US3831816A

US3831816A - Chemical syringe

Info

Publication number: US3831816A
Application number: US00374983A
Authority: US
Inventors: R Pauliukonis
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-06-29
Filing date: 1973-06-29
Publication date: 1974-08-27
Anticipated expiration: 1991-08-27

Abstract

A device with improved accuracy, repeatability and reliability in collecting a first fluid such as samples of blood in a syringe or other fluids of various volumes in a dispenser, including volumes of a few lambdas and up to a few ounces, and mixing first fluid volume with a second fluid volume ideally measured in quantities of multiples of 1 to 1,000 times the first fluid volume, which operates by means of a built-in positive displacement with cut-off by a reciprocating plunger containing a telescoping spring loaded piston rod assembly and entering a barrel filled with second fluid with provision of collecting a first fluid by suction into a receiver such as pipette through an elongated passage at the barrel end which can also serve as receiver for the first fluid, simultaneously the plunger moves up from the first discharge position to the second filling position. incorporating a means of filling the barrel only when the plunger is at the barrel top and the barrel is under partial vacuum until the plunger seal disengages the barrel rim to enter larger diameter end cap portion connected to a second fluid supply permitting an instantenous barrel filling with second fluid and means for control of volumetric displacement by cut-off when plunger starts to descend closing the barrel rim by the plunger seal and subsequently during downstroke pressurizing second fluid trapped in the barrel to simultaneously disengage the piston rod end from the elongated passage at the barrel end discharging the fluids mixed from the barrel during descend of the plunger and also washing the discharge passage with surplus of second fluid exhausting from the barrel after the first fluid was discharged under pressure of the second fluid therefrom by piston rod reentering the elongated passage by the force of a spring when the pressure of the second fluid dropped at the end of the plunger downstroke rendering the device ready to repeat the cycle of simultaneous filling of two different fluids on upward motion of the plunger and their mixing during the discharge on downward plunger motion, such motion controlled externally by mechanical or electromechanical means such device including volumetric adjustment of second fluid discharge therefrom.

Description

United States Patent [191 Pauliukonis 11] 3,831,816 [451 Aug. 27, 1974 CHEMICAL SYRINGE [76] Inventor: Richard S. Pauliukonis, 6660 Greenbriar Dr., Cleveland, Ohio 44130 22 Filed: June 29,1973 21 Appl. No.: 374,983

[56] References Cited UNlTED STATES PATENTS 3,682,174 8/1972 Cohen 128/218 M Primary Examiner-Stanley H. Tollberg 5 7 ABSTRACT A device with improved accuracy, repeatability and reliability in collecting a first fluid such as samples of blood in a syringe or other fluids of various volumes in a dispenser, including volumes of a few lambdas and up to a few ounces, and mixing first fluid volume with a second fluid volume ideally measured in quantities of multiples of l to 1,000 times the first fluid volume, which operates by means of a built-in positive displacement with cut-off by a reciprocating plunger containing a telescoping spring loaded piston rod assembly and entering a barrel filled with second fluid with provision of collecting a first fluid by suction into a receiver such as pipette through an elongated passage at the barrel end which can also serve as receiver for the first fluid, simultaneously the plunger moves up from the first discharge position to the second filling position. incorporating a means of filling the barrel only when the plunger is at the barrel top and the barrel is under partial vacuum until the plunger seal diseng'ages the barrel rim to enter larger diameter end cap portion connected to a second fluid supply permitting an instantenous barrel filling with second fluid and means for control of volumetric displacement by cut-off when plunger starts to descend closing the barrel rim by the plunger seal and subsequently during downstroke pressurizing second fluid trapped in the barrel to simultaneously disengage the piston rod end from the elongated passage at the barrel end discharging the fluids mixed from the barrel during descend of the plunger and also washing the discharge passage with surplus of second fluid exhausting from the barrel after the first fluid was discharged under pressure of the second fluid therefrom by piston rod reentering the elongated passage by the force of a spring when the pressure of the second fluid dropped at the end of the plunger downstroke rendering the device ready to repeat the cycle of simultaneous filling of two different fluids on upward motion of the plunger and their mixing during the discharge on downward plunger motion, such motion controlled externally by mechanical or electromechanical means such device including volumetric adjustment of second fluid discharge therefrom.

