U.S. patent number 3,582,218 [Application Number 04/867,340] was granted by the patent office on 1971-06-01 for multistation photometric analyzer.
This patent grant is currently assigned to N/A. Invention is credited to Norman G. Anderson.
United States Patent |
3,582,218 |
Anderson |
June 1, 1971 |
MULTISTATION PHOTOMETRIC ANALYZER
Abstract
A multistation, single-channel photometric solution analyzer
having a rotor adapted to carry a plurality of removable cuvettes
in the form of rigid, hollow, elongated bodies exteriorly engaged
by a flange seating against an axially extending surface of the
rotor. The cuvettes may be affixed to a flexible belt to facilitate
transport, installation, and removal of cuvettes as a group.
Inventors: |
Anderson; Norman G. (Oak Ridge,
TN) |
Assignee: |
N/A (N/A)
|
Family
ID: |
25349591 |
Appl.
No.: |
04/867,340 |
Filed: |
October 17, 1969 |
Current U.S.
Class: |
356/427; 356/440;
356/246 |
Current CPC
Class: |
G01N
21/07 (20130101) |
Current International
Class: |
G01N
21/07 (20060101); G01N 21/03 (20060101); G01n
021/24 () |
Field of
Search: |
;250/218
;356/196,197,198,180,201,246,208 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wibert; Ronald L.
Assistant Examiner: Chew, II; Orville B.
Claims
What I claim is:
1. In a photometric solution analyzer including a rotor assembly
for periodically interposing at least one light-transmitting
sample-analysis cuvette between a light source and means for
measuring the light transmitted through the cuvette so interposed,
the improvement wherein
a. said rotor comprises an annulus rotatable about an axis and
having an inner and an outer peripheral surface, said annulus
having at least one recess communicating with said inner surface
and extending radially toward said outer surface, said annulus
carrying light-transmitting means adjacent said recess for passing
light through said annulus and said recess, and
b. said cuvette comprises a hollow, elongated, rigid body having a
closed end portion of light-transmitting material insertable in
said recess for registry with said light-transmitting means, and
flange means affixed to said cuvette at a location remote from said
closed end portion for seating against said inner surface of said
annulus to maintain said end portion in registry with said
light-transmitting means.
2. The combination of claim 1 wherein said light-transmitting means
comprises a pair of aligned apertures disposed on either side of
said recess and extending from said recess to the exterior of said
annulus.
3. The combination of claim 1 wherein said flange means is integral
with said cuvette.
4. The combination of claim 1 wherein said cuvette is exteriorly
affixed to a flexible flat member extending in a plane
substantially normal to the major axis of said cuvette.
5. The combination of claim 1 wherein said cuvette is composed of
glass.
6. The combination of claim 1 wherein said cuvette is composed of a
plastic.
7. The combination of claim 1 wherein said cuvette contains a solid
barrier which is sealably joined to the inner surface thereof and
which divides the interior of the cuvette into adjoining chambers
which communicate through an open region above said barrier, said
barrier presenting a substantially flat and upright surface to said
closed end portion and a sloping surface to the opposite end of
said cuvette.
8. In combination with a photometric solution analyzer comprising
an annulus rotatable about an axis and formed with
circumferentially spaced recesses extending radially outward from
an inner peripheral surface thereof, with each of said recesses
adapted to receive a closed, light-transmitting end portion of a
cuvette readily insertable in and removable from said annulus,
means for effecting the insertion and removal of said cuvettes from
said recesses comprising belt means disposable within said annulus
in a contiguous relation with the inner surface thereof and having
a plurality of cuvettes affixed to a face thereof at spaced-apart
locations along the length thereof, each affixed cuvette having a
closed, light-transmitting end portion extending away from said
face, the center-to-center spacing of said affixed cuvettes
corresponding to that of said recesses.
9. The combination of claim 8 wherein said belt means and said
cuvettes are of unitary construction.
10. The combination of claim 8 wherein said belt means is adapted
to seat against the inner peripheral surface of said annulus when
said affixed cuvettes are mounted in said recesses.
