Multi-Residue Pesticide Screening And . - Chem-agilent
Multi-Residue Pesticide Screeningand Quantitation in Difficult FoodMatrixes Using the Agilent 6495 TripleQuadrupole Mass SpectrometerApplication NoteAuthorsAbstractDan-Hui Dorothy Yang, Anabel Fandino,This Application Note describes a UHPLC/MS/MS-based multi-residue methodand Na Pifor the determination of more than 250 pesticides and pesticide metabolites inAgilent Technologies, Inc.food samples. The method benefits from the increased chromatographic resolutionSanta Clara, CAof the Agilent 1290 Infinity UHPLC System, the versatile ionization capabilitiesThomas GlaunerAgilent Technologies, Inc.Waldbronn, Germanyof the Agilent Jet Stream ionization source, and the innate sensitivity of theAgilent 6495 Triple Quadrupole LC/MS System. The method has been applied tothe analysis of pesticide residues in complex matrixes such as black tea. Matrixeffects in the ionization were controlled by extensive dilution of the sampleextracts prior to injection.Our results demonstrate that the increased sensitivity of the 6495 TripleQuadrupole LC/MS System enables the accurate quantitation of targetedpesticides below the maximum residue limits (MRLs) specified by the EuropeanCommission, most of them even in the 1:100 diluted extracts, with improvedprecision and excellent robustness.
IntroductionThe screening and quantitation ofpesticide residues in food products is oneof the most important and demandingapplications in food safety. There aremore than 1,000 pesticides and pesticidemetabolites that can be present in foodand, thus, are regulated and controlled.The European Commission regulation (EC)396/2005 and its annexes set maximumresidue limits (MRLs) for more than170,000 matrix‑pesticide combinationsfor food1. Similar regulations are in placein other regions. Most pesticides areanalyzed with multi‑residue methodscovering hundreds of compounds,which are applied to various foodcommodities for both screening andquantitation. Therefore, fast and reliableanalytical methods are required toallow identification and quantitationof hundreds of pesticides at lowconcentrations in a broad range of foodmatrixes with confidence. Criteria for theidentification of pesticide residues andrequirements for method validation andquality control procedures for quantitationare specified in guidance documents suchas SANCO/12571/20132.Matrix effects in electrospray ionization,which change considerably betweendifferent food samples, present asignificant challenge to the accuratequantitation of pesticides. There aredifferent strategies to compensate formatrix effects such as matrix matchedcalibrations, standard addition, or theuse of internal standards. However,matrix matched calibrations do notfully compensate for variations inmatrix effects within a commodity ora commodity group. Standard additionrequires multiple injections for eachsample, which reduces productivity.The use of isotopically labelled internalstandards is probably the most attractiveapproach, however, it is not applicable forall target compounds in a multi-residuepesticide method. Sample dilution isanother approach to minimize matrixeffects3 but requires the use of highlysensitive analytical instruments dueto the need to detect contaminantsbelow the MRLs stipulated by the EC.Furthermore, the extensive dilutionof sample extracts requires very highprecision, as even small deviationsresult in considerable inaccuracies whenmultiplied with high dilution factors.This Application Note shows thedevelopment of an UHPLC/MS/MSmethod for the screening and quantitationof hundreds of pesticides in food samples.The method was developed using thePesticide tMRM LC/MS ApplicationKit (p/n G1733BA). Transitions forall compounds in the comprehensivepesticide