Jun 08

Who is the purest of them all? The need for high quality certified reference standards

Thousands of decisions based on chemical measurements are made globally each day. This could be a clinician making a medical diagnosis, regulators identifying the presence of counterfeit drugs and removing them from sale, or a water treatment company testing their processes to ensure the water you drink is safe.

To underpin these measurements and ensure we all have confidence in them, they are calibrated through a series of reference materials – from those run on a day-to-day basis up to the highest (primary) level. The cornerstone of this reference material system is the provision of high purity reference standards as the primary calibrators, such as those produced by LGC in our role as the National Measurement Laboratory and Designated Institute for chemical and bio-measurement.

Industry increasingly requires a greater number, range and complexity of high purity reference standards to support the challenging measurements of real-world samples. This means primary calibrators must have values assigned more quickly and at significantly lower cost than traditional methods currently allow.

To address this need, scientists at LGC have been implementing the technique of quantitative nuclear magnetic resonance (qNMR). Purity determination by qNMR is much faster than traditional methods and allows for direct assay of the compound of interest rather than inferring the purity through quantitation of the myriad of minor impurities potentially present.

The use of qNMR for purity determination has been rigorously assessed and validated at LGC and its use as a primary method (with direct traceability to the international system of units, SI) has been standardised through comparison studies between National Measurement Institutes.

Earlier this year (2017) LGC became one of the few laboratories worldwide to gain ISO17025 accreditation for purity of organic materials by qNMR. The extent of the ISO17025 scope includes the determination of the purity of organic analytes of high purity (>90%) with a molecular weight of <1000 g/mol.

This accreditation provides demonstrable evidence of LGC’s expertise and supports our new qNMR facility in providing reference material characterisation and quantitative measurement research for customers across the AgBio, biopharmaceutical, chemicals, consumer products and forensic industries.


If you would like to find out how we could use our NMR expertise to address your measurement challenges, please contact LGC’s Measurement Services.

LGC is accredited to ISO Guide 34 for the production of reference materials.


May 26

Accurate MIC endpoints with automation

LGC’s drug development team regularly assess new methods to refine and strengthen our existing analytical services across all disciplines.


An old-school stalwart of microbiology testing, minimum inhibitory concentration (MIC) testing identifies the lowest concentration of a substance that prevents visible growth of a bacterial strain.


The MIC is the bacteria’s tipping point and is the mainstay of in vitro antimicrobial susceptibility testing (AST) for any new antimicrobial drug or treatments or for monitoring the emergence of resistant strains against existing antibiotics.




At LGC,MIC testing is done in line with CLSI M100-S27E Performance Standards for Antimicrobial Susceptibility Testing (2017) and CLSI M07-A10 (2015) using a MIC endpoint broth microdilution test. A serial dilution of an antimicrobial stock solution is dispensed into microtitre plates. Bacterial suspensions are made in broth culture to a standard density of colony forming units (cfu) this is then added to the plates and the effect on growth observed. The same test can be repeated for multiple culturable bacteria with multiple antimicrobials and the MICs compared.


Traditionally these measurements are done by eye, but optical density readings (OD600) to determine MIC endpoints are a promising alternative – reducing error and time and permitting high-volume screening in the laboratory.


Download our poster on “Alternative Minimum Inhibitory Concentration (MIC) Test Methods: The Use of Optical Density Readings to Determine an MIC Endpoint” to read more about the results from side-by-side comparisons of visual MIC testing with automated endpoint determination on a range of aerobic bacteria and antibiotics.


Alternative Minimum Inhibitory Concentration (MIC) Test Methods poster

Authors; April Taylor, Scientist, LGC and Ed Siegwart, Senior Scientist, LGC


To find out more about our anti-infective drug development and surveillance expertise, please contact us




May 19

Measurement and alcohol: it’s World Metrology Day!

Tomorrow (20 May) is World Metrology Day, the birthday of the signing of the Metre Convention in 1875. This convention set the framework for global collaboration in the science of measurement (metrology).

