Patent Description:
The present invention relates to a method of analyzing pH in soil, the method comprising: a) obtaining a soil sample; b) adding a liquid to the soil sample to form a soil slurry; c) flowing the soil slurry through a filter to form a filtrate; d) blending an indicator composition with the filtrate to form a soil mixture; and e) flowing the soil mixture through an analysis tool along a flow direction whereby a pH value of the soil mixture is measured; and wherein the flow direction is oriented such that the soil mixture flows orthogonally to the direction of gravity.

The method of the present invention is defined in claim <NUM>.

Other embodiments of the present invention include a method of analyzing pH in soil, the method comprising: a) obtaining a soil sample; b) adding a liquid to the soil sample to form a soil slurry; c) flowing the soil slurry through a filter to form a filtrate; d) blending an indicator composition with the filtrate to form a soil mixture; and e) flowing the soil mixture through an analysis tool along a flow direction whereby a pH value of the soil mixture is measured; and wherein soil mixture comprises a surfactant and the flow direction is substantially horizontal and orthogonal to the direction of gravity.

Other embodiments of the present disclosure include a method of analyzing buffer pH in soil, the method comprising: a) obtaining a soil sample; b) adding a liquid to the soil sample to form a soil slurry; c) flowing the soil slurry through a filter to form a filtrate; d) blending an indicator composition with the filtrate to form a soil mixture; and e) flowing the soil mixture through an analysis tool along a flow direction whereby a buffer pH value of the soil mixture is measured; and wherein the flow direction is oriented such that the soil mixture flows vertically.

Other embodiments of the present disclosure include a method of analyzing buffer pH in soil, the method comprising: a) obtaining a soil sample; b) adding a liquid to the soil sample to form a soil slurry; c) flowing the soil slurry through a filter to form a filtrate; d) blending an indicator composition with the filtrate to form a soil mixture; and e) flowing the soil mixture through an analysis tool along a flow direction whereby a pH value of the soil mixture is measured; and wherein soil mixture comprises a surfactant and the flow direction is substantially horizontal and orthogonal to the direction of gravity.

Moreover, the features and benefits of the disclosure are illustrated by reference to the exemplified embodiments. Accordingly, the disclosure expressly should not be limited to such exemplary embodiments illustrating some possible non-limiting combination of features that may exist alone or in other combinations of features; the scope of the disclosure being defined by the claims appended hereto.

According to the present invention the soil analysis is performed to determine the pH of a soil sample.

According to the method of the present invention, the pH may be tested according to the following methodology. A soil sample may be obtained and blended with liquid to create the soil slurry. The soil slurry may then flow through the filter element to create a filtrate, whereby one or more indicators may be added to the filtrate to create a mixture.

The soil mixture may then be analyzed for pH by absorbance that may be read via a spectrophotometer at a wavelength of <NUM> or <NUM>.

In some embodiments, the pH test analysis may occur inside of the analysis tool <NUM> and as the soil mixture flows along the vertical FD, whereby the vertical FD is substantially parallel to gravitational direction GD such that the soil mixture flows downward at least partially under the effects of gravity. In some embodiments, the pH test analysis may occur inside of the analysis tool 110a and as the soil mixture flows along the vertical FD, whereby the vertical FD is substantially parallel to gravitational direction GD such that the soil mixture flows upward against the effects of gravity.

In alternative embodiments, the pH test analysis may occur inside of the analysis tool <NUM> and as the soil mixture flows along the horizontal FD, whereby the horizontal FD is substantially orthogonal to the gravitational direction GD and the soil slurry flows horizontally through the analysis tool <NUM>.

According to embodiments of the pH test analysis that utilize vertical FD and horizontal FD, the soil slurry may comprise a surfactant. It has been surprisingly discovered that the addition of a non-ionic surfactant provides an unexpected improvement in optical clarity that enhances the spectrophotometer pH test analysis while ionic surfactants fail to provide such improved optical properties. Non-limiting examples of non-ionic surfactant include <NUM>-nonylphenyl polyethylene glycol, poly(ethylene glycol)(<NUM>) tridecylether, and mixtures thereof. The surfactant of this embodiment may be substantially free of ionic surfactant. The surfactant of this embodiment may be substantially free of anionic surfactant. The surfactant of this embodiment may be substantially free of cationic surfactant.

It has also bee surprisingly discovered that for the embodiments of the pH test analysis that utilize a vertical FD, the soil slurry may also be substantially free of surfactant and still achieve the desire optical clarity while the same optical clarity is not achieved in the absence of such surfactants in t he horizontal FD.

