Patent Description:
The measurement of aluminum is important to ensure water quality. Applications for aluminum measurement may include waste water treatment, drinking water treatment, monitoring natural bodies of water, aqua farming, beverage/food manufacturing, pharmaceuticals, boiler systems, industrial processes, petrochemical processes, chemical tanks, or the like. Aluminum is important for aquatic life and viability of natural bodies of water. Additionally, proper levels of aluminum may be necessary in manufacturing or processing operations such that reactions or processes within the operations properly occur. Proper measurement of aluminum may also be important to prevent interference of aluminum with a reaction in a solution.

Aluminum is an abundant metal in the earth's crust. Aluminum may leach from rock and/or soil into a water supply. Aluminum may also be introduced as aluminum hydroxide or aluminum sulfate in water treatment processes. Some studies have linked the presence of aluminum to dementia such as Alzheimer's disease. There are a number of methods to measure aluminum in drinking water. However, many aluminum tests require the minimization of possible interfering species for the test. Also, some aluminum detection tests are not accurate with regards to low concentrations of aluminum.

Article <NPL>, discloses acidic aluminium solutions being injected into a buffered carrier stream and merging with a chrome azurol S/cetylpyridinium chloride stream. Furthermore, ethanol in the reagent stream enhances the absorbance of the ternary complex.

Disclosed is a method for measuring aluminum concentration in an aqueous sample, comprising the steps described at claim <NUM>. The dependent claims outline advantageous ways of carrying out the method.

For a better understanding of the embodiments, together with other and further features and advantages thereof, reference is made to the following description, taken in conjunction with the accompanying drawings. The scope of the invention will be pointed out in the appended claims.

Colorimetric methods are commonly used to measure aluminum levels. One method includes the Hach Method <NUM> test kit, using TNTplus™ <NUM>. This method requires a recommended sample pH that is between <NUM> and <NUM>. The method also requires the sample temperature to be at <NUM> - <NUM>. Reagents for the method suggests storing reagents at <NUM> - <NUM>. The method also requires <NUM> minutes of time to yield a measurement of aluminum, which is a significant length of time. Additionally, the method only measures a range of <NUM> - <NUM> parts per million (ppm) of aluminum. Thus, this method does not provide for measurement of lower aluminum concentrations or may provide inaccurate readings if the aluminum concentrations are too low. Additionally, samples are recommended to be stored at a pH of less than <NUM> for later analysis. The method requires careful pipetting and addition of reagents in addition to the <NUM> minute wait time for the reaction to complete. The method uses standard colorimetric techniques providing a measurement of aluminum in a sample typically as milligrams per liter. However, the colorimetric assay requires the use of a sample blank to be subtracted from the test result. Additionally, interfering ions may lead to inaccurate readings. These interfering ions include Mg<NUM>+, K+, Na+, NH<NUM>+, Cl-, NO<NUM>-, SO<NUM><NUM>-, Ca<NUM>+, Ag+, Mn<NUM>+, Cd<NUM>+, Co<NUM>+, Ni<NUM>+, Sn<NUM>+, Pb<NUM>+, PO<NUM><NUM>-, Cu<NUM>+, Hg<NUM>+, Fe<NUM>+, Fe<NUM>+, Zn<NUM>+, Si<NUM>+, Cr<NUM>+, Cr<NUM>+, and F-.

Thus, the current aluminum testing methods have limitations which are overcome by the methods and techniques as described in more detail herein. One limitation of the current technique is that it requires a longer process than the methods described herein. Additionally, the traditional colorimetric methods require the preparation of a separate "blank" vial. The extra step of preparing a blank vial can introduce error to the measurement based upon individual human techniques in preparing the blank. Also, since the traditional colorimetric techniques are sensitive to a multitude of interferants, the presence of interfering ions may reduce the accuracy of content of a sample containing aluminum. Additionally, the methods described herein provide a larger range of aluminum detection beyond those of conventional techniques. Specifically, the described method and system provides for measurement of aluminum concentrations at lower concentrations than the traditional measurement techniques.

