EP0646236A1

EP0646236A1 - A method and system for sampling and determining the presence of contaminants in containers

Info

Publication number: EP0646236A1
Application number: EP93914003A
Authority: EP
Inventors: Stephen J. Macdonald; Daniel B. Dennison; David H. Fine; David R. Rounbehler; Gregory J. Wendel
Original assignee: Coca Cola Co
Current assignee: Coca Cola Co
Priority date: 1992-06-01
Filing date: 1993-05-19
Publication date: 1995-04-05
Also published as: NZ253476A; CA2135878A1; KR950702028A; CN1080723A; IL105814A0; AU4382993A; TR28391A; EP0646236A4; RU2125721C1; WO1993024825A1; BR9306456A; AR248316A1; AU672011B2; MX9303152A; HU9403443D0; KR0184531B1; JPH07507393A; ZA933728B; HUT75420A; NO944597L

Abstract

A method of sampling and determining the presence of certain residues of contaminants in containers comprising the steps of: injecting compressed air into said containers in order to displace at least a portion of the contents thereof; evacuating a sample of the container contents so displaced by applying suction thereto; and analyzing the sample evacuated to determine the presence or absence of the certain residues therein. The compressed air is injected through a nozzle into an opening in the containers to displace a portion of the container contents and form a sample cloud outside of the container. The sample cloud is then at least partially evacuated by suction and the sample is analyzed for the presence of contaminants such as nitrogen containing compounds or hydrocarbons. In one embodiment about 90 % of the sample evacuated is diverted from the analyzer and recirculated into the air injector. A wide range of potential contaminants are detectable if beverage bottles are stored uncapped, prior to testing to give beverage product volatiles sufficient time to dissipate.

Description

A METHOD AND SYSTEM FOR SAMPLING AND DETERMINING THE PRESENCE OF CONTAMINANTS IN CONTAINERS

BACKGROUND OF THE INVENTION

The present invention relates to a container inspection system for sampling and determining the presence of certain substances, such as residues of contaminants within containers such as glass or plastic bottles. More specifically, the present invention relates to an improved sampling and analyzing system and method for determining the presence of residues of these contaminants in containers such as beverage bottles rapidly moving along a conveyor past a test station in a container sorting system.

In many industries, including the beverage industry, products are packaged in containers which are returned after use, washed and refilled. Typically refillable containers, such as beverage bottles, are made of glass which can be easily cleaned. These containers are washed and then inspected for the presence of foreign matter.

Glass containers have the disadvantage of being fragile and, in larger volumes, of being relatively heavy. Accordingly, it is highly desirable to use plastic containers because they are less fragile and lighter than glass containers of the same volume. However, plastic materials tend to absorb a variety of organic compounds which may later be desorbed into the product thereby potentially adversely affecting the quality of the product packed in the container. Examples of such organic compounds are nitrogen containing compounds such as ammonia, organic nitrogen compounds, and hydrocarbons including gasoline and various cleaning fluids.

SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to provide a method and system for detecting the presence or absence of a wide range of specific substances - e.g., contaminants such as nitrogen containing compounds and hydrocarbons, in containers as the containers move rapidly along a conveyor on the way to or from a washer assembly or the like.

It is another object of the present invention to provide a system and method for sampling and analyzing residues in containers as they move along a conveyor without stopping the movement of the containers or impeding the movement in any way in order that high speed sampling rates of about 200 to 1000 bottles per minute may be achieved.

It is still another object of the present invention to provide a system and method for sampling and analyzing residues in containers moving along a conveyor without contacting the container being tested with any of the sampling and analyzing mechanisms.

It is yet another object of the present invention to provide a system and method for sampling and analyzing residues in containers moving along a conveyor without the physical insertion of any probes or the like into the containers.

It is a further object of the present invention to provide a system and method for detecting a wide range of contaminants in beverage bottles with minimum interference from volatiles of beverage ingredient residues ("product") in the bottles.

