Apparatus and method of collecting a sample for determination of 1, 4 dioxane in drinking water

A method of collecting a sample for determination of 1,4-dioxane in drinking water includes providing a reagent dispenser operable to dispense a microbial inhibitor. A sample bottle having a predetermined inner volume is provided to a preparation site. The dispenser is calibrated to dispense a calibrated weight of the microbial inhibitor, such that a ratio of the calibrated weight to inner volume substantially equals a predetermined concentration of microbial inhibitor per liter of water determined to acidify water to a pH of 4 or less. The sample bottle is transported to a field site. The field site is remote from the preparation site. A sample of water is collected in the sample bottle at the field site that substantially fills the inner volume of the sample bottle. The dispenser is operated to substantially dispense the calibrated weight of microbial inhibitor into the sample of water.

BACKGROUND

1,4-dioxane has been classified by the U.S. Environmental Protection Agency (the EPA) as an emerging contaminant. It is a clear liquid that is often used as a solvent stabilizer in the manufacture of other chemicals. It is a by-product that is present in many goods, including paint strippers, dyes, greases, antifreeze and aircraft deicing fluids. 1,4-dioxane is also found in some consumer products such as deodorants, shampoos and cosmetics.

1,4-dioxane is a likely human carcinogen and has been found in groundwater at sites throughout the United States. Once it makes its way into sources of drinking water, 1,4-dioxane tends to stay there, as it does not break down easily. Further, it is completely miscible in water, highly mobile and very resistant to microbial degradation.

Accordingly, there is an increasing need to reliably test for 1,4-dioxane in drinking water sources. Additionally, there is an increasing need to be able to reliably obtain and prepare drinking water samples from field sites and to transport them back to a suitable laboratory for 1,4-dioxane testing.

Suffolk County Water Authority (Oakdale, N.Y.) is a public benefit corporation and is specifically created to supply potable water to residents of Suffolk County, N.Y. There are many other districts or entities that perform the same function in communities throughout the United States. Many such water providers have an increasing need to reliably sample and test ground water produced at numerous sites throughout their distribution system for 1, 4, dioxane. Moreover, many environmental laboratories, that often service these water providers, are also increasingly required to receive samples of water taken in the field and test them for 1,4-dioxane.

One example of an emerging de facto standard for sampling and testing ground water for 1,4-dioxane is the EPA Method 522 (herein Method 522). Method 522 is titled:“Determination of 1, 4-Dioxane in Drinking Water by Solid Phase Extraction (SPE) and Gas Chromatography/Mass Spectrometry (GC/MS) with Selected Ion Monitoring (SIM),”
and was first published in September of 2008.

Method 522 requires that a microbial inhibitor be added in precise amounts to a drinking water sample immediately after the sample has been collected. The microbial inhibitor is utilized to substantially reduce microbial growth in the sample during transport and storage of the sample, prior to testing. However, Method 522 is silent as to how the microbial inhibitor may be added.

For Suffolk County Water Authority and other large water purveyors, that may be required to take several thousand drinking water samples per year, reliably and accurately adding such a microbial inhibitor to each sample at each field site can be problematic. This is because it is expensive to carry laboratory measuring equipment to every field site that is remotely located from the laboratory where the testing is to take place. Additionally, such laboratory measuring equipment is more prone to damage or wear in the field. Further, the probability for human error increases dramatically when the measuring equipment is used in the field.

Accordingly, there is a need for a method that can reliably and accurately preserve drinking water samples collected in the field, and store them for future testing in a laboratory. Additionally, there is a need for equipment that can be utilized in such a method that is not prone to breaking down and can reduce the probability of human error.

BRIEF DESCRIPTION

The present disclosure offers advantages and alternatives over the prior art by providing a method of collecting a sample for determination of 1,4-dioxane in drinking water utilizing a reagent dispenser to preserve the drinking water sample. The method reduces the probability of human error. The reagent dispenser dispenses a microbial inhibitor into the collected sample of drinking water reliably and accurately without the need for expensive and fragile laboratory equipment.