Its aim – to ensure we use uniform measurements across the globe ­– remains as important for industry, trade and society today as it was over 140 years ago.

The theme for World Metrology Day 2017 is ‘Measurements for transport’, chosen because transport plays such an important role in the modern world: we travel but so does the food we eat, the clothes we wear, the goods we use and the raw materials they are made from. Ensuring all this travelling happens safely, efficiently and with minimal environmental impact requires a surprising range of measurements.

Calibration to save lives

As the National Measurement Laboratory and Designated Institute for chemical and bio-measurement, LGC forms part of the UK National Measurement System (NMS) that provides the core measurement infrastructure for the UK. The measurements we make support manufacture and trade, protect consumers and enhance quality of life.

LGC’s certified reference alcohol standards play a crucial role in supporting the safe transport of people and goods. The number of people estimated to have been killed in drink drive accidents in Great Britain has decreased from 1,640 in 1979 to 240 in 2013 and routine work-place testing for alcohol use also prevents accidents. LGC ethanol primary reference standards and LGC ethanol calibration services now support 50% of the breathalyser market. In addition, our standards supply 150+ clients for clinic-based work-place testing.

Furthermore, with tax revenues from alcohol sales contributing £10.5 bn to HMRC, the accurate measurement of the alcohol percentage in wines and spirits is critical to correctly calculate duty liability. To support the calibration of automatic density meters routinely used in industry to determine alcoholic strength, LGC supplies certified reference materials to over 40 distilleries, councils and testing laboratories.


Our certified reference materials to support measurement for transport

Contact LGC Standards for more information on these and other materials


Our impact

In our role as a National Measurement Laboratory we develop innovative capabilities to address measurement challenges of the future, supporting government, academia and industry to promote productivity and economic growth. Find out more about the impact of our work.


If you would like to find out how you could use measurement expertise to address your measurement challenges, contact LGC’s Measurement Services.


May 08

How do you give coffee authentication an extra shot?

With a high market value and commercial importance coffee is in the top 10 products most at risk of food fraud.

A recent paper by the Government Chemist team at LGC, and the Institute of Global Food Security in Queen’s University, Belfast (QUB), tackles the question of where and how to analytically check the coffee supply chain.

Analysing the results of several studies in the scientific literature Dr Michael Walker and a team from QUB have produced key instructions for probing the authenticity of coffee.

Michael Walker, Referee Analyst, Government Chemist Programme, LGC, said, “Coffee is one of the most widely traded tropical products and is produced in over 50 developing countries around the world. Because of its high market value and commercial importance it is increasingly the target of adulteration by dilution of cheaper materials. This fraud can take many forms, from swapping cheaper materials – e.g. coffee husks, chicory, cereal grains, woody tissue, cocoa or soya beans, acai berries or exogenous sugars – or substituting the more expensive Arabica species with cheaper beans.

M Cup Coffee IStock 000012881314Medium[1]“Adulteration of coffee has been around for a long time. Indeed, one of the first large scale samplings of foodstuff performed by the Laboratory of the Government Chemist, which was set up in 1842, was of coffee for adulteration and ceased in 1863. At that time adulterants included chicory, and, later, orange pips and iron oxide, burnt sugar or caramel, locust beans, ground acorns, and even date stones being found in 1878. (Weighed in the balance, PW Hammond and Harold Egan, HMSO, 1992, pp 40-43) But the food fraud episode of 2013 has reiterated that consumers need clear and accurate information so they can make informed choices about their diet and the foods they buy. This choice might reflect lifestyle, economic or health concerns but, in a multicultural society, it can also reflect religious practices.”

The full paper contains outline experimental details and references to the key studies so that any laboratory wishing to check coffee in the supply chain can make a good start.

Most of the common modern adulterants can be detected by chromatography of marker carbohydrates as detailed in standard methods (BS ISO 24114 and BS 5752-15) with the help of chromatograms of authentic coffee/ adulterant mixtures. Looking at DNA by Real Time PCR is a viable alternative to the chemical methods.