The objects of the present invention are fulfilled by providing a method of sampling and determining the presence of certain substances such as volatile residues in containers comprising the steps of: injecting fluid into said containers in order to displace at least a portion of the contents thereof; evacuating a sample of the container contents so displaced by applying suction thereto; and analyzing the sample evacuated to determine the presence or absence of the certain residues therein.

In a preferred embodiment the fluid injected into the containers is compressed air which is injected through a nozzle to provide an air blast within the interior of the container. This air blast creates a cloud of the vaporous contents of the container which emerges from its opening whereby it may be evacuated by suction from outside of the container to sample a portion of the container contents.

Injection of fluid and evacuation of sample may be continuous operations or may be performed in steps. If steps are utilized, the step of initiating the injection of fluid into the container preferably precedes in time the initiation of the step of evacuating a sample in order to provide time for the formation of the sample cloud. However, the performance of the steps of injecting and evacuating may slightly overlap in time. Alternatively, the steps of injecting and evacuation may be spaced in time but this is dependent on the rate of sampling desired. A still further alternative is to synchronize the steps of injecting and evacuating to occur simultaneously for the same duration.

In a preferred embodiment the injection of fluid from the nozzle and the suction applied by the evacuation means are continuously on at the test station. In this embodiment the containers or bottles are rapidly and continuously moved through the test station on a rapidly moving conveyor. The bottles are moved through the test station at a rate of 200 to 1000 bottles per minute. A rate of 400 bottles per minute is preferable and is compatible with current beverage bottle filling speeds. The desired test rate may vary with the size of the bottles being inspected and filled. The injector nozzle is disposed upstream of the direction of conveyor movement from the suction tube of the evacuator so the injection of fluid into each container slightly precedes in time the evacuation of the resulting sample cloud.

In another embodiment of the present invention a portion of the sample evacuated (about 90%) is diverted and the remaining portion of the sample passes to an analyzer for determination of the presence or absence of the certain residues. The purpose of diverting the first portion of the sample is to limit the amount of sample that passes to the analyzer to manageable quantities in order to achieve high speed analysis. In addition if the volume of the sample is too large it may foul or clog the detector. However, it is initially desirable to evacuate essentially the entire sample cloud to clear the area of the test station from the contents of that sample cloud to provide clean surroundings for the successive containers. This eliminates spurious carry over signals of residue (crosstalk of container contaminants) unrelated to the container being tested at a given point in time.

If desired the diverted portion of the first sample may be channeled through an optional air filter and recirculated into the compressed air being injected into subsequent containers to arrive at the test station. This provides for an efficient use of the diverted first portion of the sample and of a pump utilized for diversion and compression, and avoids the need to exhaust that first portion of the sample to the atmosphere surrounding the test site.

In a further embodiment a wide range of contaminants are detectable without interference from product volatiles by providing a method of sampling and determining the presence of volatiles of certain contaminants in a container which was previously filled with a beverage, said container including an opening which is closeable by a cap, comprising the steps of: storing said container with the cap removed for a sufficient period of time to permit detectable quantities of volatiles of ingredients in residues of the beverages to evaporate and egress from said container; evacuating a sample of volatiles remaining in the container after expiration of said sufficient period of time; mixing the sample with a chemical reactant to cause a chemical reaction therewith in order to generate chemiluminescence of the reactants; and optically analyzing radiation emitted by chemiluminescence of the sample and reactant to determine the presence or absence of said volatiles of certain contaminants without interference from detectable levels of chemiluminescence of volatiles of ingredients of beverage residues. Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitative of the present invention and wherein:

Fig. 1 is a schematic block diagram of the sampling and residue analyzing system of the present invention illustrating a plurality of containers moving seriatim along a conveyor system through a test station, reject mechanism and washer station;

Fig. 2 is a block diagram illustrating a possible implementation of the system of Fig. 1 in a detector system in which the contaminant being detected may be a nitrogen containing compound; and