12 Claims, 3 Drawing Figures CHEMICAL SYRINGE This invention relates to mixing equipment, and more specifically to the equipment used with various chemicals requiring mixing of two liquids of different nature in precise quantities repeatedly for subsequent service or for analytical studies.

Syringes representing present state of the art in this type of equipment are incapable of providing accurate, repeatable and reproduceable operation because they either employ a unidirectional cycle for simultaneous suction of sample and of reagent in separate individual compartments interlocked by valves each complex in its design and subject to volumetric efficiencies which as a whole can not physically provide unit operation of dependable performance, or they are made to perform separately collecting sample first then mixing such sample with reagent taken separately in a receiver with no toriously inaccurate results.

A syringe that would alleviate above mentioned shortcomings has been invented. The object of the present invention is therefore to provide a syringe design that advances superior performance characteristics and permits a solution to an age old problem of accurate measurements and mixing of two different liquids precisely in a repeated cycle.

A further object is to provide less complex design entailing such control capability by elimination of components and of steps in sample collection and in mixing such sample with appropriate reagent simultaneously in a syringe which is simple to make and to operate.

Another object of this invention is to provide a syringe which incorporates washing capabilities of sample cavities by reagent outflow at the cycle end to intensity cleanness and to prevent sample contamination in automatic sequential system operation involving multiple sample collection and accelerated analytical testing within novel techniques.

Devices of this type which require fewer components for syringe construction and operation, and improve ultimate performance of the system are obviously desirable.

These and other objects and advantages of the invention will become more fully apparent from the following description of the embodiment of the invention, taken together with the accompanying drawings:

IN THE DRAWINGS FIG. 1 identifies a cross-section of the syringe with components positioned at the end of the suction cycle with plunger extended.

FIG. 2 shows the same syringe with components positioned during the discharge of syringe prior to the cycle completion with plunger retracted and piston rod withdrawn from discharge passage'opening leading to the pipette for fluid exhaust. I

FIG. 3 identifies the same syringe at the end of the cycle with plunger retracted and piston rod positioned inside fluid passage opening after fluid discharge, ready to start suction inside pipette by the piston rod and inside syringe barrel by the plunger during the next cycle;

Shown in FIG. 1 is a syringe housing with a barrel ll of elongated configuration with one open end 12 counterbored by a cavity 13 which continues inwardly to terminate wth a shoulder 14 having central smaller diameter fluid passage opening 15 exiting at the other end 16 which in the illustrated case retains a pipette 17 for sample collection from a test tube 18. Open end 12 adaptable to be closed by an end cap 19 having central opening 20 with O-ring seal 35 shows a plunger 21 with telescoping piston-rod assembly 44 therein in the extended position, and plunger seal 22 disengaged from the close fitting engagement inside counterbore 13 while a piston rod 23 of a piston 24 situated inside coaxial plunger blind-end opening 25 has piston rod end 26 still engaged inside opening 15 to block fluid communication therethrough. A side port 27 supplying the reagent into syringe enters the end cap 19 to communicate with a counterbore 28 coaxially entering end cap open end 29 which is provided with threads 30 adaptable to close open end 12 of barrel l1 likewise threaded by mating threads 30-a and, in the illustrated case, showing a gap 31 between end cap face 32 and barrel shoulder33 at which threads 30-a end, identifies means for control of volumetric discharge of reagent from the barrel cavity 13 during plunger down stroke in operation. With the gap 31 closed and shoulder 33 positioned tight against the end cap face 32, the plunger face 34 would nearly bottom the barrel shoulder 14 when plunger is moved to rectract from the position shown in FIG. 1 to that shown in FIG. 3 displacing nearly all fluid that entered the cavity 13 of the barrel 11. With the gap 31 present as shown in FIG. 1, and with fixed plunger stroke length, the volume of reagent retained in the cavity 13 is proportional to the length of the gap 31 which can be made smaller or larger depending on needs to vary such volumetric reagent discharge from barrel cavity, with provisions of simple volume adjustment identified hereby. Means other than those identified to change volumetric displacement can easily be incorporated herein without significantly affecting the operation of this device. The fact remains however that the syringe includes means for volumetric change should such volume change be needed, without resorting to more complicated volume adjustments. The syringe when assembled without the gap 31 and shoulder 33 against face 32 could be used with or without volumetric adjustment of reagent discharge from the barrel cavity 13, and it would displace less volume when assembled as. illustrated in FIG. '1 with gap 31 shown as compared with volumetric displacement without gap 31 as shown in FIG. 3, when plunger stroke length is fixed.

