What is TOC & why it's measurement in production process usable water is important in the pharmaceutical industrial environment in respect to product quality

1. Introduction to Total Organic Carbon (TOC)
Water purity is critical for a number of industries such as pharmaceutical and
semiconductor manufacturing and power generation. The presence of bacteria and
other organic compounds in the water can suggest a failure in filtration, storage and
other components and systems. Left unfiltered, these compounds can create significant
challenges, from damaging expensive industrial system to negatively impacting product
quality and threatening profitability. Detecting the presence of these organic
contaminants and quantifying their concentration can help protect consumers, industries
and the environment.
For this post, we will focus on how pharmaceutical organizations address these organic
threats. Organizations such as the United States Pharmacopoeia (USP), Japanese
Pharmacopoeia and the European Pharmacopoeia have made Total Organic Carbon
(TOC) analysis the standard test for quality when it comes to water purity and water for
injection. The USP has gone as far as making TOC water monitoring a requirement at
all stages of the pharmaceutical industry.
What is TOC?
TOC is the measure of the level of organic molecules or contaminants in purified water.
TOC is an analytic technique that helps organizations understand whether the water
they are using is pure enough for their processes. All water, no matter how pure,
contains some carbon materials. Many of these materials are introduced into the water
from the water source, or from materials and systems during purification and production.
They can also come directly from workers involved in the processes. They may include
natural or altered products of living systems or man-made and synthetic compounds.
What does TOC Measure?
TOC analysis measures the following:
 Total carbon (TC),
 Inorganic carbon (IC),
 Total organic carbon (TOC),
 Purgeable organic carbon (POC) and
 Nonpurgeable organic carbon (NPOC).
What are the Components of TOC Analysis?
There are three parts of TOC analysis: sampling, oxidation and detection.
To meet required regulations, it is recommended the sampling system have automatic
sampling, acidification, and sparging for TOC analysis, automatic dilution capability
and autocalibration using a single stock standard in order to improve reproducibility and
increase throughput.

2. To determine the level of TOC, the organic carbons must be oxidized. There are several
types of oxidation methods on the market today. These methods, which convert TC into
CO2, include:
 Photocatalytic oxidation: Organics convert to carbon dioxide in the presence of
UV light
 Chemical oxidation: Mix sample with Persulfate in a UV-irradiated chamber to
convert organics to carbon dioxide
 High-temperature combustion: Mix sample with oxidation catalyst in a chamber
heated to 95-100 degrees Celsius to convert organics to carbon dioxide
Studies suggest that the combination of the Persulfate with the heat and UV light
produced more accurate and faster analysis.
TOC Analyzers use two types of detection systems, non-dispersive infrared (NDIR) and
conductivity detectors (direct and membrane). NDIRs, which consist of a light source,
cell and a detection portion, are more popular due to stability and interference issues
with conductivity detectors. “Both types of conductivity detectors are susceptible to
interference from changes in pH and temperature. Also, all conductivity techniques
suffer from interferences from gases such as chlorine dioxide, sulfur dioxide or other
noxious gases.”[i]
Why is it Important to Measure TOC?
In the pharmaceutical industry, high purity water is a key ingredient used throughout the
production processes. Ensuring that the purity of the water helps to eliminate the impact
that bacteria and other organic compounds may have on product quality. Organic
compounds combine with other elements to produce molecules that can prove harmful
to products and to the environment once the water is discharged. In addition to water
purity levels, TOC analysis can also provide validation of the cleaning methods
companies use for maintaining drug-manufacturing equipment.