A method of collecting a sample for determination of 1,4-dioxane in drinking water in accordance with one or more aspects of the present disclosure includes providing a reagent dispenser operable to dispense a microbial inhibitor. A sample bottle having a predetermined inner volume is provided to a preparation site. The dispenser is calibrated to dispense a calibrated weight per water sample of the microbial inhibitor, such that a ratio of the calibrated weight per water sample to inner volume of the sample bottle substantially equals a predetermined concentration of microbial inhibitor per liter of water determined to acidify water to a pH of 4 or less. The sample bottle is transported to a field site, the field site being remote from the preparation site. A sample of water is collected in the sample bottle at the field site that substantially fills the inner volume. The dispenser is operated to substantially dispense the calibrated weight per water sample of microbial inhibitor into the sample of water collected in the sample bottle.

A reagent dispenser in accordance with one or more aspects of the present disclosure includes a housing. A container of microbial inhibitor is disposed within the housing. A dispensing system is disposed within the housing and operable to dispense the microbial inhibitor from the container. The dispensing system is calibrated to dispense a calibrated weight per water sample of the microbial inhibitor, such that a ratio of the calibrated weight per water sample to inner volume of a sample bottle substantially equals a predetermined concentration of microbial inhibitor per liter of water determined to acidify water to a pH of 4 or less.

A kit in accordance with one or more aspects of the present disclosure includes a supply of microbial inhibitor and a reagent dispenser. The reagent dispenser is operable to dispense the microbial inhibitor. The dispenser is calibrated to dispense a calibrated weight per water sample of the microbial inhibitor, such that a ratio of the calibrated weight per water sample to inner volume of a sample bottle substantially equals a predetermined concentration of microbial inhibitor per liter of water determined to acidify water to a pH of 4 or less.

DETAILED DESCRIPTION

The terms “substantially”, “approximately”, “about”, “relatively,” or other such similar terms that may be used throughout this disclosure, including the claims, are used to describe and account for small fluctuations, such as due to variations in processing. For example, they can refer to less than or equal to ±10%, such as less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%. Also by way of example, such terms may only include positive fluctuations, such as up to plus 5% or up to plus 10%.

Referring toFIG. 1, an example of a method100of collecting a sample for determination of 1,4-dioxane in drinking water in accordance with aspects described herein is depicted. As will be discussed in greater detail herein, the method100enables a precise amount of a microbial inhibitor202to be added reliably and accurately to drinking water samples206immediately after the samples have been collected. Additionally, the method100does not require the use of expensive and fragile laboratory measuring equipment. Further the method100reduces the probability of human error when utilized by hundreds of personnel to collect thousands of samples from hundreds of field locations (or sites).

The method100begins at102ofFIG. 1, wherein a reagent dispenser200(seen inFIG. 2) is provided. The reagent dispenser200is operable to dispense a specific microbial inhibitor202(seen inFIG. 2). The microbial inhibitor202may be sodium bisulfate and may be in the form of a dry granulated salt in order to meet the requirements of EPA test method522.

Though sodium bisulfate is used as an example of a microbial inhibitor, one skilled in the art would recognize that other microbial inhibitors may also be used. Some examples of potential alternative microbial inhibitors include: copper sulfate, diazolidinyl urea, potassium dihydrogen citrate or the like.

The method proceeds to104ofFIG. 1, wherein one or more sample bottles208(seen inFIG. 2), having a predetermined inner volume209, are also provided and delivered to a preparation site. The sample bottles208are operable to collect drinking water samples206at field sites that are remotely located from the preparation site.

The sample bottles208may be amber colored to prevent direct sun light from penetrating a collected water sample206. The predetermined inner volume209of the sample bottle208may be any known volume that is sized to be manually portable. However, the inner volume209is often an integer multiple of 250 milliliters (ml), such as 250 ml, 500 ml, 750 ml or 1.0 liters.

The method proceeds to106ofFIG. 1, wherein the reagent dispenser200is calibrated to dispense a calibrated weight per water sample205(seen inFIG. 2) of the microbial inhibitor202, such that a ratio of the calibrated weight per water sample205to inner volume209of the sample bottle208substantially equals a predetermined concentration of microbial inhibitor per liter of water determined to acidify water to a pH of 4 or less.