Fig. 3 is a graph of signal intensity vs. wavelength of defected radiation emitted by chemiluminescence in the analyzer of the system of Fig. 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to Fig. 1 there is illustrated a conveyor 10 moving in the direction of arrow A having a plurality of uncapped, open-topped spaced containers C (e.g. plastic beverage bottles of about 1500 c.c. volume) disposed thereon for movement seriatim through a test station 12, reject mechanism 28 and conveyor 32 to a washer system. The contents of containers C would typically include air, volatiles of residues of contaminants, if any, and volatiles of any products such as beverages which had been in the containers. An air injector 14 which is a source of compressed air is provided with a nozzle 16 spaced from but aligned with a container C at test station 12. That is nozzle 16 is disposed outside of the containers and makes no contact therewith. Nozzle 16 directs compressed air into containers C to displace at least a portion of the contents of the container to thereby emit a sample cloud 18 to a region outside of the container being tested. The column of injected air through nozzle 16 into a container C would be typically of the order of about 10 c.c. for bottle speeds of about 200 to 1000 bottles per minute. A rate of 400 bottles per minute is preferable and is compatible with current beverage bottle filling speeds. The desired test rate may vary with the size of the bottles being inspected and filled. Only about 10 c.c. of the container contents would be displaced to regions outside of the bottle to form sample cloud 18.

Also provided is an evacuator sampler 22 which may comprise a vacuum pump or the like coupled to a sampling tube or conduit 20. The tube is mounted near, and preferably downstream (e.g., about 1/16 inch) of the air injector 14 so as to be in fluid communication with sample cloud 18 adjacent to the opening at the top of containers C. Neither nozzle 16 nor tube 20 contacts the containers C at test station 12; rather both are spaced at positions outside of the containers in close proximity to the openings thereof. This is advantageous in that no physical coupling is required to the containers C, or insertion of probes into the containers, which would impede their rapid movement along conveyor 10 and thus slow down the sampling rate. High speed sampling rates of from about 200 to 1000 bottles per minute are possible with the system and method of the present invention. The conveyor 10 is preferably driven continuously to achieve these rates without stopping or slowing the bottles down at the test station.

A bypass line 24 is provided in communication with the evacuator sampler 22 so that a predetermined portion (preferably about 90%) of the sample from cloud 18 entering tube 20 can be diverted through bypass line 24. The remaining sample portion passes to a residue analyzer 26, which determines whether specific substances are present, and then is exhausted. One purpose of diverting a large portion of the sample from cloud 18 is to reduce the amount of sample passing from evacuator sampler 22 to residue analyzer 26 in order to achieve high speed analysis. This is done in order to provide manageable levels of samples to be tested by the residue analyzer 26. Another purpose for diverting a portion of the sample is to be able to substantially remove all of sample cloud 18 by evacuator 22 from the test station area and divert the excess through bypass line 24. In a preferred embodiment the excess portion of the sample passing through bypass line 24 returned to air injector 14 for introduction into the subsequent containers moving along conveyor 10 through nozzle 16. However, it would also be possible to simply vent bypass line 24 to the atmosphere.

A microprocessor controller 34 is provided for controlling the operation of air injector 14, evacuator sampler 22, residue analyzer 26, a reject mechanism 28 and an optional fan 15. Container sensor 17 including juxtaposed radiation source and photodetector is disposed opposite a reflector (not shown) across conveyor 10. Sensor 17 tells controller 34 when a container arrives at the test station and briefly interrupts the beam of radiation reflected to the photodetector. Optional fan 15 is provided to generate an air blast towards sample cloud 18 and preferably in the direction of movement of containers C to assist in the removal of sample cloud 18 from the vicinity of test station 12 after each container C is sampled. This clears out the air from the region of the test station so that no lingering residues from an existing sample cloud 18 can contaminate the test station area when successive containers C reach the test station for sampling. Thus, sample carryover between containers is precluded. The duty cycle for operation of fan 15 is controlled by microprocessor 34 as indicated diagrammatically in Fig. 1. Preferably fan 15 is continuously operating for the entire time the rest of the system is operating.