Accordingly, an embodiment includes preparation of a chromeazurol S indicator solution. Preparation of the chromeazurol S indicator solution includes preparing the chromeazurol S in a buffer solution. Chromeazurol S may also be referred to as Mordant Blue <NUM>. In an embodiment, the buffer contains an additive. For example, the buffer solution may contain acetate, succinic acid, sodium succinate, or the like. The buffer facilitates the generation of a calibration curve, for example, succinic acid/sodium succinate buffer was used to generate the calibration curve of <FIG>. However, this is a non-limiting example and other buffer solutions may be used. The buffer is selected to maintain a pH at, around, below, or greater than pH <NUM>. The buffer is also selected as to not interfere with an analyte, such as aluminum. Additionally, the buffer solution contains a surfactant. In an embodiment, the chromeazurol S indicator solution is placed in an aqueous sample containing aluminum. The delivery method of reagents, for example, the chromeazurol S, to the aqueous sample, may be accomplished through pipetting, droppers, test strips, powder pillows, using a solid, using a liquid solution, or the like. In the presence of aluminum within the sample, the chromeazurol S chelates the aluminum in the sample to create a colored complex. Colorimetric techniques measure a concentration of the aluminum from the colored complex. For example, the measuring may be a measurement of an absorbance at a wavelength for the colored complex. The measuring may include taking a ratio of absorbance collected at multiple wavelengths. Different measurement devices may be used to perform the measurement, for example, a portable parallel analyzer (PPA, such as the SL1000 available from Hach Company, Loveland, CO), test strips, colorimetric analyzers, spectrophotometers, pocket colorimeters, online process instruments, and the like.

The illustrated example embodiments will be best understood by reference to the figures. The following description is intended only by way of example, and simply illustrates certain example embodiments.

While various other circuits, circuitry or components may be utilized in information handling devices, with regard to an instrument for aluminum measurement according to any one of the various embodiments described herein, an example is illustrated in <FIG>. For example, the device circuitry as described in <FIG> may be used for communicating measurements to another device or may be used as the device for receiving measurements. Device circuitry <NUM> may include a measurement system on a chip design found, for example, a particular computing platform (e.g., mobile computing, desktop computing, etc.) Software and processor(s) are combined in a single chip <NUM>. Processors comprise internal arithmetic units, registers, cache memory, busses, I/O ports, etc., as is well known in the art. Internal busses and the like depend on different vendors, but essentially all the peripheral devices (<NUM>) may attach to a single chip <NUM>. The circuitry <NUM> combines the processor, memory control, and I/O controller hub all into a single chip <NUM>. Also, systems <NUM> of this type do not typically use SATA or PCI or LPC. Common interfaces, for example, include SDIO and I2C.

There are power management chip(s) <NUM>, e.g., a battery management unit, BMU, which manage power as supplied, for example, via a rechargeable battery <NUM>, which may be recharged by a connection to a power source (not shown). In at least one design, a single chip, such as <NUM>, is used to supply BIOS like functionality and DRAM memory.

System <NUM> typically includes one or more of a WWAN transceiver <NUM> and a WLAN transceiver <NUM> for connecting to various networks, such as telecommunications networks and wireless Internet devices, e.g., access points. Additionally, devices <NUM> are commonly included, e.g., a transmit and receive antenna, oscillators, RF amplifiers, PLLs, etc. System <NUM> includes input/output devices <NUM> for data input and display/rendering (e.g., a computing location located away from the single beam system that is easily accessible by a user). System <NUM> also typically includes various memory devices, for example flash memory <NUM> and SDRAM <NUM>.

It can be appreciated from the foregoing that electronic components of one or more systems or devices may include, but are not limited to, at least one processing unit, a memory, and a communication bus or communication means that couples various components including the memory to the processing unit(s). A system or device may include or have access to a variety of device readable media. System memory may include device readable storage media in the form of volatile and/or nonvolatile memory such as read only memory (ROM) and/or random access memory (RAM). By way of example, and not limitation, system memory may also include an operating system, application programs, other program modules, and program data. The disclosed system may be used in an embodiment to perform aluminum measurement of an aqueous sample.

Referring now to <FIG>, an embodiment provides a measurement of an aluminum concentration in an aqueous environment. A chromeazurol S indicator solution is prepared. The chromeazurol S indicator solution is placed in a sample, for example, an aqueous sample, that contains aluminum. The chromeazurol S chelates aluminum within the sample. This chelating process causes a colored complex to form. The resulting colored complex is used to identify the concentration of aluminum within the sample. Using colorimetric techniques, parameters of the colored complex may be measured. The colorimetric techniques are used to measure the absorbance of the colored complex at one or more wavelengths. The absorbance is proportional to an absorbance at a wavelength, the ratio of absorbance measured at multiple wavelengths, or the like.