The calibrated weight per water sample205may be any weight of microbial inhibitor202that, when mixed with a sample of drinking water206, may acidify the water to a pH of 4 or less. For example, if sodium bisulfate is utilized as the microbial inhibitor202, it has been determined that a concentration of substantially 1.0 gram (g) of microbial inhibitor per liter (L) of water will, in most cases, lower the pH of the water from a value of 7 to a value of 4 or less.

To illustrate by way of a specific example, the microbial inhibitor202may be sodium bisulfate and the sample bottles208may have an inner volume209of 250 milliliters (mL). As such, the reagent dispenser200may be calibrated to dispense a calibrated weight per water sample205of 250 milligrams (mg) in order to attain the desired concentration of 1.0 g/L.

The dispenser200does not have to dispense the calibrated weight per water sample205in one application. Again, by way of the same specific example wherein the microbial inhibitor202is sodium bisulfate and the sample bottles208have an inner volume209of 250 ml, the reagent dispenser200may be sized to dispense a discrete calibrated weight per application204(seen inFIG. 2) of 125 mg of sodium bisulfate with each application. As will be explained in greater detail herein, each application of the dispenser200may be applied by fully depressing (i.e., pumping) a triggering mechanism218(seen inFIG. 3) associated with the dispenser200. Accordingly for the specific example used herein, it would take two pumps of the dispenser's triggering mechanism218to dispense the calibrated weight per water sample205of 250 mg of sodium bisulfate into the 250 ml sample bottle. This is because each pump of the triggering mechanism218would dispense a calibrated weight per application204of 125 mg of sodium bisulfate.

Moreover, if the calibrated weight per application205of the sodium bisulfate for any given size sample bottle208was within plus 10% of an integer multiple of 125 milligrams, it would take that integer number of pumps to dispense the calibrated weight per application205from the dispenser200of this example. More specifically, for a 500 ml sample bottle, it would take 4 pumps of the dispenser200, dispensing a calibrated weight per application204of 125 mg of sodium bisulfate per pump, to provide the required calibrated weight per water sample205. Further, for a 750 ml sample bottle it would take 6 pumps of the dispenser's triggering mechanism202and for a 1 liter sample bottle it would take 8 pumps.

The method proceeds to108ofFIG. 1, wherein, at the preparation site, a predetermined weight of dechlorination reagent211(seen inFIGS. 2 and 7) is disposed into the sample bottle208prior to transporting the sample bottle to the field site. The preparation site may be any site where the controlled deposit of dechlorination reagent211into the sample bottles208is practical. For example, the preparation site may be a laboratory or a shipping and receiving area of a facility of a water purveyor.

The dechlorination reagent211is added to the sample bottles208such that a ratio of the predetermined weight of dechlorination reagent211to the inner volume209substantially equals a predetermined concentration of dechlorination reagent per liter of water determined to reduce chlorine and chloramine residuals. Again, for the specific example being use to illustrate the method100, the dechlorination reagent211may be a sodium sulfite and the ratio of predetermined weight of dechlorination reagent211to inner volume209may substantially equal 50 milligrams per liter.

The method proceeds to110ofFIG. 1, wherein the sample bottles208(with the dechlorination reagent211disposed inside) are transported to a field site. The field site is remote from the preparation site. For example, the field site may be a public water supply wellfield, an industrial facility, a residential facility, a distribution point in the distribution system of a water district or any site that has a drinking water system flowing through it.

The method proceeds to112ofFIG. 1, wherein at the field site, water from which a water sample206is to be taken, is allowed to flow in order to flush the water system until the water temperature is stabilized. Typically, this will take approximately 3 to 5 minutes.

The method proceeds to114ofFIG. 1, wherein a sample of water206is collected in the sample bottle208at the field site that substantially fills the inner volume209. For example, the sample bottles208may be filled to their neck or to a predetermined fill line scribed on the sample bottle. As the water sample206is being collected, care must be taken not to flush out the dechlorination reagent211.

The method proceeds to116ofFIG. 1, wherein the sample bottles208are capped after collecting the water sample206and agitated by hand until the dechlorination reagent211is dissolved.

