Description

Elemental Microanalysis
MEDAC is an analytical and chemical consultancy servcice specialising in elemental Microanalysis. Now in our 25th year we provide a professional and reliable elemental microanalysis analysis service to pharmaceutical, fine chemical and biotechnology companies and academic institutions. Our customer base is spread world-wide and we are happy to hear from new clients wherever you are located.
Since 1997 we have been registered to the ISO 9001 quality management system with BSI, currently ISO9001 : 2008 for "the provision of a micro-analysis service". Our certificate number is FS37919.


CHN Elemental Analysis
CHN elemental analysis is performed by combustion analysis using elemental analysers. The original analytical method is based on the complete and instantaneous oxidation of the sample by dynamic flash combustion which converts all organic and inorganic substances into combustion products. The resulting combustion gases pass through a reduction furnace and swept into the chromatographic column by the He carrier gas. Here they are separated and eluted as Nitrogen, carbon dioxide, water and sulphur dioxide, and detected by a thermal conductivity detector (TCD) which gives an output signal proportional to the concentration of the individual components of the mixture. The instrument is calibrated with the analysis of known standard compounds.
CHN elemental analysis is a cost-effective means of establishing sample purity on a wide range of sample types from volatiles to polymers. It is an essential tool in sample characterisation when used in conjunction with other techniques. Same-day sample turnaround is available for extremely urgent requests although most results are reported within two working days. The minimum sample size needed is 1mg.


Sulphur Elemental Analysis
Sulphur is analysed is performed by combustion analysis using elemental analysers. The original analytical method is based on the complete and instantaneous oxidation of the sample by dynamic flash combustion which converts all organic and inorganic substances into combustion products. The resulting combustion gases pass through a reduction furnace and swept into the chromatographic column by the He carrier gas. Here they are separated and eluted as Nitrogen, carbon dioxide, water and sulphur dioxide, and detected by a thermal conductivity detector (TCD) which gives an output signal proportional to the concentration of the individual components of the mixture. The instrument is calibrated with the analysis of known standard compounds. sulphur elemental analysis.
Sulphur elemental analysis is a useful counterpart to other elemental analysis, such as C, H & N and is available for most sample types. A same-day service can be arranged for particularly urgent samples and our normal turnaround time is within two working days. The minimum sample size is 1mg.


Oxygen Elemental Analysis
Oxygen elemental analysis is performed in much the same way as CHN and S analyses using the same elemental combustion analysers, although configured differently for the O analyis. The technique used is based on the Unterzaucher modified method. The sample is weighed into a silver foil capsule and dropped into the reactor furnace which is maintained at 1060?C, where the sample is pyrolised. Quantitative conversion of oxygen to carbon monoxide is achieved by a layer of nickel coated carbon. The pyrolised gas mixture then passes through an adsorption filter where halogenated compounds are retained. The gas mixture flows into the chromatographic column for separation of CO from N2, CH4 and H2. The CO is measured using a TCD which produces a signal proportional to the concentration. The instrument is calibrated with the analysis of known reference compounds.
Oxygen elemental analysis can be carried out on most organic compounds although those containing quantities of fluorine can interfere with the process. Samples containing metals cannot be analysed. Our normal turnaround time for oxygen analysis is within two working days but shorter turnaround times can be arranged for extremely urgent samples. The minimum sample size is 1mg.


Halogens
Three halogens analysed by means of Sch?niger flask combustion are chlorine, bromine, iodine. The resulting absorption solutions are routinely analysed by gravimetric titration methods, including the specific methods for bromine and iodine. Ion-chromatography may also be used to analyse the absorption solutions.
Fluorine is another halogen combusted in this way and measured by ion chromatography.
Sample size can vary from 5mg to 50mg, and the usual turnaround is within three working days.


ICP-OES
Our Varian Vista MPX ICP-OES (optical emission spectroscopy) system is employed to analyse a very wide range of sample types from steel tubing to fine chemicals, with almost everything else thinkable inbetween. A simultaneous system it is capable of analysing up to 66metals in the sample solution in one go.
A key to metals analysis is correct sample preparation. We have considerable experience of a wide range of preparation techniques and digestion methods for a variety of sample types. These include microwave digestion using a CEM Mars5 oven, wet acid digestion on hotplates, and hydrofluoric acid.
Normal turnround time is within two working days and a same day service can be arranged for extremely urgent samples. Sample size requirements vary depending on the metals content, but generally vary from 2mg to 1g.



ION Chromatography
A wide range of anions may be analysed by modern ion chromatography (IC) methods. Common anions such as sulfate, sulfite, nitrate, nitrite, halides, phosphates, etc. can be analysed. In addition ion chromatography is a powerful technique of use in the determination of fluoride, chloride and bromide anions.
Detection limits depend on the sample type but, for aqueous solutions, analysis in the ppb (ng/ml) region are possible. Turnround times for IC are normally within two working days and a same day service can be arranged for extremely urgent samples.

Minimum sample size is from 5 mg.



Air Sensitive Samples
Analysis on Air-sensitive compounds and hygroscopic samples are no challenge to our company. Samples are handled and sealed under an inert Argon atmosphere in our Faircrest glove box. In this manner air-sensitive samples can be analysed for C, H & N, S, P, halogens and metals.
Most analysis are performed within three working days. Minimum sample size depends on the analysis required. Please contact us for details.


Samples are carefully handled under a dry Argon atmosphere. Using this technique, air sensitive samples can be analysed for C, H & N, S, P, halogens and metals.


Ash content Sulphated Ash Residue on Ignition
Ashing is the heating of a substance to leave only non-combustible ash. There are several different forms of sample preparation that are considered as ashing including dry ashing and the sulphated ashing of a sample.
Ashing is suitable for samples containing a significant amouint of combustible organic material as the sample matrix and requires 1g of material.


Water content
Using our new coulometric Karl Fischer analyser from Metrohm we are able to measure the water content in a variety of sample types. Ideal for low level detection the coulometric system can reliably measure up to approximately 5% water content by weight.
The coulometric KF titration is a version of the classical water determination method developed by Karl Fischer. In the coulometric titration the iodine needed is generated directly in the electrolyte by electrochemical means. The quantitative relationship between the electric charge and the amount of iodine being generated is used for high-precision dispensing of the iodine. As the coulometric KF method is an absolute determination no titer need be determined. The end point is indicated voltametrically by applying an alternating current of constant strength to a double platinum electrode. This results in a voltage difference between the Pt wires of the indicator electrode which is drastically lowered in the presence of minimal quantities of free iodine. This fact is used to determine the end point of the titration.


Other Services
Medac has built up a network of other services to meet the demands and requirements of our customers. Our other services include mass spectroscopy, including peak matching and accurate mass analysis, IR and UV-VIS spectroscopic services, GC and HPLC analyses and high field NMR.


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