Direct Injection of Biological Fluids

From a bioanalytical viewpoint, a very useful application of MLC is the ability to inject biological fluids (serum, plasma and urine) directly into a chromato-graphic system with no protein precipitation, analyte extraction steps or pressure build-up problems. These advantages are extremely beneficial in areas such as therapeutic drug monitoring because the analyte extraction steps, traditionally necessary in chromato-graphic methods, are eliminated. In this way, analysis time is reduced and accuracy and precision are increased because the possible analyte co-precipitation with the protein is avoided.

Figure 7 Comparison of the detected fluorescent peaks of identical concentrations of pyrene (P), biphenyl (B) and naphthalene (N) separated by HPLC on a 30 cm x 4.0 mm i.d. alkylnitrile column. The broken line (---) shows the separation and enhanced fluorescence obtained with the 0.024 mol L~1 SDS mobile phase. The solid line (-) shows an analogous separation done with a traditional 40: 60 methanol/water mobile phase. In both separations 10 |L of solution containing 1.3x10~7g (N), 7.0 x 10~8 g (B) and 1.1 x 10~8 g (P) were injected. (Reproduced with permission from Armstrong DW, Hinze WL, Bui KH and Singh HN (1981) Enhanced fluorescence and room temperature liquid phosphorescence detection in pseudophase liquid chromatography (PLC). AnalyticalLetters 14: 1659-1667, copyright Marcel Dekker, Inc.)

Figure 8 Chromatogram of a urine sample spiked with: 1, amiloride (30 ^g mL_1, 3.67 min); 2, spirolactone (5 ^g mL_1, 4.02 min); 3 metandienone (1.2 ^g mL_1, 4.57 min); 4, phenylpropanolamine (56 ^g mL_1, 8.63 min); and 5, clostebol (30 ^g mL_1, 11.67 min). Mobile phase: 0.1 mol L"1 SDS/3% 1-pen-tanol. Flow rate: 1 mL min-1. Column temperature: 60°C. UV detection at 260 nm. Column: Spheri-5 C18 (10 cm x4.6 mm i.d.). (Reproduced with permission from Carretero I, Maldonado M, Laserna JJ, Bonet E and Ramis-Ramos G (1992) Detection of banned drugs in sport by micellar liquid chromatography. Analyt-ica Chimica Acta 259: 203-210, copyright Elsevier Science Publishers, B.V.)

Figure 7 Comparison of the detected fluorescent peaks of identical concentrations of pyrene (P), biphenyl (B) and naphthalene (N) separated by HPLC on a 30 cm x 4.0 mm i.d. alkylnitrile column. The broken line (---) shows the separation and enhanced fluorescence obtained with the 0.024 mol L~1 SDS mobile phase. The solid line (-) shows an analogous separation done with a traditional 40: 60 methanol/water mobile phase. In both separations 10 |L of solution containing 1.3x10~7g (N), 7.0 x 10~8 g (B) and 1.1 x 10~8 g (P) were injected. (Reproduced with permission from Armstrong DW, Hinze WL, Bui KH and Singh HN (1981) Enhanced fluorescence and room temperature liquid phosphorescence detection in pseudophase liquid chromatography (PLC). AnalyticalLetters 14: 1659-1667, copyright Marcel Dekker, Inc.)

Figure 8 Chromatogram of a urine sample spiked with: 1, amiloride (30 ^g mL_1, 3.67 min); 2, spirolactone (5 ^g mL_1, 4.02 min); 3 metandienone (1.2 ^g mL_1, 4.57 min); 4, phenylpropanolamine (56 ^g mL_1, 8.63 min); and 5, clostebol (30 ^g mL_1, 11.67 min). Mobile phase: 0.1 mol L"1 SDS/3% 1-pen-tanol. Flow rate: 1 mL min-1. Column temperature: 60°C. UV detection at 260 nm. Column: Spheri-5 C18 (10 cm x4.6 mm i.d.). (Reproduced with permission from Carretero I, Maldonado M, Laserna JJ, Bonet E and Ramis-Ramos G (1992) Detection of banned drugs in sport by micellar liquid chromatography. Analyt-ica Chimica Acta 259: 203-210, copyright Elsevier Science Publishers, B.V.)

Micellar systems such as SDS or polyoxyethylene lauryl ether (Brij-35) solubilize the serum proteins and cause their elution with the void volume. Furthermore, surfactant monomers compete with the analyte for protein-binding sites, thereby releasing it for complete quantitation.

Figure 8 shows the separation by MLC of a mixture containing diuretics (amiloride and spirolactone), anabolic steroids (metandienone and clostebol) and a stimulant (phenylpropanolamine) added to a urine sample at concentrations of |g mL-1.

Solar Panel Basics

Solar Panel Basics

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