Returning back to FIG. 1 we see spring 36 abutting blind plug 37 with air vent hole 38 of the plunger operating end 39 at one spring end and piston 24 provided with appropriate seal 40 at the other spring end to maintain piston against shoulder 25-a of opening 25 and rod end 26 inside opening 15 for communication of port 27 via annular space 41 formed between counterbore 28 of end cap 19 and the plunger 21 end of which is disengaged from cavity 12 permitting an instantaneous feeding of the barrel with reagent every time plunger is pulled out of the seat at the end of suc-' tion stroke. The discharge of the reagent from the barrel cavity can not take place until the plunger becomes depressed to change the direction. and to reengage the open end 12 of the barrel cavity 13 upon retraction of plunger during discharge stroke cutting off an exact amount of fluid at the rim of barrel cavity during the initiation of such discharge cycle and compressing this fluid volume during down stroke sufficiently to exert ample force over piston side 42 provided .with piston rod 23 and facing reagent under pressure to move upward during plunger down-stroke simultaneously opening fluid exhaust passage rather automatically as the reagent is normally incompressible and the downstroke of plunger is expected to exert substantial force for this automatic fluid exhaust control from within providing novel means for controlled and repeatable performance of syringe with precision unattainable henceforth. This is clearly illustrated in FIG. 2 which shows the same syringe with components positioned to permit reagent discharge prior to the cycle completion via dis charge opening 15 leading to pipette 17 for exhaust into a receiver 43 for further analysis by other instruments in an automatic system, designated to perform analytical studies of blood or other two component chemicals. In particular this is evident from the fact that the spring 36 in FIG. 2 is compressed due to the piston 24 upward motion caused by reagent pressure inside cavity 13 entering plunger opening 25 for acting over piston face 42 with resultant axial motion against spring 36 for as long as the plunger descends during the downstroke cycle maintaining the piston 24 under pressure and piston rod end 26 disengaged from opening 15 to ascertain fluid discharge via pipette 17. The reagent supply port 27 in FIG. 2 identifies direct communication with annulus 41 formed between plunger 21 and end cap 19 counterbore 28 but separated from entering barrel cavity 13 by plunger seal 22 at one end and from exiting into the atmosphere via openig 20 at the other end by end cap seal until the position of plunger changes to that shown in FIG. 1 at which the barrel cavity becomes instantaneously filled during filling stroke described when discussing FIG. 1. To note is the fact that the spring 36 when compressed as shown in FIG. 2 exerts a biasing force constantly acting against piston 24, seeking the opportunity to return the piston 24 with rod 23 to the original position with compression spring 36 extended as that shown in FIG. 1 or FIG. 3. During the spring compression from that shown in FIG. 1 to that shown in FIG. 2 the hole 38 permits air venting rendering unobstructed piston 24 upward motion and spring 36 compression as that shown in FIG. 2. Gap 31 shown in FIG. 2 identifies volumetric adjustment in existence during this cycle phase.

