PHOSPHORUS, REACTIVE (0.00 to 5.00 mg/l PO 4

Transcription

1 PHOSPHORUS, REACTIVE (0.00 to 5.00 mg/l PO 4 ) PhosVer 3 Method, Test N Tube Procedure USEPA accepted for reporting wastewater analysis * Method 8048 For water, wastewater, and seawater 1. Enter the stored program number for reactive phosphorus (PO 4 ), Test N Tube. Press: PRGM The display will show: PRGM? Note: For most accurate results, perform a Reagent Blank Correction using deionized water (see Section 1). 2. Press: 82 ENTER The display will show mg/l, PO4 and the ZERO icon. Note: For alternate forms (P, P 2 O 5 ), press the CONC key. 3. Insert the COD/TNT Adapter into the cell holder by rotating the adapter until it drops into place. Then push down to fully insert it. Note: A diffuser band covers the light path holes on the adapter to give increased performance.the band should NOT be removed. 4. Use a TenSette Pipet to add 5.0 ml of sample to a Reactive Phosphorus Test 'N Tube Dilution Vial. Cap and mix. Note: For samples with extreme ph, see the Interference section. * Procedure is equivalent to USEPA Method and Standard Method 4500-P E for wastewater. 481

2 5. Clean the outside of the vial with a towel. Note: Wiping with a damp towel, followed by a dry one, will remove fingerprints or other marks. 6. Place the sample vial into the adapter. Push straight down on the top of the vial until it seats solidly into the adapter. Note: Do not move the vial from side to side as this can cause errors. 7. Tightly cover the sample vial with the instrument cap. 8. Press: ZERO The cursor will move to the right, then the display will show: 0.00 mg/l PO4 Note: For multiple samples, zero only on the first sample. Read the remaining samples after adding the PhosVer 3 Reagent. 9. Using a funnel, add the contents of one PhosVer 3 Phosphate Powder Pillow to the vial. 10. Cap the vial tightly and shake for seconds. Note: The powder will not completely dissolve. 11. Press: TIMER ENTER A 2-minute reaction time will begin. Note: Read samples between 2 and 8 minutes after the addition of the PhosVer 3 reagent. Note: A blue color will develop if phosphate is present. 12. Immediately after the timer beeps, place the sample vial in the adapter. Push straight down on the top of the vial until it seats solidly into the adapter. Note: Do not move the vial from side to side as this can cause errors. 482

3 13. Tightly cover the vial with the instrument cap. 14. Press: READ The cursor will move to the right, then the result in mg/l phosphate (PO 4 ) will be displayed. Note: Standard Adjust may be performed using a prepared standard (see Section 1). Sampling and Storage Collect samples in plastic or glass bottles that have been acid cleaned with 1:1 Hydrochloric Acid Solution and rinsed with deionized water. Do not use commercial detergents containing phosphate for cleaning glassware used in this test. Analyze samples immediately after collection for best results. If prompt analysis is impossible, preserve samples for up to 48 hours by filtering immediately and storing at 4 C. Warm to room temperature before analyzing the sample. Accuracy Check Note: Clean glassware with 1:1 hydrochloric acid solution. Rinse again with deionized water. Do not use detergents containing phosphates to clean glassware. Standard Additions Method a) Fill three 25-mL graduated mixing cylinders with 25 ml of sample. b) Snap the neck off a Phosphate PourRite Ampule Standard, 50 mg/l as PO 4. c) Use the TenSette Pipet to add 0.1 ml, 0.2 ml and 0.3 ml, respectively, to the three 25-mL aliquots of sample prepared in step a. Mix well. 483

4 d) Analyze each sample as described in the procedure; use 5.0 ml of the prepared standard additions for each test. The concentration should increase as follows: 0.2 mg/l, 0.4 mg/l, 0.6 mg/l PO 4, respectively. e) If these increases do not occur, see Standard Additions in Section 1 for more information. Method Performance Standard Solution Method To check accuracy, use a 1.0 mg/l Phosphate Standard Solution listed under Optional Reagents. Or, prepare a 1.0-mg/L PO 4 standard by pipetting 2 ml of solution from a Phosphate Voluette Ampule Standard for Phosphate, 50 mg/l as PO 4, into an acidwashed, Class A 100-mL volumetric flask. Dilute to the mark with deionized water. Substitute this standard for the sample and perform the procedure as described. Precision In a single laboratory, using a standard solution of 5.00 mg/l PO 4 and two lots of reagent with the instrument, a single operator obtained a standard deviation of ±0.08 mg/l PO 4. Estimated Detection Limit (EDL) The EDL for program 82 is 0.07 mg/l PO 4. For more information on derivation and use of Hach s estimated detection limit, see Section