At <NUM>, a chromeazurol S indicator solution is prepared. The chromeazurol S may be from a commercial source or synthesized in house. Unlike conventional techniques, the preparation of the indicator solution is performed at, around, below, or greater than pH <NUM>. Preparation of the indicator solution at, around, below, or greater than pH <NUM> allows for a greater range of aluminum to be measured as compared to the conventional techniques. Preparation of the chromeazurol S indicator solution includes preparing the chromeazurol S in a buffer solution. The buffer components of the buffer solution are selected based upon interaction with aluminum. In other words, the components are selected in order to reduce interaction with aluminum. Additionally, the buffer components are selected to chelate with interfering metals or the like that may be expected within the aqueous sample. In one embodiment, the buffer contains acetate, or succinic acid. The buffer and/or indicator solution may additionally or alternatively contain an additive. The additive contains a surfactant or alcohol. The surfactant produces micelles in the solution. The wavelength maximum shifts as a result. The micelles, and subsequent wavelength shift, are selected to utilize either an apparatus or condition that requires a shift in absorbance wavelength. For example, if a measurement device is tuned for a particular absorbance wavelength measurement, the surfactant is added in order to produce a reaction that will result in an absorbance measurement that can be measured by the device.

At <NUM>, the chromeazurol S indicator solution is placed into a sample, for example, an aqueous sample. As an example, a user may want to measure an aluminum concentration in a natural water source (e.g., pond, lake, stream, etc.), in a residential water source (e.g., swimming pool, residential water supply, etc.), commercial or municipal water source (e.g., water treatment facility, water holding tank, facility water supply, laboratory sample, etc.), or the like. Thus, the chromeazurol S indicator solution is placed or otherwise introduced to the aqueous sample. Different techniques for introducing the indicator solution to the aqueous sample may be utilized. For example, the sample may be placed in a vial, measurement device, vessel, or the like, and then the indicator solution is introduced to the sample, for example, through use of a dropper, pipette, powder pillow, test strip, or the like. Alternatively, the indicator solution may be placed in a vial, measurement device, vessel, or the like, and the sample is thereafter introduced to the indicator solution.

The sample contains aluminum. The aluminum may be in a pure or compound form. Additionally or alternatively, the aluminum may be in a liquid form or a finely suspended form in the aqueous sample. In an embodiment, the aluminum sample and/or indicator solution is added to a reaction vessel or other chamber of a measurement device. The introduction of the aluminum sample and/or indicator solution may be automated or manual. For example, a sample for testing may be pumped, aliquoted, pipetted, or introduced in any manner into a vessel or device. The aluminum for testing may be from any number of sources, for example, the aluminum may be from municipal water, drinking water, surface water, wastewater, industrial effluent, a natural waterway, a manufacturing process, swimming pool, or the like. The method and system may have more than one reaction vessel. For example, an aluminum sample is introduced into a first vessel and subsequent steps of an embodiment occur in another vessel or vessels. For example, the sample is introduced into a first vessel or chamber, the indicator solution is introduced into a second vessel or chamber, and then the sample and indicator solution is mixed into a third vessel or chamber.

A chamber, vessel, cell, or the like, contains an aqueous sample, chromeazurol S indicator solution, buffer, and associated reagents. A device may contain one or more bottles of reagents which contain necessary reagents such as, but not limited to, chromeazurol S indicator solution, buffers, or any reagent that may not be premixed before the measuring process. The reagents contained in the one or more bottles may be pump fed or gravity fed. The flow of the reagents is metered to ensure proper volume delivery to the measurement cell. The aqueous sample is fed through a pressured inlet, a vessel, or the like. The aqueous sample is introduced into the measurement chamber by a pump or gravity fed. The sampling device may be in series or parallel to an aqueous flow. The device has a system to ensure proper mixing of the aqueous sample, chromeazurol S indicator solution, and related reagents.

The aqueous sample includes a sample from a natural body of water, a holding tank, a processing tank, a pipe, or the like. The aluminum containing sample may be in a continuous flow, a standing volume of liquid, or any combination thereof. In one embodiment, the aluminum containing sample is introduced to a vessel, for example, a test chamber of the measurement device. Introduction of the aluminum containing sample into the measurement device includes placing or introducing the aluminum containing sample into a test chamber manually by a user or using a mechanical means, for example, gravity flow, a pump, pressure, fluid flow, or the like. For example, a water sample for aluminum testing is introduced to a measurement or test chamber using a pump. In an embodiment, valves or the like control the influx and efflux of the aqueous solution into or out of the one or more chambers, if present. In an embodiment, pumps, valves, and piping control and direct the flow of reagents, for example, the indicator solution. In an embodiment, these systems are automated or controlled by a processor.

