Two Step Extraction Of Pyrethrins From Pyrethrum

Two yard kick upion Of Pyrethrins From genus genus PyrethrumThe experimental determination of the concentration and brook of pyrethrins from chrysanthemum pyrethrum immixer is usually carried out with chromatographic techniques and accordingly, a lot of methods form been developed over the years Wang et.al, (1997). These include exalted gear performance tranquil chromatography (HPLC) Todd et.al, (2003) Essig and Zhao, (2001b), brag chromatography (GC) Essig and Zhao, (2001a) and super exact fluid chromatography (SFC) Wenclawiak and Otterbach, (1999). GC was chosen for convenience in this theme. The introductory off-step involves victimisation n-hexane as answer to repeat the pyrethrins from the solid adjudicate (grounded and unsieved with particles sur present of about 30 meshes), and and so the second-step, a civilization step involves the engagement of supercritical atomic piece 6 dioxide as firmness of purpose to obtain the pyrethrins from the crude hexane draw up (CHE). The hexane roots (100g warning size), in a water bath at controlled temperatures and supple stirring, gene dictated pyrethrins concentrations varying from 69.85 95.50mg/ml and submits of 0.85 3.76% of the dry weight. fall efficiencies under several check offs were investigated and the best bloodline condition was 400C in 4hrs. Comp bed with the product from the factory, several undesirable components embody in the CHE. The SFE was carried out with a self built unit ( redundantction vessel of 120ml) with a savour size of 40ml of CHE. Concentrations of 57.25 93.79mg/ml and devolves (after the second downslope) of 0.99 2.15% were obtained with the best condition being 350C at a nip of 20MPa in 2hrs. Comp atomic number 18d with the product from the factory, this specimen conveys two extra components (Tricosane and Tetracosane) as well apply in dirt ball control. depict words Solvent beginning supercritical ampere-second dioxide pyrethrins two-ste p stemma crude pyrethrins call forthIntroductionPyrethrum flowers argon from the Chrysanthemum genus and are cognise commercially as painted daisies, painted ladies, buhach, chrysanthemum cinerariaefolium, ofirmotox, insect powder, Dalmatian insect flowers, or parexan. It is believed to be recorded first in Dalmatia Visiani, (1842-1852). However, opposites contend that its insecticidal bodily process was first proven by Antun Drobac (1810-1882) Bakaric, (2005). Yet there are claims that it was first identified as having insecticidal properties around 1800 in Asia Jeanne, (2009) and that the Crushed and powdered plants were design as insecticides by the Chinese as early as gee BC Amrith, (2004). The flower contains about 1-2% pyrethrins by dry weight, just now around 94% of the constitutional proceeds is concentrated in the assembleds Casida and Quistad, (1995). The chemical anatomical structure of the bustling ingredients, pyrethrins I and pyrethrins II was identified in 1924 Chandler, (1948) Coomber, (1948). Kenya is the worlds main producer today with to a greater extent than 70% of the global supply Jones, (1973). The natural active ingredients are referred to as Pyrethrins consisting of cinerin I, jasmolin I, pyrethrin I, cinerin II, jasmolin II and pyrethrin II. The first three (chrysanthemic acid esters) are referred to as pyrethrins I (PYI), and the rest (pyrethric acid esters) as pyrethrins II (PYII) Essig and Zhao, (2001a). Pyrethrins, though in dissoluble in water, are soluble in many positive solvents WHO, (1975). They are non-volatile at ambient temperatures non-toxic to mammals and other worm-blooded animals full(prenominal)ly unstable in climb down (photodegradable) biodegradable that toxic to aquatic animals Todd et.al, (2003) Chen and Casida, (1969) WHO, (1975). Their exercise is mainly in biological figure out protection domestic insecticides Gnadinger, (1936) and the formulations of artificial pyrethroids Todd et.al, (2 003). Although pyrethrins are soluble in a number of organic solvents (benzene, hexane, vegetable oil ether, alcohol, acetone, methanol, chlorinated hydrocarbons, etc) other considerations (practical, economic and environmental concerns) limit the usage. These considerations reduce the choices to just few. wiz of the qualities of Hexane in extracting pyrethrins is its ability to military forceively dissolve the active ingredients minus contaminants. other is that its removal from the concrete is achieved at lower temperatures limiting degradation imputable to prolonged warmnessing. Again, its low boiling point is a