Nitrate - Camlab
Contents
1. Nitrate DOC316 53 01069 Cadmium Reduction Method Method 8171 MR 0 1 to 10 0 mg L NO N Powder Pillows 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 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 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 0 mg L Nitrate Nitrogen Standard solution Adjust shaking times to obtain the correct result Rinse the sample cell immediately after use to remove all cadmium particles Retain the used sample for proper2. 3 Filla NitraVer 5 Nitrate AccuVac Ampul with sample Keep the tip immersed while the Ampul fills completely Place a stopper over the Ampul tip A one minute reaction period will begin m gt om 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 Read 11 READ the results in mg L NO3 N Nitrate 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 see Seawater calibration Ferric iron Interferes at all levels Interferes at all levels Compensate for nitrite interference as follows Nitrite 1 Add 30 g L Bromine Water drop wise to the sample until a yellow color remains 2 Add one drop of 30 g L Phenol Solution to destroy the color 3 Proceed with Step 2 of the test 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 Seawater calibration Chloride concentrations above 100 mg L will cau
3. SO per liter and store at 4 C The results are reported as total nitrate and nitrite e 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 See Optional reagents and apparatus Nitrate Page 5 of 8 Nitrate Correct the test result for volume additions by dividing the total volume acid base sample by the original sample volume and multiplying the test result by this factor Accuracy check Nitrate Page 6 of 8 Standard additions method sample spike Required for accuracy check 1 Nitrate Nitrogen Standard 100 mg L NO3 N TenSette Pipet and Pipet Tips After reading test results leave the sample cell unspiked sample in the instrument Select Options gt More gt Standard Additions from the instrument menu 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 Open the standard solution bottle 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 Follow the Cadmium reduction method for powder pillows test procedure for each of the spiked samples starting with the 0 1 mL sample spike Measure each of the spiked samples in the instrument Select GRAPH
4. ain A five minute reaction period will begin An amber color will develop if nitrate is present 9 Within two minutes after the timer expires wipe and insert the prepared sample into the cell holder 10 mL 4 6 Blank Preparation When the timer expires fill a second sample cell with 10 mL of sample Read 10 READ the results in mg L NO3 N Refer to the user manual to display other chemical forms 7 Wipe and insert the blank into the cell holder Zero 8 ZERO the instrument The display will show 0 0 mg L NO3 N Nitrate Page 3 of 8 Nitrate Cadmium reduction method for AccuVac Ampuls Stored Programs 359 N Nitrate MR AV Start 1 Select the test Insert an adapter if required see nstrument specific information Refer to the user manual for orientation 5 Invert the Ampul 48 52 times as the timer counts down Zero 9 ZERO the instrument The display will show 0 0 mg L NO3 N Nitrate Page 4 of 8 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 An amber color will develop if nitrate is present 10 Within two minutes after the timer expires wipe the Ampul and insert it into the cell holder 3 OK 01 00 4 Start the instrument timer D tus coe hay
5. ample Follow the Cadmium reduction method for powder pillows test procedure 3 To adjust the calibration curve using the reading obtained with the standard solution select Options gt More gt Standard Adjust from the instrument menu 4 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 Precision Sensitivity Program Standard 95 Confidence Limits of Concentration change Distribution per 0 010 Abs change 353 5 0 mg L NO3 N 4 8 5 2 mg L NO3 N 0 04 mg L NO3 N 359 5 0 mg L NO3 N 4 6 5 4 mg L NO3 N 0 05 mg L NO3 N 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 400 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 Catalog number Sample cell 10 mL square matched pair 2 2495402 Stopper Neoprene solid size 1 2 1480801 Nitrate Page 7 of 8 Nitrate Required apparat
