Manchester Analytical Geochemistry Unit
This facility includes a number of analytical instruments, mostly for the purposes of elemental analysis of waters and solid geological media, together with sample preparation areas.
Equipment and labs
The Chemistry Laboratory housed in Room 1.18 contains facilities for sample preparation and analytical method development available to both undergraduate and postgraduates, including:
- Fume-cupboards with operating extractor fans are used to restrict lab users' contacts with dangerous (particularly gaseous) substances which may be used or produced during (for example) dissolutions of solid samples with concentrated acids.
- Drying ovens are running routinely at 50º for the drying of cleaned apparatus. We’ve found that most rinsed wet items of apparatus will dry adequately at 50º rather than using higher temperatures. Another small oven can be controlled more precisely between 30º and 140º: to determine, for example, a sample’s weight loss at 110º.
- Microwave digestion is used to attack resistant solid samples and dissolve them in (usually) very aggressive reagents. The samples are completely enclosed during treatment so that external contaminations (such as bits of operator and specks of Manchester) are excluded from sample solutions.
- Deionised water. We have equipment to produce 15 MΩ deionised water for general lab. use. The 18 MΩ deioniser can be used to prepare smaller volumes of even purer deionised water.
This instrument has been developed for the determination of hydrogen but is also capable of detecting in its present configuration helium, oxygen, nitrogen and methane.
This instrument is comprised of the following equipment:
- 7697A Headspace 12 position Autosampler
- 7890 Thermal Conductivity Detector
- 7890 Gas Chromatography System
The following conditions are required to use the equipment:
- Column: HP Molesieve 30meter long, 0.53 millimetre diameter, 25 micron film.
- Carrier gas: Argon
- Sample loop: 1ml
- Inlet: split 1:100
- Oven: 50◦C (15 min)
- TCD: 180◦C
The Agilent 7890A GC is the instrument for screening complex mixtures of volatile organic compounds. It is fitted with a programmable temperature vaporising (PTV) and on-column injector, a flame ionization detector (FID), a flame photometric detector (FPD) for detection of organic sulphur or phosphorous compounds and an Agilent 7683 autoinjector and robotic sample tray to facilitate high sample throughput.
Furthermore, the latest QuickSwap capillary flow technology is used allowing the splitting of the column effluent –sending the sample to both detectors- providing the most information from a sample in a single run and providing the possibility for backflushing. In addition, both the injector and oven can be cooled (independently), using liquid nitrogen.
The Agilent 5975C GC/MSD is a single quadrupole, benchtop GC/MS instrument and is the instrument for screening and characterising complex mixtures of volatile organic compounds. It is fitted with a programmable temperature vaporising (PTV) and on-column injector and can operates both in electron ionisation (EI) and chemical ionisation (CI) mode. An Agilent 7683 autoinjector and robotic sample tray is fitted to the GC to facilitate high sample throughput, as well as the latest QuickSwap capillary flow technology allowing column changes or inlet maintenance without venting the MS and backflushing. In addition, both the injector and oven can be cooled (independently), using liquid nitrogen.
The ICP-AES has a range of uses, including the analysis of a wide range of elements in solution, sequentially.
Detection limits vary from element to element and depend upon the method and the nature of sample and standards used, but 10-100 ppb is potentially achievable for a wide range of elements.
Analysis of 24 water samples + 12 standards for Na, K, Ca, Mg, Si, S, P, Fe and Mn might typically take half a day of instrument time.
- Concepts, instrumentation and techniques in inductively coupled plasma optical emission spectrometry
Liquid samples should normally be aqueous, acidified (typically 2% HNO3 or equivalent), filtered (removing particles > 0.45 um) and with a total dissolved solids content of less than 10,000 ppm. Samples not conforming with these requirements may require pretreatment. Non-compliance with these requirements must be drawn to the attention of MAGU staff, not least of all to prevent damage to equipment.
Solid samples dissolved by mixed acid digestion, often involving HF. This procedure must be done in the Chemical Laboratory (Room 1.18) in consultation with Dr Ragazzon-Smith. Special training is required (see Dr Polya or Dr Ragazzon-Smith to make arrangements).
The ICP-MS instruments are housed within the Department in a class 1000 cleanroom. Adjacent sample and standard preparation facilities are housed in a class 100 cleanroom.
The main functions of the ICP-MS are:
- Producing ions and other species in a high temperature plasma.
