Parenteral nutrition (PN) and total parenteral nutrition (TPN) describe the intravenous provision of essential nutritional elements, thus bypassing digestive systems.
It is required when all or part of a person's gastrointestinal tract is not functioning correctly, for example because of an illness or through the consequences of an accident or surgery, when people can't obtain adequate nutrition via oral or enteral routes.
Typical formulations contain glucose, amino acids, electrolytes, lipids and vitamins.
Standard formulations are available for patients that are metabolically stable and can tolerate some over/under provision, but patient-specific prescriptions can be formulated for special cases.
Electrolytes (sodium, potassium, calcium and magnesium) are key nutritional elements of TPN solutions.
These play important roles in the body, including regulation of hydration, blood pH and nerve and muscle function.
Ion chromatography analysis of the four cationic electrolytes can be carried out by ion chromatography ([IC], a process for separating ions and other charged or polar molecules).
The principle behind ion chromatography can be broken down as follows: Firstly, an eluent (mobile phase) delivers the sample through the IC system.
A column (stationary phase) separates the analytes by retaining them to different degrees based on ionic interactions between the analytes and the column-packing material.
Finally, the conductivity detector measures the change in resistance of the eluent (caused by the separated analytes) as it passes through the detector.
Running standards of known strength can achieve qualification and quantification.
Metrohm's Professional ICs quantify low ppm levels of the four electrolytes in samples of TPN solutions.
The following Metrohm equipment provides a complete system for the analysis of the cationic electrolytes (sodium, potassium, calcium and magnesium) in TPN and PN solutions.
The 881 Compact IC pro - Cation is an intelligent IC for determining anions, cations or polar substances without suppression (no need for membranes).
It is solvent compatible and contains an integrated eluent degasser and a column heater.
The 858 Professional Sample Processor delivers the sample to the IC.
It can accommodate large sample numbers and customised racks can be manufactured to accommodate a variety of sample vials.
Extra rinse options and sample-dilution modules can be added to automate the entire sample-analysis process.
The Metrosep C4 Icolumn can determine monovalent and divalent cations.
All four cation electrolytes can be fully resolved on this column.
The column is solvent compatible and allows for good separation of analytes.
Icolumns store information about the column operating parameters and technical information.
When an Icolumn is inserted into a Metrohm Professional IC instrument, operating hours, maximum pressures and flow rates are automatically stored on the column.
This information stays with the column, so can be recalled even if the column is used with another instrument.
The MagIC Net 1.1 Professional PC program controls the compact IC system and sample processor.
The software permits control and monitoring of all the system components, data acquisition, evaluation and monitoring as well as report generation.
Results outside of defined ranges can be automatically flagged by the software and brought to the attention of the operator.
MagIC Net complies with FDA regulation 21 CFR part 11 as well as GLP.
The method developed by Metrohm UK separates the four electrolytes (sodium, potassium, calcium and magnesium) from a complex matrix in a single run of only 15-minutes long.
It is capable of measuring levels ranging from g/l to low ppm in the same solution, using one dilution step.
The method requires minimal sample preparation (1:50 dilution with ultra-pure water) which can be carried out by Metrohm's automatic inline dilution system.
This chromatogram shows a 10ppm standard with full separation between peaks.
This chromatogram shows a typical TPN sample with 1:50 dilution.
All analytes of interest are well resolved from the complex matrix.
This chromatogram shows a typical TPN component containing a number of amino acids.
Other ingredients could contain a range of essential elements and vitamins.
The ability to quickly and simply quality check the TPN solutions in a single analysis before they are supplied to patients is essential.
The Metrohm Cation system can provide an automated solution and can manage a high throughput of samples.