Claims for specific coffee bean geographic origin can be checked by discriminant molecular markers, although these are not as yet available for all coffee growing areas. Solvent extraction and Fourier Transform Infrared spectroscopy, FTIR, for the markers has the advantage that the FTIR spectra for authentic dichloromethane extracts are freely available online.

Discrimination between Arabica and Robusta species in coffee samples is possible via the marker compounds kahweol and 16-O-cafestol, predominant in Robusta. Determination of the latter by Nuclear magnetic Resonance, NMR, spectroscopy has the advantage of speed and relative simplicity.

Perhaps the most intriguing coffee authenticity problem is posed by Kopi Luwak, coffee beans harvested from the faeces of the palm civet cat. Processing in the digestive tract of this cat indigenous to Indonesia contributes to Kopi Luwak’s mystique and price. Although proof of identity of Kopi Luwak has been made more difficult by the possibility of mimicking the effect of the cat’s gut on beans by the use of microorganisms and enzymes, discriminant markers identified by Gas Chromatography – Mass Spectrometry, GC-MS, has proved successful. The question as to whether or not any residual civet cat DNA can be detected on ground roast coffee can be detected remains unanswered.

Thorburn Burns, D., Tweed, L. & Walker, M.J., 2017, Ground Roast Coffee: Review of Analytical Strategies to Estimate Geographic Origin, Species Authenticity and Adulteration by dilution,  Food Anal. Methods  doi:10.1007/s12161-016-0756-3

If you would like to find out how you could use our dPCR expertise to address your measurement challenges, please contact LGC’s Measurement Services.

Apr 20

Transplant care: ensuring consistency across the globe

Reference materials (RMs) are the cornerstone of accurate and traceable measurements – they are measurement standards which can be used to validate analytical methods, establish traceability and support quality control.

A month ahead of World Metrology Day, we look at the use of our certified reference materials (CRMs, reference materials with evidence of metrological traceability and a statement of measurement uncertainty) to support measurements in the clinic. CRMs help remove measurement variation between hospitals, ensure more precise prognoses and ultimately improve patient care.

CRMs allow manufacturers to establish the traceability of calibrators supplied with diagnostic equipment and they support medical and clinical laboratories to validate their methods in line with the traceability and uncertainty requirements as defined in the International Organisation for Standardization (ISO) standard 15189 (Medical laboratories – Requirements for quality and competence).

One area where standardisation is necessary is the monitoring of immunosuppressants, the therapeutic drugs used to prevent patients rejecting a donor organ after a transplant. With 4,500 organ transplants carried out in the UK each year, there are tens of thousands of people for whom monitoring the dosages of these drugs is crucial in order to allow the donor organs to remain functional for as long as possible.

Whilst life-saving at the right doses, immunosuppressants have a very narrow therapeutic range. Too little and the body rejects the organ. Too much and unnecessary toxic effects occur, potentially causing diabetes, skin cancer or even resulting in kidney failure, leading to a need for dialysis or even further organ donation.

Improving the accuracy of immunosuppressant monitoring through the use of higher order reference standards could reduce the number of rejections and give patients the best possible chance of an improved quality of life, away from hospital beds and dialysis machines.

Over the past few years LGC, as the UK National Measurement Laboratory and Designated Institute for chemical and bio-measurement, has been producing certified reference materials for two commonly prescribed immunosuppressants (tacrolimus, sirolimus) to underpin the standardisation of existing or in-development assays.

A new material has recently been released to extend the current portfolio and support a greater number of laboratories, secondary standards producers and assay developers ensure compliance with ISO 15189, ultimately helping ensure consistent care across transplant centres globally.


Immunosuppressant certified reference materials (CRMs) available from LGC Standards

These materials are produced under LGC’s accreditation to ISO Guide 34 and accredited to ISO 17025. ERM-AC021a and ERM-DA110a are both listed on the JCTLM database of higher order reference materials.

Apr 05

The new ICH Q3D Elemental Impurities Guideline – nothing to fear if you act now

The ICH Q3D Guideline on Elemental Impurities has been adopted by the European and US Pharmacopoeias, meaning that by the end of 2017 all new and existing products in Europe and the US will need to be assessed.

