WO1999044056A1 - Method for the determination of hexavalent chromium using ultrasonication and strong anion exchange solid phase extraction - Google Patents
Method for the determination of hexavalent chromium using ultrasonication and strong anion exchange solid phase extraction Download PDFInfo
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- WO1999044056A1 WO1999044056A1 PCT/US1999/004200 US9904200W WO9944056A1 WO 1999044056 A1 WO1999044056 A1 WO 1999044056A1 US 9904200 W US9904200 W US 9904200W WO 9944056 A1 WO9944056 A1 WO 9944056A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/22—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators
- G01N31/226—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators for investigating the degree of sterilisation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/22—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators
Definitions
- This invention relates to a method for the determination of hexavalent chromium (CA 1 ). More specifically, the present invention relates to a simple, fast, sensitive, and economical method for the determination of CA 1 which is especially adapted for environmental and work place samples (including solid and air samples). The present method can be used in both laboratory and field analysis.
- the trivalent state is relatively non-toxic, and is an essential nutrient in the human diet.
- Cr has been shown to be a human respiratory carcinogen in epidemiological studies of workplace exposures, and has been classified by the U S Environmental Protection Agency (EPA) as a Group A inhalation carcinogen.
- EPA U S Environmental Protection Agency
- Spectrophotometric and colorimetric methods have been developed for the determination of CrA See. for example, Alvarez et al., Talanta, 1989, 36(9), 919; Haukka. analyst, 1991, 1 16. 1055; Abel et al., Am. Ind. Hyg. Assoc. I, 1974, 35, 229.
- the most prevalent colorimetric method uses the selective reaction of Cr with 1,5- diphenylcarbzide (DPC) under acidic conditions to yield a red-violet Cr VI - diphenylcarbazone complex.
- NIOSH method 7600 NIOSH Manual of Analytical Methods, Eller & Cassinelli (eds.), National Institute for Occupational Safety and Health, Cincinnati, Ohio, 4 th ed, 1994
- alkaline extraction is used to help stabilize the Cr 1 species.
- Stripping voltammetry Wang et al.. Analyst, 1992, 1 17, 1913; Elleouet et al., Anal. Chim. Acta, 1992, 257, 301
- ion chromatographic assays Pierowell et al., Anal. Chem., 1995, 67, 2474; Vercoutere et al.. Mikrochim.
- SPE solid phase extraction
- Off-line SPE methodologies involve the use of packing materials that may contain functional groups of different polarity such as C 8 or C, 8 bonded silica phases (Falco et al., Analyst, 1997, 122, 673-677).
- on-line SPE followed by high pressure liquid chromatography, a critical parameter is the selection of an adequate precolumn in order to avoid band broadening of the first eluded peaks, and to allow for the percolation of large sample volumes (Kiss et al., J. Chromatogr., 1996. 725. 261-272).
- Numerous solid-phase extractants such as pure or modified silica, alumina, magnesia, activated carbon,
- Ultrasonic extraction for the purpose of dissolving target heavy metal analytes in environmental samples is also a technique that has not been used extensively, although it offers great promise (Lugue de Castro et al.. Trends Anal Chem.. 1997. 16. 16-24). UE has been demonstrated to perform well for the quantitative dissolution of several heavy metals in a variety of environmental matrices (Harper et al.. Anal. Chem.. 1983, 55, 1553-1557; Sanchez et al., Analusis, 1994. 22. 222-225. Ashley. Electroanalysis, 1995, 7, 1 189-1 192z), including hexavalent chromium (James et al.. Environ. Sci. Technol., 1995, 29, 2377-2381).
- This invention relates to a method for the determination of hexavalent chromium (CA 1 ).
- CA 1 hexavalent chromium
- SAE-SPE strong anion exchange solid phase extraction
- the method generally involves: (1) ultrasonication in basic buffer solution to extract Cr l from environmental matrices; (2) strong anion exchange solid phase extraction to separate Cr from other chromium species and potential interferents; (3) acidification of the eluate containing the CA 1 ions: (4) complexation of Cr vl with a complexing agent to form a soluble, colored Cr ⁇ -complex; and (5) spectrophotometric determination of the colored Cr I -complex.