standard mix (p/n 5190-0551)and a few additional pesticides of interestwere included in the method. An Agilent1290 Infinity UHPLC System was coupledto the highly sensitive Agilent 6495 TripleQuadrupole LC/MS System operated withdynamic MRM mode with fast polarityswitching. Several modifications to theprevious high-end triple quadrupole massspectrometer design resulted in higheranalytical performance. New mass filter one (MS1) ionoptics for increased precursor iontransmission An improved curved and taperedcollision cell providing enhancedMS/MS spectral fidelity A new ion detector operating atdynode accelerating voltages of upto 20 kV A new autotune optimized forspeed and sensitivityIn addition, the 6495 Triple QuadrupoleLC/MS System uses the proven AgilentJet Stream Ionization source and the dualstage ion funnel. Enhanced sensitivitygives enhanced peak area response andimproved peak area precision, whichultimately leads to lower detection limitscompared to previous designs. Theenhanced sensitivity was used for theextensive dilution of complex food sampleextracts to minimize matrix effects in theelectrospray ionization. The improved2precision of the analytical method isdemonstrated for diluted black teasamples.ExperimentalReagents and chemicalsAll reagents and solvents were HPLC orLC/MS grade. Acetonitrile and methanolwere purchased from Honeywell(Morristown, NJ, USA). Ultrapure waterwas produced using a Milli-Q Integralsystem equipped with a LC-Pak Polisherand a 0.22-µm point-of-use membranefilter cartridge (EMD Millipore, Billerica,MA, USA). Formic acid was from Fluka(Sigma-Aldrich Corp., St. Louis, MO, USA)and ammonium formate solution (5 M)was from Agilent (p/n G1946‑85021).Pesticides were included in the Agilentcomprehensive pesticide mixture(p/n 5190-0551). A limited number ofadditional pesticides were purchasedfrom Fluka (Sigma-Aldrich Corp., St. Louis,MO, USA). Immediately before use, theeight submixes of the comprehensivepesticide mixture and the mixed stocksolution of the additional pesticideswere combined and further dilutedwith acetonitrile to a final pesticideworking solution containing more than250 pesticides at a concentration of10 µg/mL. This solution was used forspiking the QuEChERS extracts andfor the preparation of the calibrationsamples. Eight calibration sampleswith concentrations ranging from 0.02to 100 ng/mL were prepared in pureacetonitrile.Sample preparationTea, orange, and tomato samples wereobtained from a local grocery store.Samples were extracted according tothe citrate buffered QuEChERS protocolusing Agilent BondElut QuEChERSkits (p/n 5982-5650). Ten grams ofhomogenized fruit and vegetable or2 g of tea were weighed into 50-mLpolypropylene tubes and extractedwith 10 mL acetonitrile for 1 minutewhile shaking vigorously by hand. Thetea samples were wetted with 8 mLultrapure water for 2 hours prior toextraction. Raw extracts were cleanedup by dispersive SPE using primary
secondary amine (PSA, p/n 5982‑5256).In black tea samples, graphitized carbonblack (GCB) contained in the AgilentBondElut QuEChERS EN dispersiveSPE tubes (p/n 5982-5356H) was alsoused for cleanup. Final extracts of blanksamples were spiked in five relevantconcentrations with the comprehensivepesticide working solution and thendiluted 1:5, 1:10, 1:20, 1:50, and 1:100 withacetonitrile. Matrix matched standardsand dilutions were prepared immediatelybefore injection, and were measured withfive technical replicates.EquipmentSeparation was carried out using anAgilent 1290 Infinity UHPLC systemconsisting of an Agilent 1290 InfinityBinary Pump (G4220A), an Agilent 1290Infinity High Performance Autosampler(G4226A), a sample cooler (G1330B), andan Agilent 1290 Infinity ThermostattedColumn compartment (G1316C). TheUHPLC system was coupled