According to the embodiments directed to the pH analysis, non-limiting examples of indicator may include chlorophenol red sodium salt, phenol red sodium salt, Bromocresol Green sodium salt, Bromocresol green (<NUM>,<NUM>-Dibromo-<NUM>-[<NUM>-(<NUM>,<NUM>-dibromo-<NUM>-hydroxy-<NUM>-methyl-phenyl)-<NUM>,<NUM>-dioxo-<NUM>-oxa-9λ6-thiabicyclo[<NUM>. <NUM>]nona-<NUM>,<NUM>,<NUM>-trien-<NUM>-yl]-<NUM>-methyl-phenol, <NUM>,<NUM>',<NUM>,<NUM>'-Tetrabromo-m-cresolsulfonphthalein Bromocresol green, <NPL>) with Nitrazine yellow (<NUM>-(<NUM>,<NUM>-Dinitrophenylazo)-<NUM>-hydroxynaphthalene-<NUM>,<NUM>-disulfonic acid disodium salt, <NUM>-(<NUM>,<NUM>-Dinitrophenylazo)naphthol-<NUM>,<NUM>-disulfonic acid disodium salt, Nitrazol Yellow, <NPL>).

In one embodiment, the indicator composition may include Bromocresol green and Nitrazine yellow in a weight ratio of Bromocresol green to Nitrazine yellow of <NUM>:<NUM> to <NUM>:<NUM>. In other embodiments, the weight ratio is <NUM>:<NUM> to <NUM>:<NUM>. In one embodiment, the indicator composition may include <NUM> wt. % to <NUM> wt. % Bromocresol green, <NUM> wt. % to <NUM> wt. % Nitrazine yellow, and a liquid.

In one embodiment, the indicator may include <NUM> wt. % to about <NUM> wt. % of Bromocresol green sodium salt and <NUM> wt. % to about <NUM> wt. % of Nitrazene yellow. In one embodiment, the indicator may include <NUM> wt. % of Bromocresol Green sodium salt and <NUM> wt. % of Nitrazene yellow. In one embodiment, the indicator may include Bromocresol Green sodium salt and Nitrazene yellow in a <NUM>:<NUM> weight ratio.

In one embodiment, the indicator may include <NUM> wt. % to about <NUM> wt. % of chlorophenol red sodium salt and <NUM> wt. % to about <NUM> wt. % of phenol red sodium salt. In one embodiment, the indicator may include <NUM> wt. % of chlorophenol red sodium salt and <NUM> wt. % of phenol red sodium salt. In one embodiment, the indicator may include chlorophenol red sodium salt and phenol red sodium salt in a <NUM>:<NUM> weight ratio.

Optionally, a flocculating agent can be added (as described above, for example using polyacrylamide as described above). In one embodiment, a molar concentration for calcium chloride is <NUM> to <NUM> including all concentrations and sub-ranges there-between.

The soil slurry may be mixed with the flocculating agent in a volume ratio of <NUM>:<NUM> soil slurry: flocculating agent. In other embodiments, a volume ratio of slurry to flocculating agent may be <NUM>:<NUM> to <NUM>:<NUM> including all ratios and sub-ranges there-between.

In a non-limiting example of the liquid is water, but other liquids can be used.

According to the embodiments directed toward a vertical FD used in pH analysis, an extractant may be blended with the soil slurry. Non-limiting examples of extractant include calcium chloride, potassium chloride, sodium chloride, or magnesium chloride. The extractant may be present in concentration ranging from about <NUM> to about <NUM> - including all concentrations and sub-ranges there-between. In one embodiment, the extractant comprises calcium chloride in a concentration of about <NUM>.

In some embodiments, the soil sample may be prepared by mixing the the filtrate with the indicator and subsequently performing the absorbance reading at <NUM> when using indicator that includes Bromocresol Green sodium salt and Nitrazene yellow.

In some embodiments, the soil sample may be prepared by mixing the filtrate with the indicator and subsequently performing the absorbance reading at <NUM> when using indicator that includes chlorophenol red sodium salt and phenol red sodium salt.

According to this embodiment, the soil slurry and soil mixture may not be subjected to a centrifuge force before performing the pH absorbance reading.

According to an embodiment of the present disclosure, buffer pH may be tested according to the following methodology. A soil sample may be obtained and blended with liquid to create the soil slurry. The soil slurry may then flow through the filter element to create a filtrate, whereby one or more indicators may be added to the filtrate to create a mixture.