- the ultrasonication step is carried out in the presence of a slightly basic ammonium buffer and the complexing agent is 1 ,5-diphenylcarbazide.
- This present method can effect the extraction of both soluble (K : Cr0 4 ) and insoluble (K 2 CrO 4 ) forms of Cr without inducing CrTM (Cr 2 O 3 ) oxidation or CA reduction.
- the method allows for the dissolution and purification of Cr VI from environmental and workplace air sample matrices for up to 24 samples (or even higher numbers) simultaneously in less than about 20 minutes (excluding the ultrasonic extraction time).
- the present method is simple, fast, quantitative, and sufficiently sensitive for the determination of occupational exposures of CrA
- the method is especially applicable for on-site monitoring of CA in environmental and industrial hygiene samples, including both solid samples (e.g., soil, paint chips, dust, solid residues, and the like) and air samples
- One objective of the present invention is to provide a method for the detection of CA in a sample, said method comprising:
- the ultrasonication step employed to liberate CA from the sample matrix is preferably carried out using a slightly basic ammonium buffer and the complexing agent is preferably 1 ,5-diphenylcarbazide
- the amount of Cr I present in the sample is determined using any appropriate technique More preferably, the amount of Cr I present in the sample is determined using a simple and direct spectrophotometric procedure which can be used in the field or on-site
- Another objective of the present invention is to provide a method for the quantitative detection of CA in a sample suspected of containing CA, said method comprising
- step (6) subjecting the CA-] ,5- iphenylcarbazone complex, if present, from step (5) to a spectrophotometric analysis in order to determine the amount of Cr VI present in the sample
- FIG. 1 is a flowchart illustrating the general procedures utilized in the present method
- FIG. 2 is a flowchart illustrating one preferred embodiment oft he present invention
- Figure 3 illustrates the breakthrough of CA using a strong anion exchange solid phase extraction column.
- Curve 1 uses an elution solution of 0.02 M ammonia sulfate and 0.02 M ammonia hydroxide buffer
- Curve 2 uses an elution solution of 0.05 M ammonia sulfate and 0.05 M ammonia hydroxide buffer
- Curve 3 uses an elution solution of 0.5 M ammonia sulfate and 0.5 M ammonia hydroxide buffer
- Curve 4 uses an elution solution of 1 .0 M ammonia sulfate and 1.0 M ammonia hydroxide buffer
- Figure 4 illustrates the elution of varying concentration of CA 1 using a strong anion exchange solid phase extraction column with varying.
- Curve 1 uses an elution solution of 0.5 M ammonia sulfate and 0.5 M ammonia hydroxide buffer
- Curve 2 uses an elution solution of 1 .0 M ammonia sulfate and 1 0 M ammonia hydroxide buffer
- Curve 3 uses an elution solution of 2.0 M ammonia sulfate and 2.0 M ammonia hydroxide buffer
- This invention provides a simple, fast, sensitive, and economical field method for the determination of hexavalent chromium (Cr % ), especially in environmental samples and workplace air samples.
- the present method combines ultrasonic extraction and a strong anion exchange solid phase extraction (SAE-SPE) technique to allow the filtration, preconcentration, and isolation of CA 1 in the presence of other chromium species and interferents.
- SAE-SPE strong anion exchange solid phase extraction
- the present method is generally illustrated in Figure 1 .
- ultrasonication 10 is used to extract CA 1 in the sample from its environmental matrix.
- a strong anion exchange solid phase extraction (S.AE-SPE) step 12 preferably using a column or cartridge system, is used to separate Cr I from other chromium species and potential interferents.
- the CA species are then eluted from the column or cartridge and collected.
- the eluant containing the Cr I species is then acidified in step 14.
- the acidified eluant is then treated with a complexing agent in step 16 to form a colored CA-complex which can be detected in step 18 using any appropriate means (e.g., visual, spectroscopic, or similar methods).
- FIG. 2 This preferred embodiment involves a first ultrasonication step 20 using a slightly basic ammonium buffer solution to extract Cr vl from the environmental matrices at a pH to avoid significant CrTM oxidation and/or CA 1 reduction.
- a strong anion exchange solid phase extraction (SAE-SPE) step 22 is then used to separate Cr vl from other chromium species and potential interferents.