needed flavour and it discharge be recycled, reducing the weight of the concrete. Above all, it is inexpensive, considered environmentally friendly, little toxic, non-corrosive, and non-reactive traits which make it the dominant solvent adopted, especially for processing plant (biological) materials (products) which are often thermally labile, lipophilic, and non- volatile and are required to be unplowed and refined at around room temperatures. Carbon dioxide (CO2) has a critical temperature of 31oC which makes it particularly an attractive medium for these kinds of tasks. Though other supercritical fluids (SCFs) show critical temperatures in this critical state and can be adapted as solvents, they are often difficult to handle and obtain in perfect(a) state, whitethorn be toxic, explosive or ecologically unsafe. Supercritical carbon dioxide (Sc-CO2) is by far, the most extensively occasiond due to its non-toxic, inert and non-flammable nature. It is similarly natural, inexpensive, plentiful, non-toxic and inflammable and generally environmentally accepted Schneider et.al, (1980). Its most important properties are enhanced dumbness, viscosity, diffusivity, heat capacity and thermal conductivity. Higher densities contribute to great dissolution of compounds while low viscosities enable easy penetration into samples and facilitation of fl ow of extracted (targeted) molecules from the source materials with fewer hindrances Dunford et.al, (2003). Diffusivity offers easy and faster transport through samples thus offers amend inception strengths and dissolved ingredients are also easily detached from the supercritical solvent by drop in weightlifture Fattori et.al, (1988). Sc-CO2, for the supra and many reasons used as solvent in extraction saves both(prenominal) time and money while retaining overall extraction precision and the true with high purity and healthy products that are of excellent quality Raventos et.al, (2002) Mohamed and Mansoori, (2002). Expectedly, a lot of research is now focused on the extractions of plant materials with supercritical carbon dioxide due primarily to the global growing solvent (organic) regulations and more(prenominal) importantly, the economic benefits (in terms of low operating temperatures faster extractions and easier purifications, and of course better product quality). Sta hl and Schutz Stahl and Schutz, (1980) extracted pyrethrins with CO2 and proposed that in the 20C to 40C temperature feed corruption (usually associated with pyrethrins extraction) does non occur. Sims patented in the US, an extraction of pyrethrins using liquid carbon dioxide Sims, (1981) and Wynn and others patented using Sc-CO2 Wynn et al. (1995). Wenclawiak and coworkers compared extracts obtained with ultrasonic (USE) and Soxhlet extractions (SEX) with hexane and Sc-CO2 extractions (SCE) and report that operate extraction with SCE gave better pyrethrins content Wenclawiak et.al, (1995).2. 0. Experimental2.1. Materials and ChemicalsGrounded chrysanthemum (light green with a symptomatic smell) sample and two pyrethrum concretes (yellow) were obtained from Yunnan Juxiang instinctive Plant Products Company in China. The pyrethrins content of the concretes was claimed to be 50.0% (29.50% PYI and 20.50% PYII) and 85.15% (46.33% PYI and 38.82% PYII). Six individual streamer so lutions (using standard amplification method) were prepared (from the 85.15% PY concrete-higher content, less(prenominal) impurities) for standardization of the analytical method. Analytical grade hexane (97.0%) and neutral spirits (99.7%) were purchased from Sinopharm Chemical Reagent Co. Ltd in China, and used directly without any pre-treatment. CO2 (99.0 %) float was supplied by Xin Hongli torpedo Company also in China.2.2. ExperimentsThree disparate experiments were performedTo establish the standard/calibration curves for determining the components,To implement hexane extraction and come up the production of total PY in the grounded sample, andTo implement SFE and determine the break down of total PY in the CHE.2.3. Establishing Standard CurvesThe GC (Agilent) conditions used for establishing the standard curves are as follows split injector with 201 split ratio at 2500C northward as carrier gas at 1.6mL/min ow rate barb flashiness of 0.1 L temperature program started at 1800C, kept for 11 minutes, change at 100C/ min to 2000C, kept for 8 minutes, heated to 210 0C at 100C/min, kept for 18 minutes, then heated to 2450C at 30 0C/min, maintained for 4 minutes FID detector HP-5 Column, 30 mm 0.32 mm id., 0.25 m lm thickness. This column was chosen because it gives the best resolution, identication and quantication for products containing OH and C=O Rosana, (2003). 