Solid-phase micro-extraction technology (SPME) and its applications.

related topics . Solid Phase Extraction (SPE) - A widely used sample pre-processing technology Sg solid phase micro-extraction technology (SPME) and its applicationsSummary: Solid-phase micro-extraction (SPME) is a new sample pre-processing technology produced in response to modern instrument requirements. With people's in-depth understanding of its principles and technological development, the continuous application and development of new SPME devices, SPME has been widely used in environmental protection and water treatment, clinical medicine, public security case handling, national defense and so on. In this paper, the principle, extraction conditions and the current situation of joint technology are reviewed.key words: solid-phase micro-extraction; extraction conditions; co-use technology; application; overview The Solid Phase Micro Extraction (SPME) And It's Application Abstract: Solid phase micro-extraction (SPME) is a new kind of modern instrument before method output sample. Along with people as to it #39;s the principle develop deep with the tite into the comprehension, the new SPME equip continuously applied with the development, SPME through and applied handle in the environment protection and fluid matter, the clinical medicine, public security and #39;s case, national defense etc.. Present this text as to it #39;s principle, the conditions of extraction, coupling with other analytical technologies to proceeds the overviewed..Keywords: solid-phase micro-extraction; the conditions of the extraction; coupling with analytical technologies; application; ReviewSolid-Phase Microextraction (SPME) is a new test sample analysis pre-processing technology that has emerged internationally in recent years. Pioneered in 1990 by Arrhohe and Bowliszyn of Waterloo University in Canada, the commercialized solid phase micro-extraction device was launched by Supelco corporation in 1993 and won the Pittsburgh Analytical Instruments Conference Award in 1994.solid-phase extraction
is one of the best pre-sample treatment methods, with a series of advantages such as simplicity, low cost and ease of automation. Solid phase micro-extraction is developed on the basis of solid-phase extraction, retaining all its advantages, discarding its need for column fillers and the use of solvents for de-absorption, it only needs a solid-phase micro-extraction device similar to the sampler can complete all pre-treatment and sample work. The needle of the device has a telescopic rod, connected with a molten quartz fiber, its surface is coated with
chromatography
fixed phase, in general, molten quartz fiber hidden in the needle, when necessary, can push the sampler pusher to make quartz fiber from the needle out.analysis, the sample is first placed in a special container for solid-phase micro-extraction with diaphragm plugs, which can also be heated or stirred by magnetic roors if inorance salts, derivatives or pH adjustments need to be added at the same time. Solid-phase micro-extraction is divided into two steps, the first step is extraction, the needle is inserted into the sample container, the introduction of quartz fiber in the sample analysis of the sample to extract, the second step is to insert the needle into the chromatography sampler, the introduction of quartz fiber to complete the desorption, chromatography analysis and other steps. There are two ways to extract solid-phase micro-extraction: one is the direct insertion of quartz fiber into the sample for extraction, suitable for gas and liquid analysis parts, and the other is top-empty extraction, suitable for all substituts in the sample volatile, semi-volatile analysis parts.Because of the above advantages, SPME quickly in pharmaceutical and biological sample analysis, environmental monitoring and analysis,
food testing
and other aspects have a place, with the development and maturity of various combination technologies and new coating materials, SPME is no longer limited to the above-mentioned aspects, in medicine, biopharmaceuticals (such as fatty acid separation determination, biopolymers such as
protein
adsorption extraction) has a greater development, SPME has become an important area of analysis..PrincipleSolid phase micro-extraction device is very small, like a chromatography syringe, by the handle and extraction head or fiber head two parts, extraction head is a coat stainless steel tube 1 cm long, coated with different fixed phase of molten quartz fiber head, fiber head in the stainless steel tube can be freely stretched, used for extraction, adsorption sample, handle for installation or fixation of the extractor head, can be permanently used..The theoretical development of SPME is broadly divided into two, one is the early equilibrium theory, the other is the non-equilibrium theory developed in recent years.equilibrium theory holds that in the process of adsorption or absorption, an adsorption or absorption balance is established between solid-gas or solid-liquid phases, and the amount of adsorption is: n . . #39 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . #39 . 1-1)where n is the amount that the adlyte is adsorbed to the solid phase coating, K is the equilibrium constant between the solid phase (or gas phase) and the liquid phase, V is the volume of the solid phase coating, and C is the initial concentration of the adlyte in the sample solution. As can be seen from the formula, n is a quantity related to the equilibrium constant, the volume of the solid phase coating, the sample volume and the initial concentration of the adlyte in the sample solution. The solid-phase coating selected in SPME has a strong affinity for the extracted organic ingredients, and a large K can guarantee effective abundance and improve the sensitivity of the analysis. Usually the K value is not large enough for the adlyses to be extracted into a solid-phase coating, so SPME is only a balanced sampling method. If the sample volume remains constant, n and c are exponential rather than linear throughout the concentration interval. Formula (1) is established only when c is low, i.e. the balance is within the linear range of the adsorption iso-temperature line. If the sample solution has a sufficiently low concentration (50 micrograms per liter or less), in order to maintain a linear relationship between the response value (n) and c, the sample volume is also limited (e.g. less than 5 ml), otherwise the linear response relationship is not maintained.non-equilibrium theory side that in a certain period of time, due to the slow mass transmission process, the balance is not fully achieved. Taking into account the diffusion process of the adlyses in the two phases, the amount of the adlyses extracted into the solid-phase coating is: n-C﴾1-exp (-A (2mm-#39; KV-2mm-#39; V-#39;)/mVV-#39; 2m-#39; KVV-#39 ﴿ (KVV-#39;/KV-V-#39;) (1-2) type K is the adlyte's equilibrium constant between the sample medium and the coating, A is the surface area of the coating, m, m-#39; the mass transfer coefficient of the analyzer in the sample and in the solid-phase coating (m is the diffusion factor divided by the coating thickness). When SPME is sampled, it is not necessary for the adverse to be fully extracted or balanced until it is established, provided that a reliable and stable response value and concentration are obtained under strict conditions. When the adsorption (absorption ) time is infinitely long, the amount of the equilibrium analyde in the solid-phase coating is #39 n-#39 #39 #39; 2 Choice of solid-phase micro-extraction technical conditions 2.1 Factors affecting the extraction effect 2.1.1 Selection of extraction heads The extraction head is the core of the SPME device, and the nature of the coating has become the key to the success of the SPME method. So be very careful about your choices. The choice of coating should be determined by the nature of the substance to be tested, generally according to the principle of similar phase dissolution, the polar large substance to be tested to choose a strong polar coating, the polarity of the choice of weak polar coating material.