- Step 22 is preferably carried out using a column or cartridge containing pre-packed strong anion exchange material.
- CA is then removed from the column or cartridge preferably using, for example, a sli ⁇ htlv basic ammonium solution.
- the collected eluant containing Cr v ⁇ is then acidified in step 24.
- An effective amount of 1.5-diphenylcarbazide is added to the eluant containing CA in step 26 to form a soluble, colored CrAi ⁇ -c ⁇ phenylcarbazone complex.
- the amount of Cr l is determined using a suitable spectrophotometric technique.
- the ultrasonication step employed to liberate CA 1 from the sample matrix should be carried out using a slightly basic aqueous buffer solution so as to reduce the levels of CrTM oxidation and Cr" reduction to low (i.e., insignificant) levels.
- the pH of buffered solution used in the ultrasonic extraction step is in the range of about 7.2 to 9.0, preferably in the range of about 7.5 to 8.5, and most preferably about 8.0.
- the ultrasonic solution is a buffered aqeuous ammonium solution containing between about 0.02 M to 0.2 M (NH 4 ),SO 4 and about 0.02 M to 0.2 M NH 4 OH.
- NH 4 ) 2 SO 4 even more preferably about 0.025 M to 0.1 M (NH 4 ) 2 SO 4 and about 0.025 M to 0.1 M NH 4 OH. and most preferably about 0.05 M (NH 4 ) 2 SO 4 and about 0.05 M NH 4 OH at a p ' ⁇ of about 8.0.
- Other alkaline buffers e.g., tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) where ammonium or ammonium hydroxide is used to obtain the desired basic pH; ammonium carbonate; generally basic buffers containing NH ⁇ cations
- Tris-HCl tris(hydroxymethyl)aminomethane hydrochloride
- ammonium or ammonium hydroxide is used to obtain the desired basic pH; ammonium carbonate; generally basic buffers containing NH ⁇ cations
- the ultrasonic extraction step can be carried out using any conventional ultrasonic bath.
- Ultrasonification for about 15 to 60 minutes at about room temperature or slightly elevated temperatures should be sufficient to release the Cr ⁇ q contained in the sample
- the ultrasonification is carried out a temperatures less than about 40 °C in order to minimize oxidation and reduction reactions. Routine experimentation can easily be carried out to determine the optimum ultrasonification conditions for any particular sample.
- the sample can be filtered if desired to remove solid material before application to the strong anion exchange resin.
- the sample is treated using a strong anion exchange resin to separate the CA 1 species from other chromium species as well as other potential interferents.
- the Cr I which is retained on the strong anion exchange resin can be eluted using a slightly basic aqueous buffer
- Suitable strong anion exchange resins include, for example, styrene- divinylbenzene polymer resins to which tertiary ammonium groups have been bound (e g . Dowex 1 -X8 from Fluka Chemical. Ronkonkoma, NY) and quaternary amine bonded silica with CI ' as the counter ion (Supelco, Inc., Bellefontaine, PA)
- Other strong anion exchange resins can be used so long as they allow separation of Cr vl from CrTM and other potential interferents.
- cartridges pre-packaged with the strong anion exchange resins are much easier to use and are, therefore, preferred.
- Strong anion exchange resins with a capacity of about 0.1 to about 2 0 meq/g are generally preferred.
- the strong anion exchange resins are conditioned or activated according to known procedures, such procedures are normally supplied by the resin manufacturer
- PA can be attached to an appropriate small vacuum pump via a metering valve in order to assist passage of the sample and other reagents through the resin
- a cartridge (3 ml) containing about 500 mg quaternary amine bonded silica sorbent with Cl " as the counter ion (capacity about 0 2 meg/g) is placed in the solid- phase extractor and then conditioned with about 3 ml of deionized water to activate the functional groups in order to allow the Cr" to be absorbed on the resin
- the sample generally about 1 to 5 ml
- obtained from the sonification extraction step is then loaded on the cartridge and passed through the resin at a flow rate of about 1 ml'min to about 2 ml/min
- the Cr I remains on the resin.