A reject mechanism 28 receives a reject signal from microprocessor controller 34 when residue analyzer 26 determines that a particular container C is contaminated with a residue of various undesirable types. Reject mechanism 28 diverts contaminated rejected bottles to a conveyor 30 and allows passage of unconta inated, acceptable bottles to a washer (not shown) on a conveyor 32. An alternative option is to place the bottle test station downstream of the bottle washer in the direction of conveyor travel, or to place an additional test station and sample and residue analyzing system after the washer. In fact it may be preferable to position the test station and system after the washer when inspecting bottles for some contaminants. For example, if the contaminant is a hydrocarbon, such as gasoline which is insoluble in water, it is easier to detect residues of hydrocarbons after the bottles have been washed. This is because during the washing process in which the bottles are heated and washed with water, water soluble chemical volatiles are desorbed from the bottles by the heating thereof and then dissolved in the washing water. Certain hydrocarbons, on the other hand, not being water soluble, may then be sampled by a sampler 22 downstream of the washer, to the exclusion of the dissolved, water-soluble chemicals. Therefore, the detection of such hydrocarbons can be performed without potential interference from other water soluble chemicals if the bottles pass through a washer before testing.

Referring to Fig. 2 there is illustrated a specific embodiment of a detector system for use with the sampling and analyzing system of Fig. 1 wherein like reference numerals refer to like parts. As illustrated, a nozzle 16 is provided for generating an air blast which passes into a container (not shown) being inspected. The air passing through nozzle 16 may be heated or unheated it being advantageous to heat the air for some applications. Juxtaposed to the nozzle 16 is sample inlet tube 20 including a filter 40 at the output thereof for filtering out particles from the sample. Suction is provided to tube 20 from the suction side of pump 82 connected through the residue analyzer 26. A portion of the sample (for example, 90-95% of a total sample flow of about 6000 c.c. per minute), as described in connection with Fig. 1, is diverted through a bypass line 24 by means of connection to the suction side of a pump 46. Pump 46 recirculates the air through an accumulator 48, a normally open blast control valve 50, and back to the air blast output nozzle 16. A backpressure regulator 54 helps control pressure of the air blast through nozzle 16 and vents excess air to exhaust 57. Blast control valve 50 receives control signals through line 50A from microprocessor controller 34 to normally maintain the valve open to permit the flow of air to the nozzle.

Electrical power is provided to pump 46 via line 46A coupled to the output of circuit breaker 76 which is in turn coupled to the output of AC filter 74 and AC power supply PS. The detector assembly 27 in the embodiment of Fig. 2 is an analyzer which detects the residue of selected compounds such as nitrogen containing compounds in the containers being inspected by means of a method of chemiluminescence. This type of detector is generally known and includes a chamber for mixing ozone with nitric oxide, or with other compounds which react with ozone, in order to allow them to react, a radiation-transmissive element (with appropriate filter) , and a radiation detector to detect chemiluminescence from the products of reaction. For example, when NO, produced from heating nitrogen compounds (such as ammonia) in the presence of an oxidant (e.g. oxygen in air), chemically reacts with the ozone, characteristic light emission is given off at predetermined wavelengths such as wavelengths in the range of about 0.6 to 2.8 microns. Selected portions of the emitted radiation of chemiluminescence, and its intensity, can be detected by a photomultiplier tube.

Accordingly, in the system of Fig. 2 ambient air is drawn in through intake 60 and air filter 62 to an ozone generator 64. Ozone is generated therein, as by electrical discharge into air, and is output through ozone filter 66 and flow control valve 68 to the detector assembly 27 wherein it is mixed with samples from containers input through intake tube 20, filter 40, flow restrictor 42, and converter 44. The sample from intake tube 20 is passed through a converter 44, such as an electrically-heated nickel tube, in which the temperature is raised to approximately 800*C to 900"C before being input to detector assembly 27. Temperatures in the range of 400'C to 1400'C may also be acceptable. When nitrogen-containing compounds such as ammonia are so heated, NO (nitric oxide) is produced, and the nitric oxide is supplied to the chamber of the detector assembly 27. Compounds other than NO which may react with 0₃ and chemiluminescence may also be produced in converter 44 e.g., organic compounds derived from heating of gasoline or cleaning residue. A temperature controller 70 supplied with electrical power through a transformer 72 is used to control the temperature of converter 44.