- Extraction of ions from the plasma, attenuation of polyatomic interferences.
- Separation of the ions according to mass charge ratio using a quadrapole mass filter.
- Detection and data processing.
Analysis of aqueous solutions
Analysis of aqueous solutions for most elements, but with the notable exception of halides and some metals. The instrument operates in rapid sequential mode to analyse a predetermined list of elements. Detection limits may be as low as 0.01 ppb in solution under the usual operating conditions although 0.1 ppb is more commonly achieved. Polyatomic interferences are attenuated by means of a pressurised octopole collision/reaction cell that can be used with no gas, Helium or Hydrogen as the collision/reaction cell gas.
The instrument can also be coupled to a fully automated High Pressure Liquid Chromatography system primarily for Arsenic and Iodine speciation.
0.45 um) and with a total dissolved solids content of less than 1000 ppm. Samples not conforming to these requirements may require pretreatment. Non-compliance with these requirements must be drawn to the attention of AGU staff, not least of all to prevent damage to equipment. Solid samples dissolved by mixed acid digestion, often involving HF. This procedure must be done in the Chemical Laboratory (Room 1.18) in consultation with Dr Ragazzon-Smith. Special training is required (see Dr Polya or Dr Ragazzon-Smith to make arrangements).
All samples to be accompanied by suitable hazard assessments.
Ion chromatography is a form of liquid chromatography. It is used to determine anions and cations in aqueous samples. Ion exchange resins packed into columns are used as the stationary phase. The liquid or eluent which is pumped through this resin is also known as the mobile phase. The sample ions momentarily adhere to the stationary phase before they are washed off again. This interaction of the sample ions between these two phases will vary according to the species. It is this retention characteristic that allows us to differentiate between them.
A typical Ion Chromatograph consists of: eluent; pump; injection valve; guard column; analytical column; suppressor; conductivity detector (other types of detector can be used), and computer software.
A pump is used to push the mobile phase from a reservoir through the guard and analytical columns. The guard column is a shortened version of the analytical column; it reduces the likelihood of getting contaminants on to the more expensive analytical column. A sample is loaded on to a sample loop by the autosampler and introduced into the mobile phase using an injection valve. The sample ions contained in the mobile phase then flow into the columns where they interact with the ion exchange sites in the resin. If the column is an anion column, the resin will consist of millions of positively-charged sites. The anions in the sample will be temporarily attracted to these sites. Eventually, the mobile phase will ‘compete’ with the resin and elute the anion off the stationary phase and into the mobile phase once more. If the column is for cations, then the resin in the columns will consist of negatively-charged sites. The same principle applies.
The stream of ions passes into a suppressor. The suppressor is controlled electronically and reduces the background conductivity of the mobile phase by using what is effectively a neutralisation reaction. The conductivity of the ions is thus increased, relative to the background.
Finally, as the ions pass through the conductivity detector, a peak is produced which is integrated by the computer software. In general, the area under the peak is measured and compared to a series of peaks from calibration standards. Peak area is proportional to ion concentration.
- Equipment available: Dionex ICS5000, Dionex BioLC.
- Uses: ICS5000: Determination of a wide range of inorganic anions and organic acids in aqueous samples.
This is a dual channel Ion Chromatography system. One channel is a capillary system which has a very low flow rate of around 15µL/minute. This means that the pump can be left running continuously and is therefore inherently stable. The IonPac AS11-HC Hydroxide-Selective Anion-Exchange capillary column can be used to determine a huge range of inorganic and organic anions in one run.
- Examples of the chromatograms that the IonPac AS11-HC Hydroxide-Selective Anion-Exchange capillary column can produce.
The second channel incorporates a microbore Dionex AS18 column. This is used to determine common inorganic anions and certain organic species in a very short run time.
- Examples of the chromatograms that microbore Dionex AS18 column can produce. Determination of inorganic anions and organic acids in aqueous samples.
Determination of organic acids, ammonium, alkali metals and alkaline earths in aqueous samples.
This system contains two very different columns and accompanying chemistries.
One column is a Dionex ICE AS1 which is used to determine a large number of organic acids, including Isosaccharinic Acid (ISA).
The other column is a Dionex CS12A which is used to determine Group I and II elements and ammonium.
Variable, but typically around 0.05mg/L for most analytes.
