Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D4165-06 – Standard Test Method Technical Guide
🧪 Test Method Principle and Scope
This standard specifies a spectrophotometric test method for determining cyanogen chloride in water. Cyanogen chloride is a highly labile, sparingly soluble gaseous compound that forms upon chlorination of waters containing cyanide or thiocyanate. Due to its instability, rapid analysis upon sample collection is critical; the standard recommends a spot plate or comparator test immediately after sampling to minimize losses. The method is validated for reagent water, with the analyst responsible for verifying suitability for specific matrices.
⚠️ Important: Cyanogen chloride decays rapidly in solution. Use quick tests (e.g., spot plate) at the time of sampling to reduce error from time delay between collection and analysis. Refer to Fig. 1 in the standard for a typical decay curve.
⚗️ Analytical Procedure and Reagent Preparation
The core procedure involves mixing the water sample with a pyridine-barbituric acid solution. The resulting color is measured using a spectrophotometer following the principles outlined in Test Method D of ASTM D2036. Specific safety precautions apply—see sections 8.5, 8.7, and Section 9 for detailed hazard statements. The test method employs SI units throughout and has been used successfully with reagent water.
Key reagents and equipment include spectrophotometers conforming to Practices E60 and E275, and reagent water meeting Specification D1193. Sampling must follow Practices D3370 for flowing streams, and laboratory quality control should align with Guides D3856, D4210, and D5789 where applicable.
💡 Technical Tip: For optimal results, analyze samples immediately. If delay is unavoidable, collect samples in gas-tight containers and minimize headspace. The lower detectability limit is 0.005 mg CN⁻/L.
📊 Key Measured Parameters and Detection Limits
The standard provides clear performance metrics. The lower limit of detectability is established at 0.005 mg CN⁻/L. All measurements are expressed in SI units. The method relies on the color reaction between cyanogen chloride and pyridine-barbituric acid, with absorbance measured spectrophotometrically. Reference is made to Test Method D of D2036 for collaborative testing data.
| 🟦 📏 Parameter | 🔬 🎯 Value |
|---|---|
| 📉 Lower Limit of Detectability | 0.005 mg CN⁻/L |
| 📐 Measurement Principle | Color development with pyridine-barbituric acid |
| ⚗️ Instrumentation | Spectrophotometer (UV/Vis per Practices E60/E275) |
| 🧪 Matrix Suitability | Validated for reagent water; apply to other matrices with verification |
❓ Frequently Asked Questions
🔍 Why is cyanogen chloride considered unstable in water samples?
Cyanogen chloride is a labile, gaseous compound that rapidly decays or volatilizes after sample collection. The standard advises immediate testing (e.g., spot plate) to minimize losses.
💡 What is the lower detection limit of this test method?
The method can detect cyanogen chloride down to 0.005 mg CN⁻/L. This is the established lower limit of detectability according to Section 1.4 of the standard.
⚡ How does the color reaction work in this test?
The water sample is mixed with a pyridine-barbituric acid solution. The cyanogen chloride reacts to form a colored complex, which is measured spectrophotometrically as described in the summary of test method.
📌 Which ASTM standards are referenced for quality control?
Key referenced documents include D1129 (Terminology), D1193 (Reagent Water), D2036 (Cyanides in Water), D3370 (Sampling), and D5847 (Quality Control Specifications).