基于雙還原體系與膜進(jìn)樣質(zhì)譜快速測(cè)定15N加富水樣中的方法*

羅 暢 宋國棟 劉素美

羅 暢1, 2, 3宋國棟1, 2①劉素美1, 2

(1. 中國海洋大學(xué) 深海圈層與地球系統(tǒng)前沿科學(xué)中心/海洋化學(xué)理論與工程技術(shù)教育部重點(diǎn)實(shí)驗(yàn)室 山東青島 266100; 2. 青島海洋科學(xué)與技術(shù)試點(diǎn)國家實(shí)驗(yàn)室 海洋生態(tài)與環(huán)境科學(xué)功能實(shí)驗(yàn)室 山東青島 266237; 3. 中國海洋大學(xué)化學(xué)化工學(xué)院 山東青島 266100)

15N加富樣品; 硝化; 氨基磺酸; 膜進(jìn)樣質(zhì)譜

Tab.1 Some main methods, principles, and characteristics for the determination of 15N labeled

1 材料和方法

1.1 測(cè)定15N加富樣品中的分析步驟

圖1 基于鎘柱與氨基磺酸雙還原體系并結(jié)合膜進(jìn)樣質(zhì)譜測(cè)定15N加富樣品中的簡(jiǎn)單流程

整個(gè)方法涉及多項(xiàng)因素的條件測(cè)試, 影響因素和條件設(shè)定如表2, 方法的條件測(cè)試具體步驟見1.2～1.5, 方法對(duì)樣品的應(yīng)用測(cè)試見1.6。

1.2 鎘柱還原率及還原硝酸鹽濃度范圍測(cè)定

Tab.2 Influencing factors and conditions for determination of by membrane injection mass spectrometry based on cadmium column and sulfamic acid double reduction (SA) system

1.3 氨基磺酸濃度、試劑酸度及反應(yīng)時(shí)間

1.4 線性范圍、精密度及檢測(cè)限

檢測(cè)限: 以工作曲線線性回歸方程截距標(biāo)準(zhǔn)偏差的3倍除以斜率即檢測(cè)限。

1.5 鹽效應(yīng)

1.6 石老人沙灘沉積物中銨氧化與亞硝酸鹽氧化速率的測(cè)定

于2019年5月15日早上08:30 (低潮位時(shí)刻)在青島石老人沙灘(36°5′48″N, 120°28′25″E)獲取沉積物柱狀樣, 將表層10 cm沉積物以2 cm的垂向分辨率現(xiàn)場(chǎng)進(jìn)行分割裝入密封袋中; 獲取沉積物的同時(shí)獲取5 L海水, 與分割好的沉積物一同保存在裝有冰盒的保溫箱帶回實(shí)驗(yàn)室進(jìn)行后續(xù)實(shí)驗(yàn)。

2 結(jié)果與討論

2.1 鎘柱還原率

鎘柱還原率≤1, SA還原效率≤1, 為實(shí)現(xiàn)轉(zhuǎn)化率越大, 則需和越接近1。

圖2 過柱(a), 過柱(b), 不過柱(c), 過柱與過柱(d)工作曲線

圖3 不同氨基磺酸(SA)濃度(0.5～20 mmol/L)和酸度(HCl濃度0～1 mol/L)條件下, 轉(zhuǎn)化為29N2的信號(hào)比值Δ29N2/ΣN2變化(a)和轉(zhuǎn)化率(b)

Fig.3 The signal ratio Δ29N2/ΣN2 variation from to 29N2 (a) and conversion (b) under different sulfamic acid (SA) concentration (0.5～20 mmol/L) and acidity (expressed as HCl concentration 0～1 mol/L)

圖4 10 μmol/L經(jīng)鎘和15 mmol/L SA (1 mol/L HCl)試劑還原后測(cè)試信號(hào)隨時(shí)間的變化

2.3 線性范圍、檢出限和精密度

圖5 鎘柱還原-SA反應(yīng)測(cè)定的線性范圍測(cè)試

圖6 鎘柱還原-SA反應(yīng)測(cè)定的工作曲線(0～10 μmol/L)

Tab.3 Δ29N2/ΣN2 average measured at 1 and 10 μmol/L of standard and the Δ29N2/ΣN2 standard deviation and Δ29N2/ΣN2 relative standard deviation (n = 4)

2.4 鹽效應(yīng)影響

通過測(cè)定鹽度范圍為0～35的Δ29N2/ΣN2與鹽度為0時(shí)Δ29N2/ΣN2信號(hào)比值計(jì)算相對(duì)誤差(圖7), 表明當(dāng)鹽度為5、30和35, Δ29N2/ΣN2相對(duì)誤差明顯低于1%, Δ29N2/ΣN2基本未發(fā)生變化; 當(dāng)鹽度為10～25, Δ29N2/ΣN2相對(duì)誤差約為2%, Δ29N2/ΣN2受到的影響也較小。因此, 整個(gè)反應(yīng)過程可視為無顯著的鹽效應(yīng)。

圖7 鹽度為0～35時(shí)Δ29N2/ΣN2相對(duì)誤差變化

2.5 石老人沙灘沉積物中潛在的銨氧化與亞硝酸鹽氧化速率

圖8 加富樣品(a)和加富樣品(b)中生成與培養(yǎng)時(shí)間的關(guān)系

Fig.8 Relationship between production and incubation time in -enriched samples (a) and -enriched samples (b)

圖9 氧化為及氧化為的速率與沉積物深度的關(guān)系

3 結(jié)論

致謝 感謝謝成軍同學(xué)對(duì)本研究實(shí)驗(yàn)過程與儀器操作所提供的協(xié)助; 感謝廣西大學(xué)海洋學(xué)院寧志銘老師對(duì)本文的修改指正。

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LUO Chang1,2,3, SONG Guo-Dong1, 2, LIU Su-Mei1, 2

(1. Frontiers Science Center of Deep Ocean Multispheres and Earth System/Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China; 2.Laboratory for Marine Ecology and Environmental Science, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China; 3. College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China)

15N enriched sample; nitrification; sulfamic acid; membrane injection mass spectrometry

*國家自然科學(xué)基金, U1806211號(hào), 42076035號(hào), 41606093號(hào); 中國海洋大學(xué)中央高?；究蒲袠I(yè)務(wù), 202072001號(hào)。羅暢, 碩士研究生, E-mail: 1051392235@qq.com

宋國棟, 副教授, E-mail: gsong@ouc.edu.cn

2021-10-09,

2021-12-02

P734

10.11693/hyhz20211000237