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Phosphorus, Reactive

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Phosphorus, Reactive HR, 8114

How to use instrument-specific information

The Instrument-specific informationtable 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.

Phosphorus, Reactive DOC316.53.01114Molybdovanadate Rapid Liquid Method1

1 Adapted from Standard Methods for the Examination of Water and Wastewater.

Method 8114

HR (0.3 to 45.0 mg/L PO43) Pour-Thru Cell

Scope and Application: For treated and natural waters

Test preparation

Table 344 Instrument-specific information

Instrument Pour-Thru Kit Pour-Thru Cell Orientation Adapter

DR 6000 LQV175.99.20002 Arrow faces right

DR 5000 LZV479

DR 3900LQV157.99.10002 Align cell flow arrows with arrows on cell

compartment

DR 3800, DR 2800, DR 27005940400 1-inch (round) path aligned with arrow on

the adapter

LZV585 (B)

Before starting the test:

See the User Manual for Pour-Thru Module installation instructions.

Clean the Pour-Thru cell and all labware as specified inAnalysis labware treatment.

Protect the Pour-Thru Cell from contamination when not in use by inverting a small beaker over the top of the glass funnel.

Make sure the PourThru cell is completely seated in the sample cell compartment.

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. Refer to the current MSDS for safe handling and disposal information.

Description Quantity

Molybdovanadate Reagent 2 mL

Water, deionized 25 mL

Cylinder, graduated, 25-mL, poly 1

Dispenser, fixed volume, 1.0-mL, w/bottle 1

Flask, Erlenmeyer, 125-mL, PMP w/cap 2

Instrument-specific information 1
http://doc316.53.01000.pdf/http://doc316.53.01000.pdf/http://doc316.53.01000.pdf/http://doc316.53.01000.pdf/http://doc316.53.01000.pdf/http://doc316.53.01000.pdf/http://doc316.53.01000.pdf/http://doc316.53.01000.pdf/http://doc316.53.01000.pdf/

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See Consumables and replacement itemsfor reorder information.

Molybdovanadate Rapid Liquid method

1. Select the test.

Insert an adapter if

required (see Instrument-

specific information).

2. I 3. Rinse a clean plastic

125-mL Erlenmeyer flask

and a 25-mL graduatedcylinder with deionized

water.

4. Blank Preparation:

Measure 25 mL of

deionized water in thegraduated cylinder. Pour

the water into the flask.

5. Rinse another clean

plastic 125-mL Erlenmeyer

flask with deionized water.

6. Prepared Sample:

Measure 25 mL of sample

in the graduated cylinder.

Pour the water into the

flask.

7. Add 1.0 mL of

Molybdovanadate

Reagent to each flask

using a Repipet Jr.

Dispenser. Swirl to mix.

A yellow color will develop

in the sample if phosphate

is present. A small amount

of yellow may be present

in the blank due to the

reagent.

8. Start the instrument

timer.

A 7-minute reaction period

will begin.

If the sample

concentration is greater

than 30 mg/L PO43, read

at exactly seven minutes

or make a 1:1 dilution of

the sample and begin the

test again.

Description Quantity

489 P React. Mo. HR RL

Stored Programs

Start

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Interferences

See the Interfering substancestable for a list of substances, interference levels and type of

interference. See the Noninterfering substances at low concentrations (less than 1000 mg/L)table

for a list of substances that do not interfere in concentrations less than 1000 mg/L.

9. When the timer

expires, pour the blank

from the flask into the

Pour-Thru Cell.

10. ZEROthe instrument.

The display will show:

0.0 mg/L PO43

11. Pour the prepared

sample from the flask into

the Pour-Thru Cell.

12. READthe results in

mg/L PO43.

Flush the Pour-Thru Cell

with 50 mL of deionized

water.

Table 345 Interfering substances

Interfering substance Interference level

Arsenate Negative interference. Positive interference if sample is heated.

Bismuth Negative interference.

Fluoride Negative interference.