2g (85.15% concrete obtained from the company) of the extract was transferred into a 100mL flaskful containing 10mL ethanol, and then made up to the final volume of with ethanol and mixed well. Six aliquots (1mL, 2mL, 4mL, 8mL, 16mL and 32mL) of this solution were transferred into a 50mL flask distributively and diluted with ethanol again to the mark. We then calculated the concentrations of the PY in apiece aliquot, considering the percentage of each group (PYI and PYII) in the sample provided (Table A1 in the Appendix), injected (with a micro syringe) 0.1L of each solution into the G C after filtering (0.45-m membrane filter) and recorded the elution times and corresponding peak areas (Table A2) subsequently, established the standard curves to express the relationship between the areas produced by the GC and the concentrations (Figure 2).2.4. Hexane extractionWe extracted pyrethrins (from 100g of grounded sample of particle size of about 30mesh) with hexane in a water bath (YUHUA, DF-101S) in destinyes at different temperatures (35oC, 40 oC, 45 oC, 50 oC, 60 oC and 70 oC) and times (3hrs, 4hrs, 5hrs, 6hrs and 7hrs) in a 1000mL round- rotter flask, installed with a condenser. agitation was achieved by stirring sprightlyly with three big size magnetized stirrers at a step on it of 20rpm. The hexane was then removed from the pyrethrin concrete with a rotary evapourator (YUHUA, RE-2000B) at a temperature of 35 oC at a speed of 185rpm to obtain concentrated Crude Hexane Extract (CHE). Each concentrated sample was thereafter, filtered (0.45m) and 0.1L analyzed (Tables A3). This method has the advantage that the solvent is repeatedly recycled and temperature can be controlled. It offers a light coloured product with high recovery rate of pyrethrins however, not only the desired components are extracted (Figure 3). Other soluble and hydrophobic substances (waxes and pigments) are also extracted Kiriamiti et al, (2003). The solvent is removed by vacancy at lower temperature and the waxy thick mass left is the concrete composed of essential oils and other oil soluble (lipophilic) materials.3.0. Results and Discussion3.1. ExtractThe extracts (CHE) contain pigments, pertinacious oils and waxes whose colour is deep yellow with characteristic smell. It also contains several undesired components (Figure 3) compared with the pure sample from the factory (Figure 1).3.2. settlementant of Extraction TemperatureTemperature has long been reported to be a crucial factor in the extraction of natural pyrethrins Atkinson et.al, (2004). Pyrethrins are s ensitive to temperature (thermo labile) and are therefore, unanimously reported to sink above 40oC Stahl and Schuzt, (1980) Gourdon and Romdhane, (2002) Wynn et al, (1994). We investigated the effect of different extraction temperatures (40oC, 50oC, 60oC and 70oC) in fixed extraction times (5 hr gave better results than 6hr and 7hr). Our results conform to the reports (refer to Figure 4 and Table A3) the best yield (1.42) and PYI PYII ratio (4.75) is at 40oC (but the best PYII yield-0.33 is at 70oC). This suggests that targeted components are extracted effectively at this temperature (40oC), above which two problems occur (separately or simultaneously) one is the extraction of more undesirable components at the expense of pyrethrins and the other is the decomposition of pyrethrins to form iso-pyrethrins Stahl and Schuzt, (1980) Stahl, (1998) Gourdon and Romdhane, (2002) Wynn et.al, (1994) thereby reducing the yield as seen.3.3. arrange of StirringWe compared the effect of two sti rring methods on extraction yield the first with one charismatic stirrer and the second with three magnetic stirrers. The results are shown in Table A4, confirming that stirring improves extraction yield by facilitating the dissolution of the active ingredients and the effective distribution of heat. The extractions (at 40oC in 5hr) were repeated severally to ensure reproducibility and accuracy.3.4. Effect of Extraction TimeWe pass on investigated the effect of extraction time by fixing the extraction temperature at 40oC with three magnetic stirrers to establish the optimum extraction time (our sign time parameters were 5hr, 6hr and 7hr in which 5hr was the best). From Figure 5, the extraction yield step-ups steadily from 3hr to a peak at 4hr (see data in Table A5). Within this range, more desired components are extracted but after 4hr the yield decreases indicating that with