- the buffer system used to elute the CA 1 from the strong anion exchange resin may be the same or different from that used in the ultrasonification step. It should, however, be slightly basic to avoid CA 1 reduction. It is generally preferred that a buffered aqueous ammonium solution containing between about 0.25 M to 1.0 M (NH 4 ) 2 SO 4 and about 0.25 M to 1.0 M NH 4 OH is used as the eluting buffer. More preferably, the eluting buffer solution contains about 0.5 M (NH 4 ) 2 SO 4 and about 0.5 M NH 4 OH at a pH of about 8.0. Generally, the eluting buffer system is more concentrated (preferably by a factor of about 10) than the ultrasonic buffer system.
- alkaline buffers e.g.. tris(hydroxymethyl)aminomethane hydrochJoride (Tris- HC1) where ammonium or ammonium hvdroxide is used to obtain the desired basic pH; ammonium carbonate; generally basic buffers containing NH 4 * cations
- Tris- HC1 tris(hydroxymethyl)aminomethane hydrochJoride
- ammonium or ammonium hvdroxide is used to obtain the desired basic pH
- ammonium carbonate generally basic buffers containing NH 4 * cations
- the Cr ⁇ '-containing eluant is acidified using suitable acids (e.g.. 'lfuric acid, hydrochloric acid, acetic acid, and the like). Generally the pH is not critical so long as the eluant is acidic.
- the complexing agent is added to form a detectable Cr %1 -complex. The complexing agent is added in excess in order to maximize the amount of Cr '-complex formed In other words, the amount of complexing agent should be sufficient to complex with essentially all of the Cr l present in the sample.
- suitable complexing agents include 1.5-diphenylcarbazide, 2-(5-bromo-2-pyridylazo-5-
- the CrA ⁇ S-dipenylcarbazone complex is red-violet with an absorbance maxima at about 520-540 nm. Generally color formation occurs within a few seconds and is stable for several hours. Nonetheless, it is generally preferred that the detection step be undertaken shortly after complex formation.
- Quantitative or qualitative detection of the resulting Cr"-complex can be by any suitable means.
- the development of the colored Cr"- CO mplex itself visually indicates the presence of CA 1 in the sample.
- UVYVIS-based spectrophotometric detection methods are preferred for quantitative colorimetric measurement.
- a standard cataloging spectrophotometer, especially one adapted for field operation, is generally preferred so as to provide a portable, field-adapted detection method.
- a spectrophotometer operating at about 540 nm is preferred; this wavelength provides maximum sensitivity and generally eliminates interference of excess (i.e., uncomplexed) 1.5-diphenylcarbazide complexing reagent
- the present method may be either manual, semi-automated, or fully automated Manual or semi-automated analysis and detection techniques might be used, for example, for screening or spot-checking a workplace environment to determine if Cr" exposure is likely and if further, more extensi 1 " > , sampling is necessary.
- automated techniques wherein multiple samples can be evaluated at the same time are preferred.
- a flow- injection analysis system as described in Wang et al (.Analyst, 1997, 12, 1307-1312, which is hereby incorporated by reference) can be employed Such a system, employing a pump and an autosampler operating under low- pressure and computer control can be used to automate the precise manipulation of microliter amounts of samples and deliver the products to a flow-through colormetric detector for the detection of Cr".
- a pump and an autosampler operating under low- pressure and computer control
- SPE low cost vacuum manifolds for SPE can allow multiple samples to be run; generally, 24 samples (or more with appropriate modifications) at a time can easily be evaluated.
- Commercial instrumentation is also available by which the SPE process can be automated.
- the present method can provide a low cost, simple, fast, quantitative, and sensitive method for the determination of occupational exposure of Cr . This method is ideally suited for on-site monitoring of Cr" in environmental and industrial hygiene applications
- the solid-phase extractor was obtained from Supelco, Inc. (Bellefontaine, PA. USA), and was attached to a small vacuum pump via a pressure metering valve.
- the strong anion exchange cartridge used in the solid phase extraction contained 500 mg quaternary amine bonded silica sorbent with Cl ' as counter ion for strong anion exchange (capacity 0.2 meg/g): the tube size was 3 ml.
- These pre-packaged cartridges were obtained from Supelco, Inc., Bellefontaine, PA.