The soil mixture may then be analyzed for buffer pH by absorbance that may be read via a spectrophotometer at a wavelength of about <NUM>.

The buffer pH analysis may occur inside of the analysis tool <NUM> and as the soil mixture flows along the vertical FD, whereby the vertical FD is substantially parallel to gravitational direction GD such that the soil mixture flows downward at least partially under the effects of gravity. In some embodiments, the buffer pH analysis may occur inside of the analysis tool 110a and as the soil mixture flows along the vertical FD, whereby the vertical FD is substantially parallel to gravitational direction GD such that the soil mixture flows upward against the effects of gravity.

In alternative embodiments, the buffer pH analysis may occur inside of the analysis tool <NUM> and as the soil mixture flows along the horizontal FD, whereby the horizontal FD is substantially orthogonal to the gravitational direction GD and the soil slurry flows horizontally through the analysis tool <NUM>.

According to embodiments of the pH buffer analysis that utilize a vertical FD and horizontal FD, the soil slurry may comprise a surfactant. It has been surprisingly discovered that the addition of a non-ionic surfactant provides an unexpected improvement in optical clarity that enhances the spectrophotometer pH buffer analysis while ionic surfactants fail to provide such improved optical properties. Non-limiting examples of non-ionic surfactant include <NUM>-nonylphenyl polyethylene glycol, poly(ethylene glycol)(<NUM>) tridecylether, and mixtures thereof. The surfactant of this embodiment may be substantially free of ionic surfactant. The surfactant of this embodiment may be substantially free of anionic surfactant. The surfactant of this embodiment may be substantially free of cationic surfactant.

It has also bee surprisingly discovered that for the embodiments of the pH buffer analysis that utilize a vertical FD, the soil slurry may also be substantially free of surfactant and still achieve the desire optical clarity while the same optical clarity is not achieved in the absence of such surfactants in the horizontal FD.

According to the embodiments directed to the pH analysis, non-limiting examples of indicator may include chlorophenol red sodium salt, phenol red sodium salt, methyl red (<NUM>-{[<NUM>-(Dimethylamino)phenyl]diazenyl}benzoic acid) with bromothymol blue (<NUM>,<NUM>'-(<NUM>,<NUM>-Dioxido-<NUM>-<NUM>,<NUM>-benzoxathiole-<NUM>,<NUM>-diyl)bis(<NUM>-bromo-<NUM>-isopropyl-<NUM>-methylphenol), <NPL>).

In one embodiment, there is a composition that includes methyl red and bromothymol blue in a molar ratio of <NUM>:<NUM> to <NUM>:<NUM>. In other embodiments, the molar ratio is <NUM>:<NUM> to <NUM>:<NUM> or about <NUM>:<NUM>. The mixed indicator solution is made by taking <NUM>% methyl red indicator in water and mixing it <NUM>:<NUM> with <NUM>% bromothymol blue in a <NUM>/<NUM> water/ethanol mixture to make a final concentration of <NUM>% methyl red, <NUM>% bromothymol blue in a <NUM>/<NUM> water/ethanol solution by weight.

In one embodiment, the indicator may include <NUM> wt. % to about <NUM> wt. % of chlorophenol red sodium salt and <NUM> wt. % to about <NUM> wt. % of phenol red sodium salt. In one embodiment, the indicator may include <NUM> wt. % of chlorophenol red sodium salt and <NUM> wt. % of phenol red sodium salt in water. In one embodiment, the indicator may include chlorophenol red sodium salt and phenol red sodium salt in a <NUM>:<NUM> weight ratio.

According to the embodiments directed toward a vertical FD used in pH analysis, an extractant may be blended with the soil slurry.

In another embodiment, the buffer pH of a soil extract can be measured by obtaining a soil extract, combining with a buffer, adding methyl red and bromothymol blue to the soil extract to form a mixture, and then measuring absorbance of the mixture. In some embodiments, the buffer is added to the soil extract before adding the methyl red and bromothymol blue. The soil extract can be prepared as described above for the soil slurry. The soil slurry can be combined with a buffer solution in a volume ratio of <NUM>:<NUM> slurry to buffer. In one embodiment, the volume ratio is <NUM>:<NUM> to <NUM>:<NUM>. In one embodiment, the buffer solution is Sikora buffer. Sikora buffer is available from GFS Chemicals of Powell, Ohio, and it is about <NUM>% water, <NUM>% potassium chloride, <NUM>% triethanol amine and balance minors. Optionally, a flocculating agent can be added (as described above, for example using polyacrylamide as described above) and centrifuged to form a filtrate.