Initially it was thought that every marketed product would require full testing for trace metals. However, the risk based nature of ICH Q3D means that many elements can be eliminated from consideration if sufficient data are available. Elemental Impurities are rarely seen at levels that require control measures. This means that screening alone may be sufficient to satisfy the ICH Q3D requirements. Screening can fill the knowledge gap and allow an informed risk assessment to be completed prior to committing to full quantitative validation.




What are elemental impurities and how do they get there?

Elemental impurities are traces of metals that can end up in finished drug products. Elemental impurities can come from multiple points in the manufacturing process, such as deliberate addition as reaction catalysts during product synthesis, or from contact with manufacturing equipment and containers. These impurities do not typically contribute to a drugs therapeutic effect, and can cause patients harm if the levels are not monitored and controlled. Therefore, for evaluation, manufacturers need to consider all potential sources of trace metals in the final formulation and product packaging. The permitted daily exposure of each element varies, but overall, no elemental impurity should be present at more than 30% of the Permitted Daily Exposure (PDE) in the final product.


Testing required? Consider this

The wide variation in pharmaceutical material composition and the requirement for simultaneous multi-elemental determination across a wide concentration range can lead to analytical challenges.

The product, 30% PDE level, dosage route and ICH Q3D option selected all affect the sample preparation method, solvent and instrumental detection methods chosen. Each available method has a range in sensitivity and response and these must be aligned carefully with each specific product’s requirements taking into consideration the targeted elements impurities and their documented risk and exposure limits.


Help is at hand!

USP <231> Heavy Metals test is being replaced with two new chapters, USP<232> Elemental Impurities (Limits) and USP<233> Elemental Impurities (Procedures). As a consequence, the use of Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS) will become the preferred standard approach for the determination of heavy metals in drug products, replacing wet chemical tests. This means tests with better specificity, accuracy and sensitivity are now available to help sponsors confirm that their materials meet the new compliance criteria.

The implementation deadline for the new USP directive is scheduled for January 2018 and LGC is already prepared for what will be a very significant industry requirement for additional ICP-OES / ICP-MS testing of new products.

To find out more about the new guidelines and LGC’s expertise, please download the fact sheet and view our webinar.



Download fact sheet >>>


 View LGC webinar on In Vitro Antimicrobial Efficacy Testing: Potential Pitfalls and Future Methods

View webinar >>>


Author: Sarah James, Principal Scientist, CMC Analytical Services, LGC



Apr 05

Nanotechnology standardisation: for materials 100,000 times smaller than this full stop.


As the impact of nanotechnologies on human life becomes more prevalent, it is increasingly important to be able to characterise nanomaterials within biological systems and understand their behaviour in order to protect human health and the environment.

Significant efforts are being made to ensure the appropriate regulatory frameworks are in place to support this enabling technology. Alongside this, international and national standardisation efforts play a critical role in ensuring that the full potential of nanotechnology is realised and that it is safely integrated into society. LGC is involved in supporting both these areas through our involvement in a variety of organisations.


LGC provides advice to UK government (Department for Business, Energy & Industrial Strategy) on proposed amendments to the European Cosmetic Products Regulation (EC No 1223/2009). These amendments are considering the inclusion of nanomaterials as authorised cosmetic ingredients and are discussed at meetings of the EU Working Group and Standing Committee on Cosmetic Products.

The characterisation of a nanomaterial, i.e. understanding which analytical methods are appropriate and their associated limitations, is considered an important aspect in ensuring the specification described in legislation can be demonstrated through repeatable and accurate measurements.


LGC supports the standardisation of measurements in the nanotechnology field through our representation on the ISO (International Organization for Standardization) Technical Committee for Nanotechnologies (TC 229) and its British Standards Institution equivalent (BSI NTI/001). These committees meet regularly to discuss ongoing and future standardisation activities in the nanotechnology area.