Additionally or alternatively, the measurement device may be present within or introduced into a volume of the aluminum containing sample. The measurement device is then exposed to the volume of aqueous sample where it can perform measurements. For example, a handheld measurement device may include a test strip, test chip (such as Chemkeys available from Hach Company, Loveland, CO), or the like, that allows for dipping of the device or a portion of the device within the aqueous sample that then pulls a portion of the aqueous sample into the measurement device. As another example, the measurement device is located within or in proximity to a water source or sample source and periodically pulls a sample for measurement. The system may be a flow-through system in which aluminum containing sample and/or reagents are automatically mixed and measured. Once the sample is in contact with the measurement system, the system measures the aluminum in the sample using colorimetric techniques. In an embodiment, the measurement device includes one or more chambers in which the one or more method steps are performed.

At <NUM>, the system determines whether a concentration of aluminum within the sample can be determined or measured. To make this determination the system attempts to measure a concentration of aluminum in the sample, for example, using one or more colorimetric techniques. The indicator solution includes a colorimetric indicator and is sensitive to aluminum. Therefore, once introduced to a sample containing aluminum, the indicator solution, or components within the indicator solution, react with the aluminum in the sample to create a colorimetric change in the sample. Specifically, when the indicator solution is introduced to the aqueous sample, the indicator, for example, chromeazurol S, chelates the aluminum in the aqueous sample. This chelation causes a colorimetric change in the indicator solution. In other words, the chelation creates a colored complex that is of a different color than either the indicator solution alone, or the aqueous sample. In other words, the chelation causes a change in the absorbance wavelengths of the indicator solution and aqueous sample.

The colorimetric indicator is water soluble. The colorimetric indicator is chromeazurol S. The indicator gives a visual indication of aluminum concentration, which is determined via absorbance measurements made using a laboratory apparatus or other measurement device. The resulting color or absorbance change from the interaction of the indicator with the aluminum in the sample may be determined photometrically, for example, using a spectrophotometer. The measurement device measures the absorbance wavelength of the colored complex. This absorbance wavelength is proportional to a concentration of aluminum within the sample. Thus, by identifying the absorbance wavelength, the system can measure the concentration of aluminum in the sample. Two or more absorbance wavelengths are measured. The aluminum concentration is then proportional to the ratio of the multiple absorbance wavelengths. The absorbance intensity of the free chromeazurol S can also be monitored and used as an internal reference.

The concentration of aluminum may be determined in many ways. For example, comparison of a known concentration of aluminum with the indicator or absorbance wavelengths may be used to create a calibration curve of known aluminum concentrations. As another example, the absorbance of a sample containing aluminum may be determined using a set of known concentration aluminum samples to generate a calibration curve. The absorbance wavelengths of the resulting colored complex may also be compared to a "blank" to determine the concentration of aluminum within the sample.

Referring to <FIG>, an embodiment of determining an aluminum concentration within a sample using a colorimetric technique is illustrated. The described method determines whether a colorimetric change occurred within the sample. Specifically, a colorimetric change occurs in the solution due to the existence of an aluminum concentration in the solution. A ratio of absorbance is taken. A spectrophotometer obtains absorbance at two wavelengths. In the example of <FIG>, the two wavelengths are <NUM> and <NUM>. A ratio of these two wavelengths is proportional to the aluminum concentration within the sample. Thus, the system determines the aluminum concentration based upon the two wavelengths.

The method described herein chelates aluminum in the presence of the chromeazurol S indicator solution. The chelation of aluminum forms a colored complex, and results in a decrease of the absorbance intensity at <NUM> and an increase in absorption intensity at <NUM>. In this manner, the method serves as its own control. A blank sample is not required, although a blank may be prepared. A blank may be used for periodic calibration or testing. In an embodiment, a ratio absorbance is plotted over a concentration of aluminum. The reaction takes place quickly, therefore, the measurement of the concentration of aluminum is much quicker as compared to the conventional techniques. The detectable range of aluminum concentration is dependent upon a calibration curve slope. A calibration curve may be optimized with a pathlength of a sample cell and/or instrument capabilities. The change in absorbance is proportional to the aluminum concentration in a sample. Colorimetric measurement is performed with standard laboratory equipment such as a spectrophotometer.

