Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
The present invention relates to a de~ice for pulse
dosage of liquid microsamples into the flame oE an atom
absorption spectrophotometer ~A~S).
Device for puIse dosage of liquid microsamples into
the flame of AAS are known, whlch consist in a polytetra-
fluoroethylene funnel which is connected to the aggregate for
spraying of the sample by means of a special capillary. The
dosage of the solution in a volume of 50-100 microliters is
performed manually, using microllter pipettes provided with
special movable plastic nizzles (1).
It is known also a device for automatic pulse
dosage of liquid microsamples into the flame of AAS, which
is constructed based on the studies performed by Berndt and
Jackwerth (2) and used by " Perkin Elmer" . It consists a
combination of Teflon funnel provided with a microliter
~ . . .
pipette and a small pump, a system for circular step moving
of a table, where beakers containing samples to be tested
are laid upon. The operation of the device depends on the
electronics of the atom absorption spectrophotometer. It
20 permits an automatic dosage of samples of volumes 50 or 100
microliters.
A manual-acting device for pulse dosage is known,
which consists in a small container of conical bottom. The
sample of a preliminary known volume of 50-500 microliters is
pumped only once by the capillary, said capillary being
connected to the pulverizer of the AAS(3).
It is a common disadvantage of the well known
automatic devices tha-t these are extremely expensive~
In manual-acting devices for pulse dosage, relatively
high cost microli-ter pipettes o~ movable nozzles are used
and the dosage is both unconvenient and tiresome when lar~e
number of samples are to be tested, which xesults in a lower
reproducability.
The ~bject of the presen~ invention is to provide
a device for pulse dosage of liquId microsamples into the
flame of atom absorption spectrophotometer, said device being
such as to enable a simple, fast, reliable, precise and
convenient handling of the samples at bo-th a good reproduc-
ability and low cost.
This object is achieved by a device for pulse
dosage of li~uid microsamples into the flame of an atom
absorption spectrophotometer, including a distributor and
an electromagnetic valve, characterized in that the device
is constructed of two units at most, the units being located
at different levels in respect to the pulverizer of the
atom absorption spectrophotometer, wherein the distri~utors
are of the three-way type and there is a connection provided
between said distributors and the electromagnetic valves, the
three-way distributor of the higher level unit being connected
to a container for the sample, to the atmosphere by means of
an electromagnetic valve ana to the pulverizer o the atom
absorption spectrophotometer by means of the three-way distrib-
utor of the lower level unit, said distributor of the lower level
unit being connected to a container for the sample solvent.
Preferably, only one unit is used, where its
electromagnetic valve is connected to the atmosphere and
its three-way distributor is connected directly to the
pulverizer of the atom absorption spectrophotometer.
In a further embodiment where still only one unit
is used, its electromagnetic valve may be connected to a
container for the sample solvent and its three-way distributor
maybe connected directly to the container for the sample
under test.
Each of the three-way distributors may be provided
i3
with a cna~nel, which connects it with the electromagnetic
valve, s~id channel bein~ connected to a -through-hole,
wherein an angle o~ between 15 and 165 is concluded between
said channel and said through-hole. The -through-hole can
be oE a constant as well as step variable cross section.
The device according to the invention possesses
the following advantages: there is no need for microliter
pipettes; dosed volumes can be smoothly variated starting
from 50microliters to a continuous pulverization; the device
is universal-purpose concerning its applicability; a pos-
sibility is created one to work in a mode of lntegration of
the signals at a minimal volume zeroing in the flame according
to the respective solvent used, followed by a pulse dosage
of a microsample in the same solvent; a continuous dosage
of the solvent and pulse dosage of the sample, thereby
maintaining the flame stoichometry and ensuring a simplicity,
conveniency, reliability, fastness and exactness in opexation.
Moreover, the device is readily available and low cost.
~mbodiments of the invention are shown as examples
without limitative manner in the accompanying drawings, where:
Fig. 1 is a diagram of the device for pulse dosage
of liquid microsamples into the flame o~ AAS;
Fig. 2 is a further diagram of a device for pulse
dosage of liquid unicrosamples into the rame of AAS,
Fig. 3 is a diagram of a further embodiment of the
device, consisting of a single unit.
Figure 1 consists in two units located ak different
levels over the AAS pulveraizer, where three-way distributors
connected to electromagnetic valves are used. The three-way
distributor 1 of the higher level unit is connected to a
container for the sample by means o~ an opening 21 at the
through hole 2 as well as to the atmosphere by means of an
39L~j3
electromagnetic valve 6 through -the channel 31 and
opening 22 at the through-hole 2, usin~ the cube 4
provided with the opening 23 at the through-hole 20 of the
three-way distributor 10 pertaining to the lower level unit,
said three-way dis-tributor 10 being connected both to a
container 5 for the sample solvent by means of the lower level
unit electromagnetic valve 60 through the channel 32 and to
the pulverizer of the AAS by means of the opening 24 at the
through-hole 20.
There is an angle of 90 concluded between the
through-holes 2 and 20 in the three-way distributors 1 and
10 and the channels 31 and 32 provided for connection with
the corresponding electromagnetic valves.
' The device operates as follows: The flame of the
AAS is ignited. Both electromagnetic valves 6 and 60 are
opened. The pure solvent contained in the container 7?passes
through the electromagnetic valve 60, channel 32, opening 24
and by means of a plastic tube enters the pulverizer (or,
respectively, flame of the AAS). A portion of the solvent is
ascended along the plastic tube 4, thereby forming a hydraulic
seal against the air inlet from the electromagnetic valve 6.
No suction of solution of the liquid sample occurs. Thus,
zeroing of the apparatus takes place under said conditions.