FIG. 3 identifies the same syringe at the end of the plunger retraction cycle wherein the plunger 21 has bottomed at the barrel shoulder 14 or nearly touches it when the plunger downstroke externally controlled by mechanical means is at maximum and the pressure of the reagent has dropped below the spring biasing force permitting spring 36 to relax by extending and by pushing simultaneously the piston 24 with rod 23 attached permanently thereto to reenter discharge opening 15 in final steps of the return cycle and to expel all residue of reagent that may have accumulated therein upon discharge of the syringe during the interim period describedwhen discussing conditions identified in FIG. 2. Because the design of the piston rod 23 considered a close sliding fit entailing sealing characteristics when inside opening 15, in particular by purposely making rod end 26 snuggly fitting inside the opening 15, the separation and the discharge as well as suction by piston rod end within the opening 15 is thereby insured. Because the diameteral difference between rod end 26 and the rod 23 is very small the drawings identify only the length of rod end but not the diameteral differences. Also not shown is a diametral recess of the fluid discharge passage identified by 15 which in some special cases may be made slightly larger than the diameter of opening 15, in particular in cases requiring suction level control of pipette or needle. In practice therefore the piston rod end 26 in most applications may slide inside fluid discharge opening 15 snugly with rod of close fitting diameter irrespective of the rod end position therein resulting in full suction and sealing along the whole discharge passage length, and in some applications it may be made to enter discharge opening 15 having snug diameteral fit at the beginning and partway inwardly and thereafter proceed further inwardly relatively free inside a recess of the discharge passage length. I

For cases requiring large opening 15 for large capacity instruments, the rod end 26 may even employ an O- ring (not shown) to facilitate positive suction of large flows through the pipette. However, because in majority of cases such pipette collects rather small blood samples varying between 10 and 50 lambdas of volume per cycle and utilizes small diameters limited sometimes to capillary sizes, the piston rod end 26 may be produced with sealing capabilities even without the use of O-ring seals if made from plastics, glass or other suitable materials for rod construction normally used when building anticorrosive laboratory equipment. Obviously, this device would function without pipette as well by storing fluid in opening 15. The pipette 17 in such cases can be replaced by an attachment (not shown) containing appropriate directional check valves, and the syringe may become a dispenser device for mixing two different liquids in one container, mechanically operated by external means.

The invention is not restricted to the slavish imitation of each and every one of the details described above which have been set forth merely by way of example with the intent of most clearly setting forth the teachings of the invention. Obviously, devices may be provided which change, eliminate or add certain structural or procedural details without departing from the invention. I

What is claimed is:

1. A device for mixing precisely two different liquids in various quantities at fixed proportions comprising:

a housing means with fluid cavity and fluid supply and discharge means therein, plunger means inside said housing means including an intergral telescoping piston rod assembly and adaptable to be moved inside said housing means from first discharge position to second filling position by suction when plunger is urged to change such position by external device operating means, means for collecting and storing first liquid amount at fluid discharge means simultaneously when generating partial vacuum inside said cavity of said housing means for instantaneous filling of said cavity with second liquid volume when said plunger is in said filling position, means of maintaining two different liquids in said device after filling unmixed, means for discharging said fluids from said device via said discharge means during the position change of said plunger from said second filling position to said first dis-' charge position whereby said second liquid volume from said cavity is mixed thoroughly with said first liquid volume within said discharge means, automatic control means of said discharge during said position change from said second filling position to said first discharge position, said control means including said telescoping piston rod assembly whereby said piston is urged by the pressure of discharging second volume fluid to disengage said discharge means allowing said mixing of said second liquid volume with said first liquid upon such discharge caused by said plunger position change when urged by said external operating means, and means of adjusting volumetric quantities of liquids collected during said second filling cycle and mixed during said first discharging cycle, including means of precise liquid displacement from said cavity by cut-off controlled by said plunger inside said fluid cavity of said housing means, said cut-off with exact liquid volume trapped and pressurized in said cavity controlled during said position change from said second filling position to said first discharge position when said plunger is urged to change the direction of movement in said housing caused by external operating means of said device mechani cally forcing said plunger to descend inside said cavity displacing said second liquid volume there from, automatically opening liquid discharge passage controlled by said telescoping piston rod assembly urged to simultaneously ascend by said fluid pressure during said discharge cycle uncovering said discharge opening means automatically for said discharge of liquids mixed therefrom.

