Benefits of Reference Materials

The following boxes present four case studies to illustrate how the introduction of reference materials has decreased the xmcertainty of the chemical oceanographic measurement of salinity (Box 2.1), DOC (Box 2.2), and dissolved inorganic carbon (DIC) (Box 2.3). Box 2.4 illustrates the acute need for pigment reference materials, which are currently unavailable. 

Early scientists recognized that standards were needed to determine reliable values of the chlorinity and salinity of seawater. The lAPSO Standard Sea Water Service (originally based in Copenhagen) collected and distributed seawater from the North Atlantic with a known, measured chlorinity. This sample was supplied to oceanographers to standardize the AgN03 solutions used to determine chlorinity in various laboratories. 

An early attempt to resolve the discrepancy between the high values of Sugimura and Suzuki (1988) and more traditional analyses tailed to reach a definitive conclusion (Williams, 1992). The start of the Joint Global Ocean Flux Study (JGOFS) field program with the North Atlantic Bloom Experiment in 1989 put additional pressure on the various groups to resolve this issue quickly. The National Science Foundation (NSF) and the National Oceanic and Atmospheric Administration (NOAA) funded a workshop held in Seattle in July 1991 to resolve the issue. 

Prior to the Seattle Workshop, several batches of seawater from Hawaii were distributed to attendees for analysis. It became immediately clear to workshop participants that the key to making valid comparisons was both a common reference material and a uniform blank solution (Hedges et al., 1993 Sharp, 1993). The primary source of discrepancy among analysts was poor blank control, not oxidative capacity. 

During a recent expedition in the Indian Ocean, as part of the WOCE Hydro-graphic Program, members of the U.S. DOE COj Survey Science Team used these reference materials extensively for the quality control of measurements of total DIC and total alkalinity. Two manuscripts detailing the results of these measurements on reference materials were published describing the COj measurements made on that expedition and how reference materials were used to assess the overall data quality (Johnson et al., 1998 Millero et al., 1998). 

---

Proposal and journal article reviewers need to be encouraged to question the analytical quality control of measurements made without the benefit of reference materials. 

It is impossible to have a discussion of the "quality" of chemical analyses made in the support of ocean science without a clear recognition that, in large part, this depends on the skills and dedication of the individuals involved. Indeed, almost all the scientific progress made to date in the ocean sciences has been achieved without the benefit of reference materi-... 

Those scientists using available reference materials should be encouraged to report such uses explicitly in the scientific literature. A recent article by Jenks and Stoeppler (2001) goes so far as to suggest that scientific publishers should provide explicit recommendations as to how and where in a paper the use of certified reference materials should be described. Proposal and journal article reviewers also need to be encouraged to question the analytical quality control (and ultimate value) of measurements made without the benefit of reference materials. 

If the ocean sciences are to move forward and adopt the regular use of reference materials, the advantages of using such materials (and the pit-falls of not using them) need to be more broadly disseminated. Proposal and journal article reviewers should question the analytical quality control of measurements made without the benefit of reference materials. Outreach focused on how to use reference materials in the ocean sciences will further increase the awareness of the individual investigators and provide a focus for proper handling and application of a laboratory s internal reference materials. 

Substantially increased awareness and availability of reference materials offers many benefits to the ocean sciences. The regular use of such materials can provide a much-needed basis for interlaboratory and international comparison of results, making it possible to acquire accurate, meaningful global data sets that can be used to study problems requiring observations on large space and time scales. However, reference materials are costly to produce—particularly if they are certified for a number of constituents—and it has not always been clear to the ocean science community that this cost will be repaid with significant added value. 

With reference to the measurement of artificial and natural radionuclides in environmental samples, activities of the Agency s laboratories in Seibersdorf include the preparation, characterisation, and distribution of reference materials of terrestrial origin, organisation of interlaboratory comparison exercises and proficiency tests, co-ordination of the activities of the ALMERA network, provision of training and expert assistance to scientists from Member States (MS) laboratories, and provision of analytical and radioanalytical support for the benefit of the programmes and projects of the IAEA and its Member States. 