A higher rate of solvent admission is ensured compared with
the liquid consumption of the pulverizer due to the higher
level of the container 5 compared with the level of the
pulverizer and by the proper choice of the cross sections of
channels 32 and 2.
The two electromagnetic valves 6 and 60 are closed
during a short strictly defined time by means of electro-
magnetic releys actuated by a signal, submit-ted by the operator.
~L~63~
The dosage of pure solvent stops in the manner described
~bove. `The liquid sample is pumped and enters the AAS
pulverizer through a plastic tube after being passed through
a plastic ~ube, the opening 21, the through-hole 2, the
opening 22, the plastic tube ~, the opening 23, the through-
hole 20 and opening 24. Pulverization of the pure solvent is
restored after the opening of the electromagnetic valves 6
and 60. The amount of volumes being dosed is controlled by
the duration of the closure time of the electromagnetic
valves.
The device permits a continuous dosage of the
solvent and pulse dosage of the sample, i.e. sample-solvent-
sample... without any air feeding, which results in an
improvement of the flame parameters or, respectively, efficiency
of the atomization of a number of elements, while ensuring the
possibility one to work without deuterium correction.
Results obtained using the above outlines device
are given in Table 1.
The embodiment of Figure 2 is constructed of a
single unit. The three-way distributor 1 of said unit contacts
with the atmosphere by means of a channel 31 and electro-
magnetic valve 6; with the container for sample under test
by means of the opening 21 at the through-hole 2 and directly
with the pulverizer of AAS by means of the opening 22 at the
through-hole 2.
This device operates as folIows. The opening 22 is
connected to the pulverizer of AAS by means of a plastic tube.
Then, the control panel of the electromagnetic valve 6 is
switched on to the electric set. The flame of AAS is ignited.
Zeroing of the apparatus can be made either on the flame or
corresponding solvent used.
A signal submitted by the operator closes the
~;39~63~
electromagnetic valve Eor a short strictly de~ined time, said
time being controlled by electronic timers. The air access
to the through-hole 2, comming from the electromagnetic valve
6 through the channel 31, is disconnected. The solution of
the samplc under test is pumped for a short time and passes
through: a plastic tube, the opening 21, the through-hole 2,
the opening 22 and then, by means of a plastic tube enters
the pulverizer of AAS. Thus, pulse dosage of liquid micro-
samples is accomplished, which stops at the moment of opening
of the electromagnetic valve 6, i.e. a dosage of the type
sample-air sample...is performed. The amount of the volumes
being dosed is determined by the closure time of the electro-
magnetic valve 6.
Results obtained using the above said device are
given in Table 2.
The embodiment of Figure 3, the device consists
in a single unit. The three-way distributor 10 of said unit
is connected to a container 5 for the sample solvent, to the
electromagnetic valve 60 and channel 32, to a container for
the sample under test by means of the opening 23 at the
through-hole 20 and to the pulverizer of AAS by means of the
opening 24 at the. same through-hole 20.
In all possible versions of embodiment of the
device, the through-holes 2 and 20 can be of either constant
(Figs. 1,2) or step variable (Fig.3) cross sections.
63
TABLE 1
Relative absorption from 15 measurements performed
over solutions in the flame of AAS after a pulse dosage of
the type sample-solvent-sample...using the device according
to the invention.
ELEMENT CONCENTRATION SOLVENT A SR
-mkg-ml 1
Cu 2,0 MMK 0,147 5,32
10,0 H2O0,197 2,26
1 0 ---
0,4 MMK0,141 2,24
Cd 4,0 ~2 0,298 3,32
Te 4,0 MMK0,2Z4 6,29
H20
__
10,0 MMK0,518 0,70
Pb 10,0 H2O0,095 5,20
4,0 MMK0,284 1j42
Fe 4,0 H2O0,042 6,47
_
50,0 - xylene 0,280
Al 50,0 H2O0,300
50,0 MIBK0,790
Sn 50,0 ~120,120
Organic solutions of Cu, Cd, Te and Pb are obtained
by extraction of the diethyldithiocarbamate complexes of Cu,
Cd, Te and Pb with methylmetacrylate. The Fe is extracted
as a hydrochloric acid complex, and the Sn and Al are extracted
as standard caproate solutions
MMK = methylmetacrylate
MIBK = methyiisobutyl ketone
TABLE 2
Absorption o~ solutions in the ~lame of AAS,
measured after pulse dosage of the type sample-air-sample...
DEVICE ~CCORDING324,7nm -228,8nm ma~~217,Onm
TO THE INVENTIONsplit-0,7 1split-0,7 1 split-0,7
Cu-1,5mkg ml Cd-0,4mkgml Pb-S,Omkg.ml
A` SR % A SR % A SR %
aqueous device0,065 1,580,032 7.08 0,093 1,65
solutions funnel P.E. 0,058 4,33 0,027 9,48 0~074 4r88
_
solutions device0,253 0l660,127 2,82 0,076 4,60
.
MIBK Funnel P.E.0,256 0,860,100 3,28 0,081 5,04
solutions device0,221 1,180,107 3,53 0,061 5,67
.
MMK Funnel P.E.0,220 1,180,105 3,68 0,062 7,50
solutions device0,118 1,730,084 7,88 - -
0,108 0,91
__
TOLUENE Funnel P.E. 0,126 1.92 0,048 7,68
.
Absorption values are average of 25 measurements (II).
x zeroing performed on organic solvent. In other cases,
zeroing is accomplished based on the flame.
MIBK = methylisobutyl ketone
MMK = methylmetacrylate
SR ~ = relative standard shift
