Analytical Chemistry Department Chemical Faculty Gdańsk University of Technology Magdalena Michulec 4 th year PhD student
Application of proecological pre-treatment techniques for solvents residues determination in food and drug matrices
ANALYTES: hexane benzene toluene trichloromethane 1,1,1-trichloroethane tetrachloromethane trichloroethene tetrachloroethene
From the consumer s point of view... Food products: 0,1 1 µg/g Pharmaceutical products: from hundreds to thousands µg/g From the analyst s point of view...
hexane benzene toluene
HEADSPACE ANALYSIS HS SOLID PHASE MICROEXTRACTION SPME SINGLE DROP EXTRACTION SDE
GAS CHROMATOGRAPHIC SEPARATION FID Flame Ionization Detector ECD Electron Capture Detector
Chromatogram of refined oil spiked with 10 mg kg -1 of each standard compound (HSA) 1- hexane, 2 benzene, 3 toluene. Chromatogram of refined oil spiked with 10 mg kg -1 of each standard compound extracted by SPME (CAR-PDMS 75 mm). 1- hexane, 2 benzene, 3 toluene. Chromatogram of refined oil spiked with 10 mg kg -1 of each standard compound extracted by SDE. 1- hexane, 2 benzene, 3 toluene, 4 benzyl alcohol.
VALIDATION Definition: Validation is the confirmation by examination and provision of objective evidence that the particular requirements for specific intended use are fulfilled.
VALIDATION PROCEDURE LOD the limit of detection is the lowest amount of an analyte in a sample which can be detected but not necessarily quantified as an exact value. LOQ limit of quantification is the lowest amount of an analyte in a sample which can be determined as an exact value. RANGE the interval between the upper and lower concentration of analyte in the sample for which it has been demonstrated that the analytical procedure has a suitable level of precision, accuracy and linearity. LINEARITY - linearity refers to the fidelity of an output signal with respect to its input signal. In a linear relationship, output is directly proportional to input. PRECISION the closeness of agreement between independent test results obtained under stimulated conditions. Can be measured in terms of the standard deviation of the measurement system. -- repeatability
Table 1.Validation parameters for hexane, benzene and toluene (HSA). Compound Hexane Benzene Toluene Parameter 0.012 0.125 0.012 0.125 0.012 0.125 Linearity [mg kg -1 ] 0.125 5 0.125 5 0.125 5 5 200 5 200 5 200 Dynamic range [mg kg -1 ] 0.012 200 0.027 200 0.051 250 Repetability [%] 2.5 3.6 5.2 Intermediate precision [%] 3.0 3.9 5.5 Detection limit [mg kg -1 ] 0.004 0.009 0.017 Quantification limit [mg kg -1 ] 0.012 0.027 0.051
able 2. Validation parameters for hexane, benzene and toluene extracted by SPME. Compound Hexane Benzene Toluene Parameter 0.006 0. 5 0.006 0.5 0.006 0.5 Linearity [mg kg -1 ] 0.5 100 0.5 100 0.5 100 100 1000 100 1000 100 1000 Dynamic range [mg kg -1 ] 0.006 1000 0.006 700 0.006 500 Repetability [%] 4.7 3.6 5.1 Intermediate precision [%] 6.9 3.9 5.9 Detection limit [mg kg -1 ] 0.002 0.002 0.002 Quantification limit [mg kg -1 ] 0.006 0.006 0.006
able 3. Validation parameters for hexane, benzene and toluene extracted by SDE. Compound Hexane Benzene Toluene Parameter 1.8 3 0.36 5 0.3 3 Linearity [mg kg -1 ] 3 25 5 25 5 25 25 100 25 100 25 100 100 1000 100 1000 100 1000 Dynamic range [mg kg -1 ] 1.8 1000 0.36 1000 0.3 1000 Repetability [%] 2.5 2.0 1.2 Intermediate precision [%] 3 2.4 1.6 Detection limit [mg kg -1 ] 0.6 0.12 0.1 Quantification limit [mg kg -1 ] 1.8 0.36 0.3
CONCLUSIONS 1. Developed procedures are comparable in term of precision (relative standard deviation RSD: 2-5 %). 2. LOD for SPME and HS is about two orders of magnitude lower then for SDE. 3. The linearity for all three procedures is satisfactionary. 4. SDE technique represents a cheap and attractive, alternative to SPME requiring only a standard GC syringe.
SPME HSA SDE 0,006 0,012 1,8 200 1000 Concentration [mg kg -1 ]
PUBLICATIONS Conference presentations 11 posters 1 oral presentation Articles in journals 1. M. Michulec, J. Curyło, W. Wardencki, Technika mikroekstrakcji do fazy stacjonarnej (SPME) w badaniach analitycznych żywności. Chemia i Inżynieria Ekologiczna 9(10), 1117-1133, 2002. 2. M. Michulec, W. Wardencki Problem oznaczania pozostałości rozpuszczalników organicznych w wybranych produktach spożywczych i farmaceutycznych. Cz. I Analityka 1, 30-32, 2003. 3. M. Michulec, W. Wardencki Problem oznaczania pozostałości rozpuszczalników organicznych w wybranych produktach spożywczych i farmaceutycznych. Cz. II. Analityka 2, 26-29, 2003. 4. W. Wardencki, M. Michulec, J. Curyło Theoretical and practical aspects of solid phase microextraction in food analysis. International Journal of Food Science and Technology, 39 (7) 703 717, 2004. 5. M. Michulec, W. Wardencki, Determination of Solvents Residues in Vegetable Oils and Pharmaceuticals by Headspace Analysis and Capillary Gas Chromatography, Chromatographia, 60, S273 S277, 2004. 6. M. Michulec, W. Wardencki, A. Cisowski, Solvent residue determination in Vilcacora, Chemical Analysis, in press 7. M. Michulec, W. Wardencki, Development of HS-SPME-GC method for determination of solvent
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