- a portable cataloging spectrophotometer HACH DR'2010, HACH Company oveland, CO was used for spectrophotometric measurement.
- Chromium-containing reference materials were used as supplied: (1) paint chips — US EPA Certified Reference Material (CRM) 013-050, Laramie, WY; (2) coal fly ash ⁇ National Institute of Standards and Technology (N1ST) Standard Reference Material (SRM) 1633a, Gaithersburg, MD; and (3) welding dust loaded on glass fiber filters — Institute for Reference Materials and Measurements (IRMM) CRM 545) from the European Commission (IRMM Geel, Belgium).
- preloaded filter cassettes containing mixed cellulose ester membrane filters (0.8 ⁇ pore size, .37 mm diameter) w ere obtained from SKC Inc. (Eighty Four, PA).
- Solid-Phase Extraction Procedures Solid-phase extraction (SPE) was performed with the aid of an extractor and a strong anion exchange (S.AE) cartridge
- the SAE cartridge contained a silica sorbent to which a quaternary amine was bound, chloride ion functioned as the counter ion Cartridges were conditioned with 3 ml of deionized water, which activated the functional groups on the sorbent, allowing for binding of Cr l onto the SAE sorbent Subsequently, a 3 ml aliquot of sample solution was loaded on the SAE cartridge After sample loading, the cartridge was rinsed with 3 ml of deionized water to remove potential interferents Then, elution of the Cr I concentrated on the SAE cartridge was performed with 9 ml of 0 5 M ammonium sulfate buffer solution in three 3 ml fractions
- Sample Collection Workplace air samples were collected from aircraft painting operations at U S Air Force bases using 0 8 micron, 37-mm cellulose ester membrane filters Samples were obtained from different work practices including priming, sanding, alodining, cutting, and grinding The samples wr "e transported to the laboratory immediately after collection, and stored in a refrigerator at 4°C until prepared for analysis Environmental samples were collected using standard techniques
- Sample preparation consisted of adding 10 ml of 0 05 M (NH 4 )SO 4 and 0 05 M NH 4 OH (pH 8) buffer solution to the sample followed by sonication in an ultrasonic bath for 30 minutes at ambient temperature ( ⁇ 40 C C) After ultrasonication, a 3 ml aliquot of the supernatant was loaded onto a strong anion exchange cartridge The Cr l was eluted with 9 ml 0 5 M (NH 4 )SO 4 and 0 1 M NH 4 OH (pH 8) buffer solution in three 3 ml fractions at a flow rate of 2 ml/min After isolation and purification, the eluate was acidified with 100 ⁇ l 37% HC1 solution This was followed by mixing with 2 ml of 20 mM 1 ,5- diphenylcarbazide complexing reagent The reaction of 1 ,5-diphenylc
- Example 1 Absorption Capacity Studies Absorption capacities were determined using spiked Cr" solutions produced by dissolving K 2 CrO 4 in 0 02 M, 0 05 M, and 0 5 M ammonium sulfate and ammonium hydroxide buffer solutions (pH 8) Four different Cr VI spiked solutions (1 0 mM, 2 0 mM, 4 0 mM, and 8 0 mM) were prepared and loaded onto the cartridge, eluted. and analyzed in triplicate to e 'ablish the reproducibility of the procedure Breakthrough of the analyte was determined by analysis of the solution that passed through the SAE cartridge after loading of sample aliquots
- Example 2 Elution Studies. Ammonium sulfate and ammonium hydroxide buffer was used as the elution buffer solution. To obtain optimum recoveries, spiked Cr" solutions of four levels (10.0 ⁇ l, 20.0 ⁇ l, 40.0 ⁇ l, 80.0 ⁇ l) were eluted using different number of fractions of 0.5 M ammonium sulfate and ammonium hydroxide buffer solution (pH 8) Eluting power was investigated for five levels of Cr" solutions (50.0 ⁇ g, 100.0 ⁇ g, 200.0 ⁇ g, 400.0 ⁇ g, 600.0 ⁇ g) at various flow rates. In each experiment, only one parameter was changed at a time.
