Issues Associated with Sample Preparation

Contamination Issues Associated with Sample Preparation 

Serious consideration must be given to contamination issues in ICP-MS, particularly in the area of sample preparation. If you have been using flame AA or ICP-OES, you will probably have to rethink your sample preparation procedures for ICP-MS. Chapter 15 takes a closer look at the major causes of contamination and analyte loss in ICP-MS and how they affect both the analysis and the method development process. 

If the composition of the material is known to vary with time, individual samples collected at suitable intervals and analyzed separately can reflect the extent, frequency, and duration of these variations. 

Practical Guide to ICP-MS A Tutorial for Beginners, Second Edition 

FIGURE 15.1 Major factors that can influence the analytical result in ICP-MS. 

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Contamination Issues Associated with Sample Preparation... 

Combinatorial analysis has had an irrefutable effect on the very way we think of interrogating DNA sequences in the last 10 years [1], The ability to perform 104 to 106 separate analysis on the same sample simultaneously would have already changed the very nature of even routine medical analysis if were not for the fact that difficulties in interpretation and even reproducibility. Some of these problems are related to preparation issues associated with microarray DNA production others are related to the fundamental experimental design for the devices. 

Glassware is such a universal material used for sample preparation that it is very difficult to completely avoid it. However, serious consideration should be given to looking for alternative materials in as many of the ICP-MS sample preparation steps as possible. Today, the most common materials used to manufacture beakers, volumetric containers, and autosampler tubes for ultratrace elanent techniques such as graphite furnace atomic absorption (GFAA) and ICP-MS are mainly plastic based. Over the past 10-15 years, the demand for these kinds of materials has increased significantly becanse of the contamination issues associated with glassware. 

DNBP residue analysis on 20 samples of com grain were made by the Indiana Pesticide Residue Laboratory. No detectable residues were found. These results plus our experimental data and a label prepared with the assistance and cooperation of Dow Chemical (they, of course, had to accept the liability associated with the label) were submitted to Mr. Hutton, State Pesticide Administrator, on May 5, 1974. On May 13, 1974 an Indiana experimental label was issued. It is conservatively estimated that approximately 40,000 a of com were treated in Indiana in 1974. 

Sample chain of custody is a critical path control tool for preparing legally defensible data for the client. As mentioned in Section 11.3.3, some of the problems associated with the Love Canal contamination issues resulted from an insufficiently documented chain of custody process. Whenever possible, the chain of custody process begins in the field with the assignment of a bar code designation, and is subsequently carried seamlessly into and through the laboratory. 

We will first outline the scope of this chapter. The emphasis is on principles and problems associated with the use of these materials rather than on providing an exhaustive review of the literature. The examples quoted are intended only as illustrations of specific aspects. In the first section we will address the general aspects of preparation of selective layers based on EPs and their interactions with chemical species present in the sample, i.e. the issue of selectivity. The specialized use of polymers as barriers is also included here. The use of electroactive polymer layers in three principal transduction sensing modes is then discussed. Each of these sections contains examples of typical applications of electroactive polymers for chemical sensing. The overview, comparisons and future directions are discussed in section 10.6. 

Electrochemical methods are in general free from the difficulties associated with the current industry testing methods and present an opportunity for a relatively quick, simple, and inexpensive approach, free of temperature limitations and sample preparation issues. Electrochemistry has been previously employed to inspect lubricant condition over the life of engine oils [6, 7]. For example, electrochemical impedance spectroscopy (EIS) has been used for characterization of both engine oils [8] and nonaqueous colloidal dispersions [9]. 

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