饮用水中营养盐检测方案(紫外分光光度)

Nitrate inDrinking VWater 6.Rinse electrode and stirrer thoroughly with deionized water. Gently remove excess solution from theouter sleeve of the electrode by dabbing with a clean paper tissue. Do not wipe or rub the sensingelement of the electrode. 7. Place the probe and stirrer into the beaker with the 10 ppm (mg/L) standard with the electrode tipfully immersed in the solution. The stirrer should be positioned slightly below the tip of the electrode.Press the STIRRER key on the meter to turn the stirrer on. 8.Wait for stable reading (1-2 minutes). Enter standard value of“10”using UP and DOWN arrow keysand the DECIMAL/DIGIT key. 9..Press the CALIBRATE key to accept the 10 ppm (mg/L) standard and press the STIRRER key to turnthe stirrer off. 10. Rinse electrode and stirrer thoroughly with deionized water. Gently remove excess solution from theouter sleeve of the electrode. 11. Place the probe and stirrer into the beaker with the 100 ppm (mg/L) standard with the electrode tipfully immersed in the solution. The stirrer should be positioned slightly below the tip of the electrode.Press the STIRRER key on the meter to turn the stirrer on. 12. Wait for stable reading (1-2 minutes). Enter standard value of“100"using UP and DOWN arrowkeys and the DECIMAL/DIGIT key. 13. Press the MEASURE key to accept the 100 ppm (mg/L) standard and to move to the measure modeof the meter. Press the STIRRER key to turn the stirrer off. 14. Rinse electrode and stirrer thoroughly with deionized water. Gently remove excess solution from theouter sleeve of the electrode by dabbing with a clean paper tissue. Do not wipe or rub the sensingelement of the electrode. 15. Place the probe and stirrer in a prepared sample with the electrode tip fully immersed in the solution.Press the MEASURE key on the meter； the stirrer will turn on. The ISE： mg/L icon will flash as themeasurement is being made. The ISE：mg/L icon will become solid and the display value will freezewhen a stable reading is achieved. This value is logged and printed automatically and the stirrer turnsoff automatically. 16. Repeat steps 14 and 15 for additional samples. Upon completion of samples， rinse electrode withdeionized water and store the electrode according to instructions in the Electrode Storage section ofthis method note. Nitrate inDrinking Water Introduction This method provides rapid， uncomplicated determinations for the nitrate ion in drinking water. Nitrateis a National Primary Drinking Water Regulation contaminant for public drinking water. The directmeasurement of ions using ion selective electrodes is a well-established technique frequently used as astandard method of analysis. This procedure eliminates interferences associated with the presence of colorand solids. Recommended Equipment Cat.No. ISE Application Package (includes all items with a Cat. No.) 1010108 1. 4-Star benchtop pH/ISE meter 1115000 2. Orion ionplus° nitrate electrode 9707BNWP 3. Orion benchtop stirrer (or magnetic stir plate and bar) 096019 Orion benchtop electrode stand 1110001 150 mL beakers 100 mL volumetric flask 7. 2 mL and 10 mL pipettes 100 mLgraduated cylinder 1. Nitrate Standard， 100 ppm (mg/L) as N 930707 2. I1SA (Ionic Strength Adjuster) for nitrate electrode 930711 3. Reference Filling Solution， Optimum Results""F 900046 4. Interference Suppressor Solution 930710 5. D1eionized water Calibration Standard Preparation 1. Using a graduated cylinder， transfer 100 mL of the 100 ppm (mg/L) standard into a beaker with apipette， add 2 mL of the ISA solution. 2. Prepare a 10 ppm (mg/L) nitrate standard by pipetting 10 mL of the 100 ppm (mg/L) nitrate standard into a 100 mL volumetric flaskwith a pipette， add 2 mL ISA， and dilute to the mark with deionized water. Mix well. 3. Prepare a 1ppm (mg/L) nitrate standard by pipetting 10 mL of the 10 ppm (mg/L) nitrate standard into a 100 mL volumetric flaskwith a pipette，add 2 mL ISA， and dilute to the mark with deionized water. Mix well. Sample Preparation 1. Using a graduated cylinder， measure 100 mL of the sample into a beaker with a pipette， add 2 mL of the ISA solution. 2. Repeat for additional measurements. Nitrate inDrinking Water Results Five aliquots of drinking water were collected from a faucet and measured for nitrate. The data. demonstrates that the nitrate concentration is less than 1.0 ppm in the collected drinking water. Drinking Water ppm (mg/L) Nitrate Sample #1： <1.0 Sample #2： < .9 Sample # 3： 1.0 <1.0 Sample#4：Sample # 5： < 1.0 Electrode Storage For brief storage periods between sample measurements， store the electrode in nitrate standard， such as 10 ppm(mg/L) as N. The filling solution in the nitrate electrode should not be allowed to evaporate and crystallizearound junction. For longer storage periods， drain the reference compartment of the electrode and flush it withdeionized water. Disassemble the electrode as described in the electrode instruction manual. Equipment Set Up Electrode Setup 1，Remove the electrode sensing module from the plastic vial package. Make sure both o-rings are in place onthe sensing module. Remove the electrode handle from the box. 2. Grasp the outer sleeve of the electrode handle， with the fill hole end towards the electrode cap， and gentlypush the electrode inner stem through the outer sleeve. 