CADERNO DE CIÊNCIAS AGRÁRIAS
Agrarian Sciences Journal
Centrifuge 2.0 - a useful software for soil particles separation and soil solution extraction
André Somavilla
1
*, Paulo Ivonir Gubiani
2
, Pedro Bolzan Parisi
3
Abstract
The centrifugation of samples is frequently required in laboratory analysis, whether be it for chemical, physical or
biological analysis of soil. The software Centrifuge 1.0 is a simple tool available that enable researchers to quantify
the energy applied to samples during the centrifugation process. This study aims to demonstrate the new option of
calculus incorporated into the software, such as sedimentation of particles in fluids in the centrifuge and analyses
the deviation on outputs caused by variations in the values of the parameters used. In its 2.0 version, the Centrifuge
software is more useful in carrying out laboratory techniques, because it can be applied to quantify energy in samples
or sedimentation of solids particles in fluids during the centrifugation process. The software Centrifuge 2.0 is freely
available and can be obtained with the authors.
Keywords: Sedimentation. Particles size. Centrifugation. Soil Analysis.
Centrifuge 2.0 - um software útil para separação de partículas do solo e extração da
solução do solo
Resumo
A centrifugação de amostras é frequentemente necessária em análises laboratoriais, seja em análises químicas, físicas
ou biológicas do solo. O software Centrifuge 1.0 é uma ferramenta simples que permite aos pesquisadores quantificar
a energia aplicada às amostras durante o processo de centrifugação. Este estudo tem como objetivo demonstrar a nova
opção de cálculo incorporada ao software, para cálculo de sedimentação de partículas em fluidos com uso de centrí-
fuga e analisar as incertezas atribuídas aos parâmetros utilizados pelo software. Na versão 2.0, o software Centrifuge
é mais útil na execução de técnicas de laboratório, pois pode ser aplicado para quantificar a aplicação de energia
em amostras ou para sedimentação de partículas de sólidos em meio fluidos durante o processo de centrifugação. O
software Centrifuge 2.0 está disponível gratuitamente e pode ser obtido com os autores.
Palavras-chave: Sedimentação. Tamanho de partícula. Centrifugação. Análises de solo
1
Universidade Federal de Santa Maria. Santa Maria, RS. Brasil.
https://orcid.org/0000-0002-3595-6200
2
Universidade Federal de Santa Maria. Santa Maria, RS. Brasil.
https://orcid.org/0000-0002-8840-3976
3
Universidade Federal de Santa Maria. Santa Maria, RS. Brasil.
https://orcid.org/0000-0002-7752-3374
*Autor para correspondência: somavillaa@gmail.com
Recebido para publicação em 21 de outubro de 2019. Aceito para publicação em 06 de novembro de 2019
e-ISSN: 2447-6218 / ISSN: 2447-6218 / © 2009, Universidade Federal de Minas Gerais, Todos os direitos reservados.
Somavilla, A. et al.
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Cad. Ciênc. Agrá., v. 11, p. 01–05, 2019. e-ISSN: 2447-6218 / ISSN: 1984-6738
Introduction
This study aims to explicit the math principles
and the functionality of the new calculus option available
in the Centrifuge software (Somavilla et al., 2017). The
new version can be used to calculate sedimentation of
particles in fluids during the centrifugation process.
The option of introducing this function in the
software is due to the fact that the centrifugation of
samples is a procedure commonly used in laboratories of
soil chemistry, physics and biology in analyzes that sedi-
mention of particles is requerid. However, this procedure
is often carried out erroneously, mainly due to the lack
of information in traditional analysis methodologies.
Centrifugation of solid samples dispersed in fluids
has two main purposes. The first one consists in sepa-
rating all the solid particles (soil, sediment, etc.) from
the solution, for later analysis of the supernatant. The
second is to separate distinct sized solid particles (soil,
sediment, etc.) dispersed in the solution. In both cases,
centrifugation makes it possible to apply force greater
than that of gravity on the particles, which speeds up the
droop speed and reduces sedimentation time.
Fluid and solid phase separation in chemical
soil analysis methodologies is simply described as the
centrifugation of the sample at a certain rotation speed.
There are methodologies for soil phosphorus fractiona-
tion (Mehlich, 1984; Hedley e Stewart, 1982; Hedley
et al., 1982; Olsen e Sommers, 1982; Mehlich, 1953),
analysis of 31P nuclear magnetic resonance (Vestergren
et al., 2012; Rheinheimer, 2002),extraction of Cadmium,
Cobalt, Copper, Nickel, Lead, Zinc, Iron and Manganese
(Tiesser et al., 1979), soil ammonium (Silva et al., 1966),
separation of nematodes from soil (Jenkins, 1964), se-
quential extraction of heavy metals (Keller eVédy1994),
determination of the cation exchange capacity and soil
pH, (Gillman, 1979), among others. In the mentioned
examples, the authors indicate the speed of centrifuge
spin and the time of centrifugation. This is mainly due
to the fact that it is only necessary to sediment every
solid particle without the need of fractionate the diferent
particles size.
However, even in these cases, the standardization
not only of the spin speed of the centrifuge, but mainly of
the energy applied to the sample is extremally necessary.