prolonged time, as yet at the safest extraction temperature (40oC), less and less desired components are extracted and/or they decompose resulting in the decrease in yield. The drop in yield is consistent from 4hr (3.76%) to 6hr (2.15%). This implies that the optimum time ( deep down the times investigated) is not 5hr as initially expected but rather 4hr. However, the ratio of PYI PYII is best in 6hr (5.14). From 3hr to 4hr, the yield for both PYI and PYII appreciated but the increment in PYI (0.74) is greater than that of PYII (0.38) indeed the drop in the ratio. Between 4hr and 5hr, there is decrease in both PYI and PYII yields. Again, the decrease in PYI (0.98) is greater than that of PYII (0.49) accounting for the drop in ratio. The homogeneous reason accounts for the drop in ratio from 5hr to 6hr.3.5. Effect of Concentrating CHEThe effect of concentrating the CHE, on both PYI and PYII yield was analyzed (Table A6). Even though the concentrating temperature (35oC) was below the temperature above which PY degrades (40oC), there was loss in PY yield indicating degradation. This in our view may be due to the exposure of the pyrethrins directly to heat. As more hexane is evapourated, pyrethrins which hitherto, were locked in the solid sample matrix surrounded by hexane and as such shielded from direct heat, is now in direct contact with the heat and since they are sensitive to heat, decomposition is inevitable. However, the decomposition is small and negligible (about 2.25mg/ml which is about 0.41% of the total yield) due to perhaps the short concentrating time (about 30 min).4.0. Supercritical runny Extraction (SFE)The CHE is too thick (viscous) to be used directly, coupled with the presents of undesirable components (waxes and pigments). A further treatment, usually with another solvent that only dissolve the desired compounds from the concrete is necessary. Different from other works, this study carried out SFE on the CHE as a purification step. We looked at the effect of time (hr), temperature (0C) and pressure (MPa) on extraction quality and yield. We h ave not studied the effect of particle size and pre-treatment for information on this area, see the works of Kiriamiti and others Kiriamiti et al, (2002).4.1. SampleWe concentrated the CHE in a rotary evapourator (from 500ml to 40ml at 185rpm in 30 minutes) for the SFE.4.2. Extraction ProcessAt the beginning of the extraction (Figure 6), all the check valves are closed except valve 2. This allows the CO2 gas into the compressor 4 (OLSB by Zheng Zhou Co. LTD, China) to be compressed, and the pressure gauges are allowed to create equilibrium at a set pressure (10, 15 and 20 MPa). Valve 5 is then opened and the compressed fluid (Sc-CO2) is fed into the bottom of the extraction vessel 7 (120ml capacity) for up flow extraction configuration, containing the CHE (40ml) and metallic element fillings to facilitate effective contacting (increase internal mass transfer) which had earlier been heated to a set temperature (350C, 370C and 390C) and allowed to attain constant temperature with the help of the water bath 6. An appreciable time is allowed (5-10mins) for the total and complete dissolution of the crude extract and then valve 8 is opened and maintained until the pressure is in equilibrium again. The pressure reducing valve 9 is opened finally to collect the pyrethrins in the flask 10. A mass flow meter helps to determine the flow rate (1.5L/min). The extraction process is run and stopped at set times (1hr, 2hr and 3hr) and the extracts analyzed with the results tabulated (Table A8). The Metal fillings after each run were washed (10ml or 5ml of Hexane) and collected as residues to check for complete extraction.5.0. Results and Discussion5.1. ExtractsThe extracts did not contain visible pigments as was seen in the CHE. The colour was also different light yellow to orange but the smell was similar. It also contained two extra components (Figure 10) which was found (by GC mass spectrometry) to be Tricosane (Peak 6) and Tetracosane (Peak 7). This was as a result of co mparison with the pure sample from the factory (Figure 1).We compared the yield of the extracts after solvent extraction, concentrating the CHE and the SFE and noted that there was difference. The yield from the SFE was less due possibly, to the relatively high pressures used. Separation of the Sc-CO2 and the product is achieved by a drop in pressure. These high pressures have the tendency of causing the products to remain in the BPR or along the pipe (between the BPR and the flask in Figure 6) due to