The samples in the detector assembly 27 after passage through its chamber are output through an accumulator 85 and pump 82 to an ozone scrubber 56, and to an exhaust output 57 in order to clear the residue detector for the next sample from the next container moving along the conveyor 10 of Fig. 1. (As indicated above, an (optinal) fan, not shown in Fig. 2, may be employed to help clear any remaining sample cloud from near the sample inlet tube 20) . Outputs from detector assembly 27 relating to the results of the tests are output through a preamp 84 to microprocessor 34 which feeds this information in an appropriate manner to a recorder 83. The recorder 83 is preferably a conventional strip recorder, or the like, which displays signal amplitude vs. time of the sample being analyzed.

The microprocessor 34 may be programmed to recognize, as a "hit" or the detection of a specific residue, a signal peak from a photodetector of the detector assembly 27 which is present in a predetermined time interval (based on the sensed arrival of a container at the test station) and whose slope and amplitude reach predetermined magnitudes and thereafter maintain such levels for a prescribed duration. The microprocessor controller 34 also has an output to a bottle ejector 28 to reject contaminated bottles and separate them from bottles en route to a washer.

A calibration terminal 86 is provided for residue analyzer 26 for adjusting the high voltage supply 26A associated with the detector assembly. Also provided is a recorder attenuator input terminal 88 connected to the microprocessor controller 34 for adjusting the operation of the recorder. Detector assembly 27 receives electrical power from the high voltage supply 26A.

Additional controls include operator panel 90 including a key pad and display section permitting an operator to control the operation of the detector assembly 27 in an appropriate fashion.

DC power is supplied to all appropriate components through DC power supply 78 coupled to the output of power supply PS. An optional alarm enunciator 80A is provided for signaling an operator of the presence of a contaminated container. Alarm enunciator 80A is coupled to the output of microprocessor controller 34 via output control line 80C. A malfunction alarm 80B is also coupled to microprocessor controller 34 for receiving fault or malfunction signals such as from pressure switch 58 or vacuum switch 87 when pressures are outside of certain predetermined limits.

Other safety devices may be provided such as vacuum gauge 89, and back pressure control valve 54 for ensuring proper operation of the system.

Most components of the entire system of Fig. 2 are preferably enclosed in a rust-proof, stainless steel cabinet

92. The cabinet is cooled by a counter-flow heat exchanger

91 having hermetically separated sections 91A and 91B in which counter air flow is provided by appropriate fans.

As described hereinbefore the system of Fig. 2 in a preferred embodiment is utilized to detect the presence of nitrogen containing compounds in a sample, such as a refillable beverage bottle. However, it would be desirable to utilize the system of Fig. 2 to detect as wide a range of contaminants as possible including potential contaminants that would chemiluminesce in regions of the radiation spectrum, which might overlap with chemiluminescence of ingredients of a beverage (hereinafter "product") that was packaged in the beverage bottle.

This is accomplished in accordance with the present invention by a method partially illustrated in Fig. 3, and described hereinafter.

Referring to Fig. 3, which is a graph of signal intensity of radiation (in millivolts) vs. wavelength emitted by chemiluminescence, it can be observed that radiation emitted by chemiluminescence of nitrogen containing compounds (the reaction of NO + 0₃) is in the range of about 0.6 to 2.8 microns (near infrared to infrared radiation) . Consequently, when using the system of Fig. 2 and detector assembly 27 thereof, to look only for nitrogen containing compounds a cut-off filter 100 is utilized to block all chemiluminescent radiation of a sample of wavelengths below about 1 micron from reaching the photomultiplier detector of detector assembly 27. This is desirable if the detection of nitrogen compounds is of primary interest because chemiluminescent radiation emitted below 1 micron (visible light to near infrared) is potentially emitted by "product" residue in samples evacuated from refillable beverage bottles. Therefore, the 1 micron cut-off filter 100 eliminates false reject signals which might be caused by high levels of "product" residue in a bottle under test. It is of course very important to eliminate, or minimize false reject signals to minimize, waste of refillable bottles.