to an AgilentG6495 Triple Quadrupole LC/MS Systemequipped with an Agilent Jet Streamelectrospray ionization source. AgilentMassHunter Workstation Software wasused for data acquisition and analysis(v. B.07.00).Data were evaluated using the AgilentMassHunter Quantitative AnalysisSoftware. Calibration was done usingneat standard solutions and linear,1/x weighted calibration curves. Thelower limits of quantitation (LLOQs)correlate with the instrument detectionlimits (IDLs) in black tea matrix. IDL iscalculated based on the relative standarddeviation of a series of replicates ofa low level sample that is not higherin concentration as 2 to 5 times thedetection limit. The IDL is defined as theTable 1. Instrument parameters.Agilent 1290 Infinity UHPLC SystemColumnAgilent ZORBAX RRHD Eclipse Plus C18, 2.1 150 mm, 1.8 µm(p/n 959759-902)Column temperature40 CInjection volume2 µLSpeedDraw 100 µL/min, Eject 200 µL/minAutosampler temp6 CNeedle wash10 s with acetonitrile/water (50/50; v/v)Mobile phaseA) 5 mM ammonium formate 0.1 % formic acidB) 5 mM ammonium formate 0.1 % formic acid in methanolFlow rate0.4 mL/minGradient programTime00.53.517.020.020.1Stop time20.1 minutesPost time3 minutesMethodThe 1290 Infinity UHPLC Systemconditions are summarized in Table 1, anda summary of the 6495 Triple Quadrupoleparameters are shown in Table 2.Identification of polarity, precursor andproduct ions, as well as optimizationof collision energies, was taken fromthe Agilent Pesticide tMRM LC/MSApplication Kit, and was further optimizedusing Agilent MassHunter OptimizerSoftware. Analysis was carried outwith positive and negative electrosprayionization in dynamic multiple reactionmonitoring (dMRM) in a single analyticalrun. A 2-μL amount of the final extractwas injected into the UHPLC/MS/MS.minimum amount of analyte requiredto produce a signal that is statisticallydistinguishable from background noisewith a confidence level of 99 %. Thisapproach has much more relevance forroutine operation as it avoids ambiguityrelated to the variation in the chemicalnoise and subjectivity in the waysignal‑to-noise (S/N) is determined4. Inaddition, it is directly correlated to theprecision of the analytical method, whichis important when doing an extensivedilution of sample extracts.B%55501001005Agilent 6495 Triple Quadrupole LC/MS SystemIon modePositive and negative ESI with Agilent Jet StreamScan typeDynamic MRMDrying gas temperature120 CDrying gas flow17 L/minSheath gas temperature300 CSheath gas flow12 L/minNebulizer pressure30 psiCapillary voltage3,500 (pos/neg)Nozzle voltage300 V (pos); 500 V (neg)Cycle time500 msecTotal number of MRMs532 (positive: 509/negative: 23)Maximum number ofconcurrent MRMs68Minimum dwell time5.10 msMaximum dwell time249.09 msMS1 and MS2 resolutionUnit3
Results and Discussionparameters such as collision energyand cell acceleration voltage were fineoptimized but only minor deviation fromoptimized values for previous models wasobserved. The prefilter and the detectorwere adjusted according to mass duringthe instrument’s autotune. Sheath gastemperature was optimized using theMassHunter Source Optimizer Softwareto produce the highest abundance forthe majority of target compounds, and tonot compromise labile and ammoniumadduct-forming compounds.Development of theUHPLC/MS/MS methodThe pesticide screening methoddeveloped for the Agilent Pesticide tMRMLC/MS Application Kit was transferredto the 6495 Triple Quadrupole LC/MSSystem. The method was extendedto include several relevant acidicherbicides, and fast polarity switchingwas employed. Compound-dependentFigure 1 shows the chromatogram ofa tea extract spiked with more than250 pesticides at a concentrationof 10 µg/kg, and diluted 1:20 withacetonitrile prior to injection.Fenazaquin 10 dPyriproxyfenIvermectin 5FuralaxylDEET1.610 10.5 11 11.5 12 12.5 13 13.5 14 14.5 15 15.5 16 16.5 17Acquisition time (min)Figure 1. Chromatograms of more than 250 pesticides spiked into black tea at the MRL and diluted 1:20 with acetonitrile (corresponding to a concentration of0.1 ng/mL). For the sake of clarity, only part of the chromatographic peaks are labelled.4
