eluent

Trifluoroacetic acid ( TFA) was used as the retaining acid and ammonia liquor as the eluent base. The solvent system was n-hexane-acetic ester-methanol-water ( ratio by volume was 9 ∶ 1 ∶ 5 ∶ 5).

采用三氟乙酸做为保留酸，氨水作为洗脱碱，溶剂系统为正己烷/乙酸乙酯/甲醇/水（体积比为9∶1∶5∶5）。

By means of changing the concentration of OP solution and the varieties of organic additive, the enrichment condition was optimized: 5% OP+ 5% carbamide as the extractive agent, using SPE, acetonitrile as eluent.

通过改变OP水溶液浓度和有机添加剂种类，研究了萃取和富集的条件：以5%OP+2%尿素作提取液，过SPE小柱，乙腈洗脱。

Skim milk was$ 2. 99, on sale from$ 3. 49; Nonfat dry milk is an inexpensive proteinaceous eluent.

脱脂奶2.99美元，原价是3.49美元；脱脂奶粉是廉价的蛋白质洗脱剂。