The determination may also be made based upon a predicted absorbance under known conditions. Predictions may be based upon variables such as temperature, pH, turbidity, pathlength, instrumentation, or the like. For example, the system may be programmed with a calibration curve. Deviations from the predicted curve may make results less reliable and cause the system to discontinue measuring or to send an alert. As another example, the system may receive information indicating a number of measurement cycles measuring aluminum concentration are outside acceptable limits. For example, such measurements may indicate that a step in the process is suboptimal. Such steps may include aluminum chelation, indicator concentration, pH, temperature, or the like. At <NUM>, in an embodiment, if a concentration of aluminum cannot be determined, the system continues to measure aluminum, obtain another sample, attempt to chelate aluminum, or the like. Additionally or alternatively, the system may output an alarm, log an event, or the like.

If the concentration of aluminum can be determined at <NUM>, the system provides, at <NUM>, the measurement of the aluminum concentration. The change in absorption is measured using a spectrophotometer. Spectrophotometry is measurement of reflection or transmission properties of a sample measured at a given wavelength or set of wavelengths. Spectrophotometry may be a quantitative measure of how much light is absorbed by a material, for example, the colored complex resulting from the chelation of the aluminum by the indicator solution. Chromeazurol S in solution is yellow/orange in color (<NUM>), but the Aluminum - chromeazurol S complex has an absorbance maximum around <NUM>. The change in absorption may also be measured using other colorimetric measurement devices.

Alternatively or additionally, aluminum concentration measurement may be at periodic intervals set by the user or preprogrammed frequencies in the device. Measurement of aluminum by a device allows for real time data with very little human involvement in the measurement process. Cleaning of the colorimetric chamber may be required at an unspecified time interval. A programmed calibration curve may be entered into the device.

The aluminum measurement may be an output upon a device in the form of a display, printing, storage, audio, haptic feedback, or the like. Alternatively or additionally, the output may be sent to another device through wired, wireless, fiber optic, Bluetooth®, near field communication, or the like. An embodiment may use an alarm to warn of an aluminum measurement or concentration outside acceptable levels. An embodiment uses a system to shut down water output or shunt water from sources with unacceptable levels of aluminum. For example, an aluminum measuring device uses a relay coupled to an electrically actuated valve, or the like.

As will be appreciated by one skilled in the art, various aspects may be embodied as a system, method or device program product. Accordingly, aspects may take the form of an entirely hardware embodiment or an embodiment including software that may all generally be referred to herein as a "circuit," "module" or "system. " Furthermore, aspects may take the form of a device program product embodied in one or more device readable medium(s) having device readable program code embodied therewith.

It should be noted that the various functions described herein may be implemented using instructions stored on a device readable storage medium such as a non-signal storage device, where the instructions are executed by a processor. In the context of this document, a storage device is not a signal and "non-transitory" includes all media except signal media.

Program code for carrying out operations may be written in any combination of one or more programming languages. The program code may execute entirely on a single device, partly on a single device, as a stand-alone software package, partly on single device and partly on another device, or entirely on the other device. In some cases, the devices may be connected through any type of connection or network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made through other devices (for example, through the Internet using an Internet Service Provider), through wireless connections, e.g., near-field communication, or through a hard wire connection, such as over a USB connection.

Claim 1:
A method for measuring aluminum concentration in an aqueous sample, comprising:
preparing (<NUM>) a chromeazurol S indicator solution;
placing (<NUM>) the chromeazurol S indicator solution in a sample containing aluminum, wherein the placing causes the chromeazurol S to chelate aluminum within the sample creating a colored complex, wherein the sample comprises a standing volume of liquid; and
measuring (<NUM>), using colorimetric techniques, a concentration of aluminum within the sample,
characterized in that the measuring comprises measuring an absorbance at a first wavelength for the colored complex and measuring an absorbance at a second wavelength for the colored complex in the presence of the aluminum, wherein the concentration of aluminum is based upon a ratio of the absorbance at the first wavelength for the colored complex and the absorbance at the second wavelength for the colored complex in the presence of aluminum,
in that the ratio absorbance intensity is directly proportional to the concentration of aluminum within the sample and
in that the measuring comprises determining the concentration of aluminum based upon a calibration curve of the ratio.