Evaluation of increasedinstrument performanceThe MS1 ion optics has demonstrateda noticeable increase in the precursorion transmission, and an increase upto a factor of 3 has been observed,depending on the ion mass. In addition,the detector design results in signal gainsespecially for large fragment ions andnegative ions across a broad mass range.When comparing the area response ofpesticides acquired with the 6495 TripleQuadrupole System to results from theearlier model, a compound dependentarea gain of up to a factor of 5 wasobserved.Enhanced ion transmission not onlyresulted in increased peak areas butalso in improved peak area precision.These enhancements ultimately lowereddetection limits compared to previousdesigns. The empirical observation thatsupports this hypothesis is shown inFigure 2, which compares the obtainedarea RSDs on a 6495 Triple QuadrupoleSystem versus a 6490 Triple Quadrupolefor 50 pesticides spiked into black tea atthe MRL and diluted in different ratioswith acetonitrile. The selection of these50 pesticides was based on relevance.Several of those compounds were foundin official control samples above theMRL and thus, the import of tea into theEuropean Union was blocked. The area ofthe blue polygon is considerably smallerthan the area of the red polygon, whichindicates that the improved ion statisticsof the 6495 Triple Quadrupole Systeminstrument translates into considerablylower RSD values for most pesticidesat the same dilution levels. The relativestandard deviation (RSD) of a series ofreplicates at a low concentration level isa universal measure of the ion efficiency,and can be used for the estimation ofthe quantitation limits. A low RSD valuehas much more relevance than S/Nmeasurements, which can change basedon the selected noise region and thesoftware algorithm used for calculation.A particular RSD can be defined as theminimum amount that can be reliablydetected, as long as the noise level doesnot significantly contribute to RSD values.For pesticide residues, a maximumRSD of 20 % has been specified as theminimum performance requirement inSANCO/12571/2013.Acephate (1 in 100)Acetamiprid (1 in 100)Triazophos (1 in 100)Alanycarb (1 in 50)Thiamethoxam (1 in 100)25.0Aldicarb (1 in 50)Thiacloprid (1 in 100)Azaconazole (1 in 50)Thiabendazol (1 in 100)Tebufenozid (1 in 50)Tebuconazole (1 in 50)Azinphos -ethyl (1 in 20)20.0Azinphos -methyl (1 in 20)Azoxystrobin (1 in 100)Spinosyn A (1 in 50)Pyridaben (1 in 100)Pirimicarb (1 in 100)15.0Benalaxyl (1 in 100)Bifenthrin (1 in 100)10.0Buprofezin (1 in 100)Phosalone (1 in 50)Oxamyl (1 in 100)Butocarboxim (1 in 20)5.0Carbaryl (1 in 50)Nitenpyram (1 in 20)0.0Monocrotophos (1 in 100)Carbendazim (1 in 100)Methomyl (1 in 50)Chlorantraniliprole (1 in 20)Methidathion (1 in 20)Chloroxuron (1 in 100)Methamidophos (1 in 100)Chlorpyriphos (1 in 50)Metamitron (1 in 100)Cyazofamid (1 in 50)Isocarbophos (1 in 100)Cycluron (1 in 100)Imidacloprid (1 in 20)Desmedipham (1 in 100)Imazalil (1 in 20)Diethofencarb (1 in 100)Fuberidazol (1 in 100)Difenoconazole (1 in 50)Flufenoxuron (1 in 100)Dimethoate (1 in 100)Ethion (1 in 100)Dimethomorph (1 in 20)Diuron (1 in 100)Dimoxystrobin (1 in 100)Diniconazole (1 in 20)6490 (RSD in %, n 5)6495 (RSD in %, n 5)Figure 2. Comparison of area RSDs for pesticides spiked into black tea at the MRL and diluted in different ratios with acetonitrile for the Agilent 6495 LC/MS(blue) and the Agilent 6490 Triple Quadrupole (red).5