- The samples must not be acidified. The presence of any HNO3, HCl, etc. will swamp any ions of interest and also cause big shifts in their retention times.
- Samples must be filtered down to 0.2µm.
- Samples which contain heavy metals, or elements such as silver, will require special pre-treatment.
Sample volume requirements
A minimum volume of around 0.5mL of filtered sample is sufficient for most applications.
Important information for all users: A fully completed job request form and CoSHH risk assessment form must accompany all batches of samples. Failure to comply with this will mean that the samples do not get analysed.
The Agilent 6130 single quadrupole LC-MS system is the equipment used to analyse a wide range of organic geochemical components, including compounds that are thermally labile, exhibit high polarity or have a high molecular mass. The LC system consists of a degasser unit, a binary pump, a high performance well plate autosampler and a thermostatted column compartment. The single quadrupole MS system is equipped with an orthogonal multimode source providing electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) that can be used either separately or simultaneously. The MS affords a mass range of 2-3000m/z with a mass accuracy of ± 0.13 u within the calibrated mass range in scan mode.
Pyrolysis in combination with GC or GC-MS enable the analysis of more intractable, involatile macromolecules, eg ligin, cellulose, chitin, directly from natural materials of interest. The CDS 5200 pyrolysis unit can pyrolyse solids, powders and liquids, has a clean and dry function and can be connected directly through the GC or GC-MS injector port via a heated transfer line, allowing quick switchover time. Up to 8 runs per sample all with their own GC start can be performed, either to the built-in trap or directly to the GC.
The Shimadzu TOC-V CPN Dissolved Carbon and Nitrogen Analyser is used to measure dissolved Carbon and Nitrogen in water samples. Total Carbon (TC) and Total Inorganic Carbon (TIC) can be measured. By subtracting the TIC value from the TC value, the Total Organic Carbon (TOC) can be calculated. Nitrogen can be determined in the same sample as Total N.
Approx. 15mL of filtered, unacidified sample is required for each analysis. A batch of 25 samples for TOC analysis will take around 9 hours to complete. This includes standards which are analysed as ‘unknowns’ during the run to monitor stability.
Total Carbon (TC) is measured by injecting the sample into the sample port. The port is connected directly to a furnace which is heated to (680°C) All the carbon in the sample is converted to carbon dioxide and is carried in a stream of high purity air to an infra-red detector. The detector produces a signal which is directly proportional to the concentration of carbon dioxide.
Inorganic Carbon (IC) is measured by injecting the sample into the (IC) port. The sample comes into contact with a highly acidic quartz medium. Any inorganic carbon such as carbonate reacts with the acid to produce carbon dioxide. The carbon dioxide is then detected in the same way as previously.
Total Nitrogen (TN) is measured by introducing the sample to a furnace (720°C). The TN in the sample decomposes to Nitrogen Monoxide and is detected by a Chemiluminescence Gas Analyser.
The TOC-V CPN can be used over a range of sensitivities. Typically, a concentration range of 1-300mg/L Carbon can be detected (using the auto-dilution) Calibration is required at the beginning of each session. A minimum of three Calibration standards is recommended for a TC and IC analysis. Typically, the range of concentrations is 1-50mg/L Carbon.
It is expected that the TN Calibration and concentration ranges will be similar to that of TC.
All the data from the analysis is stored on the TOC-V CPN computer and can be converted to a variety of formats (such as Excel).
X-ray fluorescence (XRF) spectrometry is a non-destructive analytical technique used to identify and determine the concentrations of elements present in solid, powdered and liquid samples. The XRF spectrometer measures the individual component wavelengths of the fluorescent emission produced by a sample when irradiated with X-rays.
Wavelength separation (WDXRF) is achieved by diffraction, using an analyser crystal. The specific lattice of the crystal selects the correct wavelengths according to Bragg's law.
A sequential spectrometer employs an optical assembly called a goniometer, which is equipped with two concentric, rotatable shafts. These enable the analysing crystal to turn through angular increments (theta degrees), while the detector rotates through 2-theta degrees to intercept the diffracted beam. Spectral peaks are detected at various wavelengths, according to the conditions described by Bragg's Law.
The results of continuous scanning over an angular range can be plotted as a spectrum, from which the elements present in a sample may be identified. Individual peak intensities are measured to determine element concentrations.
