Nitrate - Camlab
Contents
1. Nitrate DOC316 53 01066 Cadmium Reduction Method Method 8039 HR 0 3 to 30 0 mg L NO3 N Powder Pillow or AccuVac Ampuls Scope and Application For water wastewater and seawater Test preparation How to use instrument specific information The nstrument specific information table displays requirements that may vary between instruments To use this table select an instrument then read across to find the corresponding information required to perform this test Table 1 Instrument specific information Powder pillows AccuVac Ampuls Instrument Sample cell Cell orientation Sample cell Adapter DR 5000 2495402 Fill line faces user 2427606 DR 3900 2495402 Fill line faces user 2427606 LZV846 A DR 3800 DR 2800 DR 2700 2495402 Fill line faces right 2122800 LZV584 C Before starting the test For more accurate results determine a reagent blank value for each new lot of reagent Follow the procedure using deionized water instead of the sample Subtract the reagent blank value from the final results or perform a reagent blank adjust A deposit of unoxidized metal will remain at the bottom of the cell after the NitraVer 5 dissolves The deposit will not affect results This method is technique sensitive Shaking time and technique influence color development For most accurate results make successive tests on a 10 mg L Nitrate Nitrogen Standard solution Adjust shaking time and technique to obtain the correct re2. addition results to the theoretical 100 recovery Standard additions method for AccuVac Ampuls sample spike 1 Fill three mixing cylinders each with 50 mL of sample and spike with 0 4 mL 0 8 mL and 1 2 mL of 250 mg L standard 2 Transfer 40 mL from each of the three mixing cylinders to three 50 mL beakers 3 Analyze each standard addition sample as described in the Cadmium Reduction Method for AccuVac Ampuls 4 Accept each standard additions reading Each addition should reflect approximately 100 recovery Standard solution method Note Refer to the instrument user manual for specific software navigation instructions Required for accuracy check e 10 0 mg L Nitrate Nitrogen Standard Solution 1 Use the 10 0 mg L Nitrate Nitrogen Standard Solution in place of the sample Follow the Cadmium Reduction Method for powder pillows and Cadmium Reduction Method for AccuVac Ampuls test procedures 2 To adjust the calibration curve using the reading obtained with the standard solution select Options gt More gt Standard Adjust from the instrument menu 3 Turn on the Standard Adjust feature and accept the displayed concentration If an alternate concentration is used enter the concentration and adjust the curve to that value Method performance Sensitivity Precision Concentration change Program Standard 95 Confidence Limits of per 0 010 Abs change Distribution Point of curve Concentration 355 10 mg L NO3 N 9 3 10 7
3. holder Interferences Table 2 Interfering substances Interfering substance Interference level Chloride concentrations above 100 mg L will cause low results The test may be used at high Chloride chloride concentrations seawater but a calibration must be done using standards spiked to the same chloride concentration Refer to Seawater calibration Ferric iron Interferes at all levels Interferes at all levels Compensate for nitrite interference as follows Before performing step 3 add 30 g L Bromine Water dropwise to the sample until a yellow Nitrite color remains Add one drop of 30 g L Phenol Solution to destroy the color Proceed with step 3 Report the results as total nitrate and nitrite H Highly buffered samples or extreme sample pH may exceed the buffering capacity of the P reagents and require sample pretreatment Strong oxidizing and reducing substances Interfere at all levels 1 See Optional reagents and apparatus Nitrate Page 5 of 10 Nitrate Seawater calibration Chloride concentrations above 100 mg L will cause low results To perform this test in water with high interference level calibrate the water using standards spiked to the same chloride concentrations as the required samples To prepare calibration standards containing 5 0 10 0 20 0 and 30 0 mg L nitrate as NO3 N 1 3 4 Prepare a 1 L volume of chloride water that matches the concentration of the samples usin
