Modified QuEChERS Method Research Articles

Trace Enantioselective Determination of Imidazolinone Herbicides in Various Food Matrices Using a Modified QuEChERS Method and Ultra-Performance Liquid Chromatography/Tandem Mass Spectrometry

A modified QuEChERS method was developed for simultaneous enantioselective determination of three imidazolinone herbicides (imazethapyr, imazamox, and imazapic) in two oil crops (soybeans and peanuts) and three food crops (wheat, maize, and rice) by chiral reversed-phase ultra-performance liquid chromatography/tandem mass spectrometry. Sample extraction was performed with 20 mL of methanol adjusted to pH 4 with 1% aqueous acetic acid. The supernatant was then cleaned with a primary secondary amine and graphitized carbon black. Several significant factors affecting the performance of the method were optimized. Under the optimum conditions, good linearity (R2 ≥ 0.9931) and acceptable recoveries (63.5–111.5%, relative standard deviation ≤ 22.7%) were obtained for each enantiomer. The limits of detection and quantification ranged from 0.34 to 1.5 μg/kg and 1.1 to 5.0 μg/kg, respectively. For all three imidazolinone herbicides, the S-enantiomers eluted before the R-enantiomers. Finally, several food samples (soybeans, peanuts, wheat, maize, or rice) were analyzed by this method. The enantiomers of the three imidazolinone pesticides (imazethapyr, imazamox, and imazapic) were not found in these samples at the microgram per kilogram level.

Residue, dissipation, and safety evaluation of etoxazole and pyridaben in Goji berry under open-field conditions in the China's Qinghai-Tibet Plateau.

The dissipation and residual levels of etoxazole and pyridaben in Goji berry under open field conditions were determined by using GC-NPD (gas chromatography with nitrogen and phosphorus detector) with modified QuEChERS method. At fortification levels of 0.01, 1, and 5mg/kg in Goji berry, it was shown that recoveries were ranged from 80.40 to 100.9% with relative standard deviation of the method (RSD) for repeatability ranged from 2.20 to 4.25%. The limit of quantification (LOQ) of the method was 0.01mg/kg. The dissipation rates of etoxazole and pyridaben were described by using first-order kinetics and its half-life, as they are 7.13days, 5.77days, and 5.99days (etoxazole) and 1.02day, 0.67day, 1.02day (pyridaben). The terminal residues of etoxazole and pyridaben were below the European maximum residue limit (MRL, 0.1mg/kg) in Goji berry when measured 7days after the final application, which suggested that the use of these insecticides was safe for humans. This study would help in providing the basic information for developing regulation to guard a safe use of etoxazole and pyridaben in Goji berry and prevent health problem from consumers.

Residue behaviour and dietary risk assessment of emamectin benzoate in mango under field condition using modified QuEChERS method combined with HPLC-MS/MS

ABSTRACTThe maximum residue limit (MRL) of emamectin benzoate in mango had not been legislated in China and no work had been done to determine the emamectin benzoate residue in mango. The aim of this study was to investigate the dissipation and terminal residues of emamectin benzoate in mango under field conditions and to assess its safe use. A high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) with modified QuEChERS for analysis of emamectin benzoate was established. It was shown that at fortified levels of 0.005, 0.02 and 0.1 mg/kg, the average recoveries were 72–102% with RSDs less than 8% for intra-day and 81–102% with RSDs less than 9% for inter-day. The half-life of emamectin benzoate in mango was 4.9 days and terminal residues mostly lower than LOQ (0.005 mg/kg) with PHIs of 5, 7 and 10 days except Sichuan province. The dietary exposure risk of emamectin benzoate on mango was negligible depending on the RQ value of 2.77–34.96%. Therefore, it would be unlikely to cause health problems if emamectin benzoate was applied according to the use pattern suggested by the manufacturers on the label. These results would be useful in establishing MRL and providing guidance on the safe use of emamectin benzoate.

