電噴霧四級桿飛行時(shí)間qtof理論-免費(fèi)閱讀
【正文】 :49:0120:49:01February 1, 2023 1意志堅(jiān)強(qiáng)的人能把世界放在手中像泥塊一樣任意揉捏。 2023年 2月 下午 8時(shí) 49分 :49February 1, 2023 1少年十五二十時(shí)，步行奪得胡馬騎。 2023年 2月 1日星期三 8時(shí) 49分 1秒 20:49:011 February 2023 1做前，能夠環(huán)視四周；做時(shí)，你只能或者最好沿著以腳為起點(diǎn)的射線向前。 All Rolling off ?Peak tailing ?Loss of peak resolution ?Decreased peak intensity Rolling 5 To smooth chromatographic data, rolling of one to three is acceptable. Rolling values higher than this can cause considerable tailing and loss of peak shape and separation, which could result in more work to extract data during processing. Rolling does not affect the number of data points and thus does not affect the size of the data file. For data reduction, increase the number of summations. Rolling averaged scans together increases the statistical reliability of your data set. Rolling Averages and Chromatography Too much Rolling Notice: Helpful Tips m/z Species Co n tam i nant 102 (M+H)+ triethy l ami ne (T E A) 123 (M+H)+ di methy l ami nopy ridi ne (D MAP ) 130 (M+H)+ di i s opropyl ethy l a mi ne (D IPE A) 144 (M+H)+ Tr i propyl ami ne ( TPA) 153 (M+H)+ 1,8 di az abi c y c l o[ ]undec 7 en e (D BU ) 182 (M+H)+ di TMS diam i nopy ridi ne 225 449 (M+H)+ (2M+H)+ Dic y c l ohex y l urea ( DC U) 239/241 [( Cl)2 Cl]+ triethy l ami ne 242 M+ tetrabutyl ammoni um (C4H9)4N+ 391 413 454 803 (M+H)+ (M+Na)+ (M+Na+CH3C N)+ (2M+Na)+ Pthal i c ac i d es ter /DO P o r D EHP di i s ooc ty l phthalate (plas ti c i s er) HP L C Flo w R ate ( u L / m i n ) Neb u lizer P r ess u r e ( p s i) Dr y Gas Flo w ( l/ m i n ) Dr y in g Ga s T em p . ( C ) 1 1 0 0 . 5 2 4 150 200 200 – 500 2 4 8 – 1 0 2 0 0 300 Typical ESI Source Conditions Typical Currents (V): Capillary 3000 – 4500 End Plate 500 (up to 2023 with buffers) ESI Common Solvents: ESI Common Buffers Methanol Ethanol Acetic Acid Propanol Isopropanol Formic Acid Butanol Water Ammonium Acetate and Formate Acetone Acetonitrile Sodium Acetate Chloroform Formamide Potassium Acetate Tetrahydrofuran Acetic Acid ESI Solvents Requiring Modifier: Benzene Carbon Disulfide Carbon tetrachloride Cyclohexane Hexane Ligroin Dichloromethane Toluene *DO NOT USE TFA. Useful Conversions 1 mM=1000 mM 1 mM=1 pmol/mL 1 mg/mL= 1 mg/mL To convert mg/mL or mg/mL to pmol/mL : pmol/mL =(mg/mL * 106)/protein MW milli = 103 micro = 106 nano = 109 pico = 1012 femto =1015 atto = 1018 靜夜四無鄰，荒居舊業(yè)貧。 9 preferred) for negative ions Acid pH (。 5 preferred) for positive ions *Manipulation of pH can enhance performance for analytes that are not normally ionized in solution. Electrospray Sample Chemistry Positive Ion Mode Negative Ion Mode Base + acid ? Sample Acid + base ? Sample RN RRRNR H RHAOC OR HOCR:B + H:B++ + ? ? + A Electrospray Buffers Choose buffers carefully for TOF instruments Electrospray Buffer Selection: ? Volatile buffers are used to modify mobile phase pH. ? May be added in mobile phase as a postcolumn addition. ? Acidic solutions favor positive ion mode. ? Formic acid, % ? Acetic acid, % ? Ammonium salts favor production of single ammonium adducts. ? General buffers ? Ammonium acetate ? Ammonium formate ? Triethylamine ? Other volatile solvents (%) ? Basic solutions favor negative ion mode. ? Ammonium hydroxide (pH 1011) **TFA can act as an ion suppressant— avoid use. APCI APCI LC/MS Advantages ?Complementary to APIElectrospray for less polar analytes. ?Good sensitivity for pounds of intermediate MW and polarity. ?Less sensitive to solution chemistry effects than APIES. ?Tolerates higher flow rates
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