Blog | Graham B Jackson

Avantor Chemicals: Powering Innovation from Lab to Large-Scale Production

September 6, 2024

Delivering Results from Beaker to Bulk Chemicals: Enabling Research, Development, Manufacturing, and Quality Control In today’s fast-paced world, chemicals play a pivotal role in driving advancements across various fields—from healthcare […]

Understanding Trace Analysis Using ICP-OES and ICP-MS

August 27, 2024

What is Trace Analysis? Trace analysis is a specialized field in analytical chemistry, focusing on the detection and measurement of very low concentrations of substances, typically in the range of […]

Overview The first stage of a trace analysis is planning the project. This chapter discusses the process of planning, which involves defining the problem and assessing the technical requirements needed to solve the problem. Without careful planning, achieving reliable results becomes a game of chance. Analytical projects fall into categories of non-routine, semi-routine, and routine: Non-routine - a project in which a validated method does not exist and little is known about the sample. Semi-routine - a project in which something significant can be stated about the sample and the method of analysis. Routine - a project in which the sample is chemically known and a validated method is available. This chapter assumes that the chemist will be analyzing samples that fall into one or more of the above categories. Before the planning process can begin, the analyst must examine the following: The need for sampling and sub-sampling Reagent quality Sample preparation Measurement QA/QC Reporting requirements Defining the Problem A discussion between the initiator and the analyst must occur, where questions are asked by both parties. The intent is to define the exact nature of the problem, why analytical work is needed, and how the results will be used following the completion of the project. Method validation requirements should also be addressed. These requirements can include either the availability of a certified reference material, or that of another validated technique -- one that is based largely on different principles. The problem's definition is further refined by asking other questions: What is it that you want to accomplish? What is the purpose? What is the current situation or state of affairs? What is taking place that you need to understand, prevent, or improve? What decisions will be made based upon the data? When the answers to these questions have been determined, the analyst is in a position to begin planning the analytical process. Detection Limits and Uncertainty The analyst should know the detection limits for all analytes at several possible wavelengths. Typically, these measurements are obtained during the establishment of the analytical instrument's capabilities. Modern axial view ICP-OES and ICP-MS instruments are likely to have detection limits under normal sample introduction modes that will meet or exceed the requirements. It is best to not rely upon the limits published by the manufacturer. In addition, the detection limits will be a function of the sample matrix, in both a physical and spectral sense. A key point involves the analytical blank. Due to numerous contamination issues, the analytical blank often determines the detection limit capabilities. It is best for the analyst to be conservative when noting the detection limits, making sure not to quote capabilities calculated from published data or determinations made under "ideal" conditions. For the less common elements, an estimate of the "real" detection limit would be a factor several times higher than the limit determined under ideal conditions. Thus, elements like Na, Mg, Ca, Fe, Cr, Cu, Zn, Si, Al, Cl, and S may have a detection limit that is significantly larger than expected, due to the analytical blank. The uncertainty of an analytical measurement is not limited to the measurement precision of the instrument. Rather, it is a statistical sum of the random and systematic errors that are encountered throughout the entire analytical process. The uncertainty is a combination of errors from sampling, storage, weight and volume manipulations, preparation, calibration, and measurement, during which contamination issues play a major role in trace determinations. The sampling error can be a major source of uncertainty. In many cases, an estimate of the sampling error can be impossible to judge. The initiator should be aware of this fact. In reality, the uncertainty of a trace measurement will not be known until the project is completed. The accuracy of this value will be only as good as the effort made to identify and measure all of the errors encountered during the entire analytical process. If measurements are being made between 3-5 times the detection limit for the less common elements, then an excellent uncertainty would be ± 30-70%. Constructing the Sampling Plan After the problem is defined, the planning process can begin. Analytical text books explain that you must consider the sample collection, sample storage, sample preparation, measurement, and reporting, along with any QA/QC requirements. With so many considerations, where should you start? A synthetic organic chemist will construct a plan by working backwards from the final product. A similar approach may work well for the trace analyst. Start by examining the following basic information: The analyte(s) of interest. The required detection limit(s). The uncertainty requirement(s). The chemical composition (matrix) of the sample. The quantity, availability, and history of the sample. Much of the above list can be determined based on information gathered while defining the problem. In most cases, analytical resources are available in-house to address the problem. For example: The basic information listed above is sufficient to determine whether publications or information is available in your reference library. Always start with a search of the literature. The identity and detection limit requirement of each analyte indicates the analyte measurement technique(s) required and the amount of sample required. The uncertainty requirement indicates the number of measurements, assuming there is sufficient sample available. The chemical composition of the sample, together with the identity of the analyte(s), indicates possible sample preparation routes. The identity of the analyte(s), together with the detection limit requirement(s), indicates the degree that contamination issues should be considered. This determines the need for analytical blanks and special apparatus or a clean area / room. The sample composition indicates potential interference issues. The sample composition or type indicates the uncertainty to be expected form the sample collection and/or the need to develop a sampling procedure and to determine sampling uncertainty. For example, the sample may be the only "world's supply", negating the need for a sampling procedure. The estimated sampling uncertainty can be used to define the analytical measurement precision (i.e. -- reducing the analytical error to less than one third of the sampling error serves no purpose). The basic information can provide the analyst with potential analytical measurement technique(s), suspected interferences, contamination issues, and the number of sample measurements required per determination (measurement refers to a complete analysis including sampling, preparation, instrumental analysis and reporting the final result and uncertainty). At this stage of the planning process, the analyst can determine if a certified reference material (CRM) should be obtained for method validation. In addition, the chemist can approximate the need for analytical reagents and apparatus and/or calibration standards. Lastly, estimate the time and cost of the project and base your initial approach on these estimates. Remember, there is always the possibility that more than one iteration may be required before an acceptable approach can be developed.