Quantitative analysis of fourteen heterocyclic aromatic amines in bakery products by a modified QuEChERS method coupled to ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS)

Heterocyclic aromatic amines (HAAs) are harmful by-products naturally formed during the heating process of foodstuffs. The present work reported an analytical method for HAAs analysis for the first time in bakery products by QuEChERS technique combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Bakery products were ultrasonically extracted with acetonitrile and sodium hydroxide solution (1 mmol/L). The obtained extracting solution was nearly dried under nitrogen stream and subsequently purified by QuEChERS technique using primary secondary amine (PSA) as adsorbents. Fourteen HAAs were separated on a C18 column with the mobile phase of a mixture of acetonitrile and 1 mmol/L ammonium acetate water solution (containing 0.04% acetic acid), and detected by MS/MS under multiple reaction monitoring (MRM) mode. The developed method was validated in terms of linearity, matrix effect, accuracy and precision. The method showed a good linearity (R2 > 0.999) for all analytes in their corresponding concentration ranges. The method limit of quantifications (LOQs, S/N = 10) of 14 HAAs were in the range of 0.3–4.5 μg/kg. The average recoveries (n = 6) at 3 spiked levels ranged from 62.8 to 96.8% with relative standard deviations (RSDs) of 1.2–7.6%. The validated method was applied in HAAs analysis in 20 bakery products and 4 kinds of HAAs (harman, norharman, AaC, PhIP) were detected with the concentrations ranging from 0.6 to 35.6 μg/kg.

Determination of polyoxin B in cucumber and soil using liquid chromatography tandem mass spectrometry coupled with a modified QuEChERS method

A sensitive and effective method based on a modified QuECHERS (quick, easy, cheap, effective, rugged, and safe) method for the determination of polyoxin B in cucumber and soil using liquid chromatography tandem–mass spectrometry (LC–MS/MS) was developed and validated. Samples were extracted using 1% formic acid in ultrapure water and purified via reversed-dispersive solid phase extraction (r-dSPE) using C18. Recovery of polyoxin B ranged from 83.0% to 112.1% with relative standard deviation (RSD) (n = 5) of 3.0–5.2%. The limit of quantification (LOQ) and the limit of detection (LOD) were 0.01 and 0.003 mg/kg for cucumber and soil, respectively. The method was subsequently applied for real sample analysis. The dissipation experiments showed that half-lives of polyoxin B in cucumber and soil were 2.5–5.0 days. The terminal residues of polyoxin B at preharvest intervals (PHIs) of 3 days and 5 days in cucumber were less than 0.05 mg/kg. We therefore suggest that the developed method can be extrapolated to other agricultural crops or food for routine analysis. It also can be used to determine the PHIs. Moreover, these results will aid in establishing the maximum residue limit (MRL) for cucumber in China.

Development and Validation of a Multiresidue Method for Fluazifop‐p–butyl and Its Two Major Relevant Metabolites in Panax ginseng Using a Modified QuEChERS Method and HPLC‐ESI‐MS/MS

AbstractFluazifop‐p‐butyl (FPB) is used to control the gramineous weeds in Panax ginseng field, which has the risk of exceeding the maximum residue limit of FPB in Panax ginseng. A modified QuEChERS sample preparation method was developed for the simultaneous determination of FPB and its two major relevant metabolites, fluazifop‐p‐acid (FP) and 2‐hydroxy‐5‐ trifluoromethylpyridin (TFMP) in Panax ginseng by using Carboxylated multi‐walled carbon nanotubes (MWCNTs‐COOH) mixed with ostade‐cylsilane (C18), primary secondary amine (PSA), and graphitized carbon black (GCB) as purification materials. Furthermore, the HPLC‐MS/MS parameters were optimized. The method was further validated by determining the linearity (R2>0.999), fortified recovery (77.6‐97.8%), relative standard deviation (<13.6%) and sensitivity (LOQ, 2.0‐ 8.6 μg kg‐1 for FPB, 3.9‐5.8 μg kg−1 for FP and 3.5‐9.0 μg kg−1 for TFMP in Panax ginseng root, leaf, and seed samples, respectively). The main advantages of the method are high recovery, high sample throughput, facile sample preparation, a smaller volume of organic solvents and low cost per sample. The entire method can withstand practice testing expected to be used for the screening of FPB residue in Panax ginseng samples.

