of quality. Excessive organic content in source water can affect production costs, create contamination, result in wastewater treatment charges, provide obstacles to following laws, and have severe environmental repercussions that can hurt a company's reputation.

Processes That Require Total Organic Carbon (TOC) Monitoring

1) Wastewater Treatment

By determining the total TOC load before it enters the treatment facility, the plant may prepare for treatment and optimize operation. Measuring the TOC discharge at the end of treatment aids in ensuring that the facility complies with the rules.

2) Drinking-Water Treatment

Natural organic matter (NOM) from decomposing plant or animal components can be found in raw water sources such as lakes, streams, and reservoirs. Organics can interact with chlorine and other disinfectants during disinfection to generate hazardous DBP (DBP reduction). To comply with standards, DBP-compliant drinking water plants must measure TOC in raw and processed water to calculate TOC percent removal. The amount of dissolved organic carbon in drinking water can also alter its odor, taste, and appearance.

3) Dairy Industry

A TOC Analyser can reveal possible product loss to wastewater at each stage of dairy processing (when milk is turned into products such as cheese or butter), assisting in process control. The facility can ensure that it complies with its regulatory discharge limit by measuring TOC at the end of the procedure. Monitoring the milk fats that leave the plant in the effluent can help to reduce product loss and wastewater treatment expenses, resulting in more revenue.

4) Industrial Boilers

The condensate from the heat exchangers in boilers must be monitored for TOC. To prevent damage, if the TOC levels in the condensate are too high, the condensate must be routed away from the boiler. Continuous TOC monitoring enables operators to make timely adjustments, avoiding equipment damage, production downtime, and revenue losses.

5) Cooling Towers

Measuring the TOC of the source and make-up water before it enters the heat exchangers ensures that no organics that could damage the equipment are present. Checking the TOC of the water after cooling guarantees that the heat exchanger has not leaked contaminants into the water that is being delivered to the receiving water body.

6) Storm Water Treatment

The treatment of stormwater is guided by TOC levels. If the TOC levels are normal, the water is directly dumped into a canal. If the TOC levels are too high, the stormwater is redirected into a retention pond before being treated at a wastewater treatment plant. Monitoring TOC assists industrial facilities in adhering to stormwater rules.

What Are The Applications Of TOC Analysis?

A) TOC Analyser in the Water Supply Industry

Since the early 1970s, Total Organic Carbon Analysis has been used to monitor water quality in the water supply business.

Organic carbon can be found in source waters as a result of decaying natural organic materials like human acid or amines, as well as manmade sources like fertilizers and detergents.

TOC analysis can estimate the presence of these contaminants in the water supply, allowing them to be treated for disinfection in water treatment plants. The reaction of the source water with chloride-containing disinfectants results in chlorinate disinfection by-products.

Furthermore, the presence of organic carbon is an essential characteristic in determining the quality of organic shale resources, which is one of the most important unconventional fuels.

B) TOC Analyser in the Pharmaceutical industry

TOC analysis is regarded as a critical technique for measuring water purity by many pharmaceutical companies. High-purity water is a critical component in the pharmaceutical manufacturing process. It must therefore be ensured that any bacteria or alternative organic compounds are eliminated so that product quality is not harmed and they are safe for consumption.

Furthermore, Total Carbon Analysis can validate the cleanliness of pharmaceutical manufacturing equipment, which is critical in avoiding product contamination.

Total organic carbon analysis is now required at all stages of the pharmaceutical industry, according to organizations such as the United States Pharmacopoeia.

Selecting The Best TOC Analysis Technique To Use

Total Organic Carbon (TOC) analysis is widely used to determine organics in water as an indicator of water cleanliness. TOC analysis is used in a wide range of applications, including ultrapure water in the electronics and pharmaceutical industries, as well as drinking water safety and municipal and industrial wastewater discharge.

TOC determination methods include Heated Persulfate, UV/Persulfate, and High-Temperature Combustion Oxidation. The detection of carbon dioxide produced during the oxidation step is another critical step in the measurement.

With so many methods for determining total organic carbon available, it can be difficult to know which one is best for your application (s). The TOC Analyzer employs two main analytical methods: high-temperature catalytic combustion oxidation and UV-persulfate oxidation.

Carbon in the sample is converted into CO2 in both methods, which is then measured with a CO2-specific Non-Dispersive Infrared (NDIR) detector. In this section, we will examine the differences between the two methods as well as the types of applications to which they are best suited.

Catalytic Combustion Oxidation TOC Analyser

Carbon is converted into CO2 in catalytic combustion systems by injecting the sample with an oxygen-rich carrier gas into a catalyst-packed tube that is typically heated to 680°C -1000°C. After that, the CO2 is swept into the NDIR detector for measurement. The catalyst speeds up the oxidation process and allows it to occur at lower temperatures than non-catalytic combustion.

With a detection limit of 50 parts per billion (ppb), this system is capable of measuring much higher concentrations up to 20,000 parts per million (ppm). This method is especially useful for samples containing particulates, difficult-to-oxidize matrices, or salt. Typical applications include wastewater and surface water treatment, as well as drinking water treatment.

UV-Persulfate oxidation TOC Analyser

The oxidation of UV-persulfate is a wet chemical process. Before going to the NDIR detector, a sparged sample is passed to a UV reactor and oxidized in solution by sodium persulphate in combination with UV radiation.

The UV-Persulfate approach has detection limits as low as 5 (ppb) and is thus well suited for low-level TOC analysis. It is typically used to measure low amounts of contamination in the pharmaceutical, biotechnology, and electronic sectors, as well as to monitor drinking water.

It is not suited for seawater or other samples with a high chloride content because the chloride reacts with the persulphate, lowering oxidation effectiveness dramatically. It is also unsuitable for samples containing a high concentration of particles.