Low-sodium table salt can contain as much as 17% magnesium salts, which can be determined photometrically with the use of a photometer and an autotitrator
Magnesium carbonate is added to cooking salt as an anti-caking agent and as an aid to improve the flow characteristics of table salt.
Many doctors and health experts believe high levels of salt (in particular the sodium part of salt) in peoples' diets can contribute to hypertension (high blood pressure).
With this in mind many companies are producing so called low sodium salt that do (as the name suggests) have lower levels of sodium but can contain as much as 17% magnesium salts.
These levels of magnesium can be determined photometrically with the use of a photometer and an autotitrator.
The sample is weighed into a beaker and 10ml of NH3/NH4Cl buffer is added along with 80mls of distilled water.
1ml of methylthymol blue salt colour indicator is added and the solution is then titrated with 0.1mol/L EDTA. The 662 Photometer is a compact, microprocessor-controlled instrument that is very versatile and has many applications.
It has been developed for direct photometric measurements and the photometric endpoint determination of titrations.
The 662 Photometer offers the additional possibility to determine the concentration of sample solutions after previous calibration.
The measured value can be compensated such that titrations with very small signal changes can be safely evaluated.
Measurements can be performed in any sample container, be it a beaker, a test tube, a titrating vessel, etc Thanks to the continuous wavelength scale with stepless adjustment, measurements can always be performed at the point of maximum absorption.
Accordingly, there is no loss of sensitivity due to non-optimal selection of the wavelength. Expensive optical cuvettes are no longer needed: the long, flexible glass-fibre light guide of the 662 Photometer makes photometric determinations just as easy as a pH measurement in a wide range of different vessels and over the entire visible wavelength range (400 - 700nm).
For photometric titrations Metrohm recommends the 662 photometer in conjunction with its Titrando range of titrators.