Determination of polybrominated diphenyl ethers in fish tissue using gas chromatography-isotope dilution tandem inductively coupled plasma mass spectrometry with a mass-shift mode

Gas chromatography inductively coupled plasma triple quadrupole mass spectrometry (GC-ICP-MS/MS) operated in N2O reaction mode (mass-shift mode) was established for the analysis of six congeners of polybrominated diphenyl ethers (PBDEs): BDE 28, BDE 47, BDE 99, BDE 100, BDE 153 and BDE 154 in fish samples. The spectral interference on the determination of PBDEs was eliminated by measuring the product ion (BrO+) instead of traditional methods measuring Br+. After comparing the signal intensities of the three reaction gases (O2, H2, and N2O), the highest sensitivity was found using N2O as the reaction gas. The results showed that bromine is an element that suffers from strong spectral overlap in ICP, mainly from Ar-based polyatomic interferences. Spectral interference was assessed by measuring the bromine isotope ratio of 81Br+ and 79Br+ of the six priority PBDEs in the He collision mode and N2O reaction mode, respectively. In the conventional He collision mode, the relative isotope ratio of 79Br/81Br (the measured isotope ratio to the natural isotope ratio) of the analytes ranged from 0.955 to 0.965, which proves that using He as the collision gas cannot completely eliminate the spectral interference. In the N2O reaction mode, the relative isotope ratio of 79Br/81Br ranged from 0.991 to 1.004, demonstrating that spectral interference can be fully eliminated. Samples were processed using the modified QuEChERs method with detection limits ranging from 0.03 to 0.09 ng g−1 with a relative standard deviation of less than 3%. Six priority PBDEs in the NIST reference materials SRM 1947 (frozen fish tissue homogenate) were determined by mass-shift mode to verify this conclusion. No statistically significant difference was observed between the measured value and the certified value, with recoveries between 95% and 114%. The method was applied to the analysis of PBDEs in marine fish samples and five PBDEs were observed (BDE28,BDE-47, BDE-99, BDE-100 and BDE-153) at concentrations ranging from 0.04 to 0.54 ng g−1.

Optimization and validation of a liquid chromatography/tandem mass spectrometry (LC-MS/MS) method for the determination of aflatoxins in maize

A LC-MS/MS method has been optimized and validated for the determination of aflatoxins (AFB1, AFB2, AFG1 and AFG2) in maize. Extraction was performed using a modified QuEChERS method with little sample preparation without the need for purification procedure. Determination was performed by high pressure liquid chromatography (HPLC) coupled to tandem mass spectrometry (MS/MS). The acquisition was performed using MassHunter software in Multiple Reaction Monitoring (MRM) mode in positive polarity. Different mobile phases were tested to control the degree of the ionization and good performances were obtained for methanol/water with 5 mM ammonium acetate. MRM experiments were optimized for each aflatoxin in order to generate sensitive transitions. Linearity was demonstrated for the aflatoxins in the range 0.225–1.25 μg/L. Limits of detection (LOD) (0.11 and 0.36 μg/Kg) and limits of quantification (LOQ) (0.36–1.19 μg/Kg) of the aflatoxins are below the maximum permitted levels set by the European Union (EU). Aflatoxins have acceptable recoveries using QuEChERS method in the acceptable range of 50–120% for levels below 1 μg/Kg. Satisfactory recoveries were also obtained in the acceptable range of 70–110% for levels between 1 and 10 μg/Kg except for AFB2. Relative standard deviation (RSD) of recoveries for the intra-day precision and inter-day precision were below 11 %. Selectivity of the method was tested and no spectral interferences were observed in the appropriate retention times. The main advantage of the proposed method is its ease of use and requires a smaller solvent consumption that reduces the time and cost of the analysis.

