US3264474A - Phosphorimeter attachment for fluorometer - Google Patents

Description

g- 2, 1956 L. R. HEISS 3,264,474

PHOSPHORIMETER ATTACHMENT FOR FLUOROMETER Filed Sept. 9, 1963 2 Sheets-Sheet 1 M 36 tilt 33 l 0 0 o g I Ill 0| l o 21 22" 2,75 12 I 'll I 25 6 /13 I I INVENTOR LOU/S R. Helss ATTORNEY 1955 L. R. HEISS 3,264,474

PHOSPHORIMETER ATTACHMENT FOR FLUOROMETER Filed Sept. 9, 1963 2 sheets sheet 2 Laws R. HE/ss ATTORNEY United States Patent 3,264,474 PHUSPHORIMETER ATTACHMENT FOR FLUOROMETER Louis R. Heiss, Silver Spring, Md, assiguor to American Instrument Company, llnc., Silver Spring, Md. Filed Sept. 9, 1963, Ser. No. 307,392

' 1 Claim. (Cl. 250-71) This invention relates to apparatus for measuring luminescence, and more particularly to an attachment for use with a fluorome-ter to permit the fluorometer to be used for phosphorimetry studies.

A main object of the invention is to provide a novel and improved phosphorimeter attachment for a fluorom eter, said attachment being arranged to freeze a sample and to enable its phosphorescence to be measured, the attachment ibeing simple in construction, being compact in size, and being easy to install in a fluorometer of standard design.

A further object of the invention is to provide an improved phosphorimeter attachment for a fluorometer, said attachment being arranged to freeze a chemical or other sample on .a paper lattice or in a suitable transparent cuvette, and being provided with rotating shutter means so that when mounted in cooperative relationship with the light source and photoelectric sensing means of a conventional electronic fluorometer, the phosphorescence of the sample can be easily and accurately measured.

A still further object of the invention is to provide an improved phosphorimeter attachment for a fluorometer, said attachment being arranged to freeze a sample by means of liquified gas but without submerging the sample directly in the liquified gas, thus preventing loss of exciting or phosphorescent energy by absorption in the walls of the liquid gas container.

A still further object of the invention is to provide an improved phosphorimeter attachment for a fluorometer, said attachment employing liquified gas to freeze a sample being tested for phosphorescence, the attachment being arranged so that the gas evaporates and flows in a dry state under positive pressure through the sample housing and around the sample container in .a manner to prevent any moisture-laden air from entering the sample housing or the adjacent portions of the instrument casing.

Further objects and advantages of the invention will become apparent from the following description and claim, and from the accompanying drawings, wherein:

FIGURE 1 is a front elevational view of a fluorometer provided with a phosphorimeter attachment according to the present invention.

FIGURE 2 is a diagrammatic horizontal cross-sectional view showing the optical relationship of the light source and photoelectric sensing means of the fluo-rometer of FIGURE 1 with the sample-containing housing and r0- tati-ng shutter assembly of a phosphorimeter attachment of the present invention, arranged for a liquid sample in a cuvette.

FIGURE 3 is a fragmentary diagrammatic horizontal cross-sectional view of the sample housing and rotating shutter assembly of a modification of the phosphorimeter attachment of the present invention arranged for supporting a sample under investigation on a paper lattice.

FIGURE 4 is an enlarged vertical cross-sectional view taken through the phosphorimeter attachment shown in FIGURE 1.

FIGURE 5 is a further enlarged fragmentary cross-sectional view, taken substantially on line 5-5 of FIG- URE 4.

FIGURE 6 is an enlarged side elevational view of a sample-supporting assembly corresponding to the modification diagrammatically illustrated in FIGURE 3.

I 3,264,474 Patented August 2, 1966 FIGURE 7 is a front elevational view of the samplesupporting assembly of FIGURE 6.

FIGURE 8 is a horizontal cross-sectional view taken substantially on line 8-8 of FIGURE 7.

US. Patent No. 3,092,722 to Hugh K. Howerton, issued June 4, 1963, and entitled Spectro-Phospho-rescence Measuring Instrument, describes a system for analyzing the phosphorescent response of substances excited by radiation by eliminating the effects of fluorescence and light scattering. This is accomplished by delaying the examination of the emission radiation until substantially complete decay of the fluorescence has taken place, but while there is still substantial phosphorescent emission. As a typical apparatus for achieving the desired results, the above patent teaches the use of a rotating masking cylinder surrounding the sample cell, said cylinder having perforations spaced in a manner to first admit exciting radiation to the sample cell, and after the time delay required for the decay of fluorescence and light scattering effects, to expose the sample cell to a photo-sensitive detection device adapted to measure the phosphorescent emission. The above patent further teaches that the sample may be submerged in liquid nitrogen in a Dewar flask during excitation.

