Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D5789-95 – Standard Test Method Technical Guide
📋 Scope and Applicability
This standard practice, D 5789 – 95, establishes the specific requirements for incorporating quality control (QC) procedures into ASTM test methods designed for the analysis of organic constituents. The requirements set forth here serve as the primary benchmarks for QC within a specific test method. They are intended to be integrated into a broader quality assurance framework that includes the more general approaches described in Practices D 3856 and D 4210.
This practice is designed specifically for quantitative test methods and explicitly states it may not be applicable to qualitative procedures. Critically, the specific QC requirements will vary depending on the type of test method, the target analyte being determined, and the sample matrix being analyzed.
⚠️ Important Limitation: The specific QC requirements outlined in this practice may not be appropriate for all test methods. They are intended primarily for quantitative test methods and will vary based on the analyte and sample matrix. Qualitative methods are generally outside the scope of this practice.
📖 Essential QC Terminology and Definitions
To ensure consistency across laboratories and methods, D 5789-95 formalizes critical terminology related to quality control. Understanding these definitions is fundamental to writing and executing compliant standard test methods for organic constituents.
| 🟦 Term | 📏 Definition per D 5789-95 |
|---|---|
| Calibration Standards | Standard solutions of known concentration, used to calibrate instrumentation, purchased externally or prepared in-house from materials of known purity or concentration. |
| External Calibration Check | Analysis of an independent standard solution (e.g., a certified reference material from NIST or another reputable supplier) to check the accuracy of the laboratory’s routine calibration standard solutions. |
| Matrix Spike | Addition of a known concentration of analyte to a sample representing a specific matrix for the purpose of evaluating interference and recovery from matrix components. |
| Method Blank | Reagent water (per Specification D 1193) known to be free of the constituent of interest or containing only a low, known concentration not exceeding five times the estimated minimum detection level. |
💡 Technical Note on Method Blanks: The standard explicitly defines a quantifiable threshold for method blanks: five times the estimated minimum detection level. This serves as a critical, objective benchmark for confirming that the reagents or analytical system do not contribute a measurable amount of the constituent of interest during routine sample analysis.
📚 Referenced Framework and Best Practices
D 5789-95 is part of a comprehensive suite of ASTM standards designed to ensure data quality in water analysis. Laboratories writing QC specifications should integrate the requirements of this practice with related standards to build a robust quality assurance program.
| 🔬 Standard | 📝 Title and Relevance |
|---|---|
| D 3856 | Guide for Good Laboratory Practices. Provides the overarching quality assurance and quality control framework for laboratories. |
| D 4210 | Practice for Intralaboratory Quality Control Procedures. Supplements the primary QC requirements, especially for reporting low-level data. |
| D 2777 | Practice for Determination of Precision and Bias. Essential for validating overall method performance against established QC criteria. |
| D 5788 | Guide for Spiking Organics into Aqueous Samples. Provides the standardized procedures necessary for conducting meaningful Matrix Spike analyses. |
❓ Frequently Asked Questions
🔍 What is the specific purpose of an “External Calibration Check” as defined in the standard?
The External Calibration Check provides an independent verification of the laboratory’s routine calibration standards. It involves analyzing a standard from a reputable external source (such as NIST) to confirm the accuracy and traceability of the in-house calibration curve.
💡 How strictly does the standard define the maximum acceptable concentration for a Method Blank?
Very strictly. The standard clearly defines that the Method Blank’s concentration must not exceed five times the estimated minimum detection level. This provides a clear, objective trigger for investigating potential contamination from reagents or the analytical system.
⚡ Is this practice suitable for all ASTM test methods?
No. D 5789-95 is specifically intended for use with quantitative test methods for organic constituents. The framers explicitly state that the requirements may not be appropriate for all test methods and are generally not applicable to qualitative test methods.
📌 Which other ASTM practices should be consulted alongside D 5789-95 for a complete QC program?
The standard points to several key practices, including D 3856 (Good Laboratory Practices), D 4210 (Intralaboratory QC and Low-Level Data), and D 5788 (Spiking Organics). Together, these provide a comprehensive approach to quality assurance.