2. A chemical syringe for mixing two liquids in precise quantities comprising: a housing means including an elongated barrel with cavity therein and one end open and adaptable to be closed by an end cap and the other end provided with small fluid discharge opening passing centrally therethrough and adaptable to be connected to a pipette, an end cap having a central passage therethrough and a mouth for closing said open barrel end, a plunger means in said housing means ineluding internally telescoping piston rod assembly therein, said plunger slidably received in said central passage of said end cap and adaptable to enter snugly said open barrel end axially for sliding therein from first fluid discharge position by pressure to the. second fluid filling position by suction when plunger is moved to shuttle by external means, fluid supply port in said end cap for communication with said barrel cavity when said plunger is moved to ascend and to disengage said barrel open end at the end of said second fluid filling position allowing an instantenous barrel filling with first fluid of large volume, means for sample collection in said pipette of small liquid volume of second fluid when said plunger is moved from said first discharge position to said second filling position by suction created by piston rod end of said telescoping piston rod-assembly inside said fluid dischargeopening of said barrel, means for holding said first and said second fluids in their respective compartments separated for as long as said plunger is in said second filling position, means for mixcharge flow control by said telescoping piston rod assembly in response to said pressurization of said first fluid inside said barrel and for mixing said first with said second fluids during said fluid discharge accompanied by said piston rod ascent from said fluid discharge opening, including means for washing pipette at the end of discharge cycle by said first fluid during the automatic reentry of said piston rod end into said discharge opening when said plunger descent is stopped discontinuing said pressurization of said first fluid with accompanied action over said telescoping piston and said biasing force exceeding said. pressure force over said piston forcing return of said telescoping piston-rod assembly to the original position with piston rod fully ing said fluids upon fluid discharge via said small fluid extended inside said discharge opening and ready to begin new suction and filling cycle of both the pipette with sample fluid from a test tube and the barrel with large fluid volume from a reservoir.

3. A chemical syringe as in claim 2 wherein when said plunger is in said first discharging position, said first fluid is subjected to pressurization inside said barrel cavity exerting pressure force on said telescoping piston of said piston rod assembly urging said piston to move into the opposite direction thereby disengaging piston rod end from said discharge opening during said discharge cycle whereby said plunger is moved to descend inside said barrel by external means, said external means including a mechanical operator attached to said plunger operating end provided with a blind plug.

4. A chemical syringe as in claim 3 including a spring providing a biasing force to said telescoping piston-rod assembly inside said plunger when located therein abutting said piston at one spring end and said blind plug at the other spring end including an air vent hole in said plug, said spring exerting suffi'cient force over said piston to retain said piston rod assembly tight against a plunger shoulder with rod extended and rod end engaged inside said discharge opening when said plunger is in said second filling position and when said plunger is in said first discharge position pressurizing said first fluid inside said barrel, said piston rod assembly is forced to telescopingly slide into plunger opening against said spring thereby compressing it further, said telescoping sliding motion controlled automatically by said pressure of said first fluid on said piston surface exposed thereto in conjunction with fluid discharge speed as regulated by the position change of said plunger during said discharge cycle, said spring tending to return to the original less preloaded position automatically returning said piston rod end into engagement with said discharge opening of said barrel when said plunger is atthe end of said first discharge cycle and said first fluid pressure has dropped to that below of said biasing force of said spring.