With the updated design of the 6495Triple Quadrupole LC/MS System,more pesticides can be detected at lowconcentrations in QuEChERS extracts ofdifferent food commodities according tothe quality criteria specified in the SANCOguidelines. In tomato and orange extracts,all pesticides were easily detected at thelowest spiked concentrations of 1 ng/g.The tea matrix at this concentration hasa slightly smaller detection rate due tothe 5-fold lower sample amount and themore complex matrix. Figure 3 showsthe detection rate of the pesticides fordifferent dilution levels in the black teamatrix.Under the applied experimentalconditions, approximately 67 % of all thespiked pesticides were easily detectedwith an RSD below 20 % in the 1:100dilution, corresponding to a concentrationof 0.02 ng/mL. In addition, approximately20 % were detected with acceptableprecision in the 1:50 dilution, and another 10 % in the 1:20 dilution. Excellentprecision was observed for replicateinjections of these samples within a72‑hour worklist.Minimizing matrix effects bydilution of sample extractsThe ability to extensively dilute sampleextracts to remove matrix effects is anattractive capability to many routinetesting labs. It enables quantitationof complex samples against a solventcalibration. A possible cause for matrixeffects in electrospray ionization is thelimited number of excess charges, andthe limited space on the surface of thecharged droplet. The dilution of thematrix frees up space at the surface,resulting in more efficient ionizationof the target compounds. In addition,the amount of matrix injected to theLC/MS system is limited, which resultsin increased robustness of the analyticalmethod, minimization of instrumentcontamination, and increased instrumentuptime.314221:5 dilution451:10 dilution1:20 dilution1701:50 dilution1:100 dilutionFigure 3. Pesticides spiked in black tea extract to 2 ng/mL and diluted at different levels. 170 pesticidescan be detected at the 1:100 dilution level with an area RSD 20 %. Additional compounds are detectedat higher concentrations, that is, at lower dilution levels.Figure 4 shows the chromatograms ofalanycarb and oxamyl spiked in black teaextract corresponding to 10 µg/kg anddiluted with acetonitrile prior to injectionin different dilution ratios.Upon 1:5 dilution, the signal for alanycarbincreased. For oxamyl and the furtherdilution levels of alanycarb, the peakareas decreased less than the extentto which the target compounds werediluted. Dilution typically causes thefinal concentrations of the pesticidesto increase until the point at whichcomplete recovery is achieved. Table 3shows the recoveries in black tea extractfor 10 pesticides and different dilutionratios.6While a weak matrix effect was observedfor diuron and flufenoxuron, the signalsuppression for monocrotophos andalanycarb in the nondiluted tea wassubstantial. However, when diluting thefinal extract 1:10, more than half of thecompounds showed adequate recoveriesof over 70 %. Very few compoundsrequired a larger dilution of 1:50, or even1:100 to minimize the matrix effects toachieve acceptable recoveries basedon a solvent calibration. In the 1:100dilution, all detectable pesticides showedfull recovery and basically no signalsuppression. This is in agreement withpublished results, which showed that theAgilent Jet Stream Ionization requiredless dilution to eliminate matrix effectscompared to equivalent techniques3.