However, it has been found that there is a substantial loss of excitation and phosphorescent energy by absorption in the walls of the quartz Dewar flask and in the liquid nitrogen when the sample is directly immersed, as above described, and also under some conditions there is a tendency for moisture-laden air to enter the portions of the instrument adjacent the sample. Another disadvantage of said direct immersion is that it is difficult to measure relatively low amounts of phosphorescence, as would be obtained, for example, from a small known volume of a chemical spotted on a piece of fibrous supporting material, such as glass fiber paper, because of the abovementioned absorption losses. A prime purpose of the present invention is to overcome the above and other limitations presented in the .apparatus disclosed in US. Patent No. 3,092,722.

Referring to the drawings, 11 designates a fiuorometer of substantially conventional design, mounted on a boxlike supporting base 12 which is provided at one side thereof with a horizontal shelf 13. The fluorometer 11 is provided with a vertical compartment 14- adapted to contain a sample cell which can be positioned to receive exciting radiation 17 from a radiant energy source 15, such as a lamp. A photosensitive device 16, such as .a photo cell or a photomultiplier unit is mounted in the fluorometer in a position to receive luminescent emission 18 from sample material in the cell. Suitable filters 19 and 20 may be mounted in any suitable manner respectively in the path of the exciting radiation 17 and the emission radiation 18.

In accordance with the present invention, a Dewar flask 21 is provided, said flask having the generally spherical lower main reservoir portion 22 communicating with the reduced vertical upstanding neck portion 23, of substantial length. The main reservoir portion 22 is supportingly mounted in the top rim portion of a rigid metal cylindrical shell 24, Which in turn is supported on the shelf 13. The Dewar flask has an exterior vertical side filling arm 25 (which communicates with the bottom of reservoir portion 22 by means of an inclined conduit portion 26 extending through an aperture in the supporting shell 24. The Dewar flask is internally silvered, and the side arm 25 is silvered up to the level of approximately the top of the bulb 22, as shown at 27. The side arm 25 rises to substantially the same level as the top of the neck portion 23.

A copper cooling rod 28 extends sealingly through a cork stopper 29 sealingly engaged in the top end of compartment 14 is formed with an aperture .31 vertically aligned with flask22. A sample housing 32 of insulating material depends through said aperture, being; threadedly engaged in a collar member 33 supported on' the top surface of horizontal top wall 30. Housing 32 is'provided with the respective apertures 34 and 35 located to pass the exciting radiation 17 and the emission ,10 mountedon collar 33 is the shutter driving motor 36 1 radiation 18, as shown in FIGURE 2. Vertically whose depending shaft 37 carries the depending vertical cylindrical shutter member 38 having the diametrically opposed shutter apertures 39, 39sequentially registerable with the admission and exit apertures 34 and 35 :as the shutter member rotates.

The top end of cooling rod 28 extends through a central aperture 51 in the bottom wall 52 of the heatinsulating housing 32. An insulating spacer washer 53 may be interposed between said bottom wall 52 and the cork stopper 29.

The top portion of cooling rod 28.is formed with an axial bore 40 communicating at its lower end with a pair of transverse diametral passages 41 and 42 formed.

in the rod andlocated just-below the bottom end of stopper :29, as shown in FIGURE 5. The top end of rod 28 is internally threaded to receive the externally threaded depending axial hollow stud portion 43 of a cylindrical sample cell carrier cup 44. Said sample carrier cup has an axial bore 45 communicating with the.

bore of stud portion 43 and with the top bore 40 of rod 28. The cup 44 is adapted to loosely receive a sample cuvette 46 of quartz or other transparent material, with suflicient clearance to allow free flow upwardly of dry nitrogen gas around the cuvette and outwardly into the adjacent portions of the apparatus.

The sample carrier cup 44 is formed with a horizontal slot 47 subtending an angle greater than the angle between apertures 34 and 35. Said slot 47 is located so as to register with both said "apertures and to allow the.

passage of the exciting radiation 17 from admission aperture 34 into the cuvette 46 anda passage of the emission radiation from a sample therein through the exit aperture 35. Thus, in FIGURE 2, apertures 34 and 35 are separated by an angleof 90 and slot 47 subtends-an angle substantially greater than 90 and is located to simultaneously register with both apertures 34and 35.

