TY - JOUR
T1 - Development of a chromatographic low pressure flow injection system
T2 - application to the analysis of methylxanthines in coffee
AU - Santos, João Rodrigo
AU - Rangel, António O. S. S.
PY - 2012/2/17
Y1 - 2012/2/17
N2 - In this work, the coupling of a commercial monolithic column to a traditional low pressure FIA system is proposed for the analysis of theobromine, theophylline and caffeine in coffee brewed samples using UV detection.The parameters mobile phase composition, flow rate and loop volume were evaluated and discussed considering the various chromatographic parameters in order to enable resolution of the methylxanthines studied within the coffee brewed sample matrix. The analyses of methylxanthines in coffee brewed samples by the proposed methodology were in good agreement with those obtained by the reference procedure based on HPLC. Relative errors were below 6% for all samples analyzed. Detection limits in the selected experimental conditions were within 10-6M range for theobromine and theophylline, and 10-5M for caffeine. The determination rate of the three methylxanthines for coffee brewed samples was ca of 10h-1.The main advantage of the proposed flow system was the possibility to perform chromatographic separations in low pressure flow systems. This substantial improvement was achieved due to the compatibility of monolithic columns within the flow injection system surpassing in this way one of the main handicaps of traditional flow analysis systems. Additional features of the strategy presented were low cost, efficiency, high versatility and low reagent consumption comparing to HPLC methodologies usually followed in the case study herein presented.
AB - In this work, the coupling of a commercial monolithic column to a traditional low pressure FIA system is proposed for the analysis of theobromine, theophylline and caffeine in coffee brewed samples using UV detection.The parameters mobile phase composition, flow rate and loop volume were evaluated and discussed considering the various chromatographic parameters in order to enable resolution of the methylxanthines studied within the coffee brewed sample matrix. The analyses of methylxanthines in coffee brewed samples by the proposed methodology were in good agreement with those obtained by the reference procedure based on HPLC. Relative errors were below 6% for all samples analyzed. Detection limits in the selected experimental conditions were within 10-6M range for theobromine and theophylline, and 10-5M for caffeine. The determination rate of the three methylxanthines for coffee brewed samples was ca of 10h-1.The main advantage of the proposed flow system was the possibility to perform chromatographic separations in low pressure flow systems. This substantial improvement was achieved due to the compatibility of monolithic columns within the flow injection system surpassing in this way one of the main handicaps of traditional flow analysis systems. Additional features of the strategy presented were low cost, efficiency, high versatility and low reagent consumption comparing to HPLC methodologies usually followed in the case study herein presented.
KW - Coffee
KW - Flow injection
KW - Low pressure chromatography
KW - Methylxanthines
KW - UV spectrophotometry
UR - http://www.scopus.com/inward/record.url?scp=84855660743&partnerID=8YFLogxK
U2 - 10.1016/j.aca.2011.12.002
DO - 10.1016/j.aca.2011.12.002
M3 - Article
AN - SCOPUS:84855660743
SN - 0003-2670
VL - 715
SP - 57
EP - 63
JO - Analytica Chimica Acta
JF - Analytica Chimica Acta
ER -