The method proceeds to118ofFIG. 1, wherein the dispenser200is operated to substantially dispense the calibrated weight per water sample205of microbial inhibitor202into the sample of water206collected in the sample bottle208. Again, by way of the specific example being utilized to illustrate the method100, the reagent dispenser200would be held over the sample bottle208opening and its triggering mechanism218would be pumped twice. Each pump would dispense substantially the calibrated weight per application204of 125 mg (e.g., plus 10%) of sodium bisulfate into a 250 ml sample bottle208that was filled with the collected water sample206. The sample bottle208would again be capped and then agitated to dissolve the sodium bisulfate into the water sample206. Accordingly, the concentration of sodium bisulfate to water in the sample bottle would be substantially 1.0 g/L and the pH of the water sample206should be reduced to 4 or less. The acidic water substantially prohibits the growth of microbes that could contaminate the sample206during transport or storage prior to testing for the 1,4-dioxane.

The method proceeds to120ofFIG. 1, wherein the water samples206are cooled to maintain their temperatures within a predetermined range of temperatures prior to delivery to a laboratory for analysis. For example, such predetermined range of temperatures may be as follows:Samples received at a laboratory during the first 48 hours after collection must not exceed 10 degrees centigrade (C).Samples that are not received at the laboratory during the first 48 hours after collection must be maintained at a temperature range of between 1 and 6 degrees C. and shall not arrive at the laboratory at a temperature above 6 degrees C.

The water samples may be cooled by several different well known methods. For example, they may be packed in ice or refrigerated.

The method proceeds to122ofFIG. 1, wherein, upon arrival at the laboratory, pH and total chlorine checks are done on all water samples206prior to analysis by the laboratory. Examples of such pH and total chlorine tests may be as follows:The total chlorine is determined prior to pH determination using any of several well-known methods. Total chlorine must be less than 0.10 mg/L or corrective action must be taken.pH is then determined using any of several well-known methods. The pH must be less than 4 or corrective action must be taken.

The method proceeds to124ofFIG. 1, wherein, after the pH and total chlorine checks are done, the water samples206are maintained within a temperature of from 1 to 6 degrees C. prior to analysis.

The method proceeds to126ofFIG. 1, wherein the water samples206may not be held for more than 28 days from the date of collection to the date of extraction. Sample extracts, wherein a water sample206goes through a solid-phase extraction process, may be stored at minus 5 degrees C. and protected from light for an additional 28 days before analysis.

The method proceeds to128ofFIG. 1, wherein the water samples206are analyzed for 1,4-dioxane. Determination of 1,4-dioxane may be done, for example, by a GC/MS (Gas Chromatograph/Mass Spectrometer) system that meets all QC requirements of the method.

Referring toFIG. 2, an example of a perspective view of a calibrated reagent dispenser200used in the method100of collecting a drinking water sample206for determination of 1,4-dioxane in drinking water is depicted. The dispenser200is operable to dispense a microbial inhibitor202in repetitive discrete calibrated weights per application204of the dispenser. As such, a total calibrated weight per water sample205of the microbial inhibitor202(e.g., an integer multiple of the calibrated weight per application204) may be added reliably and accurately to drinking water samples206immediately after the samples206have been collected in a sample bottle208.

An example of a commercial reagent dispenser that may be calibrated and/or modified to dispense a specific microbial inhibitor202is a Hach Swiftest™ dispenser having a product number of 2802300 that is made by the Hach Company of Loveland, Colo., USA (herein the Hach dispenser). The Hach dispenser is normally used for chlorine testing in water samples. However, the Hach dispenser may be calibrated and/or modified to enable 1,4-dioxane testing.

The sample bottle208has an inner volume209designed to contain substantially that volume209of water sample206after the sample bottle208has been substantially filled with the water sample206. Additionally, the sample bottle208may also contain a dechlorination reagent211deposited into the sample bottle208at a preparation site. The dechlorination reagent211is designed to reduce chlorine and chloramine residuals in the water sample206after it has been dissolved into the water sample206.

The reagent dispenser200includes a housing210that contains and supports a dispensing system212. The dispensing system212is operable to receive a container214of the microbial inhibitor202. The dispenser200also has a cover216designed to enclose and protect the dispensing system212within the housing210.