smut molecules
or volatile substances commonly used thick film 100 micron extraction head, larger molecules or semi-volatile substances using 7 micron extraction head, taking into account the polarity and volatility of the admiss, can also have 85 microns, 65 microns, 75 microns, 30 micron polarity extraction head selection. Fixed phase layer can be applied to quartz fibers in the form of non-bonding, bonding or partial crosslinking, the stability of the coating in organic solvents is: bonding phase >searly cross-linking> non-bonding phase, non-bonding phase in organic solvents also have a greater swelling. The most commonly used solid-phase coating substances are polymethyl sioxane (PDMS) and polyacrylate (PA), the former for non-polar compounds, polycyclic aromatic hydrocarbons, aromatic hydrocarbons, etc., 100 microns of PDMS is suitable for the analysis of low boiling point of the polar substances, 7 microns of PDMS is suitable for the analysis of boiling point and high boiling point of the substance. The latter is mostly used in polar compounds such as phenols. With the continuous development of SPME, new coating materials have also emerged: graphite carbon black quartz fiber for the analysis of trace compounds in water and air, characterized by porous surface, good thermal stability, do not retain water, adsorption capacity, etc. Liu et al. will bond carbon eight and carbon eighteen liquid chromatography with silicone with high temperature
epoxy fixed to the wire, it is used to analyze the water aromatic hydrocarbon compounds and polycyclic aromatic hydrocarbons, the coating surface area is large
, easy to achieve adsorption balance, can improve detection sensitivity; The analysis of ranitidine in the shredded tablets resulted in a lower detection limit (0.1 micrograms per liter), while porous divinyl benzene polymer coating materials could be used for the detection of induced denaturation agents, amphetamines and other drugs in the hetero-cyclamine class, and the detection limit was more than 1 microgram per litre; Conductive polymers are easy to introduce functional bases on or deposit metal ions on monomers and have multiple forces such as pi;-pi; action, even-pole action, acid-base action, etc., PPY energy in the air with organic solvents to maintain relative stability, and its monomers and derivatives are readable, Wu et al. as a coating material successfully on the s beta -The analysis of substances such as the subject blocker proves that PPY has a high extraction efficiency, PPY can also be used for the detection of drugs such as acetaminothyst, and even ion-type objects to be tested; coating material must meet the treatment of the test has a strong extraction capacity, but also in the commonly used organic solvents to maintain sufficient stability, in fact, the coating is difficult to meet both aspects, such as PA after the use of 10-20 times because of damage and can no longer be used, which makes the reproducible method of SPME is subject to certain constraints. The thicker the coating material, the greater the amount of absorption of the treatment, the lower the minimum detection limit, but at the same time will increase the balance extraction time, slow down the analysis speed, rather than bonding phase in the solvent has a certain amount of swelling on the coating thickness should also be considered. 2.1.2 Sample volume, container volume Since solid-phase micro-extraction is a fixed extraction process, in order to ensure the effect of extraction needs to be selected for the sample amount, the volume of the sample container. The amount of sample and the volume of the sample container have a great relationship to ensure the results, there is a matching relationship between the sample amount and the volume of the sample container, the reappearability of the sample increased significantly, and the amount of detection increased. 2.1.3 Extraction time extraction time is the time required to reach the adsorption balance from quartz fibers and samples. In order to ensure that the test results are reproducible, the extraction time should be kept in the test. There are many factors that affect the extraction time, such as distribution coefficient, diffusion velocity of the sample, sample size, container volume, substation of the sample itself, temperature, etc. In the initial stage of extraction, the analysis parts are easy and quick to rich into the fixed phase of quartz fiber, with the extension of time, the rate of accumulation is more and more slow, close to the equilibrium state even if the time extension is not meaningful to the rich, so in the exploration of experimental methods must do rich - time curve, from the curve to find the best extraction point of time, that is, the curve is close to the shortest time of flat. The general extraction time is within 5 to 60 min, but there are special cases. 2.1.4 Using inor add a small amount of sodium chloride and sulfur to the liquid sample.