A Modified QuEChERS Method for Determination of Pyrethroid Residues in Traditional Chinese Medicine Oral Liquids by High-Performance Liquid Chromatography.

Pyrethroid residues in traditional Chinese medicines have been a serious threat to the health and treatment of patients. However, because of the matrix complexity of traditional Chinese medicine, the detection of pyrethroid residues remains a challenge. Therefore, we developed a QuEChERS method coupled with high-performance liquid chromatography and ultraviolet detection (HPLC-UV) for the determination of pyrethroid pesticides in three kinds of traditional Chinese medicine oral liquid preparations, and we investigated and optimized the extraction conditions. The matrix effect was estimated in the organic solvent and the actual samples by comparing the slopes of calibration curves, and the results showed that the matrix effect is not significant when using the modified QuEChERS method. The pyrethroid pesticides could be completely separated in 30 min. The linear correlation coefficients were more than 0.999, and the recoveries of all the pyrethroid pesticides ranged from 87.2% to 104.8%. The intra-day precisions (n = 5) were 2.44–4.62%, and the inter-day precisions (n = 5) were 1.06–3.02%. Moreover, the limits of detection were in the range of 0.007–0.018 ng mL−1, while the limits of quantitation were in the range of 0.022–0.057 ng mL−1. This simple, low-cost, and highly sensitive analytical method can be a potential tool for the analysis of pyrethroid residues in traditional Chinese medicine oral liquid preparations.

Integration of five groups of POPs into one multi-analyte method for human blood serum analysis: An innovative approach within biomonitoring studies

Within this study, a new analytical strategy was developed and validated for the simultaneous determination of 78 organohalogenated contaminants in human blood serum, namely 40 flame retardants (FRs) including 7 “novel” brominated and chlorinated FRs (novel FRs), 19 perfluoroalkylated substances (PFASs), 11 organochlorine pesticides (OCPs) and 8 polychlorinated biphenyls (PCBs). The integral sample preparation procedure was implemented for the isolation of non-polar compounds, based on three-step solvent extraction using a mixture of n-hexane:diethylether (9:1, v/v), followed by purification using a solid-phase extraction (SPE) on a Florisil® column. For isolation of more polar and lipophobic analytes, the remaining fraction from the first extraction step was further processed, using a modified QuEChERS method. Depending on the polarity and volatility of target compounds, either gas chromatography coupled to (tandem) mass spectrometry (GC–MS/(MS)), or ultra-high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-MS/MS), was employed for their identification/quantification. Within the subsequent pilot study, the new validated procedure was successfully applied to the monitoring of organohalogenated contaminants in 38 samples of human blood serum obtained from Prague, Czech Republic. From 78 targeted analytes, 10 PFASs, 10 OCPs, 8 PCBs and 6 BFRs were detected in serum at concentrations above method quantification limits (MQLs). In the serum samples, the amounts of determined PFASs were in the range<0.01–8.97ngmL−1 (mean 0.631ngmL−1), OCPs and PCBs ranged from <0.1–1626ngg−1 lw (mean 40.0ngg−1 lw) and<0.1–481ngg−1 lw (mean 63.3ngg−1 lw), respectively.

Health risk assessment of pesticide residues in fruits and vegetables from farms and markets of Western Indian Himalayan region

The extensive use of pesticides in agriculture has become a very common practice in developing countries like India. Consequently, the increased concentration of residues of these hazardous pesticides in fruits and vegetables is manifested. The study aimed to assess the health hazards associated with the presence of pesticide residues in fruits and vegetables sampled from farms and markets of Kinnaur district of Himachal Pradesh (India). Residues of predominant pesticides used in the region, belonging to the group of organophosphates, pyrethroid and phthalimide, were analysed using gas chromatograph quadrupole mass spectrometer (GC-MS/MS). The pesticide extraction from the matrix was done following the modified QuEChERS method. Results indicated varying concentrations of pesticide residue in market and farm samples with farm samples more contaminated than market samples. Chronic health hazards prediction indicated that organophosphorus groups (methyl parathion and triazophos) posed health risk to children in the study area.

