Certification of Organic Substances

A major share of elemental analysis will eventually evolve into speciation analysis. 

This point was clearly outlined in a special issue of Spectrochimica Acta (edited by Donard and Caruso 1998). 

The list of elements and their species listed above is not exhaustive. It is limited to the relatively simple compounds that have been determined by an important number of laboratories specializing in speciation analysis. Considering the economic importance of the results, time has come to invest in adequate CRMs. There is a steadily increasing interest in trace element species in food and in the gastrointestinal tract where the chemical form is the determinant factor for their bioavailability (Crews 1998). In clinical chemistry the relevance of trace elements will only be fully elucidated when the species and transformation of species in the living system have been measured (ComeUs 1996 Cornelis et al. 1998). Ultimately there will be a need for adequate RMs certified for the trace element species bound to large molecules, such as proteins. 

New developments are, however, needed to make a major step forward in the field of speciation analysis. The first part, isolation and separation of species, may be the easiest one to tackle. For the second part, the measurement of the trace element, a major improvement in sensitivity is needed. As the concentration of the different species lies far below that of the total concentration (species often occur at a mere ng/1 level and below), it looks like existing methods will never be able to cope with the new demands. A new physical principle will have to be explored, away from absorption spectrometry, emission spectrometry, mass spectrometry, and/or more powerful excitation sources than flame, arc or plasma will have to be developed. The goal is to develop routine analytical set-ups with sensitivities that are three to six orders of magnitude lower than achieved hitherto. 

Certified reference materials (CRMs) to validate measurements of organic constituents were introduced in the early 1980 s, more than a decade after the development of the first natural matrix CRMs for inorganic constituents. There are three types of CRMs to support measurements of organic constituents  

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Pure organic substance, including certification or provision of natural or iso-topically enriched single substance calibration materials... 

When comparing the data obtained with 5 replicates of three successive steps there is a tendency to increased CV, but several exceptions can be noted, in the present study the differences between CV are small from one step to the other, this shows also the limit in establishing the uncertainty budget for measurements of complex organic trace substances, this study was performed in the certification of BCR-CRM 682... 

Long-term reproducibility is the prime quality of an analytical method used for the study of stability. Stability must be performed on the element or substance to be certified. Extrapolations on the stability of tracers are of little interest. If the uncertainty of the method for an analyte is poor, even for large sample intakes, the analyst must refer to the experience on similar materials with higher contents or to the general chemical properties of the substance or element. In any other situations certification may be impossible. Such difficulties are mainly encountered in organic or organo-metallic analysis. Experience has shown that some substances may be stable in a matrix but unstable in another even similar one [46-47]. All analytical methods suffer from long term reproducibility. In some cases analysts have developed tools and tricks to minimise this effect. 

Products subject to positive certification are chemical substances, mixtures, or articles containing a chemical substance or mixture as those terms are defined under TSCA, which are either on the TSCA Inventory, or are not on the TSCA Inventory but are being imported in compliance with TSCA. A chemical substance is any organic or inorganic substance of a particular molecular identity including (i) any combination of such substances... 

Every producer or handler is required to submit an organic production and handling system plan , which has to be approved by the certification bodies ( 205.201). In the plan, each farm has to ensure that all requirements of the standards are fulfilled. Strictly speaking, this would mean that sustainability is achieved, as required according to the introductory paragraph quoted above. The priority issues mentioned in this context, however, are rather the avoidance of product contamination and the restriction of substances used in production, and it seems unlikely that salinity control is enforced. 

Pesticides approved for organic production also have to comply with the PSD requirements. However, it must be stressed that the use of any plant protection product on an organic crop is seen very much as being a matter of last resort. Growers need to seek derogations for their use from their certification body. The EU is currently undergoing a complete review of all pesticide approvals and there is a strong likelihood that substances such as copper and sulphur will be dropped from the approvals list in future. 

In principle, a certificate can be granted for any substance (active substances, excipients) such as organic or inorganic substances, substances produced by fermentation as indirect gene products, and products with risk of TSE for which a monograph published in the European Pharmacopeia exists. Excluded, however, are biological substances such as proteins, products obtained from human tissues, vaccines, blood products, and preparations. 

When having all individual data available from the certification report, the analyst may wish to have a closer insight into his performance in terms of comparison to the results achieved by a similar method used in the certification. In the case of materials certified for organic trace substances e.g. dioxins in fly ashes, where methods inevitably remain affected by small systematic errors, the uncertainty calculated from the set of data of the interlaboratory certification study may appear small compared to the spread of the accepted sets of data. The half-width of the 95% confidence interval of the set of data is used as uncertainty. The user can adapt the way of determining the value of Sq above. He may wish to replace the 95% confidence interval by a tolerance interval... 

Apart from the derivatives of p-carotene, other pigments are the anthocyanins, the chlorophylls, cochineal, the betalaines, turmeric, caramel and riboflavin. In this account the historical background in brief, the chemistry of these pigments, their extraction from natural sources and their synthesis will be discussed. The present permitted natural substances and nature-identical synthetic materials (also described by the Food and Drugs Administration, the FDA, as colorants exempt from certification ) is quite small in number. Reference is also made to colourants no longer listed but which have an historical organic chemical significance such as for example brazilin and its relative haematoxylin. 

The organization should supply only active and auxiliary substances which have been inspected and found to be satisfactory. Each individual package of active and auxiliary substances must have the proper marking, batch number and number of technical inspection certificate, inspection laboratory, or the State Institute. 

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