Description
BACKGROUND OF THE INVENTION
This invention was made in the course of, or under, a contract 10
with the United States Atomic Energy Commission.
My invention relates generally to multistation, single-channel
photometric solution analyzers, and more particularly to
improvements in rotor assemblies used therein, and to means
facilitating the transport, installation, and removal of removable
cuvettes as a group.
Copending Pat. applications Ser. No. 784,739, Ser. No. 827,185,
U.S. Pat. No. 3,547,547, of common assignee, described photometric
solution analyzers wherein a rotor assembly is formed with a
plurality of sample-receiving cavities, or cuvettes, disposed in a
circular array about the axis of the assembly. Each cuvette is
provided with axially aligned transparent windows. Rotation of the
assembly successively interposes the cuvettes between a light
source and circuitry adapted to measure the phototransmittance of
the various samples in the cuvettes and thus determine chemical
species concentrations in the samples.
The analyzers described in the above-referenced patent applications
permit a substantial reduction in the time required for the
analysis of large numbers of samples. Those analyzers are, however,
subject to certain disadvantages. For example, the sample-analysis
cavities, or cuvettes, must be cleaned very carefully between runs
to avoid cross-contamination of samples, corrosion of the cuvettes
themselves, and darkening of the cuvette windows resulting from
exposure to dyes, film-forming liquids, and the like. Also, such
analyzers are not well adapted for certain analytical procedures
--as, for example, where it is desired to remove the samples
rapidly from the cuvettes, transport the samples to a heating zone
or incubation zone, and then rapidly reload the samples in a
photometric analyzer for reanalysis.
It is, therefore, a general object of this invention to provide a
photometric analyzer wherein successive samples are analyzed with
little or no cross-contamination of the samples, contamination of
the rotor, or run-to-run deterioration of the light-transmitting
properties of the analyzer rotor.
It is another object of this invention to provide a modified
photometric analyzer rotor adapted for use with removable
cuvettes.
It is still another object to provide an arrangement whereby a
multiplicity of removable cuvettes can be transported as a group,
installed in the above-mentioned modified rotor as a group, and
removed from the modified rotor as a group.
Other objects of the invention will be apparent from examination of
the following description and the appended drawings.
SUMMARY OF THE INVENTION
In accordance with my invention, the photometric analyzer rotor is
formed with a coaxial annulus formed with a circular array of
recesses extending radially outward from the inner peripheral
surface thereof for the reception of removable cuvettes. The
typical cuvette is a hollow, rigid, elongated body exteriorly
engaged by a flange and having a closed, light-transmitting end
portion. Mounting of a cuvette in one of the recesses brings said
end portion into registry with axially aligned light-transmitting
means carried by the rotor. Rotation of the rotor successively
interposes the cuvettes and their respective light-transmitting
means between a light source and a photodetector whose output is
fed to circuitry for measuring the light absorbency of said end
portions of the cuvettes.
To facilitate handling as a group, the cuvettes may be affixed to
the face of a flexible belt, the center-to-center spacing of the
affixed cuvettes corresponding to that of the recesses in the rotor
annulus.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram, partly in section, of a photometric
solution analyzer designed in accordance with this invention.
FIG. 2 is a series of four sectional views of a removable,
double-function cuvette designed for use in a system of the kind
shown in FIG. 1. The views illustrate the positions assumed by
liquids in the cuvette during four successive stages of a normal
operation of the system.
FIG. 3 is a perspective view, partly in section, of a
belt-and-cuvette assembly designed for use in the system shown in
FIG. 1.
FIG. 4 is a perspective view, partly in section, of an alternative
form of the assembly shown in FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, one form of this invention includes a rotor 1,
which is in the form of a flat-bottomed bowl having an axis of
rotation. The bowl is formed with an axially extending sidewall 2,
or annulus, coaxial therewith. As shown, the base of the bowl is
supportably mounted to a rotatable shaft 3 which in turn is
connected to any suitable drive means (not shown) for rotation of
the rotor about said axis.
