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Analytical Chemistry Overview
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Analytical Chemistry Overview

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Questions and Answers

What is the primary focus of qualitative analysis in Analytical Chemistry?

  • To identify the components present in a sample (correct)
  • To measure the concentration of substances
  • To assess the purity of a sample
  • To determine the chemical composition of a sample

    • Which of the following is NOT a common application of Analytical Chemistry?

  • Astrophysics simulations (correct)
  • Food composition analysis
  • Environmental monitoring
  • Forensic testing

    • What does the term 'gross sample' refer to in Analytical Chemistry?

  • A sample that is not representative
  • A subset of samples taken for analysis
  • The final results of an analysis
  • The total amount of material collected from a population (correct)

    • Why is it important for a sample to be representative?

    <p>To reflect the true composition of the population at the time of collection</p> Signup and view all the answers

    Which factor can influence the concentration of lead in Lake Ontario water and result in variable analysis outcomes?

    <p>The specific location within the lake where samples are collected</p> Signup and view all the answers

    How might the timings of sample collection affect the results of the lead concentration analysis?

    <p>Different times could yield different concentrations due to environmental changes</p> Signup and view all the answers

    In the context of sampling techniques, what is meant by sampling units?

    <p>Individual increments from which data is gathered</p> Signup and view all the answers

    What could potentially lead to misleading results in the analysis of lead concentration?

    <p>Ignoring environmental conditions during sample collection</p> Signup and view all the answers

    What indicates that a matrix effect is present when measuring a spiked sample?

    <p>The measured value is lower than the expected value.</p> Signup and view all the answers

    What is the acceptable range for matrix spike recovery based on historical data?

    <p>Within 3 SD of the mean.</p> Signup and view all the answers

    Which organization is recognized for certifying Standard Reference Materials (SRMs)?

    <p>National Research Council (NRC)</p> Signup and view all the answers

    What is a Certified Reference Material (CRM) primarily used for in a laboratory?

    <p>As a check on the accuracy of methods.</p> Signup and view all the answers

    In the context of matrix spikes, what should be performed after obtaining 25 data points?

    <p>Calculate mean and standard deviation.</p> Signup and view all the answers

    If a laboratory measures a spiked sample with 5.0 mg/L added Fe and obtains 15.0 mg/L, what does this suggest?

    <p>The sample matrix potentially suppresses Fe measurement.</p> Signup and view all the answers

    What is a characteristic of Standard Reference Materials (SRMs)?

    <p>They are certified by a recognized organization.</p> Signup and view all the answers

    What determines whether Dixon's Test should be applied to a data set?

    <p>If one value is significantly different from the others</p> Signup and view all the answers

    What is one necessary component of a Run Layout for sample analysis?

    <p>It specifies the order of real samples and quality control samples.</p> Signup and view all the answers

    In the case where Dixon's Test is used, how many replicates can be analyzed simultaneously?

    <p>8 replicates</p> Signup and view all the answers

    What is the impact of using a concentration greater than 10 times the MDL for MDL determination?

    <p>It causes the MDL to be falsely high</p> Signup and view all the answers

    How often should the Method Detection Limit (MDL) be recalculated?

    <p>Every year or two years depending on the laboratory policy</p> Signup and view all the answers

    What statistical values are necessary to calculate the MDL when using 7 results?

    <p>Standard deviation and a t-value of 3.143</p> Signup and view all the answers

    What happens if the standard deviation is determined from a higher concentration?

    <p>It will likely result in a higher MDL value</p> Signup and view all the answers

    Which of the following statements about Instrument Detection Limit (IDL) is correct?

    <p>IDL is less useful than MDL</p> Signup and view all the answers

    If the value of R calculated in Dixon's Test is 0.85, what action should be taken?

    <p>Reject the result that is likely an outlier</p> Signup and view all the answers

    What is the purpose of a laboratory accreditation by an external agency?

    <p>To recognize the laboratory's competence</p> Signup and view all the answers

    Which organization provides accreditation in Canada?

    <p>Canadian Association for Laboratory Accreditation (CALA)</p> Signup and view all the answers

    What is the significance of ISO Standard 17025?

    <p>It outlines the requirements for laboratory competence internationally</p> Signup and view all the answers

    How often must a laboratory undergo Performance Evaluation (PE) samples as part of the accreditation process?

    <p>Bi-annually</p> Signup and view all the answers

    What are Standard Operating Procedures (SOPs) primarily designed to ensure?

