Date: 07/08/15 Group1:: R. Surya Teja

Anshuman Pasupalak

Vaibhav Singh

DETERMINATION OF TOTAL ORGANIC

CARBON IN WATER SAMPLESAIM:

To determine the amount of organic carbon present in waste water

APPARATUS:

TOC analyser, a beaker, waste water, paraffin paper, oxygen cylinder.

THEORY:

Total organic carbon (TOC) is the amount of carbon found in an organic compound and is often used as a non-specific indicator of water quality or cleanliness of pharmaceutical manufacturing equipment.

Total Carbon (TC) – all the carbon in the sample, including both inorganic and organic carbon

Total Inorganic Carbon (TIC) – often referred to as inorganic carbon(IC), carbonate, bicarbonate, and dissolved carbon dioxide (CO2).

Total Organic Carbon (TOC) – material derived from decaying vegetation, bacterial growth, and metabolic activities of living organisms or chemicals.

Non-Purgeable Organic Carbon (NPOC) – commonly referred to as TOC; organic carbon remaining in an acidified sample after purging the sample with gas.

Purgeable (volatile) Organic Carbon (VOC) – organic carbon that has been removed from a neutral, or acidified sample by purging with an inert gas. These are the same compounds referred to as Volatile Organic Compounds (VOC) and usually determined by Purge and Trap Gas Chromatography.

Since the amount of purgeable organic carbon is very negligible when compared to the amount of non-purgeable organic carbon….it can be neglected.

Hence TOC = NPOC (approx.)

TOC measurement: The 680°C combustion catalytic oxidation method achieves total combustion of samples by heating them to 680°C in an oxygen-rich environment inside TC combustion tubes filled with a platinum catalyst. Since this utilizes the simple principle of oxidation through heating and combustion, pre-treatment and post-treatment using oxidizing agents are unnecessary, which enhances operability. The carbon dioxide generated by oxidation is detected using an infrared gas analyzer (NDIR). By adopting a newly-designed, high-sensitivity NDIR, the TOC-L series achieves high detection sensitivity, with a detection limit of 4μg/L, the highest level for the combustion catalytic oxidation method. The figure below is a schematic diagram showing TOC measurement using the 680°C combustion catalytic oxidation method and the NDIR method

The organic carbon in the sample is usually measured via an NPOC measurement as shown in the figure below. This method is the same as TOC measurement methods using acidification and sparging.

Non-Dispersive Infra-Red (NDIR) detectors are the industry standard method of measuring the concentration of carbon oxides (CO & CO2), these use Beer’s law for the measurement.

Each constituent gas in a sample will absorb some infrared at a particular frequency. By shining an infra-red beam through a sample cell (containing CO or CO2), and measuring the amount of infra-red absorbed by the sample at the necessary wavelength, a NDIR detector is able to measure the volumetric concentration of CO or CO2 in the sample.

PROCEDURE:

Turn on the TOC analyser Wait for the furnace to reach temperature 680 degree Celsius Open the oxygen(air) flow cylinder Check the gas flow and pressure (supply air pressure should be in the range of 200-

250KPa). Make necessary settings (units for measurements, dehumidifier temperature Select number of washes. RANGE- Automatically set based on standard conc’s Set the standard deviation value S.D = 0.5 INJ VOLUME = 20µL Max no. of injects = 5 CV 3.0% (default value for coefficient of variation between repetitive measures) SPARGE TIME - 3 min (for NPOC analysis) Select RINSE , NO OF NEEDLE WASHES, FLOW LINE WASHES, ACID ADDITION Select the number of verifications required Press OK, and wait for the machine to carry out the operation to get the Result.

OBSERVATION:

1) NPOC measurement in WASTE WATER:

Trial1 ----NPOC----119.9ppm (excluded)

Trial2 ----NPOC----116.4ppm

Trial3 ----NPOC----113.9ppm

Trial4 ----NPOC----110.1ppm (excluded)

Trial5 ----NPOC----116.4ppm

Mean NPOC =115.6ppm

TOC (approx.) = NPOC = 115.6ppm

2) NPOC measurement in DRINKING WATER:

Trial1 ----NPOC----3.721ppm

Trial2 ----NPOC----3.520ppm (excluded)

Trial3 ----NPOC----3.951ppm

Trial4 ----NPOC----3.816ppm

Trial5 ----NPOC----4.188ppm (excluded)

Mean NPOC =3.829ppm

TOC (approx.) = NPOC = 3.829ppm

INFERENCE:

From the standard general range of TOC in waste and drinking water, the values we got are verified and hence are correct.

SOURCE for verification:

http://www.ssi.shimadzu.com/products/literature/toc/StandardMethod5310.pdf

(As mentioned in the source attached above)

ACKNOWLEDGEMENT:

We are grateful to our T.A.- Ms. Ramya for explaining the concepts behind and guiding us in doing the experiment and Mr. Chandrashekhar Sharma Sir and giving us the opportunity to do the experiment ourselves. We are really thankful to all of you.