Zhuojin Pipe Fitting Co., LtdSimultaneous Determination of Lead Arsenic and Mercury in Salt by Three-Channel Atomic Fluorescence
Literature Overview
This paper by Liu Baolan, Lv Xiaodong, Yao Heng, Wang Mengmeng, and He Jutao, published in Chemical Analysis and Metering (2026, Vol. 35, No. 3), describes the development of a three-channel atomic fluorescence spectroscopy (AFS) method for the simultaneous determination of lead, total arsenic, and total mercury in edible salt. The study was supported by the Henan Provincial Market Supervision Administration Science and Technology Program (Project No. HNSCJK202564). While this topic belongs to the domain of analytical chemistry and food safety, the methodology and quality control principles are directly relevant to material testing and quality assurance in metallurgical and welding applications.
Method Development and Optimization
The method involves direct extraction of the salt sample with dilute acid, followed by simultaneous determination of lead, arsenic, and mercury using a three-channel atomic fluorescence spectrometer. The key reagent parameters include 1.5% hydrochloric acid as the carrier liquid, a reducing agent solution containing 1.5% potassium borohydride, 0.4% potassium ferricyanide, and potassium hydroxide, and an on-machine liquid containing 1.0% thiourea and 0.01% oxalic acid. The lamp current was set at 40 mA, and the atomization temperature was 200 degrees Celsius.
The method achieved detection limits of 6 µg/kg for lead, 5 µg/kg for arsenic, and 2 µg/kg for mercury. The average recovery rates for the three elements ranged from 80.8% to 110%, and the relative standard deviations ranged from 1.9% to 11% (n = 6). Comparison with standard methods showed no significant differences in results. The method is suitable for rapid simultaneous detection in grassroots inspection institutions.
The following table summarizes the key method parameters:
| Parameter | Lead | Total Arsenic | Total Mercury |
|---|---|---|---|
| Detection limit | 6 µg/kg | 5 µg/kg | 2 µg/kg |
| Recovery rate | 80.8% to 110% | 80.8% to 110% | 80.8% to 110% |
| Relative standard deviation | 1.9% to 11% | 1.9% to 11% | 1.9% to 11% |
| Lamp current | 40 mA | 40 mA | 40 mA |
| Atomization temperature | 200 °C | 200 °C | 200 °C |
Quality Control Considerations
From a quality control perspective, this method demonstrates several best practices that are directly applicable to material testing in metallurgical and welding applications. First, the use of a three-channel system allows simultaneous determination of multiple elements, which improves efficiency and reduces the risk of cross-contamination between samples. This principle is analogous to the simultaneous multi-element analysis performed in metallurgical laboratories using optical emission spectrometry (OES) or inductively coupled plasma optical emission spectrometry (ICP-OES).
Second, the method validation includes recovery studies and precision assessment, which are fundamental quality control requirements. According to ISO/IEC 17025 and GB/T 27025, analytical methods used in accredited laboratories must demonstrate adequate accuracy and precision. The recovery rates of 80.8% to 110% and relative standard deviations of 1.9% to 11% indicate that the method meets the required performance criteria for food safety testing.
Third, the comparison with standard methods provides an important validation step. In material testing, similar comparisons between new and established methods are required when introducing new testing procedures. This ensures that the new method produces results consistent with the established standard, thereby maintaining the integrity of the quality assurance system.
Reflections on Analytical Methodology in Engineering
This study, while focused on food safety, offers valuable insights for engineers involved in material testing and quality control. The emphasis on method optimization, detection limit determination, and inter-method comparison reflects the rigorous approach that should be applied to all analytical testing in engineering contexts. Whether testing the chemical composition of welding consumables, the hardness of heat-affected zones, or the corrosion resistance of alloy steels, the principles of method validation and quality control are universal.
The development of rapid, multi-element simultaneous analysis methods is particularly relevant to the growing need for high-throughput testing in modern manufacturing. In pipe fitting fabrication, for example, the ability to rapidly determine the chemical composition of multiple elements in a single analysis can significantly reduce inspection time and improve quality assurance efficiency. The principles demonstrated in this study, including carrier liquid optimization, reducing agent selection, and instrument parameter tuning, are directly transferable to metallurgical analytical applications.