Inorganic Orthophosphate

Inorganic Orthophosphate

DR 2800 Analytical Procedure

SPECIFICATIONS

Method           : Spectrophotometric (DR 2800)

Range              : 0.1 to 5.0 mg/L as PO₄

Testing time    : 15 Minutes

DESCRIPTION

The Inorganic orthophosphate DR 2800 procedure is an easy-to-use, economical method for determining orthophosphate levels in effluent water, boiler and cooling water, or manufacturing procces water, without having to submit samples for laboratory analysis. Inorganic phosphate-based products are used to help control both scaling and corrosion in boilers and cooling water systems. It is important to monitor orthophosphate levels to ensure that the proper level and type of phosphate is maintained in the system. With this test, the operator can readily determine the concentration of orthophosphate in the sample.

INTERFERENCES

The species listed below do not interfere under the stated values.

Species            mg/L

Fe³⁺                  150

Ba²⁺                 50

Cl⁻                   5000

Ca²⁺                 400

Pb²⁺                 20

Cu²⁺                 20

COD                 500

Al³⁺                  20

Mg²⁺                1000

CrO₄³⁻             60

Sample temperatures higher than 85⁰F (30⁰C) will convert some of the polyphosphate to orthophosphate, causing the orthophosphate test result to be erroneously high.

SAFETY PRECAUTIONS                   

Refer to Material Safety Data Sheet (MSDS) for specific reagent personal safety and disposal information.

1.      Touch:

Stored Programs

Select stored programs

736 PO₄ Ortho Inorg.

Touch:

 Start

2.      Fill two 25-mL sample cells with filtered sample.

Notes: Sample should be completely free of haze. To improve filtration of highly turbid sample, filter under pressure through glass fiber pad on top of the 0.45 micron filter membrane. Do not use a glass fiber pad alone.

Rinse all glassware with

1:1 HCL (460-SO726.77).

3.      Add 2 mL of 1:1 HCL to one of the sample cells (the blank). Swirl to mix.

Notes: When adding the test reagents, be careful that the tips of the droppers do not touch the sample cells or water therein. This precaution will avoid contamination and deterioration of the reagents.

4.      Add 2 mL of TP-1 (460-SH357) to the other sample cell (the prepared sample). Swirl to mix.

5.      Add 14 drops of fresh XP-2 (460-S5091) to each sample cell. Swirl to mix.

Notes: For best results, XP-2 solution should be prepared fresh every day. Prepareby adding one powder pillow of XP-2 or one heaping 0.5 gram scoop (blue scoop) of XP-2 (460-S5091) to a 2-oz dropper bottle and filling to the shoulder with deionized water. Cap and mix thoroughly.

6.      Touch the TIMER icon.

A ten-minute reaction period will begin.

7.      When the timer beeps, place the blank sample cell into the cell holder.

8.      Touch ZERO.

The display will show:

0.0 mg/L PO₄³⁻

9.      When the timer beeps, place the sample cell containing the prepared sample into the cell holder.

10.  Touch READ

The results in mg/L PO₄ will be displayed.