4. multiplying the test result by this factor Accuracy check Standard additions method for powder pillows sample spike Required for accuracy check Nitrate Nitrogen Standard solution 1000 mg L NO3 N Mixing cylinders 25 mL Volumetric pipet TenSette Pipet and Pipet Tips Pipet filler 100 mL Volumetric Flask Prepare a 250 mL nitrate nitrogen standard solution by pipetting 25 mL of a 1000 mg L Nitrate Nitrogen standard solution into a 100 mL volumetric flask Dilute the solution to the required volume with deionized water and mix thoroughly After reading test results leave the sample cell unspiked sample in the instrument Select Options gt More gt Standard Additions from the instrument menu See Optional reagents and apparatus Nitrate Page 6 of 10 Nitrate 4 Accept the default values for standard concentration sample volume and spike volumes After the values are accepted the unspiked sample reading will appear in the top row See the user manual for more information 5 Use the TenSette Pipet to prepare spiked samples add 0 1 mL 0 2 mL and 0 3 mL of standard to three 10 mL portions of fresh sample 6 Follow the Cadmium Reduction Method for powder pillows test procedure for each of the spiked samples using the powder pillows starting with the 0 1 mL sample spike Measure each of the spiked samples in the instrument 7 Select GRAPH to view the results Select IDEAL LINE or best fit to compare the standard
5. O3 N PO COD SQz 500 mL 2833149 TOC Water deionized 4L 27256 Optional reagents and apparatus Description Unit Catalog number Bromine Water 30 g L 29 mL 221120 Cylinder mixing 50 mL each 2088641 Pipet TenSette 0 1 to 1 0 mL each 1970001 Pipet Volumetric Class A 0 5 mL each 1451534 Pipet Volumetric Class A 1 0 mL each 1451535 Pipet Volumetric Class A 2 0 mL each 1451536 Pipet Volumetric Class A 3 0 mL each 1451503 Pipet Tips for TenSette Pipet 19700 01 50 pkg 2185696 Nitrate Page 8 of 10 Optional reagents and apparatus continued Nitrate Description Unit Catalog number Pipet Tips for TenSette Pipet 19700 01 1000 pkg 2185628 Phenol Solution 30 g L 29 mL 211220 Pipet Volumetric Class A 25 mL each 1451540 Pipet Filler Safety Bulb each 1465100 AccuVac Snapper each 2405200 Sodium Hydroxide Standard Solution 5 0 N 50 mL SCDB 245026 Sulfuric Acid concentrated ACS 500 mL 97949 Flask volumetric Class A 100 mL each 1457442 Nitrate Page 9 of 10 FOR TECHNICAL ASSISTANCE PRICE INFORMATION AND ORDERING Inthe U S A Call toll free 800 227 4224 Outside the U S A Contact the HACH office or distributor serving you On the Worldwide Web www hach com E mail techhelp hach com Hach Company 2007 2010 All rights reserved Printed in the U S A HACH COMPANY WORLD HEADQUARTERS Telephone 970 669 3050 FAX 970 669 2932 Edition 6
6. g the following equation a Add necessary Chloride concentration g L x 1 6485 g of ACS grade NaCl to 1 L of deionized water 18 8 g L is a typical seawater chloride concentration b Mix this solution thoroughly to get a homogeneous solution Use this water as the dilution water instead of the deionized water when preparing the nitrate standards Use Class A glassware or a Tensette Pipet to pipet 0 5 1 0 2 0 and 3 0 mL of the 1000 mg L Nitrogen Nitrate as NO3 N NIST Standard Solution Catalog Number 1279249 into four different 100 mL Class A volumetric flasks Dilute to the mark with the prepared chloride water Mix thoroughly Use the prepared chloride water for the 0 mg L nitrate as NO3 N standard Sample collection preservation and storage More reliable results are obtained when samples are analyzed as soon as possible after collection If prompt analysis is impossible store samples in clean plastic or glass bottles for up to 24 hours at 4 C To preserve samples for longer periods add 2 mL of Concentrated Sulfuric Acid H SO per liter and store at 4 C The results are reported as total nitrate plus nitrite Before analysis warm the sample to room temperature and adjust the pH to 7 with 5 0 N Sodium Hydroxide Standard Solution Do not use mercury compounds as preservatives Correct the test result for volume additions by dividing the total volume acid base sample by the original sample volume and
7. mg L NO3 N 0 3 mg L NO3 N 0 5 mg L NO3 N 0 8 mg L NO3 N N 361 10 mg L NO3 9 3 10 7 mg L NO3 N 0 5 mg L NO3 N 10 ppm 0 6 mg L NO3 N 30 ppm 0 8 mg L NO3 N Nitrate Page 7 of 10 Nitrate Summary of method Cadmium metal reduces nitrates in the sample to nitrite The nitrite ion reacts in an acidic medium with sulfanilic acid to form an intermediate diazonium salt The salt couples with gentisic acid to form an amber colored solution Test results are measured at 500 nm Consumables and replacement items Required reagents Description Quantity Test Unit Catalog number NitraVer 5 Nitrate Reagent Powder Pillows for 10 mL sample 1 100 pkg 2106169 OR NitraVer 5 Nitrate Reagent AccuVac Ampul 1 25 pkg 2511025 Required apparatus powder pillows Description Quantity Unit Catalog number Sample cell 10 mL square matched pair 2 2 pkg 2495402 Stopper Neoprene solid size 1 2 12 pkg 1480801 or Stopper 2 6 pkg 173106 Required apparatus AccuVac Description Quantity Unit Catalog number Beaker 50 mL 1 each 90041H Sample cell 10 mL round 25 x 54 mm 1 each 2122800 Sample cell 10 mL round 25 x 60 mm 1 6 pkg 2427606 Recommended standards Description Unit Catalog number Nitrate Nitrogen Standard Solution 10 0 mg L NO3 N 500 mL 30749 Nitrate Nitrogen Standard Solution 1000 mg L NO3 N 900 mL 1279249 Wastewater Influent Standard Mixed Parameter for NH3 N N