Recently (March 2017) a new ISO Technical Specification (TS 19590) was released that outlines an inorganic mass spectrometry method (single particle inductively coupled plasma-mass spectrometry, spICP-MS) for determining the size distribution and concentration of nanoparticles in aqueous media. Scientists from LGC provided input to this specification based on our expertise in this area[ii].

Another area of ISO activity is the development of a new TS on the analysis of nano-objects using the gentle separation technique of field flow fractionation (TS 21362). Dorota Bartczak, a Researcher in the Inorganic Analysis Team and LGC representative at ISO/BSI for nanotechnologies, has been registered as the nominated UK expert for the new TS[iii] [iv]. Development of the TS is being led by representatives of the National Institute of Standards and Technology (USA) and the National Metrology Institute (Japan), and is currently at the Working Draft stage.


LGC’s involvement supporting the development of nanotechnology regulation, and the underpinning standardisation efforts required at both a national and international level, recognises both the individual expertise of our scientists and LGC’s reputation in this field.

LGC’s input will help ensure current and future consumer safety and ultimately protect human health and the environment whilst supporting the growth and development of this enabling technology.


LGC, the National Measurement Laboratory and Designated Institute for chemical and bio-measurement


[i] Defined by recent EU regulation to be cosmetics, foods and biocides where more than half the particles are between 1 and 100 nm in size.

[ii]  Analysis of 10 nm gold nanoparticles using the high sensitivity of the Agilent 8900 ICP-QQQ. Agilent Application Note (2016)

[iii] Determination of size- and number-based concentration of silica nanoparticles in a complex biological matrix by online techniques. Bartczak D, Vincent P, Goenaga-Infante H. Anal Chem (2015) 87:5482-5485. DOI: 10.1021/acs.analchem.5b01052

[iv] LGC supporting innovation: working with Malvern Instruments. LGC Case Study (2016)

Mar 21

The stress of competition: a novel cortisol assay

case study_blood sweat tearsStress biomarkers, such as cortisol, are often used to monitor the effectiveness of an athlete’s training regime. However, levels of cortisol change quickly following exercise and so need to be monitored trackside to determine whether an athlete needs to be rested or whether they can train further and harder the next day.

Researchers at LGC have developed a unique new assay for detecting both free and total cortisol within human serum using a transportable platform technology. In collaboration with the English Institute of Sport, the assays were evaluated using blood samples from athletes (pre- and post-training) at Loughborough University via a pin prick to the finger.

Our approach successfully eliminates the need for sample processing and reduces the analyte incubation to minutes, negating the need to transit samples to laboratories and providing athletes with further information (percentage active cortisol).

This may in the future provide more robust results for athletes on which to base their training decisions and help increase the return on investment on the hundreds of millions of pounds spent on UK elite athletes.


Read our recent paper to discover how we transferred this assay across to a portable Raman platform in collaboration with Centre for Molecular Nanometrology at the University of Strathclyde:

Read our case study to find out more.


Gracie K, Pang S, Jones GM, Faulds K, Braybrook J, Graham D. Detection of cortisol in serum using quantitative resonance Raman spectroscopy (2017) Anal Methods 9:1589-1594. DOI:10.1039/C6AY03296F


LGC, the UK National Measurement Laboratory and Designated Institute for chemical and bio-measurement

Mar 15

Nitrate in infants’ vegetable food

Nitrate is a natural contaminant present mainly in vegetables and drinking water although it is frequently added as a preservative in processed meat products. Plants utilise nitrogen from the environment as part of the nitrate cycle, for their metabolism and to produce protein. Any excess quantity of nitrate is stored mainly in green leaves.  In particular, green leafy vegetables like rocket, spinach or lettuce can store high levels of nitrate with concentrations affected by the weather conditions (light, temperature) excessive fertiliser use and the type of soil.

The European Commission Regulation (EC) No 1881/2006 sets maximum levels for nitrates in some leafy vegetables (<7000 mg/kg) and processed cereal-based foods and baby foods for infants and young children (<200 mg/kg).