A Comprehensive Guide to the ICP Periodic Table: Key Elements and Their Properties

August 19, 2024

Inductively Coupled Plasma (ICP) analysis is a critical technique used in various industries to detect and measure trace metals. Understanding the behavior and characteristics of elements in this context is […]

GBJPL ICP Operations Guide: Navigating ICP-OES and ICP-MS with Precision

August 12, 2024

For over 40 years, GBJPL has been at the forefront of manufacturing inorganic certified reference materials (CRMs), earning a reputation for excellence in creating custom blends that meet the unique […]

6 Reasons to Stop Preparing Your Own Analytical Standards in the Lab

August 5, 2024

In many laboratories, it’s common practice for chemists to prepare their own analytical standards. While this DIY approach might seem economical and convenient, it actually introduces a host of challenges […]

Groundwater Quality & Testing: Ensuring Safe Drinking Water

July 23, 2024

Introduction The quality of groundwater impacts not only our health but also society and the economy. Groundwater contamination can lower property values, tarnish a community’s image, hinder economic development, and […]

Traditional Calibration Standards Methods in Atomic Spectrometry and Innovative Strategies for ICP-MS

July 18, 2024

Introduction Instrumental spectrochemical methods are essential for trace element analysis across various sample types. Different calibration strategies, including external standard calibration (EC), matrix-matched calibration (MMC), internal standardization (IS), and standard […]

Ensuring Accurate Analysis: The Role of ICP Calibration Standards

July 12, 2024

Introduction Inductively coupled plasma (ICP) spectroscopy is a powerful analytical technique used to detect and measure elements within chemical samples. With applications spanning the biomedical, pharmaceutical, environmental, and industrial sectors, […]

CPAchem Certified Reference Materials from GBJPL: Pioneering Precision in Custom Solutions

June 26, 2024

In the world of analytical chemistry, precision and reliability are paramount. CPAchem, represented by GBJPL, stands at the forefront of this field, offering tailored certified reference materials (CRMs) that set […]

BCR Standard Reference Material from GBJPL: Shaping Sustainable Climate Action

June 19, 2024

As climate change accelerates, the need for robust strategies to mitigate greenhouse gas (GHG) emissions becomes increasingly urgent. Enter the BCR Standard Reference Material, a pioneering initiative by GBJPL that […]