10 ng/g in black tea[Alanycarb]10 ng/g in black tea, 1–5 dil[Alanycarb]10 ng/g in black tea, 1–10 dil[Alanycarb]10 ng/g in black tea, 1–20 dil[Alanycarb]10 ng/g in black tea, 1–50 dil[Alanycarb]10 ng/g in black tea,1–100 dil [Alanycarb]400.1 & 238.0 Area 17,039400.1 & 238.0 Area 23,661400.1 & 238.0 Area 14,572400.1 & 238.0 Area 5,812400.1 & 91.0 Area 2,064400.1 & 238.0 Area 2,011400.1 & 91.0 Area 833400.1 & 238.0 Area 1,294400.1 & 91.0 Area 219400.1 & 91.0 Area 4,165 10 3 10 3 400.1 & 91.0 Area 4,817 10 3 400.1 & 91.0 Area 7,722 10 33.43.4 1:53.03.03.4 1:103.03.43.0 10 33.41:203.0 10 33.4 .00.60.60.60.60.60.60.20.20.20.20.20.211.6 11.8 12.011.6 11.8 12.011.6 11.8 12.011.6 11.8 12.011.6 11.8 12.011.6 11.8 12.010 ng/g in black tea[Oxamyl]10 ng/g in black tea, 1–5 dil[Oxamyl]10 ng/g in black tea, 1–10 dil[Oxamyl]10 ng/g in black tea, 1–20 dil[Oxamyl]10 ng/g in black tea, 1–50 dil[Oxamyl]10 ng/g in black tea,1–100 dil [Oxamyl]237.0 & 72.1 Area 45,373237.0 & 72.1 Area 22,084237.0 & 72.1 Area 13,029237.0 & 72.1 Area 8,135237.0 & 72.1 Area 3,354237.0 & 72.1 Area 1,741 10 3 237.0 & 90.1 Area 7,955 10 3 237.0 & 90.1 Area 3,906 10 3 237.0 & 90.1 Area 2,329 10 3 237.0 & 90.1 Area 1,436 10 3 237.0 & 90.1 Area 604 10 3 237.0 & 90.1 Area 33688 1:58 1:108 1:208 3.94.18 1:1003.53.73.94.1Figure 4. Comparison of peak areas for alanycarb and oxamyl spiked in black tea and diluted with acetonitrile 1:5, 1:10, 1:20, 1:50, and 1:100 prior to injection.Table 3. Recoveries for selected pesticides calculated for different dilution ratios. Cells shaded in green comply with requirements of SANCO/12571/2013.AnalytesNo dilution (n 5)Dilution 1:5 (n 5)Dilution 1:10 (n 5)Dilution 1:20 (n 5)Dilution 1:50 (n 5)Dilution 1:100 (n 5)Acetamiprid29.4 0.857.3 1.467.5 3.779.9 2.991.8 5.2109.5 3.4Alanycarb10.4 1.373.9 2.281.5 14.385.7 11.187.6 4.7121.7 10.8Aldicarb36.9 1.069.9 1.478.0 3.591.0 4.295.2 8.8104.9 14.1Carbaryl56.9 1.880.1 3.880.8 4.196.1 7.2102.6 6.6116.4 9.6Dimethoate33.9 1.768.6 2.484.1 5.489.0 7.988.2 8.884.7 7.5Diuron79.7 4.090.4 7.091.7 4.994.9 7.289.2 7.3100.9 13.5Flufenoxuron95.4 1.188.8 1.689.4 3.893.3 5.8100.0 6.1119.2 13.9Monocrotophos4.6 0.313.9 0.321.8 0.833.8 1.158.5 2.095.1 5.7Oxamyl20.8 0.752.6 1.965.0 2.079.7 3.091.2 4.6110.6 5.2Thiamethoxam40.0 1.445.9 0.946.6 3.852.2 1.770.9 2.997.3 2.07
ConclusionsReferencesAn UHPLC/MS/MS based multi-residuemethod for the determination of morethan 250 pesticides and pesticidemetabolites has been developed. Ittakes full advantage of the low delayvolumes of the Agilent 1290 Infinity LCSystem and its ability to handle highback pressures in UHPLC separations forincreased chromatographic resolution.The method benefits from the highlysensitive Agilent 6495 Triple QuadrupoleLC/MS System and from the versatileionization capabilities of the Agilent JetStream ionization source. Dynamic MRMacquisition and fast polarity switchingwere used to maximize dwell timesfor each individual compound. Sourceparameters were optimized to achievegood sensitivity across the suite of targetcompounds.1. Regulation (EC) No 396/2005 ofthe European Parliament and ofthe Council of 23 February 2005 onmaximum residue levels of pesticidesin or on food and feed of plant andanimal origin (including amendmentsas of 18 March 2008) and complyingwith regulation (EC) 1107/2009.The method was applied to the analysisof pesticides in complex matrixes such asblack tea. Enhanced sensitivity allowedfor more flexibility in the degree of sampledilution. With any dilution, a lower matrixamount is introduced into the LC/MSsystem leading not only to fewer matrixeffects, but also to improved methodrobustness and increased instrumentuptime. Extensive dilution of sampleextracts was applied to minimize matrixeffects, and to allow quantitation of allpesticides within the acceptable recoveryrange of 70 to 120 % based on a solventcalibration. The increased sensitivityof the 6495 Triple Quadrupole LC/MSSystem allowed the quantitation of themajority of all targeted pesticides belowthe maximum residue limits specifiedby the European Commission, even inthe 