The expenditure, and potential savings estimated by the UK Committee on Corrosion for a variety of industries are shown in Table 9.1. The savings shown are those which could be made by better use of available knowledge, and do not include the potential benefit of future research and development. The costs referred to are mainly those arising in the industries concerned, or, in certain cases, sustained by users of the products because of the need for protection, maintenance and replacement of the materials of construction. In the oil and chemical industries the costs of using corrosion resistant... 

Other references (30) describe the synthesis and performance benefits of zeolites embedded in TUD-1. This concept has been reported in the literature with other mesoporous materials, but the three-dimensional nature of TUD-1 should make these embedded zeolite materials of special benefit. 

It is concluded that MALDI-ToFMS is a suitable method for direct analysis of low-MW additives in complex polymeric materials (in dissolution), in particular as a rapid screening technique (within 0.5 h). However, in order to turn this method into a general tool for identification and quantitation, considerably more work needs to be done. Identification of additives in polymeric matrices by means of MALDI-ToFMS would greatly benefit from reference libraries of additives contained in such matrices. This is not unlike the situation observed for ToF-SIMS. 

Medical grade plastics are discussed with reference to biocompatibility and the tests that the end-product manufacturer should perform in order to ensure the safety of the material. Regulatory requirements are described, and tabulated data is presented on mostly European suppliers of medical grade plastics. The data shows that most companies rely onUSP Class VI certificates to demonstrate the suitability of their materials for the medical industry. However, it is argued that most manufacturers of medical devices would benefit more from tests carried out according to ISO 10993. 6 refs. 

In this report, this distinction between certified and information values will be drawn on a number of occasions, usually to emphasize the cost of establishing the detailed uncertainty of analytical techniques used to certify materials relative to the perceived benefit of certification. In many situations, a particular analyte—though important scientifically—is studied by a limited number of researchers, in which case it is most practical to establish an information value for that particular reference material by consensus (provided the necessary conditions of stability and homogeneity are met). 

BENEFITS OF CHEMICAL REFERENCE MATERIALS TO OCEAN SCIENCE... 

These eight research initiatives will require new strategies to ensure uniform analytical quality and comparability, and each of these areas could benefit to a greater or lesser extent from the availability of appropriate reference materials. Discussions at the Workshop (Islamorada, Florida in September 2001) held as part of this process helped the committee to clarify the ocean science community s perspectives on this, and... 

In the case of the acquisition of large-scale data sets, the benefits of using reference materials are self-evident. In the past, whenever such data sets have been acquired without using suitable reference materials, a great deal of effort has subsequently been needed to adjust the data to a common scale. But the benefit of comparability is not restricted to large programs. Matrix-based reference materials that can be exchanged between different laboratories will enable researchers to better understand their own techniques and the information they provide. 

Although each of the ten materials proposed as solid reference materials provides clear benefits (each represents a unique matrix), the following subset was considered the highest priority reference materials based... 

Now let us look at the systems and the components of the systems. Reports in the field are virtually mute on many small but annoying problems, which almost invariably accompany the operation of seawater RO systems. Here are some which have plagued us, starting with the pumps. I will not identify manufacturers, as I have avoided reference to any in this writeup. It is not my objective to accuse anyone. I just offer these comments in the hope to encourage those who I hope are aware of their product problems in the field and failures to rectify those for the benefit of all. I feel that considerably greater attention must be placed on pumps and pump materials selection for seawater RO use in order to improve reliability, simplify maintenance, and reduce failure frequency in the pump operations, and in turn improve on the RO system water supply capability. 

Assets are classified as current, fixed, or intangibles. Current assets include cash, cash equivalents, marketable securities, accounts receivable, inventories, and prepaid expenses. Cash and cash equivalents are those items that can be easily converted to cash. Marketable securities are securities that a company holds that also may be converted to cash. Accounts receivable are the amounts due a company from customers from material that has been delivered but has not been collected as yet. Customers are given 30, 60, or 90 days in which to pay however, some customers fail to pay bills on time or may not be able to pay at all. An allowance is made for doubtful accounts. The amount is deducted from the accounts receivables. Inventories include the cost of raw materials, goods in process, and product on hand. Prepaid expenses include insurance premiums paid, charges for leased equipment, and charges for advertising that are paid prior to the receipt of the benefit from these items. The sum of all the above items is the total current assets. The term current refers to the fact that these assets are easily converted within a year, or more hkely in a shorter time, say, 90 days. 

---