Determination of the dead volume of columns in reversed phase liquid chromatography

1989 ◽  
Vol 54 (4) ◽  
pp. 953-966 ◽  
Author(s):  
Ivan Vít ◽  
Jan Fähnrich ◽  
Milan Popl
Keyword(s):  
Homologous Series ◽  
Mobile Phase ◽  
Retention Volume ◽  
Reversed Phase ◽  
Dead Volume ◽  
Retention Data ◽  
Reversed Phase Liquid Chromatography ◽  
Phase Liquid ◽  
The Dead

The method for the determination of the dead volume of RPLC columns by measuring the retention volume of phloroglucinol is compared with the method based on the retention data of homologous series of organic solutes and that based on the use of isotopically labelled components of the mobile phase. The use of homologous series is tedious and moreover, satisfactory results are not always obtained. The phloroglucinol method is found well suited to replacing the method based on the use of isotopically labelled components of the mobile phase; poorer results with phloroglucinol are only obtained when the mobile phase contains more than 40% (v/v) water, for the Separon SE polymeric sorbent, and in alkaline medium.

scholarly journals Determination of Methomyl in Insecticidal Formulations by Reversed-Phase Liquid Chromatography: Collaborative Study

1996 ◽  
Vol 79 (4) ◽  
pp. 941-948
Author(s):  
James E Conaway ◽  
J B Audino ◽  
E Bane ◽  
S K Carrigan ◽  
R Glinsky ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Coefficient Of Variation ◽  
Mobile Phase ◽  
Collaborative Study ◽  
Internal Standard ◽  
Reversed Phase ◽  
Reversed Phase Liquid Chromatography ◽  
Phase Liquid ◽  
Liquid Chromatographic

Abstract A reversed-phase liquid chromatographic (LC) method for methomyl was studied. Twelve collaborators analyzed 3 solid and 4 liquid formulations on both a Zorbax octadecylsilane (ODS) column and a similar column of their choice. Methomyl and the internal standard were separated by using a mobile phase consisting of approximately 8% acetonitrile in water, which was monitored at 254 nm. The coefficient of variation on the Zorbax column ranged from 0.70 to 5.23%, while the range on the collaborators' house columns was 1.08 to 6.01%. Results with the Zorbax ODS column fell within the 5% 2-tail limits, and 10 of 11 collaborators' results fell within these limits on house columns. The LC method for determination of methomyl in insecticidal formulations has been adopted first action by AOAC INTERNATIONAL.

Determination of erythrocytic polyamines by reversed-phase liquid chromatography

1991 ◽  
Vol 37 (12) ◽  
pp. 2117-2120 ◽  
Author(s):  
Lucile Gerbaut
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Mobile Phase ◽  
High Performance ◽  
Reversed Phase ◽  
Reversed Phase Liquid Chromatography ◽  
Water Gradient ◽  
Phase Liquid ◽  
Dansyl Derivatives

Abstract A simple and rapid semiautomated procedure for determining polyamines in erythrocytes by high-performance liquid chromatography is described. Putrescine, spermidine, and spermine are converted to fluorescent dansyl derivatives, extracted with cyclohexane, and separated in <10 min on a reversed-phase C18 ODS column, with an acetonitrile-water gradient as the mobile phase. The method showed a coefficient of variation of 2.73% for spermidine and 3.27% for spermine. The respective reference values, evaluated in 10 healthy patients, were 7.88 (SD 2.09) and 5.42 (SD 1.55) μmol/L of packed erythrocytes. Only negligible amounts of putrescine were found.

scholarly journals Determination of Malathion Residues in Some Medicinal Plants by Liquid Chromatography with Gas Chromatographic/Mass Spectrometric Confirmation

1998 ◽  
Vol 81 (5) ◽  
pp. 1023-1026 ◽  
Author(s):  
Mohamed Tawfic Ahmed ◽  
Saad M M Ismail ◽  
Yahia Y Mosleh
Keyword(s):  
Liquid Chromatography ◽  
Mobile Phase ◽  
Reversed Phase ◽  
Minimum Detectable Concentration ◽  
Reversed Phase Liquid Chromatography ◽  
Average Recovery ◽  
Detectable Concentration ◽  
Phase Liquid ◽  
Chromatographic Mass

Abstract A method for determining malathion residues by reversed- phase liquid chromatography (LC) using methanol only as mobile phase is described. Malathion [diethyl(dimethoxyphosphinothiol)succinate] was applied on marjoram, mint, and chamomile. Residues were detected in fresh and dry crops by LC and confirmed by gas-LC/mass spectrometry. Average recovery of malathion was 85%. Residues detected in fresh marjoram, mint, and chamomile were 0.18, 0.23, and 0.083 mg/kg, respectively. Residues detected in dry marjoram and mint were 0.024 and 0.050 mg/kg, respectively. No malathion residues were detected in dry chamomile. The minimum detectable concentration with this method is 0.013 mg/kg. The study suggests it is safe to use malathion up to 2 sprays per season provided the crop is harvested not less than 3 weeks from the last spray

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