泥炭样品当中α-纤维素提取的实验方法探讨

摘要/Abstract

摘要： 目前,泥炭α-纤维素同位素研究已广泛应用于古气候、古环境重建,因而泥炭α-纤维素的提取也就显得尤为重要,但国内外泥炭α-纤维素的提取方法存在差异,并未形成比较统一的α-纤维素提取流程,在一定程度上限制了各实验室之间泥炭α-纤维素同位素数据的对比分析。在前人树轮、湖泊和泥炭α-纤维素提取流程的基础之上进行改善,经过反复的条件实验,最终建立了适合泥炭岩芯样品的α-纤维素提取方法。对泥炭α-纤维素提取流程的改进主要表现在4个方面:(1)样品处理前增加了清洗步骤,并设计了简单的清洗装置,可以有效清除粘土和矿物等杂质。(2) α-纤维素提取自始至终是在10 ml的Teflon离心管中进行,避免了在实验过程中多次转移样品而造成样品的损失,同时使用离心机分离缩短了样品的制备时间,并实现了α-纤维素的批量化提取。(3) NaClO₂的漂白和不同浓度的NaOH溶液的碱洗取代有机溶剂的萃取。(4)α-纤维素提取流程中增加了样品的均一化处理,保证了测试样品具有较好的代表性。红外光谱分析结果证明提取的纤维素是比较纯的α-纤维素,对40个泥炭岩芯样品α-纤维素碳同位素的相对误差分析和线性回归分析,进一步强调在α-纤维素提取流程中样品均一化处理的必要性。

关键词: 泥炭, &alpha, -纤维素, 提取流程

Abstract: Isotopes of peat α-cellulose have been increasingly applied in paleoclimatic and paleoenvironmental reconstructions, therefore, the simplification and unification of the extraction procedure for peat α-cellulose is urgently needed. Until now, the discrepancy in peat α-cellulose extraction procedures largely limited the comparative studies of reported isotopic data of peat α-cellulose from different labs and research groups. Based on the classical peat α-cellulose extraction procedure, and referring to the relevant α-cellulose extraction procedures for tree rings, lacustrine sediments and so on, after a systematically and repeatedly conditional experiment, the paper finally established an effective peat α-cellulose extraction procedure. The improved peat α-cellulose extraction procedure are simply outlined as following:(1)original peat core samples were washed with deionized water in a specific and simple cleaning device, for the effective removal of clay and minerals;(2)the wet samples were dried in the oven(~70℃), and then were finely powdered in an agate mortar with pestle;(3)humus in samples were removed by NaOH(5%)dissolution at room temperature for 24 h;(4)carbonate in samples were removed by HCl(5%)dissolution in a 80℃ water bath for 1 h;(5)lignin in samples were removed by sodium chlorite and acetic acid(acetic acid were firstly added)dissolution in a 80℃ water bath for 1 h;(6)remains of non-cellulose poly-saccharides(hemicellulose)were removed by NaOH(10%)dissolution in a 80℃ water bath for 1 h, and then by NaOH(17%)dissolution at room temperature for 45 min;(7)the samples were neutralized with HCl(1%), and then washed with a large amount of deionized water;(8)the extracts were homogenized by supersonically treated for 10 min;(9)the extracted α-cellulose samples were dried in a~70℃ oven. The purity degree was examined by comparative infrared spectrum analysis of α-cellulose extracted from peat and modern plant leaf with international standard tree ring α-cellulose. Finally, carbon isotopic composition of α-cellulose extracted from 40 peat-core samples were double or triple measured. The analyses on the obtained carbon isotopic data demonstrated that the established peat α-cellulose extraction procedure is effective and efficient. The improvements of the peat α-cellulose extraction procedure are mainly focus on the following 4 aspects:(1)a simple cleaning device was designed for the effective removal of impurities, such as clay and minerals;(2)the whole extraction procedure was performed in the same 10 ml Teflon centrifuge tube to avoid the loss of samples, and a centrifuge machine was used for the reduction of the extraction time;(3)the organic solvent extraction was replaced by bleaching by sodium chlorite solution and alkaline cleaning by sodium hydroxide solution with different concentrations;(4)final homogenization of the extracted α-cellulose for better representativeness. Briefly, a better peat α-cellulose extraction procedure has been established, due to its minor sample loess, easy and quick handling, stable and precise isotopic data.

Key words: peat samples, α-cellulose extraction, stable isotopes

中图分类号:

P532

黄超, 李英红, 郭文康, 李云霞, 饶志国. 泥炭样品当中α-纤维素提取的实验方法探讨[J]. 干旱区地理, 2015, 38(4): 728-734.

HUANG Chao, LI Ying-hong, GUO Wen-kang, LI Yun-xia, RAO Zhi-guo. Improved peat α-cellulose extraction procedure[J]. , 2015, 38(4): 728-734.

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