5 Interferences The following may interfere when present in concentrations exceeding these listed below: Aluminum Arsenate Chromium Copper Iron Nickel Silica Silicate Sulfide Substance Turbidity (large amounts) Zinc Highly buffered samples or extreme sample ph 200 mg/l Interference Level and Treatment Interferes at any level 100 mg/l 10 mg/l 100 mg/l 300 mg/l 50 mg/l 10 mg/l 6 mg/l. Sulfide interference may be removed by oxidation with Bromine Water as follows: 1. Measure 25 ml of sample into a 50-mL beaker. 2. Swirling constantly, add Bromine Water dropwise until a permanent yellow color develops. 3. Swirling constantly, add Phenol Solution dropwise until the yellow color just disappears. Proceed with step 1. May cause inconsistent results because the acid present in the powder pillows may dissolve some of the suspended particles and because of variable desorption of orthophosphate from the particles. 80 mg/l May exceed the buffering capacity of the reagents and require sample pretreatment; see ph Interferences (Section 1). The PhosVer 3 Phosphate Reagent Powder Pillows should be stored in a cool, dry environment. Sample Disposal Information Final samples will contain molybdenum. In addition, final samples will have a ph less than 2 and are considered corrosive (D002) by the Federal RCRA. 485

6 Summary of Method Orthophosphate reacts with molybdate in an acid medium to produce a phosphomolybdate complex. Ascorbic acid then reduces the complex, giving an intense molybdenum blue color. REQUIRED REAGENTS Reactive Phosphorus Test N Tube Reagent Set...50 tests Includes: (1) , (50) Orthophosphate Dilution Vials* Quantity Required Description Per Test Unit Cat. No. PhosVer 3 Phosphate Reagent Powder Pillows /pkg Orthophosphate Test N Tube Dilution Vials /pkg... * REQUIRED APPARATUS COD/TNT Adapter each Funnel, micro each Pipet, TenSette, 1 to 10 ml each Pipet Tips, for TenSette Pipet /pkg Test Tube Rack each OPTIONAL REAGENTS Bromine Water, 30 g/l ml Drinking Water Standard, Inorganic, F, NO 3 N, PO 4 3, SO mL Hydrochloric Acid Standard Solution, 6.0 N (1:1) ml Phenol Solution, 30 g/l ml Phosphate Standard Solution, 1 mg/l as PO ml Phosphate Standard Solution, Voluette ampule, 50 mg/l as PO 4, 10 ml...16/pkg Phosphate Standard Solution, PourRite ampule, 50 mg/l as PO 4, 2 ml...20/pkg H Wastewater Effluent Standard, Inorganic (NH 3 N, NO 3 N, PO 4, COD, SO 4, TOC) ml Water, deionized... 4 L * These items are not sold separately. 486

7 OPTIONAL APPARATUS Ampule Breaker, Pour Rite (2-mL ampule)... each Ampule Breaker Kit... each Aspirator, vacuum... each Cylinder, graduated, mixing, 25 ml (3 required)... each Dispenser, Repipet Jr., 2 ml... each Filter Holder, 47 mm, 300 ml, graduated... each Filter, membrane, 47 mm, 0.45 microns /pkg Flask, filtering, 500 ml... each Flask, volumetric, Class A, 100 ml... each ph Indicator Paper, 1 to 11 ph units... 5 rolls/pkg ph Meter, sension 1, portable with electrode... each Pipet, TenSette, 0.1 to 1.0 ml... each Pipet Tips, for pkg Pipet Tips, for /pkg Pipet Filler, Safety Bulb... each Pipet, volumetric, Class A, 5.00 ml... each Pipet, volumetric, Class A, 2.00 ml... each For Technical Assistance, Price and Ordering In the U.S.A. call Outside the U.S.A. Contact the Hach office or distributor serving you. 487