Simultaneous Determination of Atrazine, Pendimethalin, and Trifluralin in Fish Samples by QuEChERS Extraction Coupled With Gas Chromatography-Electron Capture Detection

A rapid, simple, and dependable method was developed and validated for the simultaneous determination of atrazine, pendimethalin, and trifluralin in fish samples. Target analytes were extracted and purified by the modified QuEChERS method prior to analysis. Ultrasound-assisted extraction (10 min) was used to improve the extraction efficiency of classical acetonitrile extraction. The organic phase was then cleaned using dispersive solid-phase extraction with 150 mg primary secondary amine and 100 mg C18-bonded silica sorbents. GC with electron capture detection was used for determination. The method resulted in good linearity (R2 = 0.9973–0.9998) and low limits of detection and quantification (0.015–0.60 and 0.050–2.0 μg kg−1). Recoveries ranged from 76.8 to 94.6% with repeatability between 2.3 and 3.8% and reproducibility between 3.4 and 4.8%. The performance parameters demonstrated the method adequacy for the detection and quantification of atrazine, pendimethalin, and trifluralin residues in freshwater fish.

Analysis of pesticide residues in commercially available chenpi using a modified QuEChERS method and GC-MS/MS determination

To ensure the safety of the commercially available chenpi, a convenient and fast analytical method was developed for the determination of 133 pesticide residues in chenpi using gas chromatography-tandem mass spectrometry (GC-MS/MS). In this study, different extraction solvents, redissolution solvents and adsorbents were tested according to the recovery and purification effect to obtain a modified QuEChERS method. The samples were extracted with acetonitrile. During the clean-up step, octadecyl-modified silica (C18) and graphitized carbon black (GCB) were selected, and aminopropyl (NH2) was used instead of primary secondary amine (PSA) because of its weaker ion exchange capacity which had little effect on the recovery of ditalimfos. Samples were quantified by matrix-matched calibration with internal standards. All pesticides showed good linearity in the respective range, both with values of r2 > 0.99. The average recoveries of the pesticides spiked samples ranged from 70.0% to 112.2% with the RSDs of 0.2%–14.4%. The modified QuEChERS method was validated and applied to twenty real samples. Five pesticides were found in eight batches, but no pesticide exceeded the maximum residue limits (MRL, MRL reference to European commission).

Supercritical fluid chromatography coupled to tandem mass spectrometry for the analysis of pesticide residues in dried spices. Benefits and drawbacks

This study describes the high sensitivity and the reduced ion suppression and matrix effect that can be achieved by supercritical fluid chromatography (SFC) in the analysis of dried spices as complex matrices. Samples selected for the evaluation were cayenne and black pepper, which are representative of complex dried spices. To carry out the evaluation of this technique, blank samples were fortified with a solution containing 162 pesticides at two concentration levels (50 and 200 μg kg−1). During the modified QuEChERS method, EMR sorbent was used as dispersive SPE in the clean-up step. The samples were analysed by supercritical fluid chromatography coupled to tandem mass spectrometry. The validation parameters studied were recovery, inter and intraday precision, linearity and matrix effect. Recoveries for the majority of compounds were in the 70–120% range recommended by DG-SANTE guidelines and showed a precision lower than 20% in terms of RSD. Matrix effect was low (0–20% signal suppression) for 132 pesticides in cayenne and 91 in black pepper. The method was used to analyse 47 real samples of spices from different countries. A high number of these samples presented one or more pesticides (81%). Some of these detected pesticides are not approved in the European Union and, in many cases, the positive findings exposed concentrations that exceed the EU MRLs.