However, it is a discovery of the present invention that if a beverage bottle is stored in an uncapped state, i.e. the top opening thereof uncovered, for a sufficient time prior to testing with the system of Fig. 2, that volatiles of "product" residue are sufficiently dissipated from the bottle that such are not detectable at sufficient levels to cause false reject signals. That is, if the 1 micron filter 100 is removed, and replaced by a quartz cut-off filter having a cut-off characteristic at .19 micron, "product" volatiles will not exist in large enough quantities to generate reject signals if the bottles were stored uncapped for a sufficient period of time. This period of time will vary for various "products". However, a storage period of about fifteen (15) hours for an uncapped bottle has yielded good results in tests conducted. These results are tabulated in the following Table I for samples evacuated from beverage bottles containing a wide range of contaminants, and "product" residues.

SAMPLE

Acetaldehye

Acetone Acetone, 15Hr, Uncapped

Brazil Gas

Brazil Gas #4

Cyclohexanone

Cyclohexanone, 15Hr, Uncapped Diesel

Downy, 15Hr, Uncapped

Exxon 100

Exxon 150

Exxon 200 Fresh Downy

Gas #1

Gas #3

Hexane

Hexane, 15Hr, Uncapped Isopropanol

Isopropanol, 15Hr, Uncapped

Kerosine

Hethanol

Methylene Chloride Methylene Chloride, 15Hr, Uncapped

Vine

Cola, Classic, 15Hr, Capped

Cola, Classic, 15Hr, Uncapped

Cola, Classic Fresh Cola, Diet, 15Hr, Capped

Cola, Diet, 15Hr, Uncapped

Cola, Diet, Fresh

Orange, 1SHr, Capped

Orange, 15Hr, Uncapped Orange, Diet, 15Hr, Capped

Orange, Diet, 15Hr, Uncapped

Orange, Diet, Fresh

Fanta Fresh

Lemon/Lime, 15Hr, Capped Lemon Lime, 15Hr, Uncapped

Lemon Lime, Diet, 15Hr, Capped

Lemon Lime, Diet, 15Hr, Uncapped

Lemon/Lime, Diet Fresh

Lemon/Lime, Fresh * Numbers in colunns 2 to 4 in millivolts ** OS - Off Scale Reading Column 1 of Table I in the upper portion lists "samples" including potential contaminants in beverage bottles which are detectable by the method and system of the present invention. These contaminants are detectable in addition to nitrogen containing compounds. The designation "Uncapped" means that the residue-containing bottle was stored for the indicated time with its top opening uncovered; undesignated entries indicate that the contaminant was present, and top opening uncovered, for only a brief time prior to testing. The "samples" in the lower part of column 1 include examples of beverage product tested ,and an indication of whether the bottles were capped, uncapped, and if uncapped the storage period of the residue-containing bottle with its top opening uncovered for example 15 hrs. The designation "Capped) means that the bottle was tested with a residue of the beverage procut present, and the top opening uncovered for only a brief period prior to testing. The designation "Fresh" means that the bottle was tested soon after opening it, and contained fresh product in liquid form, i.e. a substantially full bottle of beverage, rather than old fermented product.

Column 2 of Table I shows the intensity in millivolts of signals measured by a photomultiplier tube 104 in detector assembly 27 with a 0.19 micron quartz cut-off filter 102 at the input window of the photomultiplier tube 104. It can be seen that signals of significant detectable levels exist for these contaminants for capped or uncapped beverage bottles.

The data in column 2 also indicates that for "uncapped" beverage bottles stored for 15 hrs. that "product" volatiles are undetectable (0 millivolts) by photomultiplier tube 104.

Column 4 of Table I shows test results of a system including the 1 micron filter 100, and the levels in millivolts of detectable signals for the various contaminants or products of column 1. It can be seen that essentially all useful signal data relating to contaminants in Table I is lost with the 1 micron filter 100 in place.

Column 3 of Table I shows results with a 0.4 micron cut- off filter 106 installed at the input of photomultiplier tube

104 in place of either filters 100 or 102. It can be seen that some useful contaminant data is detectable when using a

0.4 micron cut-off filter 102.

