Dimethylglyoxime Method Method to 6.0 mg/l Ni TNTplus 856

Transcription

1 , TNTplus856, DOC Dimethylglyoxime Method Method to 6.0 mg/l Ni TNTplus 856 Scope and Application: For Water and Wastewater Test preparation Before starting the test: DR 2800: Install the light shield in Cell Compartment #2 before performing this test. Please read Safety Advice and Expiration Date on package. Recommended sample ph is Recommended sample and reagent temperature is C (59 77 F). concentrations greater than the measuring range may cause precipitation in the vial. In such cases, the water sample must first be diluted with deionized water. Undissolved nickel or nickel contained in complexes can only be determined after digestion with Metals Prep Set TNT 890. TNTplus methods are activated directly from the Main Menu when the sample vial is inserted into the sample cell holder. Collect the following items: Description Quantity Light Shield (DR 2800 only) 1 TNT856 Reagent Set 1 Pipettor, variable, µl 1 Pipettor tips, for µl pipettor 1 Pipettor, variable, 1 5 ml 1 Pipettor, tips for 1 5 ml pipettor 1 See Consumables and replacement items for reorder information. Page 1 of 6

2 Dimethylglyoxime method, TNTplus 1. Pipet 2.0 ml of sample into the vial. 2. Cap the vial and invert 2 3 times until the freeze-dried contents in the vial are completely dissolved. 3. Pipet 0.2 ml (200 µl) of Solution A into the vial. 4. Cap and invert the vial 2 3 times. 5. Wait three minutes. Install the Light Shield in Cell Compartment #2. 6. Thoroughly clean the outside of the vial. Insert the prepared vial into the cell holder. The instrument reads the barcode, then selects and performs the correct test. Results are in mg/l Ni No instrument zero is required. Reagent blanks A reagent blank can be measured and the value subtracted from the results of each test performed using the same reagent lot number. Use deionized water in place of sample and run the procedure as described. To subtract the value of the blank from a series of measurements, measure the blank per step 6. Press OPTIONS>MORE>REAGENT BLANK. Select ON. The measured value of the blank should be displayed in the highlighted box. Press OK to accept this value. The reagent blank value will now be subtracted from all results until the function is turned off, or a different method is selected. Alternately, the blank can be recorded and entered at any later time by pressing the highlighted box and using the keypad to enter the value. Page 2 of 6

3 Sample blanks Interferences Colored or turbid samples can cause high results. To compensate for color or turbidity, the procedure is repeated and the color forming reagent that is present in Solution A is not added. To determine the sample blank, run the procedure as given, but substitute 0.2 ml of deionized water in place of the 0.2 ml of Solution A in step 3. Use the red stopper to cap the sample vial. The value obtained in step 6 is then subtracted from the value obtained on the original sample to give the corrected sample concentration. Alternatively, samples that contain only turbidity may be first filtered through a membrane filter and then analyzed. Report the results as soluble nickel. Samples without color or turbidity do not require sample blanks. The ions listed in Interfering substances have been individually checked up to the given concentrations and do not cause interference. The cumulative effects and influence of other ions has not been determined. Undissolved nickel or nickel contained in complexes can only be determined after digestion with Metals Prep Set TNT 890. Table 1 Interfering substances Interfering substance K +, Na +, Cl, SO 2 4 NH + 4, NO 3, Ca 2+, PO 3 4, CO 2 3 Cr 6+, Zn 2+, F, NO 2 Al 3+, Cr 3+, Cd 2+, Co 2+, Sn 2+, Pb 2+ Fe 2+, Fe 3+, Mn 2+, Cu 2+, Mg 2+, Hg 2+ Ag + Interference level 1000 mg/l 500 mg/l 50 mg/l 10 mg/l 5 mg/l 1 mg/l Sample collection, preservation and storage Accuracy check Collect samples in acid-washed glasses or plastic containers. Adjust the ph to 2 or less with nitric acid (about 2 ml per liter). Store preserved samples up to six months at room temperature. Adjust the ph between 3 10 with 5.0 N sodium hydroxide before analysis. Correct the test result for volume additions. Standard solution method Note: Refer to the instrument user manual for specific software navigation instructions. Required for accuracy check: Standard Solution, 1000 mg/l Deionized water 250-mL volumetric flask 1-mL Volumetric pipet Page 3 of 6

4 Pipet filler 1. Prepare a 4.0 mg/l nickel standard solution as follows: a. Pipet 1.0 ml of Standard, 1000-mg/L, into a 250-mL volumetric flask. b. Dilute to the mark with deionized water. Mix well. Prepare this solution daily. 2. Use 2.0 ml of this solution in place of the sample. Follow the Dimethylglyoxime method, TNTplus test procedure. 3. To adjust the calibration curve using the reading obtained with the standard solution, navigate to Standard Adjust in the software. Instrument DR 5000 DR 2800 DR 2700 DR/2500 DR/2400 Navigate to: OPTIONS>MORE>STANDARD ADJUST OPTIONS>MORE>STANDARD ADJUST OPTIONS>MORE>STANDARD ADJUST OPTIONS>STANDARD ADJUST OPTIONS>STANDARD ADJUST Summary of method 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. In the presence of an oxidizing agent, nickel ions react with dimethylglyoxime in an alkaline solution to form an orange-brown-colored complex. Test results are measured at 463 nm. Consumables and replacement items Required reagents Description Quantity/Test Unit Catalog number TNT 856 Reagent Set 1 25/pkg TNT856 Required apparatus Description Quantity/Test Unit Catalog number Light Shield (DR 2800 only) 1 each LZV646 Pipettor, variable volume, 1 5 ml 1 each Pipettor Tips, for pipettor 1 100/pkg Pipettor, variable volume, µl 1 each Pipettor Tips, for pipettor 1 400/pkg Recommended standards Description Unit Catalog number Standard Solution, 1000 mg/l 100 ml Nitric Acid, ACS 500 ml Sodium Hydroxide Standard Solution, 5.0 N 100 ml MDB Page 4 of 6

5 Recommended standards Description Unit Catalog number Sodium Hydroxide Standard Solution, 5.0 N 50 ml SCDB Water, deionized 4 L Optional reagents and apparatus Description Unit Catalog number Bottle, sampling, low density poly, w/cap, 500 ml 12/pkg Filter Holder, glass for vacuum filtration each Filter, membrane, 47 mm; micron, hydrophilic, polyethersulfone for SUVA each Flask, filtering, glass, 1000-mL each Flask, volumetric 250 ml, Class A each Pipet, volumetric 1.0 ml, Class A each Metals Prep Set TNT 890 each TNT890 Test Tube Rack for 13-mm vials each Tubing, rubber 12 ft Pipet Filler, Safety bulb each Aspirator with check valve each Page 5 of 6

6 FOR TECHNICAL ASSISTANCE, PRICE INFORMATION AND ORDERING: In the U.S.A. Call toll-free Outside the U.S.A. Contact the HACH office or distributor serving you. On the Worldwide Web HACH COMPANY WORLD HEADQUARTERS Telephone: (970) FAX: (970) Hach Company, All rights reserved. Printed in the U.S.A. Updated February 2008, Edition 5