As shown in FIGURES 4 and 5, the level of the liquid nitrogen 48 in the Dewar flask 21 .is substantially belowthe lowermost transverse passage 42, as indicated at 49, whereby to define a gas evaporation space 50 in the top portion of neck 23; The liquid nitrogen evaporates in space 50 and passes upwardly as a gas under a small positive pressure (since the device is at room temperature) through passages42 and 41 and the aligned bores and .into the sample carrier cup 44. The copper rod 28 conducts heat away from the cup 44.- The upwardly moving dry nitrogen gas serves two purposes:

(a) It provides a cooling action, whereby to reduce. the temperature of the carrier cup to a value of the,

4. material 61 carrying a spot of sample substance ina position to be analyzed in the attachment.- The holder 60 c'omprisese a vertical rigid fmain block 62. formed with a horizontal bottom groove 63. and having a relatively long upstanding main vertical arm 64 atone side; of the groove and a relatively short upstanding ;arm.65 i the other side. The block'62 is provided .withia depending externally'threadedhollow stud 66, identical to hol- I low stud 43, whose-bore communicates with a vertical bore 67 leading to groove 63; A removable retaining sleeve 68 of generally C-shaped horizontal cross-section 1 is slidably engageable around arm 64 and is adapted to secure the sample-carrying paper member 61 between 7 arm 64 and, the vertical main wall! 69 of. thexsleeve.

Said main" wall 69 is provided .with an aperture 70 located at the same height above .the mounting. stud as aperture 47 of the cuvette holder, 44,- to expose the sample spot. on paper member. 61. The top end of wall69flis provided ,witha gripping head 71.

The holder 60, containing the" paper samplecarrier. 61, is adapted to be mounted in the attachment in the same manner asthe cuvette holder 44 above describedi Thus, as shown in FIGURE 3,the holder 60 is positioned so that the apertured 'wall 69 is substantially at an angle of 45. to the incident exciting. radiation 17 f and 'so that the ,excitingxradiation 1'Zwill pass throughthe aperture 70: and impinge on the spot of sample materialon the papercarrier .61, causing the emission radiation .18 to'emerge from the spot and eventually pass through the exit aperture '35 .of housing 32.

While certain specific embodiments of Ea phosphorimeter attachment fora fluorometer have been dis-.-

closed in the foregoing description, it will be .understood 3 that various. modifications withinithe spirit of the invention may occur to those ski1led.in;the art. Therefore it is intended that no limitationsbe placed on the invention except as defined by" the scope of the appended claim.

What is claimed is:

A phosphorimeter attachment for use with'a fiuorometer comprising a support, a sample cell housing mounted I on said support, said housing having a main peripheral walljand a bottom wall and being provided in itsmain peripheral wall;with aperture, means to receive exciting radiation and to allow the exitof luminescent radiation from a sample .contained in. said ihousing a cooling vessel adapted to contain liquified gas disposed subjacent saidhousing, a substantially straightupright heatconducting metal'rod in said cooling vessel, said rod extending upwardly sealingly through the top end of said vessel and through the .bottom wall of I said sample cell housing, and a sample receiver supportingly secured to i the :topend of said rod within said sample celllhousing, said sample receiver having an: upstanding wall provided-with a light-transmitting aperture registering with said aperturemeans, saidrod being formed with a gas passage in its upper portion opening at the top end of therod and with, a transverse passage located immediately below the top end of the .vessel. in communication with said gas passage and the top portion of the interior'of said vessel. communicatively connecting the top 1 portion :of the interior ofthe vessel with the interior of made of heat-insulating material to further reduce the possibility of such condensation.

FIGURES 6, 7 and 8 illustrate the details of a modi-. fied form of sample holder, designated generally at 60, adapted to support a piece of. paper or other absorbent said. sample receiver.

References Cited by the Examiner 1 UNITED STATES PATENTS 2,948,127 7/1956 Carter 25071.5 X 3,049,620 8/1959 George et' al. 250715 3,092,722: 2/1960 Howerton. 25077 3,092,974 7/ 1960 Haumann et al. ,62-50 RALPH G.=NILSON, Primary Examiner.

S. ELBAUM,; Assistant Examiner.

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