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染以馨新蟲(chóng) (初入文壇)
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[求助]
求waters HLB SPE小柱使用心得 已有2人參與
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想處理細(xì)胞外液的鹽然后進(jìn)LC-MS。但是每次都做得很奇怪,有的時(shí)候都不成線(xiàn)性。。。。我用的是30μL的柱子,每次上樣量是120μL,標(biāo)曲最高點(diǎn)濃度是0.75μmol/ L。我使用的是別人用過(guò)的HBL柱子,活化柱子,分別用甲醇、水600μL,洗4次。上樣前我會(huì)把水抽干,上樣的時(shí)候樣品不怎么好擴(kuò)散,一直浮在柱子表面,我就抽啊,給抽下去,壓力大概在0.2,wash用5%甲醇水1ML,也是得抽才能下去,我把水抽干以后,再上洗脫液(乙腈異丙醇1ML)。 不知道問(wèn)題出在哪了,做了好久了,心塞啊啊啊啊啊啊啊啊 |
鐵蟲(chóng) (初入文壇)
木蟲(chóng) (小有名氣)
木蟲(chóng) (小有名氣)
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文獻(xiàn):Journal of Functional Foods 18 (2015) 344–357 2.4. Identification of the peptides by LC–MS/MS The sample preparation for HPLC analysis was performed according to procedures previously reported by our group with minor modifications (Wu et al., 2009). A homemade C18 solid-phase extraction (SPE) column was activated by 1 mL of ACN and washed with a 0.1% TFA aqueous solution (v/v). The hydrolysate solution was adjusted to pH 2.7 with 10% TFA in water (v/v) and was then loaded onto the SPE column. Desalting was then performed by loading 500μL of a 0.1% (v/v) TFA aqueous solution, and this desalting step was performed three times. The desalting was performed 3 times. Then, 1.2 mL of an aqueous solution containing 0.1% (v/v) TFA and 80% (v/v) ACN was used as an elution buffer (three times) to wash the peptides. The eluate was collected, lyophilized and stored at −80 °C until use. 建議仿照這篇文獻(xiàn),使用TFA水溶液溶解樣品,再使用含TFA或FA的80%乙腈溶液進(jìn)行洗脫,這樣洗脫比較完全。 也最好不要使用舊的柱子,很可能會(huì)有上一次的殘留。如果實(shí)在想用,不妨用含0.1%TFA的80%乙腈溶液進(jìn)行洗滌,沖洗TFA后方可使用。(不過(guò)懷疑這樣能行嗎,SPE柱、HLB柱都是一次性的東西) 有人認(rèn)為T(mén)FA會(huì)對(duì)質(zhì)譜信息有干擾,近年來(lái)我們的做法漸漸把TFA改為FA。其實(shí)這兩者差別都不大,因?yàn)檫M(jìn)質(zhì)譜前通常會(huì)用凍干機(jī)凍干掉乙腈和TFA。進(jìn)質(zhì)譜前再?gòu)?fù)溶,以獲得準(zhǔn)確的上樣量。如果使用正離子模式,這個(gè)時(shí)候用請(qǐng)用FA復(fù)溶,以獲得良好的質(zhì)譜信號(hào)。 說(shuō)了太多,不知能否看懂 |

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