Abraxis: 520012: Microcystins in water by Immunoassay, Coated Tube
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Official Method Name
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Abraxis Microcystin Tube Kit (40T) PN 520012 |
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Current Revision
| 2007 |
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Media
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WATER |
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Instrumentation
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Immunoassay |
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Method Subcategory
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Organic |
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Method Source
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Citation
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Brief Method Summary
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Microcystin is detected using a colorimetric immunoassay (ELISA) procedure. A sample (0.50 mL) and an enzyme conjugate (enzyme-labeled Microcystin) are added to a test tube pre-coated with secondary antibodies (anti-rabbit) against Microcystins. Both the Microcystin in the sample (if present) and the enzyme conjugate compete for the limited binding sites on the immobilized anti-rabbit antibodies in proportion to their concentrations. At the end of an incubation period, the unbound molecules are washed and decanted. A substrate is then added which is catalyzed by the enzyme and converted from a colorless to a blue solution. The reaction is terminated with the addition of a dilute acid. The concentration of Microcystin in the sample is determined by measuring its absorbance at a specific wavelength (450 nm) using a photometer and comparing its absorbance to the absorbance of the calibrators. |
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Scope and Application
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This method determines Microcystin in water (groundwater, surface water, well water). |
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Applicable Concentration Range
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0.10 - 5.0 |
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Interferences
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Cross-reactivity: Microcystin variants RR and YR and Nodularins and high concentrations of Microcystin-LA produce false positive responses for Microcystin-LR. |
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Quality Control Requirements
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(A) Calibration with 5 standards and 1 blank, all analyzed in duplicate. (B) Precision: 3 matrix samples with different levels in the range for quantitative analysis analyzed daily for 5 days with 5 replicates in each of 5 assays. (C) Accuracy: 5 matrix samples spiked with the target analyte at 4 different levels in the range for quantitative analysis. (D) Validation: Analysis of 4 positive and 4 negative samples by an independent method, for confirmation. |
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Sample Handling
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Samples are collected in glass containers with Teflon-lined caps; for compliance monitoring, samples should be held longer than 14 days. If samples are held frozen, they can be held for longer periods of time. Immunoassay reagents are stored refrigerated until use. Samples containing gross particulate matter should be filtered using a 1 micron filter or centrifuged before use. Drinking water samples are typically dechlorinated with 0.008% sodium thiosulfate. |
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Maximum Holding Time
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14 days at 4 degrees C, longer if frozen |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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