- Table I shows the recoveries of Cr" obtained from spiked Cr VI solutions at 4 levels (10.0 ⁇ g, 20.0 ⁇ g 40.0 ⁇ g. 80.0 ⁇ g) using varying number of eluting fractions (each fraction consisted of 3 ml of 0.5 M (NH 4 ) 2 SO 4 and 0.1 M NH 4 OH (pH 8) buffer).
- Example 3 Ultrasonic Extraction of Soluble and Insoluble Cr.
- the soluble fractions of CA 1 are useful parameters for estimating levels of Cr X I that may be directly absorbed by humans, quantifying insoluble forms of CA 1 is pertinent to occupational hazards (such as PbCrO4 in chromate ore processing and painting) associated with airborne respirable dust. Therefore, an effective and reliable method for extracting both soluble and insoluble forms of Cr" without inducing CrTM oxidation or Cr” reduction is required.
- both ammonium sulfate and ammonium hydroxide buffer (pH 8) and/or Tris-HCl buffer solutions were used as the ultrasonic extraction buffer.
- ammonium sulfate and ammonium hydroxide buffer solutions were used to dissolve hexavalent chromium from environmental matrices. It is expected that conditions of the hot ammonium buffer sonication procedure might oxidize CrTM to CA 1 under diverse redox conditions of various matrices. Hence no heating and relatively low concentration of the ammonium sulfate and ammonium hydroxide buffer solution (pH 8) were used to quantify and define operationally soluble and insoluble forms of CrA
- Table II shows the results for Cr" recoveries from ammonium sulfate and Tris-HCL buffer solutions.
- Example 4 Analysis of Reference Materials. Three certified reference materials (CRMs) were chosen to evaluate the basic isolation and determination procedure of the present invention One certified reference material, US EPA CRM
- IRMM CRM 545 contained approximately 3 mg of total welding dust with about 100 ⁇ g of hexavalent chromium per filter sample. This last reference material has only just recently become available and appears to be the only known CRM for particulate hexavalent chromium.
- E.iample 5 Workplace .Air Samples. This example illustrates the use of the present method to monitor Cr" exposure at various aircraft painting and maintenance operations at U.S. Air Force bases
- Air filters used to collect airborne particulate were placed in a 15 ml plastic tube to which 10 ml of 0.05 M (NH 4 ) 2 SO 4 and 0.05 M NH OH (pH 8) buffer solution was added. This was followed by ultrasonication in an ultrasonic bath for 30 minutes ( ⁇ 40 C C). After ultrasonication, a portion (about 3 ml) of the supernatant obtained (total of about 10 ml) was loaded onto a strong anion exchange cartridge.
- Example 6 Flow Injection Analysis.
- This example illustrates the use of flow injection analysis (FIA) using UVWIS detection of the Cr-diphenylcarbazone complex. Except as noted, the general procedures and reagents used in the previous examples were employed here. (This procedure is described in more detail in Wang et al.. Analyst, 1997, 122, 1307-1312, which is hereby incorporated by reference in its entirety.)
- the flow injection system consisted of a Waters 600-MS system controller pump, a Waters 717 Plus autosampler (Millipore, Milford, MA), and a Model 783 programmable ultraviolet absorbance detector set at 540 nm (Applied Biosystems,
- the flow rate of the pump was 1.0 ml/min for the mobile phase. Upon initial start up, the system was allowed to equilibrate for about 15 minutes. A sample volume of 10 ⁇ l was used for injections.
- This FIA-UV/V1S method was used on a variety of spiked samples, certified reference materials, and workplace samples.
- the samples spikeked filters (0.8 ⁇ , 37 mm), 1.0 g spiked sand, 0.1 g CRMs, and 1.0 g other fly ash and paint chip materials
- the samples were then subjected to anion exchange separation (1.0 g Dowex 1-X8).
- the eluate was acidified and reacted with 2
- N/A in the Table indicates that no standard or reference data for Cr xn was available for those particular samples and that Cr VI recovery cannot be determined.
- the detection limit was estimated at 0.1 1 ng Cr VI .
- the results for the two CRM samples are in good agreement with those reported in Example 4 above.
