利用微孔盤儀 (microplate reader) 進行生物分析，可以降低化藥用量，是目前減少化學廢棄物的重要措施之一。總氮及總磷含量的測定，是植物營養研究經常執行的必要分析。本文目的在探討可否利用微孔盤儀結合水楊酸法 (salicylate method) 及孔雀石綠法 (malachite green method)，分別測定植物之總氮及總磷含量，以期達到減少化學廢棄物之目的。本研究之植物材料為臺灣中部山區不同海拔之赤楊共46株，其樹葉經硫酸水解後，進行微孔盤法分析。試驗結果發現，酸解樣品之硫酸濃度高於360 mM時，會降低水楊酸測定法分析總氮之測值；而酸解樣品之硫酸濃度高於433 mM時，其影響孔雀石綠測定法分析總磷之測值由降低轉為升高。經比較微孔盤法與凱式 (Kjeldahl) 蒸餾定氮法及元素分析儀 (element analyzer) 法對總氮之測定效率，顯示微孔盤法測值約高於元素分析儀10%，且高於蒸餾定氮法30%，但是其與兩法之直線迴歸決定係數 (R2) 仍然可達0.95。其次，比較微孔盤法與鉬藍法 (molybdenium blue method) 二法的總磷測定效率，顯示微孔盤儀測值約高於鉬藍法10%，二者之R2亦可達0.95。結論，經硫酸分解的植體，可以利用微孔盤法分析總氮及總磷的含量。

The usage of microplate reader in biological analysis only needs small amount of chemicals and is one of the important strategies in reducing chemical waste. Analysis of the total nitrogen and phosphorus content
is a frequent and essential process for the diagnosis of plant nutrient status. The aim of this research was to use microplate reader in combination with salicylate method or malachite green method to obtain plant total nitrogen or phosphorus content, respectively. A collection of 46 Formosan Alder (Alnus formosana Makino)leaf samples from central Taiwan mountain area among different altitudes were used for microplate analysis.The results showed the nitrogen content in microplate analysis was decline as the sulfate concentration in sample was higher than 360 mM. In addition, the effect of sulfate concentration on phosphorus measurement was from decline to rise when the sulfate concentration was higher than 433 mM. In nitrogen measurement,the reading with microplate method was higher than those with an element analyzer and the Kjeldahl method by 10 and 30%, respectively, and both of their R2 were 0.95. In phosphorus measurement, the reading with microplate method was higher than that of the molybdenium blue method by 10%, and the R2 was 0.95.
Therefore, it was concluded that the microplate method can be used to measure the total nitrogen and phosphorus content of sulfuric acid digested plant tissue.