Product category:
Materials Testing
News Release from: Metrohm UK | Subject: QC Analysis of Sodium
Edited by the Manufacturingtalk Editorial
Team on 19 May 2005
Ion chromatography of sodium in isotonic
drinks
In recent years the cost of ion chromatography instruments have fallen and they now represent a cost effective analytical solution to alternative techniques.
Water constitutes 60% of male body weight and 55% of female body weight and is eliminated through perspiration, defecation, urination and the levels in our body need to be replenished constantly An average adult needs to consume approximately 2.5 litres of water per day, a figure that increases during exercise
This article was originally published on Manufacturingtalk on 22 May 2008 at 8.00am (UK)
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Historically, water was always the preferred and choice for remaining hydrated throughout any endurance exercise but alone it causes bloating and stimulates urine output thereby making it inefficiently retained.
An isotonic or sports drink has the benefit of possessing electrolytes which aid fluid absorption and carbohydrates that provide the necessary fuel for the body to maintain peak performance and enhance post exercise recovery.
In ancient Greek, "iso" referred to equal and "tonos" meant pressure - joining the two together gave the word "isotonic".
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Ion chromatography with Metrohm represents a robust, precise quantitative technique for the analysis of sodium in a variety of different sample matrices that include isotonic drink.
In recent years the cost of ion chromatography instruments have fallen and they now represent a cost effective analytical solution to alternative techniques.
The Requirement for Isotonic Drinks Sweating is the way in which the body maintains its core temperature of 37C but this will result in the loss of body fluid and electrolytes like chloride, calcium, phosphate, magnesium, sodium and potassium.
If the levels of electrolyte are not checked and replenished then potentially this can lead to dehydration followed eventually by circulatory collapse and heat stroke if the percentage body weight lost as sweat exceeds 10% or more.
Electrolytes are essential minerals that help control the osmosis of water between the different body compartments as well as maintaining the acid-base balance required for normal cellular activities.
Carbohydrate is stored as glucose in the liver and muscle, it is the most efficient source of energy as it requires less oxygen to be burnt that either protein or fat.
During a period of exercise, the muscles increase the uptake of blood glucose, which the liver produces from its stores, to prevent the levels from falling.
The carbohydrate stores of the body are depleted gradually and if they are not restocked will result in a reduced performance.
Hence, consuming carbohydrate before and after exercise will prevent blood glucose levels from dropping too low and maintain the body's glycogen stores.
As many athletes cannot consume food before or during exercise, many opt for a formulated isotonic drink to provide the necessary carbohydrate required.
The Absorption of Fluid Factors that influence the speed at which fluid from a drink can get into the body include the speed at which it is emptied from the stomach and also the rate at which the drink is absorbed through the walls of the small intestine.
The higher the level of carbohydrate in a drink, the slower the rate at which the stomach empties.
Isotonic drinks with a carbohydrate level of 8% will be disposed from the stomach at a rate similar to that of water.
Electrolytes like sodium that are also present in the drink will reduce the urine output enabling the fluid to be quickly emptied from the stomach promoting the absorption from the intestine and encouraging fluid retention.
Ingesting drinks with no electrolyte content over short periods will result in a rise in plasma volume and a fall in the sodium concentration and osmolality (number of particles in solution) of the blood making it more dilute.
The dilution can lead to an increase in urine production which promotes a loss of bodily fluids which counteract the effects of re-hydration.
The fall in blood osmolality and sodium concentration can reduce the drive to drink which works against complete re-hydration.
Isotonic drinks provide the same amount of sodium as you get in blood plasma and drinking plain water can be a poor choice when a high fluid intake is necessary as it contains none of the carbohydrate or electrolytes that promote a more rapid recovery after a session of strenuous exercise.
During extreme endurance activities such as marathons, it is important that competitors drink beverages containing sodium electrolytes to avoid the potentially life threatening condition known as hyponatremia (a low blood sodium level).
What is Ion Chromatography? Chromatography is a method for separating mixtures of substances using two phases, one of which is stationary and the other mobile moving in a particular direction.
Chromatography techniques are divided up according to the physical states of the two participating phases.
The term Ion Exchange Chromatography or Ion Chromatography (IC) is a subdivision of High Performance Liquid Chromatography (HPLC).
A general definition of ion chromatography can be applied as follows; "ion chromatography includes all rapid liquid chromatography separations of ions in columns coupled online with detection and quantification in a flow-through detector".
A stoichiometric chemical reaction occurs between ions in a solution and a solid substance carrying functional groups that can fix ions as a result of electrostatic forces.
For cation chromatography these are sulphonic acid groups.
In theory ions with the same charge can be exchanged completely reversibly between the two phases.
The process of ion exchange leads to a condition of equilibrium, the side to which the equilibrium lies depends on the affinity of the participating ions to the functional groups of the stationary phases.
Method for the Determination of Sodium in Isotonic Drink The isotonic drink solution was diluted 1:50 with 2mM nitric acid.
The diluted sample was injected directly into the Metrohm 761 Compact IC and the response for the peaks recorded using a tartaric acid/dipicolinic acid eluent with the Metrosep C2 analytical column.
The calculation was carried out automatically using integration software IC Net 2.3 against a previously prepared calibration plot.
There are no external displays or switches on the instrument, all the hardware is fully controlled via a single RS232 connection between the IC and the PC.
All the instrument parameters can be called upon with a click of the mouse.
The 761 Compact IC comprises a low-pulsation dual-piston pump, pulsation dampener, electromagnetic injection valve, two-channel peristaltic pump suppressor module, conductivity detector, eluent organiser as well as a data recording and processing module.
All the components that come into contact with the eluent and sample are metal-free.
The detector is the heart of every ion chromatography instrument.
The Metrohm detector's temperature varies by less than 0.01C and can be optimally adapted to the ambient conditions.
This outstanding temperature stability reduces interference and allows exact conductivity measurements.
Chromatograph from Analysis of Isotonic Drink The total sodium content in the complete sample of isotonic drink analysed was found to be around 3.8 g l-1.
It can be seen from the chromatograph above that it would also be possible to quantify potassium, calcium and magnesium if these species were of interest too.
Conclusion of Sodium Analysis in Isotonic Drink using Ion Chromatography Isotonic drinks quickly replace fluids lost by sweating and supply a boost of carbohydrate so are usually the preferred choice for athletes, distance runners and those participating in team sports events.
Ion chromatography as an analytical technique has seen an enormous surge in popularity, due partly to the simplicity of many of the methods as well as other factors such as market forces driving down the expenditure costs of the equipment and an improved instrument power.
With Metrohm IC Cap, an additional user interface that sits on top of the IC Net software if required, the analysis can be started by a single mouse click which allows the instrument to be easily used by non-laboratory trained personnel if necessary.
The low running costs of IC with Metrohm instruments are surprisingly low requiring only the acquisition of chemicals required for the eluent as well as a clean, reliable source of deionised water for preparation of the standards and samples.
Ion chromatography is a precise, robust technique that requires only a very small amount of sample for the analysis and the quantified results obtained within a matter of minutes demonstrating precisely the reason why it is rapidly becoming the method of choice for many analysts in a plethora of different industries and is eminently suited to the analysis of sodium in isotonic drink. Request a free brochure from Metrohm UK ...
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