Validation and quantification of neonicotinoid insecticide residues in rice whole grain and rice straw using LC-MS/MS

ABSTRACTAn efficient analytical method was developed and validated using a modified QuEChERS method and LC-MS/MS for the detection and quantification of neonicotinoid insecticide residues in rice whole grain and rice straw. The samples were extracted using acetonitrile and cleaned up by dispersive solid-phase extraction. Validation based on five fortification levels showed good recoveries of neonicotinoids ranging from 75% to 116 % and 60% to 105 % for rice whole grain and straw, respectively. The precision ranged between 3% and 17 %, and 2% and 10 % for grain and straw, respectively. The limit of detection was from 0.007 to 0.0084 mg kg−1 and 0.005 to 0.15 mg kg−1 and the limit of quantification was in the range of 0.024–0.028 mg kg−1 and 0.016–0.051 mg kg−1 for rice whole grain and rice straw, respectively. Monitoring of farm gate samples indicated that, out of 24 samples, 1 rice whole grain sample was contaminated with thiamethoxam residues (0.07 mg kg−1).

Determination of neonicotinoids and 199 other pesticide residues in honey by liquid and gas chromatography coupled with tandem mass spectrometry

Current work presents a modified QuEChERS method for the determination of 207 pesticide residues in honey by LC–MS/MS and GC–MS/MS. Acetate buffered acetonitrile extraction with Z-Sep+ and PSA dispersive-SPE clean-up were used for sample preparation. Optimised conditions allows determination of neonicotinoids as well as other insecticides, fungicides, herbicides, acaricides, growth regulators and veterinary drugs in honey samples. Validated method enable sensitive analysis at least at concentrations from 0.001, 0.005 or 0.01 mg/kg for 45%, 41% and 14% of pesticides, respectively. Method was utilised for the analysis of 155 honey samples from Poland during 2015–2017. Residues of 21 pesticides were determined in honey. Cyano-substituted neonicotinoids (acetamiprid, thiacloprid) were quantified in 77% of samples and were the most frequently detected pesticides. Concentrations of acetamiprid was from 0.001 to 0.13 mg/kg whilst thiacloprid from 0.001 to 0.2 mg/kg. Fungicides were determined in 50% and amitraz metabolites in 35% of honey samples.

Degradation Dynamics of Halosulfuron-methyl in Two Textured Soils.

A laboratory experiment was conducted to study the degradation dynamics of halosulfuron-methyl residues in sandy loam and clay loam soil. The herbicide formulation was applied at 0.034 and 0.068mgkg- 1 equivalent to field application dose of 67.5 and 135ga.i.ha- 1 as single and double dose respectively. Soil samples were collected on 0 (1h), 1, 3, 7, 10, 15, 30 and 45days after treatments. Extraction was done using modified QuEChERS method. Residues were estimated by UPLC coupled with quadrupole Dalton mass detector. Average recoveries ranged from 85.5% to 94.5% for both soils at different fortification levels of 0.005 to 0.1mgkg- 1 with limit of detection (LOD) and limit of quantification (LOQ) as 0.001 and 0.005mgkg- 1, respectively. Dissipation followed first order kinetics with half-life of 8.4 to 10.7days in both soil at two doses. The residues reached below LOQ of 0.005mgkg- 1 after 45days of herbicide application.

Persistent Organochlorine Compounds Levels in Selected Fish Species from Lake Victoria and Associated Human Health Risks

