Trace metal analysis in agriculture

In today's environment of increased scientific and physiological knowledge it is no surprise that this knowledge has transferred to the agricultural sector.

In today's environment of increased scientific and physiological knowledge it is no surprise that this knowledge has transferred to the agricultural sector.

It is becoming increasingly apparent trace metals in the food line help stock to thrive and remain disease free.

Magnesium for example has been proven to prevent grass tetany, selenium is known to be a major factor in the fertility of cows, cobalt is a necessary supplement for the well being of sheep.

This knowledge has led to the testing of the foodstuffs that are given to stock and supplements added as considered necessary.

Often the soil that provides the majority of the basic foodstuff for animals, grass, is supplemented as these trace elements are transferred to the animal by grazing which is less labour intensive and less expensive.

With this knowledge available it is becoming necessary that exact quantities of these trace elements is known, Metrohm provide an instrument that can analyse for these trace elements in the substrates mentioned above through the use of voltammetry.

The Computrace 797 is capable of reaching ppb to ppt levels of trace elements accurately, usually for a fraction of the cost of spectroscopic techniques and without the need for separation of the metals either using solvent extraction or co-precipitation.

Voltammetry - A Brief Overview.

Heyrovsky first introduced polarography in 1922.

The term voltammetry is applied to designate the current-voltage measurement obtained at a given electrode.

Polarography is a special case of voltammetry referring to the current-voltage measurement acquired using a dropping mercury electrode with a constant flow of mercury drops.

Stripping voltammetry uses the same instrumentation as traditional polarography but a stationary electrode such as the Hanging Mercury Dropping Electrode (H.M.D.E) is used.

The voltammetric measurement is performed on a stationary mercury drop allowing one to achieve considerable increases in sensitivity.

The jump in sensitivity is possible by electrochemical pre-concentration of the metals in question at the surface of the stationary electrode before the current-voltage curve is recorded.

The recorded current is the re-dissolution (reoxidation) current of the pre-concentrated metal traces.

Voltammetry today represents a refined, clean, simple technique that offers outstanding limits of detection and is now the fastest growing analytical technique for trace analysis.

Dry Matter Digestibility ( DMD )in Animal Foodstuffs.

In livestock Farming the major cost is the supply of foodstuffs for the animals.

Over the winter periods the animals are housed and kept off the land, the quality of the foodstuff that you ration to the animals is most important.

Dry Matter Digestibility determines the quality of silage, pulp nuts, bean meal etc that would be fed to them.

In the summer when cattle are out on land, grass is generally plentiful and once animals are not sick will do well, however in the winter when ration is given to the animals the DMD value of the feed will indicate how much has to be fed to each beast on a daily basis.

The DMD value is tested by government laboratories for the department of agriculture on behalf of the farming community but it is also necessary for the manufacturer of animal feed to test also for quality and pricing purposes.

This DMD value was traditionally done by drying to constant weight in a 100 degree oven but this is very time consuming.

Metrohm offer an instrument that can analyse a product inside 5 minutes via a Karl Fischer titrator.

The 841 KF titrator can analyse moisture levels from 100 ppm to 100% and can therefore determine DMD values at any level.

The result is automatically calculated through the user friendly touch screen keypad.

Samples of any kind can be introduced as the built in homogenizer will break up any matrix releasing the full moisture content to be analysed.

The results can be printed off or can be stored on a database or transferred to a LIMS system if necessary.

If several samples are to be tested a sample changer can be connected which will reduced user time at the workbench.

Ion Chromatography for SDS detection.

Sodium DoDecyl Suphate is a detergent that is used both in industry and also in personal care products such as shampoo, toothpaste, facial cleansers etc We use products every day that contain SDS, however a recent study has shown that SDS can penetrate the body tissues it comes in contact with and can be retained.

It is linked with Catarcts in the eyes of adults, can cause hair loss by removing the natural fats on the skin of the scalp which are necessary to maintain the moisture level in hair follicles.

Another major concern is the connection of SDS with Nitrates to for Mitrosamines which are carcinogenic.

The 761 Compact IC Metrohm can analyse SDS to low PPM levels in water thus allowing us to monitor the levels of SDS being absorbed by our bodies.

SDS can be detected using direct conductivity measurement using a Metrosep 120-5-C18AQ column and a dilute phosphate eluent.

Typical elution time for SDS is 5 minutes, the system is run using IC NET 2X software which is fully CFR 21-11 compliant.

The system can also run using IC Cap which makes the system easy to use for operators and lab users alike.

Because of the low limits of detection the Metrohm 761 IC can also be used in clean downs in the pharma industry where the blending room are totally washed down and then tested for residual surfactant before a new blend takes place.

The Metrohm Titrando range of titrators ? theres always a ?clever guy in every lab! This is not a hollow boast or a joke, the titrando has several features which make it ideal for use in the pharma industry.

We will list them out below, it goes without saying that it complies with the FDA CFR 21-11.

The dosing units and exchange units have memory chips built in so the information that is contained on the chip is unique the unit.

Details like the burette volume, titrant concentration, stats on the concentration, expiry and restandardisation dates, titrant history and also user history of those that standardized it in the past.

This titrant information is assigned to a method and that method only, if an analyst tries to do a titration with the incorrect titrant or one that needs re standardizing the titrando will prevent the titration from proceeding and a warning message appears.

The titrando can be operated via a clever touchscreen or through PC software, it has full security features which means those that shouldnt be fiddling with methods of results cannot do so.

It also has a unique feature in that it can e-mail a result to say the quality manager or the plant manger so if an action is dependant on a particular result they receive it immediately.

Each modular component is recognized by the software and will flag a problem if one exists, everything is controlled by USB technology.

Theres a titrando for every type of titration in the lab.

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