Shalmi M, Kibble J D, Day J P, Christensen P, Atherton J C
Department of Pharmacology, University of Copenhagen, Denmark.
Am J Physiol. 1994 Oct;267(4 Pt 2):F695-701. doi: 10.1152/ajprenal.1994.267.4.F695.
The analysis of picomolar lithium, sodium, and potassium by electrothermal atomic absorption spectrophotometry was studied using a Perkin-Elmer Zeeman 3030 spectrophotometer. With ordinary pyrolytically coated graphite tubes, a number of interference effects associated with the sample matrix were observed. In particular, the lithium and potassium absorbance signal was depressed by chloride, an effect shown to be dependent on the preatomization heating. When an in situ tantalum-coated atomization surface was used, matrix interferences observed in lithium and potassium analyses were abolished, and the linear range for the potassium assay was extended. Technical difficulties encountered during sodium analysis at the primary wavelength were effectively circumvented by analysis at a less-sensitive wavelength (303.3 nm), at which tantalum coating also prevented significant chloride interference. The improved microanalyses were employed to reevaluate the handling of lithium, sodium, and potassium along the proximal convoluted tubule (PCT) of the anesthetized rat. The average tubular fluid-to-plasma concentration ratios for lithium [(TF/P)Li] and sodium [(TF/P)Na] were 1.13 +/- 0.08, n = 26, and 0.99 +/- 0.07 (n = 26), respectively. The tubular fluid-to-plasma ultrafiltrate concentration ratio for potassium [(TF/UF)K] was 1.09 +/- 0.05 (n = 13). Ratios did not change significantly with puncture site along the PCT for any of the ions. (TF/P)Li and (TF/UF)K were significantly greater than (TF/P)Na, indicating that lithium and potassium reabsorption do not directly parallel sodium reabsorption in the PCT.
使用珀金埃尔默塞曼3030型分光光度计研究了通过电热原子吸收分光光度法对皮摩尔级锂、钠和钾的分析。使用普通的热解涂层石墨管时，观察到了许多与样品基质相关的干扰效应。特别是，锂和钾的吸光度信号会被氯化物抑制，这种效应显示取决于原子化前的加热。当使用原位钽涂层雾化表面时，锂和钾分析中观察到的基质干扰被消除，并且钾测定的线性范围得到了扩展。在钠分析的主要波长处遇到的技术难题通过在不太敏感的波长（303.3 nm）处进行分析得到了有效解决，在该波长下钽涂层也防止了明显的氯化物干扰。采用改进的微量分析方法重新评估了麻醉大鼠近端曲管（PCT）中锂、钠和钾的处理情况。锂的平均肾小管液与血浆浓度比[（TF/P）Li]和钠的平均肾小管液与血浆浓度比[（TF/P）Na]分别为1.13±0.08，n = 26和0.99±0.07（n = 26）。钾的肾小管液与血浆超滤液浓度比[（TF/UF）K]为1.09±0.05（n = 13）。对于任何一种离子，这些比值沿PCT的穿刺部位均无显著变化。（TF/P）Li和（TF/UF）K显著大于（TF/P）Na，表明在PCT中锂和钾的重吸收并不直接与钠的重吸收平行。