The inner peripheral surface 4 of the annulus 2 is bored and
counterbored to form a recess which extends radially outward toward
the outer peripheral surface 6 of the annulus. The recess is
proportioned to receive an end of a cuvette 8. The cuvette is
formed with an exterior, annular, medial flange 19 which seats
snugly in the counterbore when the cuvette is in normal operating
position, as shown.
The cuvette 8 is a hollow and rigid body composed of transparent or
translucent material, such as glass or plastic (e.g., nylon,
Teflon, polyethylene, polypropylene). The cuvette preferably is
formed by standard molding techniques. For example, the cuvette
shown in FIG. 1 can conveniently be fabricated by combining two
molded and similar cup-shaped members, each having an exterior
flange coplanar with its open end. These members can be cemented
together, flange-to-flange, to form the cuvette 8. When the cuvette
is in operating position, a closed, light-transmitting end portion
7 thereof is in registry with axially aligned light-transmitting
means 10 carried by the annulus. The means 10 may comprise axially
aligned through-going openings (as shown in FIG. 1), transparent
windows, light-transmitting fibers, or the like.
Still referring to FIG. 1, the internal medial portion of cuvette 8
is provided with a transversely extending barrier 11. The barrier
is ramp-shaped in cross section, the bass of the ramp being affixed
to the cuvette.
The cuvette 8 is positioned in the annulus with its
barrier-containing portion lowermost. Thus, the barrier extends
both upwardly from the floor of the cuvette and part way toward the
opposite wall, presenting a sloping surface to any liquid in the
uninserted chamber 9 of the cuvette and an essentially vertical
face to any liquid in the inserted chamber thereof. At a selected
speed of the rotor, centrifugal force will cause liquid to flow
radially outward from chamber 9, over the barrier, but the barrier
prevents flow in the opposite direction whether the rotor is
rotating or at rest.
As shown, the normally uppermost surface of cuvette chamber 9 is
provided with a port 12 at a point radially inward from the barrier
11. As will be described, this port is provided for the
introduction of samples and reagents.
For simplicity, the rotor 1 has been described in terms of a single
cuvette mounted in a single recess in the annulus 2. The rotor
will, however, normally be provided with many recesses of the kind
described, each for the reception of a cuvette 8. Rotation of the
rotor interposes each of the cuvettes in turn between a photometric
light source and a photodetector, both of which are positioned to
align with the light-transmitting means 10 associated with each
cuvette. The light source, the photodetector, and the output
circuitry associated therewith for measuring the light-absorbency
of each cuvette are described in detail in aforementioned
application Ser. No. 784,739 and will not be described here as they
do not constitute a part of this invention.
In a typical operation of the system of FIG. 1, the rotor 1 is
loaded with cuvettes 8, which are oriented as shown. With the rotor
at rest, a liquid sample is introduced to the chambers 9 through
the ports 12. The rotor then is rotated to a predetermined speed
transferring the samples to the end portions 7. One or more
reagents then are admitted to the chambers 9 through ports 12, and
the rotor operated at a speed transferring them into the end
portions 7, where they blend with the sample, providing an
analytical mixture whose absorbance is then determined.
Referring to FIG. 2, the sequence of operations just described is
illustrated in terms of a cuvette which is functionally similar to
that described. In FIG. 2, the sample is designated as 13 and the
reagent as 14. The path of the light beam is indicated by an arrow.
It will be noted that in the embodiment shown in FIG. 2 the cuvette
chambers and the barrier are formed as an integral unit. It will
also be noted that in cuvettes of the kind shown in FIGS. 1 and 2,
the chamber 9 serves the function of the so-called transfer disc
described in the above-referenced patent applications.
