EDTA污染对和铁的试验依赖性影响
Davor Brinc1, Chien-Yi Lu2, Osmond Rodrigues3
1Division of Clinical Biochemistry, Laboratory Medicine Program, University Health Network, Toronto, ON, Canada; Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, ON, Canada.
概括
乙二胺酸 (EDTA) 污染可能会影响实验室结果. 和铁的测量不是EDTA污染的可靠指标,因为依赖于方法的变化.
科学领域:
- 临床化学 临床化学
- 实验室医学 实验室医学
- 分析化学 分析化学
背景情况:
- 血液样本中的乙烯二胺酸 (EDTA) 污染可以显著改变实验室测试结果.
- 虽然EDTA对和酸酶的影响是已知的,但对 (Mg2+) 和铁 (Fe2+) 的影响却不太清楚.
研究的目的:
- 通过不同的分析方法,确定EDTA度导致Mg2+和Fe2+下降50% (EC50) 并超过允许的性能极限 (APL).
- 为了评估Mg2+和Fe2+对EDTA污染的方法依赖性敏感性.
主要方法:
- 评估EDTA度 (EC50和APL) 为Ca2+,ALP,Mg2+和Fe2+使用罗氏科巴斯c 303和Abbott Alinityc平台.
- 通过使用不同的方法 (例如,西利蓝,铁烯,铁) 进行Mg2+和Fe2+测量的比较,以评估EDTA的影响.
主要成果:
- 通过西利蓝测量的Mg2+显示了对EDTA的敏感性 (EC50:0.78-1.18 mmol/L;APL:0.16-0.34 mmol/L).
- 铁素测量的Fe2+受到EDTA的影响 (EC50:5.6-8.86 mmol/L;APL:4.68-5.46 mmol/L).
- Mg2+ (异酸脱酶法) 和Fe2+ (铁烯法) 试验表明对EDTA的抗性.
结论:
- 低磁热血和低血并不是EDTA污染的明确指标.
- 测量Mg2+和Fe2+对EDTA的敏感性因使用的分析方法而异.
相关概念视频
01:18Effects of EDTA on End-Point Detection Methods
353
Different methods, such as visual observance of metal-ion indicators, spectroscopic techniques, and potentiometric methods, can determine the endpoint of an EDTA titration.
In the visual method, metal-ion indicators (metallochromic dyes), which have distinct colors in their free and complex forms, are added to the mixture to signal the titration's end point. They form stable complexes with metal ions, but these complexes are weaker than the corresponding metal–EDTA complexes. As a...
In the visual method, metal-ion indicators (metallochromic dyes), which have distinct colors in their free and complex forms, are added to the mixture to signal the titration's end point. They form stable complexes with metal ions, but these complexes are weaker than the corresponding metal–EDTA complexes. As a...
353
01:30EDTA: Direct, Back-, and Displacement Titration
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The EDTA titration types for metal ion analysis include direct titration, back-titration, and replacement titration.
Direct titration involves buffering the metal ion solution to the desired pH and directly titrating with standard EDTA until the endpoint. The optimum pH ensures a large conditional formation constant of metal−EDTA and visibility of the free indicator color in the solution. In addition, auxiliary complexing reagents are used to prevent the precipitation of metal hydroxides...
Direct titration involves buffering the metal ion solution to the desired pH and directly titrating with standard EDTA until the endpoint. The optimum pH ensures a large conditional formation constant of metal−EDTA and visibility of the free indicator color in the solution. In addition, auxiliary complexing reagents are used to prevent the precipitation of metal hydroxides...
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01:26EDTA: Auxiliary Complexing Reagents
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EDTA titrations are usually carried out in highly basic conditions, where the fully deprotonated form of EDTA, Y4−, actively complexes with the free metal ions in the solution. Several metal ions precipitate as hydrous oxide (hydroxides, oxides, or oxyhydroxides) under these conditions, lowering the concentration of free metal ions in the solution. For this reason, auxiliary complexing agents or ligands such as ammonia, tartrate, citrate, or triethanolamine are used in EDTA titrations to...
677
01:19Masking and Demasking Agents
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EDTA titrations may necessitate masking and demasking agents to temporarily protect a particular metal ion in a mixture from the EDTA reaction. These agents facilitate the sequential analysis of the metal ions by forming stable complexes with some—but not all—metal ions during certain steps.
There are many masking agents, such as cyanide, fluoride, triethanolamine, thiourea, and 2,3-bis(sulfanyl)propan-1-ol (formerly 2,3-dimercapto-1-propanol), with the masking agent chosen based on...
There are many masking agents, such as cyanide, fluoride, triethanolamine, thiourea, and 2,3-bis(sulfanyl)propan-1-ol (formerly 2,3-dimercapto-1-propanol), with the masking agent chosen based on...
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01:22EDTA: Chemistry and Properties
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Polydentate ligands are most widely used in complexometric titrations because they form more stable complexes with the metal ions than mono- or bidentate ligands due to the chelate effect. Examples of polydentate ligands are ethylenediaminetetraacetic acid (EDTA), crown ethers, and cryptands. The most important feature of optimal polydentate ligands is the ability to form 1:1 complexes in a single-step process. Amino carboxylic acid derivatives are frequently used as complexing agents. EDTA is...
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01:20Complexometric EDTA Titration Curves
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EDTA titration curves determine the free metal ion concentration. The titration curve represents the change in concentration of free metal ions (p function) as a function of the volume of EDTA added. This curve consists of three regions: before, at, and after equivalence points. Excess free metal ions are present before the equivalence point. Equal concentrations of metal ions and EDTA are present at the equivalence point. After the equivalence point, excess EDTA exists. This means slight...
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