This setup has some major advantages.
a) Speed of analysis, that can be as fast as
2.8 minutes for the 828-product line.
b) Chemical consumption is reduced. E.g.
the reduction chemicals can last up to
c) Combustion in pure Oxygen is possible,
which eliminates the need for
combustion catalysts, gives perfect,
matrix free combustion and allows
high sample masses to be analyzed.
In table 1 and 2 results have been obtained
with two different carrier gases and different
aliquot loop sizes. It is obvious that
the sensitivity of the instrument increases
with the larger (10ccm³ vs 3ccm³) loop size.
Additionally, the sensitivity is higher with
Helium compared with Argon carrier gas.
All results show highest precision and accuracy.
The sample weight used is higher on
the 928-boat type system compared with
the 828-foil/capsule system. Also, non-homogenous
samples like ham or hot dogs
can be analyzed easily and convenient.
It can be seen clearly that results
for the two flours are fully comparable
with 828 and 928 instruments, the sample
weight on 928 series is higher. These
samples were run on both instruments.
A direct comparison between the
capsules/foil vs. boat sample introduction
can be given by a test that has been
made recently for samples with a low
Liquid samples like Orange Juice, Beer
and Permeate and solid samples like Lactose
and Starch have been compared.
Different capsules and foils have been
used on the 828 Series and combustion
boats have been used on the 928 series.
As seen in picture 3 and 4 the results are
comparable even with low concentrations
in the 100-ppm range. Improved
precision is typically obtained with the
FP928 due to the larger sample mass and
the elimination of the atmospheric interference.
It can be shown that for solid and liquid
food samples both types of Dumas analyzers
give comparable results with highest
precision. Sample size is typically 200-500
mg on the 828 series, whereas the 928
series allows samples in the gram range
and more. Samples having problems with
homogeneity like meat or fibers show
some advantages when analyzed on the
928 series boat type system. Due to the
higher masses also some sensitivity advantages
are there on the 928 series boat type
system. Typical analysis times are ~2.8 to
* Optimization of Combustion Methods for the Determination of Low Level Nitrogen/Protein in
Food and Feed Products Mason Marsh, Lloyd Allen, and Fred Schultz | LECO Corporation,
Pittcon Poster 2019
** There are CN/CHN or CNS species of the 828 and 928 product line that are using IR cells
to detect Carbon/Hydrogen/Sulfur here, just as a remark.
100% wear- and maintenance-free
Submersible and heat resistant
Durable and sustainable
3 years warranty
Made in Germany