Bromate in water and drinking water – ultra low range (Photometric)

Description

We offer for customers who are interested in measuring Bromate an application which allows analyzing Bromate
ultra low in the following measuring ranges:
0.5 – 20 µg/l BrO3
–
by using a 100-mm rectangular cell.
1.0 – 40 µg/l BrO3
–
by using a 50-mm rectangular cell.
For more details please see below. For the analysis the following reagents and accessories are required:
Reagents:
3,3‘-Dimethylnaphthidine
Acetic acid 100% for analysis
Ethanol absolute for analysis
Potassium iodide for analysis
Perchloric acid 70 – 72 % for analysis
Water for analysis

Accessories:
rectangular cells 10mm or
Rectangular cells 50-mm
Syringe filter glass fiber
Syringe filter 0.20 µm
Flat-bottomed long tubes with screw caps, for measurements in 100-mm cell; or
Empty cells with screw caps 16 mm, for measurements in 50-mm cell

Photometer:
Spectroquant® Prove 600 Spectrophotometer or
Spectroquant® Prove 300 Spectrophotometer or
Spectroquant® Prove 100 Spectrophotometer

Measuring ranges and confidence interval (P = 95%):
The measurement in the 100-mm cell is only possible at the Prove 600!
100-mm rectangular cell: 0.5 – 20.0 µg/l BrO3
–
(Confidence interval ± 0.5 µg/l)
50-mm rectangular cell: 1.0 – 40.0 µg/l BrO3
–
(Confidence interval ± 1.0 µg/l)

Notes:
The vessels used must be clean and free from surfactant residues or similar substances. Pre-treat with a mixture
of isopropyl alcohol and hydrochloric acid, if necessary. Subsequently, rinse thoroughly with distilled water.
Prepare the isopropyl alcohol/hydrochloric acid mixture by placing 3 parts isopropyl alcohol in a glass beaker and
slowly adding 1 part of hydrochloric acid 25%. Follow the respective safety regulations!
Due to the low bromate concentration, which is accepted as the limit for drinking water (according to WHO and
EU Directive 10 µg/l), we recommend with each new batch of 3,3‘-dimethylnaphthidine to check the recovery
rate by means of a bromate standard in the area of the application concentration and to recalibrate the method,
if necessary. An instruction for the recalibration can be obtained separately.

1. Preparing the reagents
Preparation of an acetic acid / ethanol mixture
Reagent 1
Reagent 2
Reagent 2 has to be prepared freshly on each workday and must be prepared and stored protected from light in
closed containers. A storing in the refrigerator does not improve the shelf-life.

2. Sample preparation
In a 400-mL glass beaker evaporate 250 mL of sample solution slowly on a hot plate until almost dry. Transfer
the residue with a small amount of water for analysis into a 25-mL volumetric flask and make up to the mark.
The solution must be clear.
If necessary, filter through a fluted filter first and subsequently through a 0.20 µm syringe filter .
3. Analysis
Select method 307 (Bromate ultra low range) from the concentration mode of the photometer. Analyze the sample
against a reagent blank value.
Preparation using the 100-mm rectangular cell:
Reagent blank and measuring sample can be prepared at the same time.
Flat-bottomed long tubes with screw caps or glass beakers are suitable as mixing vessels. To 20 ml of water for
analysis (reagent blank) or 20 ml of pre-treated sample add 0.2 ml reagent 1 and mix, then add 0.4 ml reagent 2
and mix, subsequently add 0.4 ml perchloric acid 70 – 72 % for analysis and mix. Leave to stand for 30 minutes
at room temperature. Filter all test samples through a 0.20 µm syringe filter, prior to
measurement.
The measurement is conducted in a 100-mm rectangular cell. Measure the preparation with water as reagent
blank.
Preparation using the 50-mm rectangular cell:
Reagent blank and measuring sample can be prepared at the same time.
16-mm cells with screw caps or glass beakers are suitable as mixing vessels.
To 10 ml of water for analysis (reagent blank) or 10 ml of pre-treated sample add 0.1 ml reagent 1 and mix, then
add 0.2 ml reagent 2 and mix, subsequently add 0.2 ml perchloric acid 70 – 72 % for analysis and mix. Leave
to stand for 30 minutes at room temperature. Filter all test samples through a 0.20 µm syringe filter, prior to measurement.