Matrix Solid-Phase Dispersion Extraction and UPLC Determination of Sudan Dyes in Chili Powder

A new method involving matrix solid-phase dispersion (MSPD) extraction and UPLC in conjunction with photodiode array detection was developed for the rapid and simple determination of Sudan dyes in chili powder. Separation of Sudan I, Sudan II, Sudan III, and Sudan IV was achieved within 2 min on the 1.7 μm Acquity UPLC BEH C18 column by using gradient elution with a mobile phase consisting of acetonitrile–water at a flow rate of 0.5 mL min⁻¹. Optimization of MSPD extraction parameters, such as type of solid sorbent and elution solvent were carried out. Optimal conditions selected for MSPD extraction were 0.25 g of sample, 0.5 g of silica gel as solid sorbent, and 7 mL of acetonitrile–methanol (9:1, v/v) as eluting solvent. Limits of detection ranged between 0.25 and 0.30 mg kg⁻¹ depending on the dye involved. All analytes provided average recoveries from spiked (at 1, 1.5, and 2 mg kg⁻¹) chili powder samples ranging from 81 to 106%. The method was applied to the analysis of chili powder samples obtained from different countries.

     

Analysis of Para Red and Sudan Dyes in Egg Yolk by UPLC–MS–MS

Matrix solid-phase dispersion (MSPD) with alumina N as adsorbent has been used for extraction of para red, Sudan 1, Sudan 2, Sudan 3, and Sudan 4 dyes from egg yolk. The extracts were analyzed by ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS–MS). Mean recovery for the five dyes ranged from 63.2 to 98.6%, with CV 0.55–10.00%. One sample was confirmed to contain 0.3 mg kg^?1 Sudan 4.     

A multi-residue method for pesticide residue analysis in rice grains using matrix solid-phase dispersion extraction and high-performance liquid chromatography–diode array detection

Pesticides are widely used in rice cultivation, often resulting in detection of their residues in rice grains. So far, no analytical method has been available for the simultaneous determination of most rice pesticides in rice grains. This paper reports the development and validation of such a method for the determination of eight rice pesticides (penoxsulam tricyclazole, propanil, azoxystrobin, molinate, profoxydim, cyhalofop-butyl, deltamethrin) and 3,4-dichloroaniline, the main metabolite of propanil. Pesticide extraction and clean-up was performed by an optimized matrix solid-phase dispersion (MSPD) protocol on neutral alumina (5 g) using acetonitrile as the elution solvent. Samples were analyzed in a high-performance liquid chromatography–diode array detection (HPLC-DAD) system. Pesticide separation was achieved with a mobile phase of acetonitrile/water in a linear elution gradient from 30:70% (v/v) to 100:0% (v/v) in 14 min at a flow rate of 0.8 mL min^?1. Method validation was performed by means of linearity, intra-day accuracy, inter-day precision and sensitivity. Linear regression coefficients (R ²) were always above 0.9948. Limits of detection (LOD) and quantification (LOQ) varied from 0.002 to 0.200 mg kg^?1 and 0.006 to 0.600 mg kg^?1, respectively. Recoveries were investigated at three fortification levels and were found to be acceptable (74–127%) with relative standard deviations (RSD) below 12%. Application of the method for the analysis of five commercial rice grain samples showed that the pesticide levels were below the LOD. Overall, the method developed is suitable for the determination of residues of most rice pesticides in rice grains at levels below the established MRLs.     

Improving the Determination of Nitrovin in Feeds by Reversed-Phase LC with SPE

A simple reversed-phase liquid chromatographic method with ultraviolet detector (378 nm) for the determination of nitrovin in feeds was improved and validated. The mobile phase was a mixture of acetonitrile and 0.1% formic acid solution (v/v) in the ratio of 50:50 (v/v), and the flow rate was set at 1.2 mL min^?1. The extraction solution was a mixture of dimethyl formamide, acetonitrile and methanol (50:25:25, v/v), the sample was cleaned-up with reversed-phase solid phase extraction cartridge. The standard nitrovin was purified with crude nitrovin product by ethylene glycol monoethyl ether and identified by elemental analyzer. The limit of detection was 0.05 mg kg^?1 and the limit of quatification was 0.2 mg kg^?1 in feeds. The assay had satisfactory selectivity, recovery, linearity and precise repeatability and trueness.     

Fast Determination of Sudan I-IV in Chili Products Using Automated On-Line Solid Phase Extraction Coupled with Liquid Chromatography-Mass Spectrometry

A rapid, accurate and precise method for the determination of sudan I-IV in chili products using on-line solid phase extraction and LC-MS has been developed. Chili products were extracted with acetone and the analytes were cleaned up and enriched on an SPE column (C₁₈, 15–40 µm) through on-line SPE. Chromatographic separation was performed on a C₁₈ analytical column (2.1 × 150 mm, 3 µm) with gradient elution programming of 0.1% formic acid in water and 0.1% formic acid in acetonitrile. All four sudan dyes were separated in less than 8 min. Using in-house validation data, linearity coefficients of determination (R²) of more than 0.9997 were obtained. The limits of detection (LOD) and limits of quantitation (LOQ) for sudan I, II and IV were 0.03 and 0.05 mg kg^?1, respectively, and 0.04 and 0.1 mg kg^?1 for sudan III. The intra- and inter-day recoveries of the four sudan dyes in chili powder were between 90.1–101.6% and 90.2–102.0%, respectively, with relative standard deviation (RSD) between 0.014–0.164% and 0.011–0.202%, respectively. Therefore, this proposed method could be an alternative assay for the determination of sudan I-IV in chili products due to its rapidness, sensitivity, less sample and solvent consumption.     