Measurement times as short as two seconds suffice for many elements - although longer times are required for the lightest elements, which produce relatively small numbers of characteristic fluorescent photons.
Major and trace element analysis. Elements of atomic number 8 (O) to 95. Limit of detection depends on the element concerned and the concentrations of other elements that may interfere.
Routine programs are available:
- Trace element analysis: Pro-Trace produces accurate and reliable trace element analysis on a broad range of sample types - with detection limits from sub-ppm to 6ppm dependant on element. Pro-Trace uses specially prepared blank specimens and calibration standards. Typical run time 2 hours per sample. For powdered samples, sample weight 12g +3g wax binder.
- Major element analysis with Omnian: Omnian is a software package based on an advanced fundamental parameters algorithm. It has the flexibility to handle a wide variety of materials with accurate results over wide ranges of concentration (0% to 100%). Typical run time 17 minutes per sample. For powdered samples, sample weight 12g +3g wax binder.
- A Furnace is available that can be controlled at temperatures between 110º and 1100º. It can be used to determine samples’ weight losses on ignition at a stated temperature. It is useful to be able to complete the analyses of samples which contain water; and/or carbonates; and/or organic substances.
Contains extracts from the PANalytical webpage.
Further information and procedures
MAGU personnel will, subject to other work commitments, provide users with hands-on training in required preparative and analytical procedures. The emphasis of such training will necessarily be initially health and safety, and safeguarding equipment.
While advice will be given on steps that may be taken to assure data quality, assuring data quality is ultimately the responsibility of the user.
Any users wishing to make extensive use of the wet chemical facilities will be expected to have received suitable training.
Where time permits, MAGU staff will provide advice and help you select the most suitable available technique for the analytical work you may require. We strongly recommend, however, that you avail yourself of the relevant training programmes available within the Department and other Departments with the Faculty of Science and Engineering.
The table below shows typical applications of major techniques available – capabilities however do extend beyond the commonly analysed analyses and media listed.
|Instrument||Media||Typical analytes||Typical routine detection limits||Typical sample required||Comments|
|ICPAES||Water; Rock / soil/ biological media digests||Na,K,Ca,Mg, Ba,Sr, Fe, Mn, As, P,S, Si, Cu, Zn, Pb||0.1 – 1 mg/L||10 mL in 2 % HNO3 Maximum TDS 1 %||Workhorse for determining major cationic components in waters or digests|
|ICPMS||Water; Biological media digests||Transition metals including Cu, Zn, Mo, Cr, Co; Pb, Pt, U, Pu, Ba, As||0.001 – 0.01 mg/L||10 mL in 2 % HNO3 Maximum TDS 0.1 %||Trace element determinations in waters|
|ICICPMS||Water; Biological media digests||As, Se, Cr species||0.001 – 0.01 mg/L||1 mL|
|IC||Water||Cl-, SO4--, NO3-, NO2-, Br, Ac-, VFAs||0.01 – 0.1 mg/L||2 mL; not acidified||Anionic components other than HCO3-, CO3—|
Note: TDS = total dissolved solids.
The following is a partial list of operating procedures and MAGU standard operating procedures. A hard copy is available for consultation in the Chemistry Laboratory (Rm 1.18).
- General ICP.-MS. sample preparation information.
- Open dish digestion method.
- Microwave Digestion (PL001 Sample digestion using the MDS-2000 Microwave Sample Preparation System).
- Lithium metaborate fusion dissolution method.
Standard operating procedures and documentation
Standard Operating Procedures and documentation for FERA PHL 52716 198178 4 LICENCE (PDF)
- DP001 Laboratory code of Practice
- DP003 Reporting Non-Compliance with Health and Safety Regulations
- DP005 Management of Outside work
- DP006 Writing, Reviewing & Referencing Operating Procedures Standard Operating Procedures
- DP007 Analytical Error Calculations Using CHEMCAL4
- DP008 Expression of Results: Units, Errors and Significant Figures
- DP010 General Use of Volumetric Glassware
- DP011 Estimating Total Dissolved Solids from Electrical Conductivity Data
- DR970402 River Water Sampling and Acidification of River Water Samples
- DR970405 Sample Bottle Cleaning
- DR970401 Determination of Alkalinity in Natural Waters
All facilities within the Manchester Analytical Geochemistry Unit must be booked with the Laboratory Manager or their designate prior to use. A completed Job Request Form and accompanying documentation is required before any work is agreed by MAGU. To submit these forms please register on The University of Manchester PPMS system. Upload the completed forms to the PPMS system when requesting analysis.
