Total And Species Analysis Of Arsenic In Atmospheric Particles

Arsenic (As) is a common environmental poisonous substance widely distributed around the world. Human arsenic exposure causes several health problems, such as lung cancer, skin cancer and so on. One important exposure way to this metalloid comes from air. The toxicity of arsenic species differ with their chemical forms. Generally, inorganic forms are more toxic than organo arsenic species, while arsenite is considered to be more toxic than arsenate. For correct evaluate environmental quality, especially arsenic in the air dange to human health. It is very important for arsenic speciation analysis in atmospheric particulates.In present dissertation, experimental studies of arsenic speciation in atmospheric particulates were carried out. A method has been described for the rapid extraction of arsenic in atmospheric particulates by phosphoric acid. The experiment has gentler conditions,arsenic form transformation doesn,t happen between extraction and separation. This method with low detection limit and high precision, has great value to promote in environment detects, air quality assessment and so on, such as the analytic of arsenic form determination in atmospheric particulates and soil.When determination of total arsenic, digestioned by nitrohydrochloric acid, with electrothermal board heat, determinated by HG– AFS. When atomic fluorescence instrument PMT voltage 320V, primary current 80mA, assistant current 40mA, carrier gas 400 mL/min, shielding gas 1000 mL/min, KBH₄ 2%, HCl 10%, determination result is the best. With phosphoric acid as the extractant,arsenic species in atmospheric particles were extracted gently and detected through high performance liquid chromatography conjugated hydride generation atomic fluorescence technique ( HPLC-HG-AFS ). Discusses instrument conditions, mobile phase, gradient elution conditions, phosphoric acid concentrations, ultrasonic times on the influences of experiment, the results show that: (1) PMT voltage 320V, primary current 80mA, assistant current 40mA, carrier gas 400 mL/min, shielding gas 1000 mL/min, KBH₄ 4%, HCl 20% in best effect. (2) Mobile phase A 10 mM NH₄H₂PO₄, PH = 6. Mobile phase B 200 mM NH₄H₂PO₄, PH = 6. Gradient elution conditions: 0– 1 min, mobile phase A 100%. 1-3 min, A 60%, B 40%. 3-6 min, B 100%. 6 mins later, A 100% separation is the best. (3) Phosphoric acid concentration is 1 M, ultrasonic extraction 40 min has the best effects.The original arsenic species contents and the spiking species of the standard material ( GBW 08302 ) were determined to seek the best extraction method. Under the optimized chromatographic and spectrographic conditions, the arsenic species were separated baseline, with the RSDs < 2% ( n = 5 ). The method detection limits of As(III),As(V),MMA and DMA were 1.45, 1.26, 1.97 and 1.16 ng/mL, respectively. After ultrasonic extraction 40 min with 1 mol/L phosphate, the extraction efficiency of arsenic species in the spiked standard material achieved 90% without speciation transformation. The developed method was applied to analysis arsenic species concentration in the atmospheric particles. The results showed that: (1) The main arsenic species in one place of Beijing were As(III) and As(V). (2) Arsenic content in atmospheric particulates change seasonally,at the same time, influenced by temperature,humidity and wind speed factors.(3)Arsenic concentrations in atmospheric particulates below anannual limit or objective value of 6 ng/m3 fixed for arsenic according to Directive 2004/107/EC, show this regional air polluted less degree.