Therefore, the discovery of the present invention that storage of beverage bottles in an uncapped state removes the possibility of developing false reject signals from "product' volatiles, is a most significant and beneficial discovery. That is, the process of the present invention which embodies the concept of storing uncapped beverage bottles for a sufficient time to permit "product" volatiles to dissipate, enables the detection of a wide range of other contaminants such as those listed in Table I in addition to contaminants including nitrogen containing compounds.

The invention being thus described, it will be obvious that the same may be varied in many ways. For example, other forms of high speed analyzers, such as electron capture detectors or photoionization detectors, may be suitable in place of the chemiluminescence analyzer described with reference to Fig. 2. Also the sample sucked into the tube 20 may be separated into two or more streams and input to a plurality of analyzers 26. Consequently, each analyzer 26 could be used to detect different types of contaminants.

In addition the materials to be inspected are not limited to substances in containers. For example, the method and system of the present invention could be used to detect volatiles adsorbed in shredded strips or flakes of resins, or plastic stock to be recycled for manufacturing new plastic beverage bottles. This shredded or flaked plastic stock could be placed directly on a conveyor belt 10 and passed through test station 12 of Fig. 1; or the plastic stock could be placed in baskets, buckets or other types of containers disposed thereon and inspected in batches.

Still further the bottles being tested may be new bottles that have never been filled with a beverage. Thus, new bottles could be tested for excessive acid aldehyde content, which may be a byproduct of the manufacturing process.

Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

What is claimed is:

1. A method of sampling and determining the presence of volatiles of certain contaminants in a container which was previously filled with a beverage, said container including an opening which is closeable by a cap, comprising the steps of: storing said container with the cap removed for a sufficient period of time to permit volatiles of residues of the beverage to evaporate and egress from said container; evacuating a sample of volatiles remaining in the container after expiration of said sufficient period of time; and analyzing the sample evacuated to determine the presence or absence of the certain contaminants therein.

2. The method of claim 1 wherein said analyzing step includes the steps of: mixing the sample with a chemical reactant to cause a chemical reaction therewith in order to generate chemiluminescence of the reactants; and analyzing radiation emitted by chemiluminescence of the sample and reactant to determine the presence or absence of said volatiles of certain contaminants without interference from chemiluminescence of volatiles of the beverage.

3. The method of claim 2 wherein the step of analyzing includes the steps of: filtering radiation emitted by chemiluminescence of the sample to detect the presence of radiation having wavelengths above about 0.19 micron; and identifying the presence or absence of said certain contaminants from the radiation detected at characteristic wavelengths above about 0.19 micron.

4. The method of claim 2 including the further step of heating the sample to about 400"C to 1400^βC prior to said mixing step, and wherein the chemical reactant is ozone.

5. The method of claim 1 wherein said sufficient period of time is about 15 hours.

6. A method of sampling and determining the presence of volatiles of certain contaminants in a container which was previously filled with a beverage, said container including an opening which is closeable by a cap, comprising the steps of: storing said container with the cap removed for a sufficient period of time to permit volatiles of residues of the beverage to evaporate and egress from said container; injecting fluid into the opening in said container after expiration of said sufficient period of time in order to displace at least a portion of the volatiles therefrom; and evacuating a sample of the volatiles so displaced.

7. The method of claim 1 wherein said analyzing step includes the steps of: mixing the sample with a chemical reactant to cause a chemical reaction therewith in order to generation chemiluminescence of the reactants; and analyzing radiation emitted by chemiluminescence of the sample and reactant to determine the presence or absence of said volatiles of certain contaminants without interference from chemiluminescence of volatiles of residues of the beverage.

8. The method of claim 6 wherein the step of analyzing includes the steps of: filtering radiation emitted by chemiluminescence of the sample to detect the presence of radiation having wavelengths above about 0.19 micron; and identifying the presence or absence of said certain contaminants from the radiation detected at characteristic wavelengths above about 0.19 micron.

9. The method of claim 6 including the further step of heating the sample to about 400" to 1400°C prior to said mixing step, and wherein the chemical reactant is ozone.

10. The method of claim 6 wherein said sufficient period of time is about 15 hours.