It will be understood that my invention is not limited to the use
of any one type of cuvette, such as the two-chamber type shown in
FIGS. 1 and 2. As indicated in FIG. 3, for example, the cuvettes
may be single chambers 15 having flat upper and lower faces joined
to an arcuate side wall and having an open end coplanar with an
external rectangular flange. As shown, a lower edge 16 of the
flange extends inwardly and upwardly in the shape of a ramp to
serve as the above-mentioned barrier. Alternatively, as indicated
in FIG. 4, the barrier may be in the form of an external tape 20
closing all but a small upper portion of the mouth of a
single-chambered cuvette.
Again, cuvettes of the type illustrated in FIGS. 1 and 2 may be
provided with a succession of barriers 11 and, if desired, with a
series of corresponding ports 12 for the introduction of
liquids.
The above-described combination of removable cuvettes and an
analyzer rotor adapted for using the same obviates to a large
extent the contamination, corrosion, and window-darkening problems
sometimes encountered with rotors whose cuvettes are cavities
molded, machined, or otherwise formed in the rotor body.
Preferably, the removable cuvettes are formed of an inexpensive
material permitting discard of the cuvettes after several uses or
even a single use.
To facilitate the transport, insertion, and removal of a
multiplicity of removable cuvettes, I have devised a special
belt-and-cuvette assembly, three forms of which are shown in FIGS.
2, 3, and 4, respectively. In each of these arrangements, cuvettes
are affixed to a face of a flexible belt 17, each cuvette having a
closed, light-transmitting end portion 7 extending away from said
face. As shown in FIGS. 3 and 4, the cuvettes are mounted in spaced
relationship, their center-to-center spacing on the belt
corresponding to the spacing of the cuvette-receiving recesses (5,
FIG. 1) in the annulus (2, FIG. 1). The cuvettes may be removably
attached to the belt or, if desired, permanently secured thereto.
In either case, the belt can be used (a) to transport,
simultaneously, a large number of properly oriented and spaced
cuvettes, (b) to guide the mounted cuvettes as a group into their
respective recesses in the rotor, and (c) to remove the installed
cuvettes as a group. Preferably, the belt is not disengaged from
the cuvettes following insertion of the latter but is installed or
removed along with the cuvettes. Consequently, in some embodiments
the cuvettes and the belts are molded as a continuous unit. If
desired, the belt assembly is composed of an inexpensive plastic
permitting discard of the assembly after a few uses or even a
single use. As indicated in FIGS. 3 and 4 the belt may be
perforated to provide ports for the introduction of liquids to the
affixed cuvettes.
Referring again to FIG. 2, the belt 17 is illustrated as mounted
between the confronting flanges of the mating halves of the cuvette
8. The belt may, for example, be friction-fitted in slots formed at
the interface of the flanges or may be cemented to the flanges. In
the embodiment shown in FIG. 2 the flange nearer the end portion 6
seats against the inner peripheral face of the annulus 2 when the
cuvette is mounted in the rotor. In the arrangement of FIG. 3, the
external flange of the cuvette is secured to the belt 17 and seats
against the inner surface of the annulus. In the arrangement of
FIG. 4, the cuvette is formed with an integral end flange. The body
of the cuvette is passed through a hole in the belt 17, with the
flange seating against the belt. The belt seats against the inner
surface of the annulus 2 when the cuvette is installed in the
rotor. The cuvette is exteriorly engaged by the belt, and the belt
may be described as a flange which seats against the annulus. In
still another embodiment (not shown) the cuvette is not formed with
an integral flange; instead, the mouth of the cuvette is positioned
flush against the belt and bonded thereto. Thus, the belt serves
each cuvette as a flange which seats against the annulus 2.
If desired the cuvette may be designed with its body portion
forming an angle of less than 90.degree. with its flange. This
permits the cuvette to be mounted with its end portion 7 lower than
its mouth, eliminating the need for a barrier to prevent outflow of
liquid from the cuvette when at rest. If desired, removable
cuvettes may be used in combination with transfer discs of the kind
referred to above.
The foregoing description is offered for illustrative purposes
only, and it is intended that this invention be limited only by the
scope of the appended claims.
* * * * *