Page 12 - 4_TOC special applications

LAAN-A-TC-E026

Application Total Organic Carbon Analysis

News Monitoring of Algae Growth by TOC Measurement

No.O49

Global warming due to the excessive use of fossil fuels
is becoming a problem which has prompted and
accelerated the search for alternative fuels. Among the
more attractive alternatives is biomass fuel, which is
attracting considerable attention. Microalgae can be
used for the production of oil without competing with
food production, and to a greater extent than other
biofuels, its productivity per unit time and area is high,
while arable land selection possibilities are great. As for
the practical use of microalgal biomass, various studies
have been conducted at each stage of its production,
including stock selection and breeding, cultivation,
harvesting, oil extraction, and purification.
The Shimadzu TOC-L Series combustion-type total
organic carbon analyzer, with its powerful organic ŸN

substance oxidation features, permits the complete
oxidization and measurement of samples such as Fig. 1 Algae
microalgae cell culture suspensions.
Here, we introduce an example of a unique application
in which the TOC-LCPH total organic carbon analyzer is
used to track the growth process of microalgae by
directly measuring, without conducting any
pretreatment, the TOC content in a suspended culture
of microalgae cells.
The data presented here was provided by the University
of Tsukuba Shiraiwa laboratory.
T. Iharada, M. Tanaka

n Analytical Method n Measurement Results
The microalgae was cultured for 8 days, and from the Fig. 2 shows the measurement results for the total
starting day, TOC measurement was conducted once carbon (TC), total organic carbon (TOC) and inorganic
per day for both Sample 1, which consisted of culture carbon (IC) associated with the cell mass during the
along with suspended microalgae cells, and Sample 2, culture period. Also, the ratios of TOC to IC in the
which consisted of culture only obtained by removing microalgae cells are shown in Fig. 3. From these results,
the microalga cells from Sample 1 through centrifugal it was possible to obtain information regarding the
sedimentation. Then, from the difference in organic increase and decrease of TC, IC and TOC values
carbon (TOC) between Sample 1 and Sample 2, we associated with the microalgae cells throughout the
obtained the value of TOC present in the organic culture process.
matter of the microalgae cells. Further, we measured One essential element in the practical realization of
the turbidity of Sample 1, and that value was taken as microalgal biomass is establishment of the culture
an index of cell mass. conditions, and it is clear from this study that
A microscopic image of the microalgae cells of Sample 1 information regarding the carbon balance can be
is shown in Fig. 1. obtained using a TOC analyzer.

<Measurement Conditions>
Analyzer : Shimadzu TOC-LCPH total organic carbon analyzer
Catalyst : Standard catalyst
Measurement item : TOC (TC–IC)
Calibration curve : 1-point calibration curve using 1000 mg/L potassium hydrogen phthalate aqueous solution
Sample 1 : Culture solution containing suspended microalgae cells
Sample 2 : Culture solution with microalgae cells removed using centrifugal sedimentation
Water sampling method : Sample 1 water was sampled while stirring with a magnetic stirrer