Without this standardization, different equipment can
apply different energy with the same spin speed, mainly
due to variations in the distance of the spin axis. This
can lead to insufficient energy application and, conse-
quently, to faulty separation of the sample phases. The
correct amount of energy to be applied in samples cen-
trifuged using different equipment can be estimated by
the software Centrifuge 1.0. The Centrifuge 1.0 is freely
available and described by Somavilla et al. (2017) for
the extraction of soil solution.
In the specific cases where it is desired to separate
fractions of solid particles of different diameters or density
by centrifugation, as for example for separation of sand,
silt and clay (Fernández-Ugalde et al., 2013), fractions
of the clay size (Laird et al., 1991) or soil nanoparticles
(Bakshi et al., 2014), the accuracy regarding the energy
applied to the sample must be much greater. In order to
guarantee correct energy application new calculus option
of sedimentation of solid particles in fluids was added to
Centrifuge 1.0 software (Somavilla et al., 2017), resulting
in the Centrifuge 2.0 version.
Software Development
Version 1.0 of the Centrifuge software was res-
tructured. Its user interface became more dynamic and
intuitive and new functionality were incorporated (Figure
1). In addition, in the initial window a basic image was
introduced, with the definition of some parameters used
in the calculation procedures available in the software,
which facilitates the understanding by the user.
Figure 1 – Initial Layout of Centrifuge 2.0
Centrifuge 2.0 - a useful software for soil particles separation and soil solution extraction
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Cad. Ciênc. Agrá., v. 11, p. 01–05, 2019. e-ISSN: 2447-6218 / ISSN: 1984-6738
In the initial interface, the user has access to the
two main Software functions available in the “Menu”
section: “Particle sedimentation” and “Energy applied
to sample”. In each the screens (Figure 2) the user can
access the item that represents their need and perform
the calculation from a series of parameters. As an exam-
ple, it is possible to visualize in Figure 3 the interface for
quantification of the particle sedimentation time.
Figure 2 – Command tabs for the estimation of particle sedimentation (a) and quantification of energy applied to
sample (b)
Centrifuge 2.0 calculates the sedimentation of
particles in a fluid using Stokes’s law, described by Hatha
-
way (1956) and Bortoluzzi e Poleto (2013) and expressed
implicitly as:
(Eq. 1)
Where T is the total time (s); n
i
is the viscosity
(P); R
1
and R
2
are the initial and final distance of particle
from rotation axis, respectively (cm); r is de radius of the
particle (cm); N is the angular velocity (RPS); Dp and Df
are the density of the particle and de fluid, respectively
(g cm
-3
).
In Figure 3 it is possible to observe an example
of the software being used to calculate the duration of
centrifugation for the sedimentation of particles with dia-
meter greater than 0.002 mm. This example corresponds
to the separation of silt and clay fractions, commonly
performed in soil particle size analysis.
Figure 3 – Quantification of the time required for sedimentation of solid particles in fluid medium
Somavilla, A. et al.
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Cad. Ciênc. Agrá., v. 11, p. 01–05, 2019. e-ISSN: 2447-6218 / ISSN: 1984-6738
The example shown in Figure 3 was also used to
evaluate the magnitude of the deviations on the outputs
of equation (1) caused by changing the values of the
equation parameters. The analysis was performed from
the individual alteration of the equation parameters to
quantify the time, particle size, spin movement and depth.
Each parameter varied by 1, 2 and 3% for more and
less than its default value (Figure 3). The results were
expressed as percentage error in relation to the value
obtained using the standard parameter values. Although
this analysis evaluates the sensitivity of equation (1) to its
parameters, the term error was introduced to give error
connotation in the outputs if the change in parameters
is caused by an error in the choice of values.
Among the analyzed parameters, the most impor-
tant ones which cause greater error if values are erroneou-
sly introduced in the equation (1) are: spin movement
and particle size (with error up to 10%) and particle
density (with error up to 7.14%) in the depth (Figure
4). In general, the spin movement is the parameter that
requires greater accuracy, because errors in its value can
result in large errors in the fractionation of particles.
Figure 4 – Error analyses of time (a), particle size (b), depth (c) and spin movement (d)
Where: S-particle size; h-depth; ni-viscosity of fluid; Dp and Df-particle and fluid density, respectively; ri-internal spin radius; RPM-spin movement;
T-time.
Alterations in the parameters related to the fluid
(viscosity and density) resulted, respectively, in errors of
4.3 and 2.9% in the depth. Both the viscosity and the
density of the fluid are changed by changing the fluid
temperature. Thus, it is important to control fluid tem-
perature during the centrifugation process.
The sedimentation of particles by centrifuga-
tion can be performed in different fluids. As standards
for viscosity and fluid density parameters, the software
provides values for pure water at 20°C. However, these
parameters can be changed in order to make than proper
for the particular analyses conditions.
Conclusion
In version 2.0 Centrifuge software has a greater
applicability in laboratory techniques and can be used
for quantification of applied energy in soil samples and
for sedimentation of solid particles in fluid.
The spin movement and the particle diameter
are the parameters which should receive most attention
from the user due to the possibility of causing greater
output errors.
Centrifuge 2.0 - a useful software for soil particles separation and soil solution extraction
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Cad. Ciênc. Agrá., v. 11, p. 01–05, 2019. e-ISSN: 2447-6218 / ISSN: 1984-6738
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