Iron, FerrousBlue color is caused by ferrous iron but this does not affect results if the ferrous ironconcentration is less than 100 mg/L.

Molybdate Negative interference.

Silica Positive interference if sample is heated.

Sulfide

Negative interference. Sulfide interference may be removed by oxidation with Bromine Water

as follows:

1. Measure 25 mL of sample into a flask.

2. Add Bromine Water1drop-wise with constant swirling until permanent yellow color

develops.

3. Add Phenol Solution1drop-wise until the yellow color just disappears. Proceed with

step 7.

1 See Optional reagents and apparatus.

Thiocyanate Negative interference.Thiosulfate Negative interference.

Thorium Negative interference.

Highly buffered samples or

extreme sample pHMay exceed the buffering capacity of the reagents and require sample pretreatment.

Molybdovanadate Rapid Liquid method (continued)

Zero Read

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Sample collection, preservation and storage

Collect samples in clean plastic or glass bottles that have been cleaned with 1:1 Hydrochloric

Acid Solution*and rinsed with deionized water.

Do not use detergents that contain phosphate for cleaning labware.

Analyze samples immediately for best results.

If prompt analysis is not possible, preserve samples by filtering immediately and storing the

sample at 4 C (39 F) or below for up to 48 hours.

Warm stored samples to room temperature before analyzing.

Analysis labware treatment

1. Clean containers by normal means (do not use detergents containing phosphorus), then rinse

with deionized water.

2. Soak for several minutes in a 1:25 dilution of Molybdovanadate Reagent in deionized water.

3. Rinse well with deionized water. Dedicate these containers for HR PO43analysis.

4. Fill the Pour-Thru Cell with this same mixture of Molybdovanadate reagent and deionized

water and let stand for several minutes.

5. Rinse the Pour-Thru Cell with 50 mL of deionized water.

Table 346 Noninterfering substances at low concentrations (less than 1000 mg/L)

Pyrophosphate Tetraborate Benzoate

Citrate Lactate Formate

Oxalate Tartrate Salicylate

Al3+ Selenate Mg2+

Ca2+ Ba2+ Sr2+

Li+ Na+ K+

NH4+ Cd2+ Mn2+

NO3 NO2

SO42

SO32 Pb2+ Hg+

Hg2+ Sn2+ Cu2+

Ni2+ Ag+ U

Zr4+ AsO3 Br

CO32 ClO4

CN

IO3 Fe3+ SiO44

* See Optional reagents and apparatus.

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How to clean the Pour-Thru Cell

The Pour-Thru Cell may accumulate a buildup of colored products, especially if the reacted

solutions are allowed to stand in the cell for long periods after measurement. To clean the Pour-

Thru Cell:

1. Remove the color by rinsing with a 1:5 dilution of ammonium hydroxide*

2. Follow with several deionized water rinses.

3. Invert a beaker over the glass funnel of the Pour-Thru Cell when not in use.

Accuracy check

Standard additions method (sample spike)

Required for accuracy check:

Phosphate VoluetteAmpule Standard Solution, 500-mg/L as PO43

Ampule breaker

TenSette Pipet and tips

Mixing cylinders (3)

1. After reading test results, leave the sample cell (unspiked sample) in the instrument.

2. Select standard additions from the instrument menu: OPTIONS>MORE>STANDARD

ADDITIONS.

3. 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.

4. Open the standard solution ampule.

5. Use the TenSette Pipet to prepare spiked samples: add 0.1 mL, 0.2 mL and 0.3 mL of

standard to three 25-mL mixing cylinders and fill to 25 mL with the fresh sample. Mixthoroughly.

6. Follow the Molybdovanadate Rapid Liquid methodtest procedure for each of the spiked

samples, starting with the 0.1 mL sample spike. Measure each of the spiked samples in the

instrument.

7. Select GRAPHto view the results. Select IDEAL LINE (or best-fit) to compare the standard

addition results to the theoretical 100% recovery.