Particularly if you are a new user of the facility, you will normally:
- Consult with MAGU personnel regarding technical requirements and instrumental (if appropriate) technique selection; it is presumed by MAGU personnel that users will be aware and able to effectively communicate their data requirements, particularly with regard to:
- number of samples
- nature of samples
- amount of each sample
- determinands required
- anticipated range of concentration of determinands
- precision required
- accuracy required.
- In line with health and safety guidelines conduct a risk assessment of the work carried out and complete a COSHH form as appropriate.
- Undertake any training required. A booking form is normally required for all use/hire of AGU facilities or services.
All users of Manchester Analytical Geochemistry Unit (MAGU) facilities are required to comply with the SEES health and safety policy and code of practice and in particular those elements of policy and practice pertaining to MAGU facilities.
Before commencing any work using MAGU facilities, new users of the facilities must see the Laboratory Manager (or their designate) who will appraise them of the health and safety requirements.
All samples to be analysed in the MAGU must be accompanied by a suitable written risk assessment. The assessment must contain a description of the type of materials being analysed together with details of any hazard they pose. A single COSHH risk assessment may be used to cover the analysis of a number of batches of identical samples. It is the responsibility of the person submitting samples to prepare the COSHH risk assessment (with advice from their supervisor if appropriate) and not the staff of the laboratory involved.
- Anon (2014). University of Manchester, SEES, Health and Safety Policy and Code of Practice, March 2014.
- SEES Health and Safety.
- WHO/IUPAC (1992). Chemical Safety Matters. University Press, Cambridge, 284pp.
Authorship and acknowledgements
All research and teaching users of MAGU facilities should explicitly acknowledge the MAGU (Manchester Analytical Geochemistry Unit) and the relevant personnel when analyses or instrumental data obtained using the unit are included in manuscripts for publication, papers, reports, theses, dissertations and, where appropriate, abstracts and public presentations. Co-authorship by MAGU personnel is normally only expected on manuscripts intended for publication as papers or abstracts where:
- the publication concerns the development of an analytical technique in which particular MAGU personnel have significantly contributed; or
- particular MAGU personnel have materially contributed to the intellectual content of the manuscript or the reduction of instrumental data.
Reporting analytical data
Analytical data reported in manuscripts for publication normally (requirements may vary depending on the editorial policy of the journal/publisher) should be accompanied by (i) a brief description of the analytical methods and instrumentation used, and (ii) a description of the quality of the data.
The detail of the method description required should normally be sufficient for a competent reader in principle to be able to reproduce the procedure followed. Where appropriate reference to a standard procedure, whether an MAGU standard operating procedure or a published procedure, may serve to reduce the volume of description required. The brand and type of major instrumentation should be noted as well as any critical instrumental settings and operating conditions.
Description of data quality should include estimates or assessments of:
- the representativeness of the samples analysed;
- the precision of the measurements made; and
- the accuracy of the data reported.
Together with the bases for making such estimates.
While MAGU staff may have considerable experience of typical precisions and accuracies obtained by certain techniques for commonly analysed media, these typical precisions and accuracies will not apply universally to all sample sets. In practice, the estimates of precision and accuracies for the analysis of a given sample set should be determined by the inclusion and due consideration of appropriate replicate and standard samples in the sample set analysed. For reported analyses of labile components or trace components, in particular, explicit consideration should be given to inaccuracies introduced by sample degradation and laboratory contamination respectively, while for all determinands, explicit consideration of instrumental drift and matrix-dependent effects should be made.
Unless otherwise explicitly stated, MAGU normally provides uses with instrumental data with no certification of data quality – assessing data quality and ensuring the appropriate samples (calibration standards, certified reference materials, blanks, procedural blanks, drift standards, standard additions) is the responsibility of the user.
Head of Mass-Spectrometry and Optical Facilities
Room Number: GE-003 [Chemistry Building]
Tel: +44 (0)161-275-4599
Professor of Environmental Geochemistry, Head of Unit
Room Number: G27 [Williamson Building]
Tel: +44 (0)161 275 3818
Bart van Dongen
Lecturer in Organic Geochemistry
Room Number; 2.50 [Williamson Building]
Tel: +44 (0)161 306 7460