The container214may be composed of any appropriate material suitable to contain the microbial inhibitor. For example, the container214may be glass, plastic or metal.

Referring toFIG. 3, an example of an exploded perspective view of the dispensing system212of dispenser200is depicted. The dispensing system212includes a triggering mechanism218, a metering piston220and a metering receptacle222.

The triggering mechanism218of dispensing system212includes an elongated lever member224, a trigger226, a connecting rod228and an optional indicating post230. The lever member224has first end portion232and an opposing second end portion234with a lever through-hole236positioned therebetween. The lever through-hole236is sized to pivotally attach to a housing post238that is an integral part of the housing210. The housing post238provides support for the lever member224and acts as a fulcrum upon which the lever member224may pivot.

The trigger226is positioned on the first end portion232and extends laterally from a first side240of the lever member224. The connecting rod228is positioned on the second end portion234and extends laterally from an opposing second side242of the lever member224. The optional indicating post230is positioned on the second end portion234and extends laterally from the first side240of the lever member224. As such, when the trigger226is moved (or pumped) in a right to left counterclockwise direction (as indicated by arrow244), the connecting rod228and indicating post230will move in a left to right counterclockwise direction (as indicated by arrow246).

The optional indicating post230will protrude out of the housing210to indicate that the trigger226is being pumped and as the triggering mechanism218rotates in the counterclockwise direction. The optional indicating post230will recess into the housing210to indicate that the trigger226has been released and as the triggering mechanism rotates in the clockwise direction.

The metering piston220of dispensing system212includes a connecting tab248and a calibrated metering through-hole250. As will be explained in greater detail herein, the connecting tab248is operable to pivotally connect to the connecting rod228and be advantageously anchored thereto by a connecting pin252that extends entirely through the tab248and connecting rod228to provide structural strength. Also, as will be explained in greater detail herein, the metering through-hole250has a calibrated through-hole volume254that is sized to dispense a discrete calibrated weight per application204of microbial inhibitor202from the dispenser200.

The metering receptacle222of the dispensing system212includes a receptacle body256having an inner hollow cylindrical core258that is sized to slidably receive the metering piston220. The metering receptacle222also includes a engagement port260disposed on a top surface261of the receptacle body256, wherein the container port260has female threads for engaging with the container214of microbial inhibitor202. The engagement port260also includes a first metering passageway262, which extends from a bottom of the engagement port to the core258of the metering receptacle222.

The metering receptacle222also includes a dispensing shaft264that is offset from the engagement port260and disposed on an opposing lower surface263of the body256of the metering receptacle222. The dispensing shaft264includes a second metering passageway266that extends through the dispensing shaft264and into the core258. The first metering passageway262and the second metering passageway266are offset by a distance268within the core258.

Referring toFIG. 4, an example of a top exploded view of the dispensing system212taken along the line4-4in depicted. This view is looking down on the body256of the metering receptacle222, the metering piston222and the connecting rod228.

The connecting rod228includes a pair of bifurcated branches270each with a first pin through-hole272extending entirely through. The bifurcated branches are sized to receive and straddle the connecting tab248of the metering piston220therebetween. A second pin through-hole274extends entirely through the connecting tab248. The second pin through-hole274substantially aligns with the first pin through-holes272when the tab248is engaged with the bifurcated branches270.

The connecting pin252is sized to securely fit entirely through the first pin through-holes272of each branch270and entirely through the second pin through-hole274of the tab248to provide enhanced structural strength to the connection between metering piston220and connecting rod228. The pin may be made of any appropriate material for the design application, but is preferably made of a metal, such as steel, tin or iron.

During operation of the triggering mechanism218, the metering piston220will be made to traverse the distance268within the core258of the metering receptacle222such that the metering hole250will reciprocate between an alignment with the first metering passageway262and an alignment with the second metering passageway266.

Advantageously, the connecting pin252enables the tab248of the metering piston220to pivotally engage with the branches270of the connecting rod228when the metering piston250is reciprocating within the core258. Additionally, the connecting pin provides the structural strength required to prevent the connecting rod228and metering piston220from separating during operation of the dispenser200.

