实验报告英文

determination of heavy metals in soil by atomic absorption spectrometry(aas) name: xufei group: the 3rd group date: sep. 20th 2012part 1 the introduction1.1the purposes(1)learn how to operate the atomic absorption spectrometry;(2)learn how to do the pretreatment of soil samples;(3)get familiar with the application of atomic absorption spectrometry.1.2the principlesatomic absorption spectrometry (aas) is a technique for measuring quantities ofchemical elements present in environmental samples by measuring the absorbedradiation by the chemical element of interest. this is done by reading the spectraproduced when the sample is excited by radiation. the atoms absorb ultraviolet orvisible light and make transitions to higher energy levels . the concentration is calculated based on the beer-lambert law. absorbance isdirectly proportional to the concentration of the analyte absorbed for the existingset of conditions. the concentration is usually determined from a calibration curve,obtained using standards of known concentration. calibration curve method: preparestandard solutions of at least three different concentrations, measure the absorbanceof these standard solutions, and prepare a calibration curve from the values obtained.then measure the absorbance of the test solution adjusted in concentration to ameasurable range, and determine the concentration of the element from the calibrationcurve. part 2 the materials and apparatus part 3 the procedure3.1 operating procedure for aas (2) install required hollow cathode lamp. select “t” before turning to the powerand hollow cathode lamp. then select appropriate la mp current and preheat for 30min.(3) make sure electrical meter to point to zero and then turn on high-voltagepower.(4) select appropriate slit width.(5) rotate monochromator and select required wavelength. if the power meter istoo high or low, adjust negative high voltage until the meter reads full scale.(6) adjust light point and wavelength so that the meter represents the maximumvalue.(8) inject distilled water into the flame and continue to preheat the burner.inject distilled water into the flame after each sample.(9) select “e”, inject blank solution into the flame and adjust the meter tozero.(10) optimize analysis conditions and measure standard solution and samples.(12) select “t” before turning off high voltage power, decrease lamp currentand then turn off the lamp. at the same time, all buttons should be on originalpositions.(13) check the equipment before leaving the laboratory.3.2 determination of soil samples (1) preparation of extracting solution (0.05 mol/l edta solution) 18.6 g of edta is dissolved with water in a beaker (500 ml). the ph is adjustedto 7.0 using dilute ammonia. the mixture is transferred into a volumetric flask(1000ml), dilute to the mark and mixed well.(2) treatment of soil samples 2.50 g of air-dried soil (60- 100 mesh) is put into an erlenmeyer flask withstopper (100 ml). 12.5 ml of edta solution is added. the mixture is shaken for 1hand then filtered. the filtrate is preserved for analysis.(3) preparation of cu standard stock solution 0.10 g of cu is dissolved in 15 ml of (1:1) nitric acid solution. the mixtureis transferred into a volumetric flask (1000 ml) and diluted to the mark withre-distilled water. the concentration of the stock standard solution is 100g/ml. (theconcentration should be calculated according to the mass of cu).the working custandard solution (10μg/ml) is obtained by diluting 10 ml of cu standard stocksolution to 100 ml with re-distilled water.(4) plotting of the standard curve 0 ml, 1 ml, 2 ml, 3 ml, 4 ml and 5 ml of cu standard solution (10μg/ml) are addedrespectively to 6 volumetric flask (10 ml) with 1 ml of 5 mol/l hydrochloric acid.the mixture is diluted with re-distilled water and mixed well to give 0μg/ml, 1.00μg/ml,2.00μg/ml, 3.00μg/ml, 4.00μg/ml, 5.00μg/ml of cu, respectively. theabsorbance is measured at wavelengths of 3247 ?. the standard curve is constructedby plotting absorbance vs. concentration.(5) determination of samples the sample solution is analyzed using the same procedure and conditions as forthe standard curve. the concentration of cu is obtained from the standard curve basedon the absorbance.part 4 the results4.1 the raw data 4.2 aas standard curve 4.3 calculationthe absorbance of sample is 0.0511. according to the formula above :y=0.0446x+0.0024,r2=0.9997 the concentration of cu in the sample is:1.091mg/l. part 5 discussionin this experiment, we use the aas to determine cu in soil. i learn how to operatethe aas and the limitation. in the experimental process, standard solution wasprepared in strict accordance with the experimental requirements and i learn how todeal with the data. finally we get the standard curve, then, the sample concentrationis calculated according to the absorbance of the sample. ultimately, we get the linear formula is y = 0.0446x + 0.0024 and r2=0.9997. fromaccording to the formula and the absorbance of cu in the sample is 0.0511, we drawthe concentration of cu in the sample is 1.091μg/ml. we have known that theconcentration of test sample measured by instrument is 1.091mg/l. we can say our result of experiment is so very accurate from the standard curveof cu and the value of r(r2=0.09997). the accurate data is due to the efforts of weeveryone. thanks for every members of our group.i have some suggestions for our experiments. firstly when we’ll do an experiment,we must prepare our pre-lab by ourselves and translate it into chinese .only do likethis, we can understand the experiment well. secondly we should prefer to solute theproblems in the experiment rather than ask for ta. finally, everyone should understandhis own task in the experiment.篇二：英文实验报告的格式和写法英文实验报告的格式和写法【转】2010-10-04 06:03 一份最标准的实验报告的格式：1. abstract2. introduction3. method4. results5. discussion6. conclusion7. reference分别来分享下近来学到的。