废水、污水中汞检测方案(测汞仪)

RAPID ANALYSIS OF TOTAL MERCURY IN WASTE WATERS AND PROCESS WATERS USING DIRECT PYROLYSIS TECHNIQUE INTRODUCTION A conventional standard method of total mercury determination in water using atomic absorption spectrometry (AAS) involves preliminary sample digestion that takes from 30 minutes to 8 hours depending on the digestion conditions. The use of a mercury analyzer RA-915M with Zeeman background correction in combination with PYRO- 915+ pyrolysis attachment provides direct determination of mercury in process and waste waters contaminated with mercury without digestion or any other sample preparation stages. MEASUREMENT METHOD The measuring method is based on thermal atomization of mercury from a sample using a PYRO-915+ attachment and its consequent determination by flameless AAS with Zeeman background correction using a RA-915M mercury analyzer. A water sample is placed into the sample boat with a charcoal bed, which is inserted into the first chamber of the atomizer, where the sample is heated at a temperature of 200–800°C (depending on the selected operation mode). The mercury compounds are evaporated and partially dissociated, forming elemental mercury. All the gaseous products formed are transported into the second chamber of the atomizer by a carrier gas (ambient air). Mercury compounds are totally dissociated and the organic matrix of the sample is burnt out. Downstream from the atomizer the air flow enters the analytical cell heated up to 700°C, and the mercury atoms are detected by RA-915M analyzer. This approach does not involve preconcentration on a gold trap and “cooling step”, thereby eliminating ensuing problems. The use of ZAAS combined with a “dry” converter provides the highest sensitivity with no interferences from the sample matrix. Purified ambient air is used for combustion, so that no cylinders with oxidizer or compressed gases and “clean room” environment are required. The total time needed for determination of mercury is not longer than 2 minutes. RA-915M is compliant with US EPA 7473 and ASTM D7622 methods. MEASUREMENT RANGE The measurement range of the mass concentration of total mercury in waste, process or other waters is 3– 50000 µg/l without dilution. For water with low mercury concentration (natural, potable, treated waste water) LUMEX specialists have developed methods for determination of mercury using RA-915M analyzer with RP-92 attachment with the detection limit 0.2 ng/l. ANALYSIS FEATURES As compared to the determination of mercury in two stages (digestion + spectroscopic determination), the proposed method has the following advantages: Direct determination of total mercury; Rapid analysis; Low reagent consumption; Low running cost – needs no chemical reagent. EQUIPMENT AND REAGENTS The following equipment and materials are used for analysis: Mercury analyzer RА-915М with PYRO-915+ attachment; PC with Windows® ХР/Vista/7/8 and RAPID software; SRM of mercury, concentration 1g/l; Activated coconut charcoal, 12/40 mesh, mercury-free (<2 ppb). The information in this leaflet is supplemental. To get more specific information on this method, please contact the developer of this method LUMEX INSTRUMENTS Group. NORTH AMERICA Lumex Instruments Canada 0890278 B.C. Ltd. E-mail: info@lumexinstruments.com www.lumexinstruments.com EUROPE Lumex Analytics GmbH E-mail: info@lumexanalytics.de www.lumexanalytics.de RUSSIA Lumex-Marketing LLC E-mail: sales@lumex.ru www.lumexinstruments.com CHINA Beijing Lumex Analytical Equipment Co. Ltd. E-mail: lumex@lumex.com.cn www.lumexcn.com        采用传统的常规方法（原子吸收光谱法）测定水中总汞的含量，根据不同的消化条件分别需要30分钟至8小时的初步样品消化。 而使用塞曼背景校正的汞分析仪RA-915M与Pyro-915 +热解附件相结合，可不用消解等任何前处理步骤，也不用担心样品受到污染的情况下直接对汞污染废水中的汞含量进行测定。