Tintometer Inc.: Lovibond PTV 1000: Continuous measurements of turbidity in drinking water by white light LED
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Official Method Name
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Continuous measurement of drinking water turbidity using a Lovibond PTV 1000 white light LED turbidimeter |
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Current Revision
| Revision 1.0, December 28, 2016 |
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Media
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WATER |
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Instrumentation
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Nephelometer |
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Method Subcategory
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Physical |
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Method Source
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Citation
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Brief Method Summary
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The method is based upon a comparison of the intensity of a collimated beam of light that is generated by a white light emitting diode (LED) that is scattered by the sample under defined conditions with the intensity of the same white light LED light scattered by a standard reference suspension. The higher the intensity of scattered light, the higher the turbidity. Readings, in NTU, are made in a nephelometer. |
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Scope and Application
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Turbidity measurement in any colorless drinking water samples with a turbidity less than 10 Nephelometric Turbidity Units (NTU). |
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Applicable Concentration Range
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0 to 10 NTU |
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Interferences
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(A) Floating debris and coarse particulate matter within the sample may settle out of suspension resulting in low turbidity readings. (B) Finely divided air bubbles will cause random high spikes in readings. Incorporate a sample deaerator for the removal of entrained air from the sample stream. (C) Dissolved, light absorbing substances or chemicals in the sample, i.e., the presence of color, can absorb portions of the incident light spectra, resulting in low turbidity readings, although this effect is generally not significant for drinking water. (D) Light-absorbing particles in suspension within the sample, such as activated carbon of significant concentration, can cause low readings. (E) Certain dissolved molecules or compounds can impart a fluorescence effect that can result upon the interaction with shorter wavelengths from the incident light source used in this method. This interference should be considered at turbidities below 0.100 NTU. (F) Construction materials of the nephelometric device within the measurement chamber can result in elevated stray light due to spurious reflections of the incident beam can cause a false positive bias at the bottom end of the range. |
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Quality Control Requirements
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LABORATORY REAGENT BLANK (LRB), PRIMARY CALIBRATION STANDARD (PCAL), QUALITY CONTROL SAMPLE (QCS), SECONDARY CALIBRATION STANDARDS (SCAL), STOCK STANDARD SUSPENSION (SSS), Reagent water, turbidity-free. |
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Sample Handling
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N/A |
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Maximum Holding Time
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N/A |
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Relative Cost
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Sample Preparation Methods
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