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D1246-16 – Standard Test Method Technical Guide
ASTM D1246−16 outlines a potentiometric test method for measuring bromide ion in water, ground water, and drinking water. The method employs a bromide ion-selective electrode and a reference electrode, with measurements taken using a pH meter or selective ion meter. This method is suitable for bromide concentrations from 0.5 mg/L to 1000 mg/L, and the range can be extended by diluting the sample.
🧪 Summary of Test Method
Bromide ion concentration is determined potentiometrically using a bromide ion-selective electrode in conjunction with a single-junction, sleeve-type reference electrode. Potential readings are taken on a pH meter with an expanded millivolt scale capable of 0.1 mV resolution, or on a selective ion meter with a direct concentration scale. The electrodes are calibrated using known bromide solutions, and the same background conditions are maintained for unknowns through the addition of an ionic strength adjustor.
The following table summarizes the key specifications of the test method:
| 🔧 Parameter | 📏 Specification |
|---|---|
| 🧪 Analyte | Bromide Ion (Br⁻) |
| ⚙️ Method | Potentiometric with ion-selective electrode |
| 📊 Concentration Range | 0.5 mg/L to 1000 mg/L |
| 💧 Sample Types | Water, ground water, drinking water |
| 📟 Instrument | pH meter (0.1 mV) or selective ion meter |
⚗️ Calibration and Measurement Procedure
Calibration is performed using standard bromide solutions with the same background ionic strength as the samples. An ionic strength adjustor is added to both standards and samples to maintain consistent conditions. For samples with ionic strength above 0.1 M, standard solutions should be prepared to match the sample composition. The measurement procedure involves reading potentials and determining concentrations from the calibration curve.
💡 Tip: For less precise work, a pH meter with a millivolt scale readable to 1.0 mV is adequate, but no supporting data are available for this lower precision.
📊 Precision, Bias, and Quality Control
The precision and bias of this test method were determined on natural and ground waters. It is the analyst’s responsibility to validate the method for untested matrices. The standard also references practices for quality control, including guide D5810 for spiking and practice D5847 for writing quality control specifications.
| 📋 Aspect | 🟦 Requirement |
|---|---|
| 🎯 Precision | Determined on natural and ground waters |
| ⚡ Bias | Applicable to tested matrices, validation required for others |
| 📘 Quality Control | Follow Guides D5810 and Practice D5847 |
⚠️ Note: The method has been approved by the U.S. Department of Defense. Ensure that all safety, health, and environmental practices are followed as per the user’s responsibility.
❓ Frequently Asked Questions
🔍 What is the applicable concentration range for bromide measurement?
The method can analyze bromide concentrations from 0.5 mg/L to 1000 mg/L. This range can be extended by diluting an appropriate aliquot of the sample.
💡 What equipment is required for this test method?
A bromide ion-selective electrode, a single-junction sleeve-type reference electrode, and a pH meter with an expanded millivolt scale (0.1 mV readability) or a selective ion meter are required.
⚡ How should samples with high ionic strength be handled?
For samples with ionic strength above 0.1 M, prepare standard solutions with a composition similar to that of the sample to ensure accurate calibration.
📌 What types of water can be tested with this method?
This test method is applicable to water, groundwater, and drinking water. The precision and bias were established on natural and ground waters.