In some embodiments, the soil sample may be prepared by mixing the <NUM> of the filtrate with <NUM> of the indicator and subsequently performing the absorbance reading at <NUM> when using indicator that includes chlorophenol red sodium salt and phenol red sodium salt.

A fifth experiment was performed to test the impact of horizontal FD and vertical FD as it relates to surfactant for a pH soil analysis.

The samples of Examples <NUM>-<NUM> were prepared by blending soil and water together at a <NUM>:<NUM> ratio to create a slurry, whereby the slurry is pulled into the extraction portion of the system and extractant is added at a <NUM>:<NUM> ratio of slurry to extractant, with the extractant being <NUM> calcium chloride. After extraction, the extracted samples were filtered and the filtrate was subsequently blended with indicator to create a soil mixture, the indicator including a <NUM>:<NUM> ratio of bromocresol green sodium salt and nitrazene yellow. Each soil mixture of Examples <NUM>-<NUM> were then flowed along the horizontal FD through the analysis tool, and each soil mixture of Examples <NUM>-<NUM> were then flowed along the vertical FD through the analysis tool.

The sample of Example <NUM> included a non-ionic surfactant. The sample of Example <NUM> included an anionic surfactant. The sample of Example <NUM> included a cationic surfactant. The sample of Example <NUM> was free of surfactant. The sample of Example <NUM> included a non-ionic surfactant. The sample of Example <NUM> included an anionic surfactant. The sample of Example <NUM> included a cationic surfactant. The sample of Example <NUM> was free of surfactant.

Each sample of Examples <NUM>-<NUM> were analyzed by the analysis tool at a wavelength of <NUM> to determine the pH in the sample. After mixing, each sample produces turbidity and the ability to read through each sample was recorded as either a pass or fail value - whereby the pass value equates to an optical property sufficiently clear to allow for the reading of the pH a wavelength of <NUM> the fail value equates to an optical property insufficiently clear to not allow for reading of the pH at a wavelength of <NUM>. The results are set forth below in Table <NUM>.

As demonstrated by Table <NUM>, it was discovered that the addition of non-ionic surfactant provided for the optical clarity needed to perform the pH test analysis at a wavelength of <NUM> when operating in the horizontal FD and vertical FD while ionic surfactants failed such test. Table <NUM> also demonstrates that no surfactant in the filtration systems having a vertical FD exhibited sufficient optical clarity for the pH test analysis as compared to the horizontal FD filtration systems which surprisingly failed the same test.

A sixth experiment was performed to test the impact of horizontal FD and vertical FD as it relates to surfactant for a buffer pH soil analysis.

The samples of Examples <NUM>-<NUM> were prepared by blending soil and water together at a <NUM>:<NUM> ratio to create a slurry, whereby the slurry is pulled into the extraction portion of the system and extractant is added at a <NUM>:<NUM> ratio of slurry to extractant, with the extractant being sikora buffer. After extraction, the extracted samples were filtered and the filtrate was subsequently blended with indicator to create a soil mixture, the indicator including a <NUM>:<NUM> ratio of chlorophenol red sodium salt and phenol red sodium salt. Each soil mixture of Examples <NUM>-<NUM> were then flowed along the horizontal FD through the analysis tool, and each soil mixture of Examples <NUM>-<NUM> were then flowed along the vertical FD through the analysis tool.

Each sample of Examples <NUM>-<NUM> were analyzed by the analysis tool at a wavelength of <NUM> to determine the buffer pH in the sample. After mixing, each sample produces turbidity and the ability to read through each sample was recorded as either a pass or fail value - whereby the pass value equates to an optical property sufficiently clear to allow for the reading of the buffer pH a wavelength of <NUM> the fail value equates to an optical property insufficiently clear to not allow for reading of the buffer pH at a wavelength of <NUM>. The results are set forth below in Table <NUM>.

Claim 1:
A method of analyzing pH in soil, the method comprising:
a) obtaining a soil sample;
b) adding a liquid comprising a surfactant to the soil sample to form a soil slurry;
c) flowing the soil slurry through a filter to form a filtrate;
d) blending a pH indicator composition with the filtrate to form a soil mixture; and
e) flowing the soil mixture through an analysis tool along a flow direction that is substantially orthogonal to the direction of gravity, whereby a pH value of the soil mixture is measured.