Nile perch (<i>L. niloticus </i>) and Nile tilapia (<i>O. niloticus</i>) are the major commercial fish species in Lake Victoria region of Tanzania. This study was conducted to assess the levels of persistent organochlorine compounds, namely PCBs and OCPs in these two fish species and the probable human health risks associated with the consumption of these two fish species from Lake Victoria. Fish samples were collected between May and August 2016 and the necessary anthropometric measurements such as length and weight were taken. The extraction was done using a modified QuEChERS method and the identification and quantification of the chemicals were done using GC/ECDs. The results of this study revealed that fish species sampled were undersize, which was an indication of overfishing and abuse of bylaws. Among the 19 OCPs which were considered, only four (β- HCH, HCB, Aldrin and Dieldrin) were detected at measurable quantities. β- HCH ranged from <0.24 to 1.19µg/kg. The mean concentrations were 0.77±0.43µg/kg and 0.56±0.16µg/kg for <i>L. niloticus</i> and <i>O. niloticus</i> respectively. HCB levels ranged from <0.18 to 0.59µg/kg in <i>L. niloticus</i> and <0.18µg/kg in <i>O. niloticus</i>. Aldrin ranged from <0.14 to 0.34µg/kg in <i>L. niloticus</i> whereas it was not detected in <i>O. niloticus</i>. Moreover, Dieldrin residues ranged from <0.17 to 1.06µg/kg in <i>O. niloticus</i> but were not detected in <i>L. niloticus</i>. Generally, there were slightly higher levels of the detected OCPs in <i>L. niloticus</i> than the corresponding levels in <i>O. niloticus</i> mainly due to their differences in trophic levels and feeding habits. The indicator PCBs were not detected in all the investigated fish samples. The levels of all the detected organochlorines were far below the MRL set for fish and fishery products suggesting that the fresh fish from Lake Victoria are safe for human consumption. Low levels of the detected residues and non- detection of many organochlorines considered indicate that contamination in Lake Victoria has not reached alarming levels. The human health risk assessment of the detected organochlorines showed cancer risk from 8.6E-06 to 3.2E-05 for children and from 7.8E-06 to 1.3E-05 for adults indicating that there is a low cancer risk for both age groups. The non- cancer risks (HI) on the other hand, were 5.7E-02 for children and 4.7E-02 for adults, which is an indication of an insignificant risk.

Determination of morphine and 6-monoacetylmorphine in putrefied blood using ultra performance liquid chromatography-tandem mass spectrometry

This study was performed to develop an ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method to detect and quantify morphine and 6-monoacetylmorphine in putrefied blood for forensic toxicological purposes. A modified QuEChERS method was implemented as follows:extraction of morphine and 6-monoacetylmorphine from putrefied blood was performed with an acetonitrile-water (4:1, v/v) mixture, and 30 mg NaCl and 60 mg anhydrous MgSO4 were subsequently added as salting out agents to induce phase separation. The supernatant was cleaned by adding 25 mg primary secondary amine sorbent (PSA) and 25 mg anhydrous MgSO4. Separation of the target compounds was performed using a ZORBAX Eclipse Plus C18 column by UPLC over a 4 min gradient elution where 0.01% (v/v) ammonium hydroxide buffer (A) and acetonitrile (B) were used as the mobile phase. MS/MS was used in positive electrospray ionization (ESI+) mode and multiple-reaction monitoring (MRM) was performed to detect the target drugs. This method achieved satisfactory recoveries (R) for morphine and 6-monoacetylmorphine with mean recovery values ranging from 81.84% to 103.44% and 81.03% to 104.46% respectively. The developed method also provided efficient purification of the sample from endogenous interferences with matrix effect (ME) ranging from 83.04% to 107.61%. The method was validated and the limit of detection (LOD) and limit of quantification (LOQ) were 1 and 5 μg/L, respectively, for both compounds and the precision with RSD ranged from 1% to 12%. This method proved to be quick, sensitive, rugged, and suitable for the analysis of illegal drugs in putrefied whole blood.

GC-MS Modified Quechers Method for Multiresidue Pesticide Determination in Red Wine

This work reports a new selective and accurate multiresidue procedure for determination of 25 pesticides in red wine by GC-MS. Proposed procedure uses an original approach in sample preparation technique based on QuEChERS theory. Main focus of method development was modification of salts thus increasing ionic strength of solution which improved pesticides partitioning and extraction efficiency. LOQs were in the range 0.01–250 μg L–1 with 56 % of target pesticides below or equal to 10 μg L–1. RSD for most pesticides was &amp;lt; 20 % and recoveries were in the range 70–120 %. Matrix effect was found to be high for five pesticides confirming sample preparation procedure to be efficient. The proposed procedure was applied to 12 wine samples of different variety with determination of 40 % of target pesticides. Developed GC-MS methodology provides novel, selective and accurate approach for determination of 25 pesticide residues in red wine.