Analysis of TOC by Shimazu

1
Analysis of TOC by Shimazu

• µconvi laboratory 
• Kang min Chon

2
Introduction

• Organic carbon
• The most abundant element found in all
  organisms. In aquatic environments, organic
  carbon is produced by plant photosynthesis and
  bacterial growth.
• Inorganic carbon
• Not organic compounds(carbonate,
  bicarbonate species primarily)
• Total organic carbon
• The amount of carbon bound in an organic
  compound and often used as a non-specific
  indicator of water quality.

3
Formations of Carbon in water
4
(No Transcript)
5
Principles of TC Analysis
ltCombustion of TCgt
CaHbNcOd nO2 MeCO3 MeHCO3 CO2 
aCO2 b/2 H2O cNO CO2 MeO CO2 1/2 Me2O
1/2 H2O CO2
Oxidation   Combustion   (680?,Pt catalyst)
6
Flow of TC Analysis
Detector
7
Principles of IC Analysis

• ltReaction of IC By Acidifyinggt
• Me2CO3 2HCl --gt CO2 2MeCl H2O
• MeHCO3 HCl --gt CO2 MeCl H2O
• Carbon dioxide and dissolved carbon dioxide
  in the sample are volatilized by bubbling air or
  nitrogen gas that does not contain carbon dioxide
  through the sample.

8
Flow of IC Analysis
5ml Syringe
IC Reagent
Detector
9
Principles of NPOC Analysis

• After eliminating the IC component. The remaining
  TC is measured to determine total organic carbon,
  and the result is generally referred to as TOC.
• However, this analysis is referred to NPOC to
  distinguish it from the TOC value obtained by
  calculating the difference between TC and IC.
• NPOC stands for non-purgeable organic carbon and
  refers to organic carbon that is present in a
  sample in a non-volatile form. NPOC and
  TOC(obtained by IC elimination) are identical.

10
Principles of POC Analysis

• POC analysis is used to measure the volatilized
  component of TOC, which is produced during  the
  NPOC sample process. As a result, NPOCPOC is
  equivalent to TOC
• When CO2 absorber eliminates the carbon dioxide
  that was generated along with the POC substances.
  POC components that are easily caught in the CO2
  absorber produce low values in POC analysis. POC
  result are not absolute.

11
Flow of NPOC and POC Analysis
5ml Syringe
12
Principles of Measuring TOC

• TC-IC Method
• TOC is measured as the difference between
  the TC and IC analysis value. For sample
  containing more IC than TOC the NPOC method is
  recommended for such samples.
• Detection accuracy decrease with increase IC
  concentration, the NPOC method is also
  recommended for sample containing IC
  concentration exceeding 10ppm for TOC/TN catalyst
  and 5ppm for high sensitivity catalyst.

13

• NPOC Method 
• The NPOC method is the most widely used TOC
  analysis method.
• Samples that become foamy during sparging
  tend to form bubbles that flow out of the
  syringe, which removes the concentrated TOC
  sample components and leaves a small amount of
  TOC in the syringe. The TC-IC method is recommend
  in this situation.
• Purgeable organic substances in the sample
  can be lost during the sparging process.

14

• When the sample contains purgeable organic
  substances, TOC should not be measured by the
  NPOC method.
• If the dissolved purgeable organic component
  in the water sample is large, the amount
  volatilized during sparging is relatively small.
• Generally, the amount of purgeable organic
  substances in natural environmental, public and
  purified water is small as result, NPOC can be
  referred to as TOC.

15

• POC NPOC Method
•   The POC NPOC method should be used when
  the amount of POC present in the sample cannot be
  disregarded.
• The CO2 absorber eliminates the carbon
  dioxide that was generated along with the POC
  substances. Therefore, POC components that are
  easily caught in the CO2 absorber produce low
  values in POC analysis. POC result obtained using
  this technique are not absolute.

16
NDIR(Non-Dispersive Infrared Gas Analyzer

• NDIR techniques for the measurement of various
  gases rely on the energy absorption
  characteristics of a particular gas in the
  infrared region.
• lt Lambert-Beer's Lawgt
• A edc
• A absorbance e molar
  extinction coefficient
• d pathlength in cm c molar
  concentration
• gt The amount of light absorbed in any unit
  volume is proportional to the molar concentration.

17

• Infrared energy passes through two identical
  tubes and falls on a detector.
• The first tube is the reference cell and is
  filled with a non-absorbing gas(N2). The second
  tube is the measurement cell and contains the gas
  sample to be analyzed.
• Energy in the region of interest is absorbed by
  the gas in the measurement cell, attenuating the
  energy passing through the cell and falling on
  the detector.

18

• This attenuated energy is compared to the
  unattenuated signal from the reference cell. The
  difference is proportional to the amount of
  absorbing gas in the measurement cell.