The connecting rod228in this example is illustrated with bifurcated branches270that straddle the connecting tab248of the metering piston220. However, one skilled in the art would recognize that the metering piston230may include a bifurcated tab that straddles a single end portion of the connecting rod228. In either case, for proper structural integrity, the connecting pin252should extend entirely through both the tab248and connecting rod228.

Referring toFIG. 5, an example of a perspective view of the dispensing system212in a non-dispensing first position276is depicted. Also referring toFIG. 6, an example of a perspective view of the dispensing system212in a dispensing second position278is depicted. During operation, when the trigger226is not squeezed, an elastomeric band280holds the dispensing system212in the non-dispensing first position276. Additionally, when an operator fully squeezes (e.g., pumps) the trigger226than the elastomeric band280is stretched and the dispensing system212moves to its dispensing second position278.

Though an elastomeric band280is utilized in these examples as the device that holds the dispensing system212in the first position, one skilled in the art would recognize that other resilient devices may also be used to do essentially the same thing. For example, a spring may be used rather that an elastomeric band.

Referring more specifically toFIG. 5, during operation, when the dispensing system212is in the non-dispensing first position276, the elastomeric band280pulls the triggering mechanism218flush against the metering receptacle222. In this position, the metering hole250is aligned with the first metering passageway262and microbial inhibitor202is allowed to fill the volume254of the metering hole250.

Since the volume254of the metering hole250determines the weight of microbial inhibitor202that will be dispensed per application, then it is important that the volume254be sized to receive the calibrated weight per application204that is required for any specific microbial inhibitor202. More specifically the volume of the metering hole250must be sized to receive a calibrated weight per application204that is an integer multiple of the calibrated weight per water sample205. The calibrated weight per water sample205being such that a ratio of the calibrated weight per water sample205to inner volume209of the sample bottle208substantially equals a predetermined concentration of microbial inhibitor202per liter of water determined to acidify water to a pH of 4 or less.

The volume254of the metering hole250may be sized for a specific microbial inhibitor by any number of well-known methods. For example, the metering hole250may be drilled or molded to a certain size.

Additionally, different metering pistons220may be sized to fit the same metering receptacle222, but have different sized metering holes250for different microbial inhibitors. Moreover, different metering pistons may be sized to fit the same metering receptacle222, but have different sized metering holes250for different calibrated weights per application204for the same microbial inhibitor202.

Accordingly, by way of our previous example, wherein the microbial inhibitor is sodium bisulfate, the sample bottles208have an inner volume of 250 mL and the required calibrated weight per water sample is 250 mg, then the volume254of the metering hole250may be sized to contain 125 mg of sodium bisulfate. As such, each application of the dispenser200will provide 125 mg per pump and it will take an integer multiple of two pumps to apply the calibrated weight per water sample.

Alternatively, the metering hole250of the given example may be sized to contain 250 mg of sodium bisulfate. As such, each application of the dispenser200will provide 250 mg per pump and it will take an integer multiple of one pump to apply the calibrated weight per water sample.

Referring more specifically toFIG. 6, when the dispensing system212is in the dispensing second position278, the trigger226is pumped and the triggering mechanism218is pivoted away from the metering receptacle222. In this position, the metering hole250is aligned with the second metering passageway266and the microbial inhibitor202is allowed to dispense freely through the second metering passageway266and into a sample bottle208.

Referring toFIG. 7, an example of a perspective view of a dispenser kit300for collecting a sample for determination of 1,4-dioxane in drinking water is depicted. The dispenser kit300includes at least a calibrated dispenser200and a container214of microbial inhibitor202. The container214may have a removable threaded cap284to secure the microbial inhibitor202within the container214during transport.

More preferably, however, the kit would also include a sample bottle208sized to receive an integer multiple number of calibrated weights per application204from the calibrated dispenser200in order to obtain a required calibrated weight per water sample205. The sample bottle208may have a removable threaded cap282to secure the water sample within the sample bottle208during transport. Even more preferably, the sample bottle208of the kit may also include a predetermined weight of dechlorination reagent211in order to reduce chlorine and chloramine residuals.

It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail herein (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein.

Although the invention has been described by reference to specific examples, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the disclosure not be limited to the described examples, but that it have the full scope defined by the language of the following claims.