Abstract
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Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
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AU28801/99A AU748361B2 (en) | 1998-02-27 | 1999-02-25 | Method for the determination of hexavalent chromium using ultrasonication and strong anion exchange solid phase extraction |
EP99909636A EP1058845A1 (en) | 1998-02-27 | 1999-02-25 | Method for the determination of hexavalent chromium using ultrasonication and strong anion exchange solid phase extraction |
CA002320828A CA2320828A1 (en) | 1998-02-27 | 1999-02-25 | Method for the determination of hexavalent chromium using ultrasonication and strong anion exchange solid phase extraction |
US09/622,547 US6808931B1 (en) | 1998-02-27 | 1999-02-25 | Method for the determination of hexavalent chromium using ultrasonication and strong anion exchange solid phase extraction |
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US7613798P | 1998-02-27 | 1998-02-27 | |
US60/076,137 | 1998-02-27 |
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EP (1) | EP1058845A1 (en) |
AU (1) | AU748361B2 (en) |
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Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20120053388A1 (en) * | 2008-12-01 | 2012-03-01 | Robert Stanforth | Process for solubilizing, reducing and fixing hexavalent chromium contained in chromite ore processing residue into trivalent chromium |
CN102519948A (en) * | 2011-11-24 | 2012-06-27 | 中国科学院宁波材料技术与工程研究所 | Detection method for hexavalent chromium ions |
US10274468B2 (en) | 2016-11-16 | 2019-04-30 | Raytheon Company | Methods and kit for determining presence of trivalent chromium conversion coating |
CN111157517A (en) * | 2020-01-03 | 2020-05-15 | 吉林烟草工业有限责任公司 | Method for detecting hexavalent chromium in cigarette mainstream smoke |
CN113358809A (en) * | 2021-06-09 | 2021-09-07 | 北京科技大学 | Method for determining soluble anions of pollutants on surface of material and application of method |
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CN111157650A (en) * | 2020-01-07 | 2020-05-15 | 中国电子技术标准化研究院 | Ion chromatography detection method for hexavalent chromium content in polymer material of electronic and electrical product |
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1999
- 1999-02-25 AU AU28801/99A patent/AU748361B2/en not_active Ceased
- 1999-02-25 EP EP99909636A patent/EP1058845A1/en not_active Withdrawn
- 1999-02-25 CA CA002320828A patent/CA2320828A1/en not_active Abandoned
- 1999-02-25 WO PCT/US1999/004200 patent/WO1999044056A1/en active IP Right Grant
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SU1571497A1 (en) * | 1987-09-18 | 1990-06-15 | Dolgorev Anatolij V | Method of determining ruthenium |
RU2024848C1 (en) * | 1991-04-11 | 1994-12-15 | Институт геохимии и аналитической химии им.В.И.Вернадского РАН | Method for chromium determination |
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Title |
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DATABASE WPI Section Ch Week 9107, Derwent World Patents Index; Class E31, AN 91-049845, XP002106790 * |
DATABASE WPI Section Ch Week 9530, Derwent World Patents Index; Class A89, AN 95-230115, XP002106791 * |
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
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US20120053388A1 (en) * | 2008-12-01 | 2012-03-01 | Robert Stanforth | Process for solubilizing, reducing and fixing hexavalent chromium contained in chromite ore processing residue into trivalent chromium |
US8323593B2 (en) * | 2008-12-01 | 2012-12-04 | Trc Environmental Corporation | Process for solubilizing, reducing and fixing hexavalent chromium contained in chromite ore processing residue into trivalent chromium |
CN102519948A (en) * | 2011-11-24 | 2012-06-27 | 中国科学院宁波材料技术与工程研究所 | Detection method for hexavalent chromium ions |
US10274468B2 (en) | 2016-11-16 | 2019-04-30 | Raytheon Company | Methods and kit for determining presence of trivalent chromium conversion coating |
CN111157517A (en) * | 2020-01-03 | 2020-05-15 | 吉林烟草工业有限责任公司 | Method for detecting hexavalent chromium in cigarette mainstream smoke |
CN113358809A (en) * | 2021-06-09 | 2021-09-07 | 北京科技大学 | Method for determining soluble anions of pollutants on surface of material and application of method |
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AU748361B2 (en) | 2002-06-06 |
AU2880199A (en) | 1999-09-15 |
EP1058845A1 (en) | 2000-12-13 |
CA2320828A1 (en) | 1999-09-02 |
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