5. A chemical syringe as in claim 2 wherein said barrel is adaptable to be adjusted within said engagement with said end cap providing volumetric displacement control of said first fluid discharge from said barrel cavity when said plunger stroke is fixed.

6. A chemical syringe as in claim 2 wherein said biasing force means are separated from'said first fluid inside said barrel cavity by seals.

7. A chemical syringe as in claim 2 wherein said fluid separation andholding first fluid inside barrel cavity and second fluid inside said pipette during said second filling cycle including seals in said plunger end and in said rod end, said rod end seal providing means for holding said first and said second fluids in their respective compartments separated for as long as said plunger is in said second filling position.

8. A chemical syringe as in claim 2 wherein said mixing of said first and said second fluid is accomplished during said first plunger discharge position when said plunger descends and said piston rod end ascends from said discharge opening allowing exhaust of said first fluid into said pipette before exiting into the receiver together with said second fluid forced by said first fluid pressure therefrom mixed, including washing said pipette by said first fluid flow therethrough.

9. A chemical syringe as in claim 2 including means for controlling sample collection inside pipette, said means including recess inside discharge opening facing pipette to facilitate free sliding fit of the piston rod end therein when plunger is at the end of said discharging cycle and the piston rod assembly is urged to reenter said discharge opening by said biasing force wherein when the plunger is in filling cycle, said plunger end seal enters said opening end adjacent said chamber cavity for sealing and pipette suction means of closer fit provided therein.

10. A device as in claim 1 for mixing two different liquids wherein the first fluid is collected by suction inside said discharge passage means and the second fluid is collected via fluid supply port entering large diameter end cap portion inside said barrel cavity simultaneously when said plunger is urged to move upward, and mixing said first with said second fluids during said discharge stroke when said plunger is urged to move downward, said plunger motion controlled externally by mechanical means, said mechanical means urging said position change of said plunger in a reciprocating fashion continuously in a device dispensing mixed fluids automatically.

lll. A device as in claim 1 wherein said collecting and storing of said first liquid at fluid discharge means including an attachment containing directional check lected therein.

Claims

1. A device for mixing precisely two different liquids in various quantities at fixed proportions comprising: a housing means with fluid cavity and fluid supply and discharge means therein, plunger means inside said housing means including an intergral telescoping piston rod assembly and adaptable to be moved inside said housing means from first discharge position to second filling position by suction when plunger is urged to change such position by external device operating means, means for collecting and storing first liquid amount at fluid discharge means simultaneously when generating partial vacuum inside said cavity of said housing means for instantaneous filling of said cavity with second liquid volume when said plunger is in said filling position, means of maintaining two different liquids in said device after filling unmixed, means for discharging said fluids from said device via said discharge means during the position change of said plunger from said second filling position to said first discharge Position whereby said second liquid volume from said cavity is mixed thoroughly with said first liquid volume within said discharge means, automatic control means of said discharge during said position change from said second filling position to said first discharge position, said control means including said telescoping piston rod assembly whereby said piston is urged by the pressure of discharging second volume fluid to disengage said discharge means allowing said mixing of said second liquid volume with said first liquid upon such discharge caused by said plunger position change when urged by said external operating means, and means of adjusting volumetric quantities of liquids collected during said second filling cycle and mixed during said first discharging cycle, including means of precise liquid displacement from said cavity by cutoff controlled by said plunger inside said fluid cavity of said housing means, said cut-off with exact liquid volume trapped and pressurized in said cavity controlled during said position change from said second filling position to said first discharge position when said plunger is urged to change the direction of movement in said housing caused by external operating means of said device mechanically forcing said plunger to descend inside said cavity displacing said second liquid volume therefrom, automatically opening liquid discharge passage controlled by said telescoping piston rod assembly urged to simultaneously ascend by said fluid pressure during said discharge cycle uncovering said discharge opening means automatically for said discharge of liquids mixed therefrom.