clotting as a result of the pressure drop in spite of our use of heating tapes to minimize this effect. This is confirmed by the value of the yield in the residue (0.05%) which is far less compared to the difference between the concentrated sample yield (3.30%) and that of the SFE (2.15%, see Table A10).5.2. Effect of PressureAccording to Kiriamiti and others, the quantity of pyrethrins extracted decreases with decreasing pressure due to (i) the effect of density on the solvability of pyrethrins, (ii) the slightly high density of CO2, (iii) the moderate variation in density with pressure, and (iv) the very low undesirable extracted products Kiriamiti et al, (2002). Our results conclusively conform to this (Table A7). The best extraction pressure was at 20MPa (at 350C and 2hrs). The concentration of PY also increases within this pressure range (from 81.34mg/ml 93.79mg/ml). Similar phenomenon was observed for both 1hr and 3hrs, indicating that more pyrethrins were extracted than the undesirable components within this pressure range (Figure 7).5.3. Effect of Extraction TimeThe quantity of pyrethrins extracted decreases with extraction time at higher temperatures (above 400C), explaining that either pyrethrins decompose at these empyreal temperatures or more undesirables are extracted instead. From Table A8, the yield and concentration of PY increase from 1hr to a maximum in 2hr (1.35% 2.15% and 90.42mg/ml 93.79mg/ml at 350C and 20MPa). some(prenominal) however decrease in 3hr (1.24% and 82.30mg/ml, Figure 8). This implies that pyrethrins were extracted faster than the undesirables from 1 to 2hr but as the extraction proceeds, more undesirables were then extracted at the expense of the pyrethrins or which decompose. Therefore, prolonged extraction time rather favours the extraction of undesirables or promotes decomposition of pyrethrins.5.4. Effect of TemperaturePyrethrins are thermo labile and therefore require being touch on at low temperatures. Therefore, high extraction temperature does not only degrade the pyrethrins but also favours the extraction of undesirables (Figure 9). Within the temperature range we investigated, the best yield was at 350C (Table A9).6. 0. ConclusionsPyrethrins are usually purified with organic solvents (ethanol, methanol, acetone, acetonitrile, petroleum ether etc) or their mixtures Kasaj et.al, (1999) Henry et.al, (1999) Duan et.al, (2006) which are generally expensive, flammable and explosive and above al l, face strict legislative controls Patrick, (2003). Alternatively, carbon dioxide is used to refining and purification. Sims proposed the use of liquid carbon dioxide Sims, (1981). Similar to our method, Kiriamiti and others reported the extraction of pyrethrins from crude hexane extract (CHE) from batch extraction experiment using carbon dioxide Kiriamiti et.al, (2003) but with different extracting conditions and synopsis method (HPLC). It is worth noting that our set up is very simple and less expensive coupled with the fact that our sample, after the SFE, contains two extra components (Tricosane and Tetracosane) not reported so far as part of the purification step. These components are not hazardous Directive 67/548/EEC and have similar characteristics (may cause respiratory and digestive irritations), uses (as insecticides and biopesticides) and effects (they may not be detrimental to the insects but they certainly disrupt their behaviuor patterns and flushes them out for the more deadly pyrethrins I) as pyrethrins II Chemcas.org Chemnet.com PPDB, (2011) Wylie, (1972) Lewis et.al, (1975). We developed a simple but efficient two-step surgical operation for the extraction of pyrethrins from chrysanthemum (pyrethrum flowers) and investigated the effect of various operating parameters on concentration and extraction yield. Based on the experimental results, we conclude that the two-step extraction of pyrethrins (first with hexane in a water bath and second with SC-CO2 as a purification step) is feasible and effective the optimum extraction condition for high pyrethrins yield (3.76%) for the n-hexane extraction was 400C in 4hr that vigorous stirring facilitated this and that it is possible to achieve extraction yield of 3% or even more envisaged by Casida and Quistad. To our knowledge, this is the first time such a high recovery of pyrethrins is reported. A number of reasons may be attributed to this high recovery i) extraction procedure, ii) choice of solve nt, iii) vigorous stirring and above all, vi) the type of sample used. 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