1:100 diluted extracts with improvedprecision and excellent robustness.2. Guidance document on analyticalquality control and validationprocedures for pesticide residuesanalysis in food and feed.Document N SANCO/12571/2013.Implemented by ocs/allcrl/AqcGuidanceSanco 2013 12571.pdf3. Stahnke, H., et al. Reduction of MatrixEffects in Liquid Chromatography Electrospray Ionization MassSpectrometry by Dilution of theSample Extracts: How Much Dilutionis Needed? Anal. Chem. 2012, 84,pp 1474-1482 (incl. supportinginformation).4. Parra, N.P., Taylor, L. Why InstrumentDetection Limit (IDL) is a BetterMetric for Determining the Sensitivityof Triple Quadrupole LC/MS Systems.Agilent Technologies TechnicalOverview, publication number5991‑4089EN, 2014.www.agilent.com/chemThis information is subject to change without notice. Agilent Technologies, Inc., 2014Published in the USA, June 13, 20145991-4687EN
Agilent 1290 Infinity UHPLC system consisting of an Agilent 1290 Infinity Binary Pump (G4220A), an Agilent 1290 Infinity High Performance Autosampler (G4226A), a sample cooler (G1330B), and an Agilent 1290 Infinity Thermostatted Column compartment (G1316C). The UHPLC system was coupled to an
1.6 Wood Residue Combustion In Boilers 1.6.1 General1-6 The burning of wood residue in boilers is mostly confined to those industries where it is available as a byproduct. It is burned both to obtain heat energy and to alleviate possible solid residue disposal problems. In boilers, wood residue is normally burned in the form of hogged wood, bark,
4.4 Emerging and re-emerging infections 43 4.5 Clinically insignificant transfusion-transmissible infections 44 5 Blood screening, quarantine and release 45 5.1 Blood screening process 45 5.2 Approaches to blood screening 45 5.3 Pooling for serological assays 47 5.4 Sequential screening 47 5.5 Blood screening and diagnostic testing 48 5.6 Emergency screening 48 5.7 Screening plasma for .
Plant Health Engineering Division, NIPHM Page 1 INTRODUCTION PESTICIDE APPLICATION TECHNIQUES Pesticide application plays an important role in pest management. Proper technique of application of pesticide and the equipment used for applying pesticide are vital to the success of pest control operations.
than that of cottonseed hull. The residue after environmental protection treatment, through drying and analysis of the dried residue, shows that the biopharmaceutical residue is rich in a variety of - organic substances, and no heavy metal mercury is detected. It is a very high-quality organic matrix material. 3.
build up, leaving a thin film of carbon residue on the rock surfaces. This residue forms the outline of the organism and is called .! A. petrified residue B. carbonaceous film C. trace fossil residue D. carbon-dated remains GEOLOGIAL PERSPECTIVE
A low fiber diet is a normal diet with a reduced amount of fiber (less than 10-15g of fiber) whereas the low residue diet includes the low fiber diet and some other foods that are high residue but low fiber. For example, milk doesn't have any fiber but can leave a residue in the large intestines.1
Ciba Specialty Chemicals conducted the following small-scale rheology modifier trials at Alcoa's Western Australian operations: x Superthickener bypass at the Wagerup residue area - testing was on a dilute slurry of the fine mud residue only. x Sand separation plant bypass at the Pinjarra residue area - testing was on a slurry consisting of a
1. Pesticide Law and Regulations – Chapters 2 and 13 of the Core Manual or Module 1 of the DVD a. Federal pesticide laws (FIFRA) b. Maryland Laws and Regulations c. Certification requirements d. Enforcement of pesticide laws and regulations 2. Label Comprehension – Chapter 3 and Chapter 10 page 150 of the Core Manual or Module 2 of the DVD a.