8. sult Use this technique for all the samples Rinse the sample cell immediately after use to remove all cadmium particles Prepared samples will contain cadmium and must be disposed of according to federal state and local hazardous waste regulations Refer to the current MSDS for safe handling and disposal instructions Nitrate Page 1 of 10 Nitrate Collect the following items Description Quantity Powder Pillow Test NitraVer 5 Nitrate Reagent Powder Pillow Sample Cells 1 inch 10 mL with stopper AccuVac Test NitraVer 5 Nitrate Reagent AccuVac Ampul Beaker 50 mL Sample Cell for blank See Consumables and replacement items for reorder information Cadmium Reduction Method for powder pillows CAUTION Hazardous waste exposure Prepared samples contain cadmium Refer to the current MSDS for safe handling and disposal instructions Follow all federal state and local hazardous waste disposal regulations Stored Programs 355 N Nitrate HR PP Start 1 Select the test Insert an adapter if required see nstrument specific information Refer to the user manual for orientation Nitrate Page 2 of 10 10 mL Sun 2 Filla sample cell with 10 mL of sample Q 01 00 4 Start the instrument timer A one minute reaction time will begin 3 Prepared Sample Add the contents of one NitraVer 5 Nitrate Reagent Powder Pillow Stopper Nitrate Cadmium Reduc
9. the user manual for orientation 5 Invert the Ampul 48 52 times as the timer counts down Nitrate Page 4 of 10 L 2 Prepared Sample Collect at least 40 mL of sample in a 50 mL beaker Me OK 05 00 6 When the timer expires start the timer again A five minute reaction period will begin Do not agitate or disturb the sample during this time An amber color will develop if nitrate is present we OK 01 00 4 Start the instrument timer b o o coe s 3 Tap the bottom of a NitraVer 5 Nitrate AccuVac Ampul on a hard surface to dislodge powder Fill the Ampul with sample Keep the tip immersed while the Ampul fills completely Insert a cap over the Ampul tip A one minute reaction period will begin gt 10 mL 8 Wipe the blank and insert it into the cell holder 7 Blank Preparation When the timer expires fill a round sample cell with 10 mL of sample Nitrate Cadmium Reduction Method for AccuVac Ampuls continued CAUTION Hazardous waste exposure Prepared samples contain cadmium Refer to the current MSDS for safe handling and disposal instructions Follow all federal state and local hazardous waste disposal regulations Zero Read 9 ZERO the instrument 10 Within one minute 11 READ the results in The display will show after the timer expires mg L NO3 N wipe the Ampul and insert 0 0 mg L NO3 N into the cell
10. tion Method for powder pillows continued CAUTION Hazardous waste exposure Prepared samples contain cadmium Refer to the current MSDS for safe handling and disposal instructions Follow all federal state and local hazardous waste disposal regulations i Me i eS OK al 05 00 5 Shake the cell 6 When the timer 7 Blank Preparation 8 Wipe the blank and vigorously until the timer expires start the timer When the timer expires fill insert it into the cell holder expires again A five minute a second sample cell with Note Some solid materials reaction period will begin 10 mL of sample may not dissolve y An amber color will develop if nitrate is present Zero Read 9 ZERO the instrument 10 Within one minute 11 READ the results in The display will show after the timer expires mg L NO37 N wipe the prepared sample Fo displ ther chemical 0 0 ma L NO _N i play other chemica g 3 and insert it into the cell ioris reler tothe user holder manual Nitrate Page 3 of 10 Nitrate Cadmium Reduction Method for AccuVac Ampuls CAUTION Hazardous waste exposure Prepared samples contain cadmium Refer to the current MSDS for safe handling and disposal instructions Follow all federal state and local hazardous waste disposal regulations Stored Programs 361 N Nitrate HR AV Start 1 Select the test Insert an adapter if required see nstrument specific information Refer to
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