2. A chemical syringe for mixing two liquids in precise quantities comprising: a housing means including an elongated barrel with cavity therein and one end open and adaptable to be closed by an end cap and the other end provided with small fluid discharge opening passing centrally therethrough and adaptable to be connected to a pipette, an end cap having a central passage therethrough and a mouth for closing said open barrel end, a plunger means in said housing means including internally telescoping piston rod assembly therein, said plunger slidably received in said central passage of said end cap and adaptable to enter snugly said open barrel end axially for sliding therein from first fluid discharge position by pressure to the second fluid filling position by suction when plunger is moved to shuttle by external means, fluid supply port in said end cap for communication with said barrel cavity when said plunger is moved to ascend and to disengage said barrel open end at the end of said second fluid filling position allowing an instantenous barrel filling with first fluid of large volume, means for sample collection in said pipette of small liquid volume of second fluid when said plunger is moved from said first discharge position to said second filling position by suction created by piston rod end of said telescoping piston rod-assembly inside said fluid discharge opening of said barrel, means for holding said first and said second fluids in their respective compartments separated for as long as said plunger is in said second filling position, means for mixing said fluids upon fluid discharge via said small fluid discharge opening in said barrel when said plunger is moved to descend pressurizing said first fluid inside said barrel when said plunger end reenters said barrel open end during the discharge cycle and continues downward, means for an automatic opening of said discharge passage by disengaging said piston rod end therefrom when first fluid pressure is large enough to overcome biasing force means holding said piston rod end in said discharge opening including means for discharge flow control by said telescoping piston rod assembly in response to said pressurization of said first fluid inside said barrel and for mixing said first with said second fluids during said fluid discharge accompanied by said piston rod ascent from said fluid discharge opening, including means For washing pipette at the end of discharge cycle by said first fluid during the automatic reentry of said piston rod end into said discharge opening when said plunger descent is stopped discontinuing said pressurization of said first fluid with accompanied action over said telescoping piston and said biasing force exceeding said pressure force over said piston forcing return of said telescoping piston-rod assembly to the original position with piston rod fully extended inside said discharge opening and ready to begin new suction and filling cycle of both the pipette with sample fluid from a test tube and the barrel with large fluid volume from a reservoir.

4. A chemical syringe as in claim 3 including a spring providing a biasing force to said telescoping piston-rod assembly inside said plunger when located therein abutting said piston at one spring end and said blind plug at the other spring end including an air vent hole in said plug, said spring exerting sufficient force over said piston to retain said piston rod assembly tight against a plunger shoulder with rod extended and rod end engaged inside said discharge opening when said plunger is in said second filling position and when said plunger is in said first discharge position pressurizing said first fluid inside said barrel, said piston rod assembly is forced to telescopingly slide into plunger opening against said spring thereby compressing it further, said telescoping sliding motion controlled automatically by said pressure of said first fluid on said piston surface exposed thereto in conjunction with fluid discharge speed as regulated by the position change of said plunger during said discharge cycle, said spring tending to return to the original less preloaded position automatically returning said piston rod end into engagement with said discharge opening of said barrel when said plunger is at the end of said first discharge cycle and said first fluid pressure has dropped to that below of said biasing force of said spring.

6. A chemical syringe as in claim 2 wherein said biasing force means are separated from said first fluid inside said barrel cavity by seals.

7. A chemical syringe as in claim 2 wherein said fluid separation and holding first fluid inside barrel cavity and second fluid inside said pipette during said second filling cycle including seals in said plunger end and in said rod end, said rod end seal providing means for holding said first and said second fluids in their respective compartments separated for as long as said plunger is in said second filling position.

11. A device as in claim 1 wherein said collecting and storing of said first liquid at fluid discharge means including an attachment containing directional check valves.

12. A device as in claim 11 including sealing means for improved suction of collecting said first fluid and for separating said first from said second fluids collected therein.