6. hazardous waste disposal for cadmium 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 8 Nitrate Collect the following items Description Quantity Powder Pillow Test NitraVer 5 Nitrate Reagent Powder Pillow AccuVac Test Sample Cells see nstrument specific information Stopper Neoprene 1 solid NitraVer 5 Nitrate Reagent AccuVac Ampul Beaker 50 mL Sample Cell for blank see nstrument specific information See Consumables and replacement items for reorder information Cadmium reduction method for powder pillows Stored Programs 353 N Nitrate MR 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 8 10 mL q 2 Filla sample cell with 3 Prepared Sample 10 mL of sample Add the contents of one NitraVer 5 Nitrate Reagent Powder Pillow Insert a stopper into the cell 4 Start the instrument timer A one minute reaction period will begin Shake the cell vigorously until the timer expires Note Some solid material will not dissolve Cadmium reduction method for powder pillows continued Nitrate Me OK 05 00 5 When the timer expires start the timer ag
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8. se 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 1 0 3 0 5 0 and 10 0 mg L nitrate as NO3 N 1 Prepare a 1 L volume of chloride water that matches the concentration of the samples using the following equation a Add necessary Chloride concentration g L x 1 6485 g of ACS grade NaCl to 1 L of deionized water Note 18 8 g L is a typical seawater chloride concentration b Mix this solution thoroughly to make sure that it is a homogeneous solution Use this water as the dilution water instead of the deionized water when preparing the nitrate standards 2 Use Class A glassware or a Tensette Pipet to pipet 1 0 3 0 5 0 and 10 0 mL of the 100 mg L Nitrogen Nitrate as NOa N NIST Standard Solution Catalog Number 194749 into four different 100 mL Class A volumetric flasks 3 Dilute to the mark with the prepared chloride water Mix thoroughly 4 Use the prepared chloride water for the 0 mg L nitrate as NO3 N standard Sample collection preservation and storage e Most 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
9. to view the results Select IDEAL LINE or best fit to compare the standard addition results to the theoretical 100 recovery Standard additions method for AccuVac Ampuls sample spike Required for accuracy check 500 mg L Nitrate Nitrogen Ampule Standard Solution Ampule breaker TenSette Pipet and Pipet Tips Mixing cylinder 50 mL 3 Fill three mixing cylinders each with 50 mL of sample and spike with 0 1 mL 0 2 mL and 0 3 mL of 500 mg L Nitrate Nitrogen Ampule Standard Solution Transfer 40 mL from each of the three mixing cylinders to three 50 mL beakers Analyze each standard addition sample as described in the Cadmium reduction method for AccuVac Ampuls 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 Standard Solution Method Required for accuracy check 5 0 mg L Nitrate Nitrogen Standard Solution prepared 100 mg L Nitrate Nitrogen Standard Deionized water 100 mL volumetric flask Nitrate e 5 mL Volumetric pipet and pipet filler OR e TenSette Pipet and Pipet Tips 1 Prepare a 5 0 mg L nitrate nitrogen standard solution as follows a Pipet 5 0 mL of 100 mg L Nitrate Nitrogen Standard into a 100 mL volumetric flask b Dilute to the mark with deionized water Mix well 2 Use this 5 0 mg L nitrate nitrogen standard solution in place of the s
10. us AccuVac Description Unit Catalog number Beaker 50 mL each 50041H Sample cell 10 mL round 25 x 54 mm each 2122800 Sample cell 10 mL round 25 x 60 mm 6 pkg 2427606 Recommended standards Description Unit Catalog number Mixed Parameter Drinking Water Standard for F NO3 N PO 4 SO 500 mL 2833049 Nitrate Nitrogen Standard Solution 100 mg L NO3 N 900 mL 194749 Nitrate Nitrogen Standard Solution 500 mg L NO3 N 10 mL ampules 16 pkg 1426010 Water deionized 4L 27256 Optional reagents and apparatus Description Unit Catalog number Ampule breaker for 10 mL ampules each 2196800 Bromine Water 30 mg L 29 mL 221120 Cylinder mixing 50 mL each 2088641 Flask volumetric 100 mL each 1457442 Pipet TenSette 0 1 1 0 mL each 1970001 Pipet Tips for TenSette Pipet 1970001 50 pkg 2185696 Pipet Tips for TenSette Pipet 1970001 1000 pkg 2185628 Pipet volumetric Class A 5 0 mL each 1451537 Pipet volumetric Class A 1 0 mL each 1451535 Pipet volumetric Class A 3 0 mL each 1451503 Pipet volumetric Class A 10 0 mL each 1451538 Pipet Filler safety bulb each 1465100 Phenol Solution 30 g L 29 mL 211220 5 0 N Sodium Hydroxide Standard Solution 1L 245053 Sulfuric Acid concentrated 500 mL 97949 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 mai
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