Baby food: organic green broccoli and spinach puree

Leafy vegetables have the highest median value of nitrate content. In an EFSA report (2008), the highest nitrate value was found in an oak-leaf lettuce sample from Norway (19925 mg/kg). For rucola, 56% of the samples analysed gave values over 4500 mg/kg. In baby food, the nitrate levels are much lower and according to Rebelo et al. (2015), the highest level was observed in retail, vegetable-based baby foods, with a maximum of 129 mg/kg. Several different analytical methods are used for the analysis of nitrate in foods and beverages including Ion chromatography, Spectroscopic methods and HPLC-Conductivity or other detector.

Nitrate on its own is non-toxic, however the conversion of nitrate to nitrite and N-nitroso compounds can potentially be dangerous for human and especially infant’s health, although some of the other metabolised nitrogen compounds may have positive effects (e.g. nitrogen monoxide- anti-hypertensive effect). According to the IARC Monograph (2010) ingested Nitrate and nitrite under conditions that result in endogenous nitrosation is considered “probably carcinogenic to humans” (Class 2A).

The physiology of babies and infants is very different to adults and it is important to control the type of substances ingested via foods and beverages. It is very common for mashed or pureed fruit and vegetables either home prepared or from the market to be fed to babies during the first months of their life. The process of conversion of nitrate to nitrite is accelerated when the vegetables are pureed; therefore the production of infant pureed food at home and improper storage conditions of any purchased baby vegetable food can potentially be dangerous to a baby’s health. The primary health concern is methemoglobinaemia, otherwise known as blue-baby syndrome as nitrite is able to oxidise haemoglobin resulting in reduced oxygen transfer around the body.

The European Food Safety Authority (EFSA) published a report in 2010 about the possible public health risks for infants and young children from the presence of nitrates in vegetables and according to this, the nitrate levels in vegetables together with the consumption data is not a health concern for most children. However, according to the same report, the risk to babies and infants 1-3 years old eating more than one spinach meal a day cannot be excluded.

To allow your laboratory to show with confidence, the quality of your analysis in measuring nitrate in infant vegetable food, LGC Standards has introduced sample 798 to the food chemistry proficiency testing scheme.


Application form

Sample 798 is available in round FC252 to be despatched on the 18th of April 2017. For more information please see Scheme Documentation or to participate, please complete the application form and return it to ptcustomerservices@lgcgroup.com.


EFSA Panel on contaminants in the food chain (CONTAM), ‘Scientific opinion of the Panel on Contaminants in the Food Chain: Nitrates in vegetables’, EFSA Journal, 689, 1-79:, 2008.
http://onlinelibrary.wiley.com/doi/10.2903/j.efsa.2008.689/pdf (accessed 27 February 2017)

EFSA Panel on contaminants in the food chain (CONTAM), ‘Scientific opinion: Statement on possible public health risks for infants and young children from the presence of nitrates in leafy vegetables’, EFSA Journal, 8(12):1935-, 2010. http://onlinelibrary.wiley.com/doi/10.2903/j.efsa.2010.1935/epdf, (accessed 27 February 2017)
International Agency for Research on Cancer (IARC) , ‘ Monograph on the evaluation of carcinogenic risks to humans, Ingested Nitrate and Nitrite and Cyanobacterial Peptide toxins’, Volume 94, 2010, http://monographs.iarc.fr/ENG/Monographs/vol94/index.php,   (accessed 23 February 2017)

By Savvas Xystouris, Technical/Development Manager, Proficiency Testing, LGC

Mar 13

Are your assay values below specification?

“The result I’ve found for the assay value in my API or finished dosage form is below my specification. Is there a problem with my reference standard?” is a question often asked by users of pharmaceutical reference materials. Some may even assume that there has been some degradation with the reference material they have applied.

12290805 Pills Pharma Drugs MulticolouredHowever, only in rare cases can a finding like this be related to an issue with the reference standard. And certainly it cannot be linked to a normal degradation of the standard at all, because in such a case you would rather find an assay value too high for the analyte in question…..

These issues are covered in greater depth here and are also a theme of LGC’s upcoming seminar.

Don’t forget you can keep up with other blogs from LGC’s Standards teams here.

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