* Optional reagents and apparatus.

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Standard solution methodNote: Refer to the instrument user manual for specific software navigation instructions.

Required for accuracy check:

10.0-mg/L Phosphate Standard

1. Use the 10.0-mg/L Phosphate Standard solution in place of the sample. Follow the

Molybdovanadate Rapid Liquid methodtest procedure.

2. To adjust the calibration curve using the reading obtained with the standard solution, navigate

to Standard Adjust in the software: OPTIONS>MORE>STANDARD ADJUST.

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

Summary of method

In the molybdovanadate method, orthophosphate reacts with molybdate in an acid medium to

produce a phosphomolybdate complex. In the presence of vanadium, yellow

vanadomolybdophosphoric acid is formed. The intensity of the yellow color is proportional to the

phosphate concentration. Test results are measured at 430 nm.

Program Standard

Precision

95% Confidence Limits of

Distribution

Sensitivity

Concentration change

per 0.010 Abs change

489 10.0 mg/L PO43 9.910.1 mg/L PO4

3 0.34 mg/L PO43

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Consumables and replacement items

Required reagents

Description Quantity/Test Unit Catalog number

Molybdovanadate Reagent 2 mL 500 mL 2076049

Water, deionized 25 mL 4 L 27256

Required apparatus

Description Quantity Unit Catalog number

Cylinder, graduated, 25-mL, poly 1 each 108140

Dispenser, adjustable 1 each 2563137

Flask, Erlenmeyer, 125-mL, PMP w/cap 2 each 2089843

Recommended standards

Description Unit Catalog number

Phosphate Standard Solution, 10-mg/L as PO43 946 mL 1420416

Phosphate Standard Solution, Voluetteampule, 10-mL, 500-mg/L as PO43 16/pkg 1424210

Wastewater Influent Standard for NH3N, NO3N, PO4, COD, SO4, TOC 500 mL 2833149

Optional reagents and apparatus


Ammonium Hydroxide, ACS 500 mL 10649

Bromine Water, 30 g/L 29 mL 221120

Cylinder, graduated mixing, 25 mL each 189640

Hydrochloric Acid Solution, 6.0 N, 1:1 500 mL 88449

Phenol Solution, 30 g/L 29 mL 211220

Pipet, TenSette, Pipet, 0.1 - 1.0 mL each 1970001

Pipet Tips, for TenSette Pipet 19700011

1 Other sizes are available

50/pkg 2185696

Pipet Tips, for TenSette Pipet 19700011 1000/pkg 2185628

Filter Paper, folded 12.5 cm 100/pkg 69257

Filter Funnel, Analytical, 65 mL each 108367

Thermometer, Non-Mercury, -10 to 225 C each 2635700

Sampling Bottle with cap, low density polyethylene, 250 mL 12/pkg 2087076
http://www.hach.com/hc/search.product.details.invoker/PackagingCode=2076049http://www.hach.com/hc/search.product.details.invoker/PackagingCode=27256http://www.hach.com/hc/search.product.details.invoker/PackagingCode=27256http://www.hach.com/hc/search.product.details.invoker/PackagingCode=2076049

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HACH COMPANYWORLD HEADQUARTERSTelephone: (970) 669-3050

FAX: (970) 669-2932

FOR TECHNICAL ASSISTANCE, PRICE INFORMATION AND ORDERING:Call 800-227-4224

Contact the HACH office or distributor serving you.

www.hach.com [email protected]

In the U.S.A.

Outside the U.S.A.

On the Worldwide Web ; E-mail

toll-free


Hach Company, 2007, 2010, 2012. All rights reserved. Printed in the U.S.A. Edition 7

Optional standards


Voluette Ampule breaker, 10 mL each 2196800

Phosphate, Standard Solution, 3 mg/L 946 mL 2059716



Phosphate, Standard Solution, 50 mg/L, 10 mL Voluette Ampules 16/pkg 17110



DOC316.53.01114_Ed7

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