3 Slide the outer sleeve， spring， and cap down the electrode cable until the outer sleeve is beyond the innerstem. With one hand， grasp the middle of the inner stem without touching the reference pellet. With the otherhand， screw the sensing module onto the stem until it stops and the sensing module is flush against thestem. Then tighten an additional one-quarter turn and stop. Do not over tighten. The sensing moduleshould be firmly attached to the inner stem. 5.Holding the electrode cable， slide the outer sleeve， spring and cap over the inner stem. 6 With one hand grasp the outer sleeve； do not touch the sensing membrane. With the other hand， pull onthe cable and gently screw the cap onto the inner stem. Stop when resistance is felt. Do not over tightenor continue to turn the cap! The cap will not completely stop! If the inner body turns at all， the cap is tootight and removal of the cap and reassembly is necessary. 7.Lift the filling solution bottle’s spout to a vertical position. 8 Insert the spout into the filling hole in the outer sleeve of the electrode and add a small amount of fillingsolution to the chamber. Then tip the electrode to moisten the o-ring at the top and return electrode to avertical position. 9 Holding the electrode by the barrel with one hand， use the thumb to push down on the electrode cap，allowing a few drops of filling solution to drain wetting the inner cone. 11. Fill outer body with Optimum Results F filling solution to approximately 1/4 full. Release the electrodecap allowing the electrode’s outer sleeve to return to its original position immediately. If the outer sleevedoes not return to its original position immediately， check to see if the o-ring is moist and repeat steps 8-10until the outer sleeve has returned to its original position. Add more filling solution until the amount offilling solution within the electrode body is level with the bottom edge of the electrode filling hole 12. Check the membrane surface of the sensing module to make sure it is dark and homogeneous with nobubbles on the inner surface. To ensure electrode continuity， grasp the outer sleeve and electrode cap andshake the sensing module end firmly. For initial meter setup， follow the steps on the Quick Reference Guide that is attached to the meter itself. TheQuick Start Guide included with each meter also contains a layout of the meter keypad for reference. Thewords in all capital letters such as POWER indicate a key on the meter， and words in quotations such as “Unit"indicate information on the meter display. 1. Connect the electrode to the meter. 2. Connect the stirrer to the meter. 3. Press the POWER key on the meter to turn meter on. 4， Note that the arrow on the left of the screen indicates the active line. If not the top line is not active， pressthe LINE SELECTION key to change the selected line to the top line. Press the SETUP. Use the UP or DOWN keys to enter ISE setup. Press the LINE SELECTION key toselect the bottom line. Press UP or DOWN arrow keys to select “3”for“rES”. Press LINE SELECTIONkey to accept setting. 6 Press LINE SELECTION key to select middle line， and press DOWN arrow key to select “nL In”which isan abbreviation for non-linear blank correction. 7. Press the LINE SELECTION key to select the bottom line. Press UP or DOWN arrow keys to select“off’for "nL ln". Press LINE SELECTION key to accept setting. 8.Press LINE SELECTION key to select middle line， and press DOWN arrow key to select “rAng”. 9 Press the LINE SELECTION key to select the bottom line. Press UP or DOWN arrow keys to select“HigH”for "rAng”. Press LINE SELECTION key to accept setting. 10. Press LINE SELECTION key to select middle line， and press DOWN arrow key to select “Unit". 11. Press the LINE SELECTION key to select the bottom line. Press UP or DOWN arrow keys to selectmgL"for “Unit". Press LINE SELECTION key to accept setting. 12. Press MEASURE key to return to measurement mode. If all steps were followed correctly the meter display will show three digits in the top line and“ISE： mg/L”tothe right of the top line. The meter and electrode are now ready for calibration. Note： The Orion Benchtop Stirrer must be turned on in General Instrument setup before analysis，please see the Quickstart guide for instructions. Calibration and Analysis 1. Allow all the standards and the samples to attain room temperature for precise measurements since themeasurement is temperature sensitive. 2 Calibrate the meter using the 1 ppm (mg/L)， 10 ppm (mg/L)， and 100 ppm (mg/L) standards， stirring thestandards at a uniform rate. 3 Place the electrode and stirrer into the beaker with the 1 ppm (mg/L) standard with the electrode tip fullyimmersed in the solution. The stirrer should be positioned slightly below the tip of the electrode. Press theSTIRRER key on the meter to turn the stirrer on. Press the CALIBRATE key. 4 Wait for a stable reading (1-2 minutes). Enter standard value of“1.0"using UP and DOWN arrow keysand the DECIMAL/DIGIT key. 5. Press the CALIBRATE key to accept the 1.0 ppm (mg/L) standard and press the STIRRER key to turn thestirrer off. www.thermo.com of of of of 本文章详细介绍了饮用水中硝酸盐的测定，包括校准液、水样的准备，校准和测量过程，以及电极和仪表的维护等内容。