HJ 758-2015 in English
VALIDWater quality - Determination of haloacetic acids - Gas chromatography
- Issued on:2015-10-22
- Implemented on:2015-12-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
$321.00
本标准规定了测定水中卤代乙酸类化合物的气相色谱法。
本标准适用于地表水、地下水、生活污水和工业废水中一氯乙酸、一溴乙酸、二氯乙酸、
三氯乙酸、一溴一氯乙酸、一溴二氯乙酸、二溴乙酸、一氯二溴乙酸和三溴乙酸共九种卤代乙酸类化合物的测定。
当取样量为40 ml 时，本方法的检出限为2 μg/L，测定下限为8 μg/L。
Introduction
Background and significance of the standard
As a supporting technical specification for the Environmental Protection Law of the People's Republic of China, this standard establishes a systematic detection method for 9 halogenated acetic acids in water for the first time, filling the gap in my country's monitoring standards in this field. Its release and implementation has important regulatory value for the prevention and control of drinking water disinfection by-product pollution.
Core principle of the method
The gas chromatograph-electron capture detector (GC-ECD) system is used to convert halogenated acetic acids into methyl halogenated acetic acid esters for detection through extraction with methyl tert-butyl ether (MTBE) under acidic conditions and derivatization with sulfuric acid and methanol. The key steps include:
| Steps | Conditional parameters | Quality control points |
|---|---|---|
| Derivatization | 50℃±2℃ water bath for 120min | Time temperature deviation ≤10min/2℃ |
| Chromatographic separation | Dual column system (14% cyanopropylphenyl/5% phenyl stationary phase) | Relative retention time deviation ≤2% |
| Detection limit | 2μg/L (sampling volume 40ml) | Blank value |
Key technological innovations
1. Anti-interference design: Eliminate the interference of organic pollutants through pH adjustment-n-hexane pre-extraction, and monitor the recovery rate of the substitute 2-bromobutyric acid throughout the process (required to be 70-130%)
2. Double internal standard system: Use 1,2,3-trichloropropane as a quantitative internal standard, and add it before derivatization to ensure process control
Implementation tips
- Experimental safety: All operations must be carried out in a fume hood, and protective equipment must be worn when contacting reagents such as MTBE and concentrated sulfuric acid
- Derivatization control: Strictly control the derivatization temperature (50±2℃) and time (120±10min). Exceeding the temperature limit will cause the recovery rate to drop by more than 15%
- Chromatographic maintenance: It is recommended to replace the liner after every 200 injections, and the purity of the ECD detector tail gas must be ≥99.999%
Method Validation Data
Validation by 6 laboratories showed that for a spike concentration of 160μg/L, the recoveries of the nine target substances in industrial wastewater were 90.8-97.6%, and the inter-laboratory RSD was ≤14%. The repeatability limit of the typical compound trichloroacetic acid (TCAA) was 27μg/L.
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