    <p>Clear and unambiguous analysis procedures</p> Signup and view all the answers

    What does a control chart typically display over time?

    <p>Quality characteristic measurements</p> Signup and view all the answers

    In a control chart, what do the upper control limit (UCL) and lower control limit (LCL) indicate?

    <p>The maximum and minimum limits for quality characteristics</p> Signup and view all the answers

    What aspect of laboratory accreditation involves documentation of accuracy, precision, and linearity?

    <p>Standard Operating Procedures (SOPs)</p> Signup and view all the answers

    What does a Control Chart indicate when a point falls outside the specified limits?

    <p>The measurement may be incorrect and needs investigation.</p> Signup and view all the answers

    How often should control charts be updated according to the protocols?

    <p>In real time each day the instrument is run.</p> Signup and view all the answers

    When calculating standard deviations in a Control Chart, what mathematical adjustments are suggested?

    <p>Mean ± 3 standard deviations should be used.</p> Signup and view all the answers

    What is required for multi-element/compound methods in Control Charting?

    <p>Monitoring at least 10% of the total number of compounds.</p> Signup and view all the answers

    What should be done in response to an out-of-control situation observed on a Control Chart?

    <p>Investigate the cause immediately, on the same day.</p> Signup and view all the answers

    What does a Control Chart primarily help operators identify?

    <p>Trends that may indicate process performance changes.</p> Signup and view all the answers

    What is the purpose of documenting responses to out-of-control situations?

    <p>To maintain a record of quality assurance processes.</p> Signup and view all the answers

    What does the mean/average represent in the context of a Control Chart?

    <p>A calculated value that indicates average process performance.</p> Signup and view all the answers

    Study Notes

    Analytical Chemistry

    • It's the science and technology used to determine the chemical composition of samples.
    • It answers:
      • What is in the sample? (Qualitative analysis)
      • How much of it is there? (Quantitative analysis)
      • Examples of use are clinical, forensic, environmental, food, quality control, and scientific research.

    Samples

    • A population refers to all the material of interest.
    • A sample refers to a smaller portion of the population.
    • It's used to infer information about the population.
    • Multiple samples are called sampling units or increments.
    • The collection of these samples is called the gross sample.
    • Samples are taken to represent the composition of the population.

    Representative Samples

    • Lead concentration in Lake Ontario water should be specific.
    • The concentration may vary based on the sample location, depth, time of day, season, and whether it's dissolved lead or total lead.

    Quality Control (QC)

    • Method Detection Limit (MDL) is the lowest concentration that can be reliably measured by a given method.
    • Outliers are values that differ significantly from the rest of the data set.
    • Dixon's Test determines if a suspected outlier should be rejected.
    • The MDL is calculated with reliable data after rejecting outliers.
    • It is crucial that the MDL is calculated with reliable and accurate data.
    • The MDL must be determined regularly, at least annually, and when major changes to the method are implemented.
    • Matrix Spikes assess the impact of the sample matrix on the measured analyte concentration.
    • Certified Reference Materials (CRMs) have certified values for specific compounds and are used for QC purposes.
    • CRMs are samples that have been extensively analyzed.
    • Standard Reference Materials (SRMs) are certified by recognized organizations such as NRC or NIST.
    • CRMs and SRMs are crucial for evaluating the accuracy of analytical methods.
    • Run Layout specifies the order in which real samples and QCs are analyzed.

    Laboratory Accreditation

    • Laboratory Accreditation is a formal recognition of a laboratory's competence.
    • It's granted by agencies like CALA, SCC, and NELAP.
    • Accreditation is based on ISO Standard 17025.
    • Laboratories must participate in Performance Evaluations and site assessments.

    Standard Operating Procedures (SOPs)

    • SOPs are written instructions for conducting analyses.
    • They ensure consistency and eliminate ambiguity.
    • Validation data (MDLs, accuracy, precision, linearity) is required for SOPs.
    • Control Charts are used to monitor a process's performance.
    • They plot measured values over time.
    • They are used to identify trends and address potential issues within a process.
    • Control charts are continuously monitored in real-time.
    • Out of control situations are addressed promptly.
    • Control charts are audited regularly by QA.

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    Description

    Explore the fundamentals of Analytical Chemistry, focusing on the science and technology used to ascertain the chemical composition of samples. Learn about qualitative and quantitative analysis, the importance of representative sampling, and its applications in various fields such as clinical and environmental studies.

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