MSPD Procedure for Determination of Carbofuran, Pyrimethanil and Tetraconazole Residues in Banana by GC–MS

An extraction method based on matrix solid-phase dispersion was developed to determine carbofuran, pyrimethanil and tetraconazole in banana using gas chromatography–mass spectrometry. The best results were obtained using 2.0 g of banana, 1.0 g of silica as dispersant sorbent and n-hexane:ethyl acetate (1:4, v/v) as eluting solvent. The method was validated using banana samples fortified with pesticides at different concentration levels (0.05–2.0 mg kg^?1). Average recoveries (four replicates) ranged from 68 to 111%, with relative standard deviations between 6.6 and 20.5%. Detection and quantification limits for banana ranged from 0.02 to 0.05 and 0.05 to 0.10 mg kg^?1, respectively.     

Determination of Cypermethrin Residues in Crucian Carp Tissues by MSPD/GC-ECD

A sensitive matrix solid-phase dispersion (MSPD)/gas chromatography-electron capture detector (GC-ECD) method was developed to determine cypermethrin residues in three tissues (muscle, liver, and gill) of crucian carp. Cypermethrin was simultaneously extracted by MSPD and determined by GC-ECD. The main parameters affecting extraction yield and selectivity, such as the type of solid adsorbent material, choice of elution solvents and their volume, were investigated to obtain interference-free extracts and quantitative cypermethrin recovery. Fortified recoveries in muscle, liver, and gill samples ranged from 84.9% to 106.1%, and relative standard deviations were <8% with fortification levels of 0.05–1 mg kg^?1. Detection limits were 1.4–2.1 μg kg^?1, and quantitation limits were 5.8–7.8 μg kg^?1. The proposed method was successfully applied to determination of cypermethrin in fish tissue samples.     

Rapid monitoring of carvacrol in plants and herbal medicines using matrix solid-phase dispersion and gas chromatography flame ionisation detector

Matrix solid-phase dispersion (MSPD) method coupled with gas chromatography flame ionisation detector as a quick and easy extraction technique has been developed to extract carvacrol from plants and herbal medicines. Influence of important parameters on the MSPD method efficiency, such as the sorbent material, the ratio of sample to sorbent material, elution solvent and volume of the elution solvent has been evaluated and optimised. Carvacrol was successfully extracted by diatomaceous earth as sorbent with 350 μL of dichloromethane as elution solvent. The calibration curve showed good linearity (r² = 0.9965) and precision (RSD < 8.16%) in the concentration range of 0.5–100 μg mL^? 1 for carvacrol. The limit of detection and limit of quantification were 0.1 and 0.5 μg mL^? 1, respectively. The recoveries were in the range of 74.4–80.5% with relative standard deviation (RSD) values ranging from 8.4% to 9.8%. The reported MSPD extraction method revealed to be simpler and faster than conventional methods used to quantify carvacrol from plants and herbal medicines.     

Uncertainty Analysis of Chlormequat Residue in Fruits by LC�CMS�CMS

A method for determination of chlormequat (CCC) residue in fruits by liquid chromatography?Ctandem mass spectrometry (LC?CMS?CMS) was developed. Residue of CCC was extracted from samples with methanol?Cwater (v/v, 1:1) containing 1.0% acetic acid, cleaned up by strong cationic exchange (SCX) cartridge, and then determined by LC?CMS?CMS. The method showed good linearity over the concentration range 0.002?C5.0 mg kg^?1 with correlation coefficient above 0.997. The limit of detection (LOD) and limit of quantitation (LOQ) for CCC were 5 × 10^?4 mg kg^?1 (S/N = 3) and 0.002 mg kg^?1 (S/N = 10), respectively. Recoveries for CCC at three spiked levels (0.025, 0.050, and 0.20 mg kg^?1) were in the range 80?C102%. Estimation of measurement uncertainty was calculated for CCC at the level of 0.025 mg kg^?1 in fruits. The results demonstrated that the uncertainty of recovery was the main contribution to the combined standard uncertainty. The relative combined standard uncertainties associated with the method ranged from 11 to 13%, depending on the sample matrices.     

Determination of Pentachloronitrobenzene and Its Metabolites in Ginseng by Matrix Solid-Phase Dispersion and GC–MS–MS

A rapid method was developed for the determination of pentachloronitrobenzene (PCNB) and its metabolites pentachloroaniline, pentachlorothioanisole residues in ginseng. Extraction and clean-up were carried out in a single step and analysis was accomplished by gas chromatography–mass spectrometry with multiple reaction monitoring. The main parameters affecting extraction yield and selectivity, such as type and amount of dispersant material, clean-up co-sorbent and extraction solvent were evaluated. The best results were obtained using 1 g ginseng, 2 g florisil as dispersant sorbent, 0.5 g neutral alumina as clean-up co-sorbent, and subsequent extraction with 10 mL acetone–n-hexane (5:5, v/v) with assisted sonication and repeated with another 5 mL of the same solvent mixture. The method was validated by analysis of ginseng samples fortified at different concentration levels (0.01–0.10 mg kg^?1). Average recoveries (n = 5) ranged from 85 to 95% with relative standard deviation between 2.5 and 11.2%. Spiked blank samples were used as standards to counteract the matrix effect observed in the chromatographic determination. The detection limits ranged from 0.2 to 0.9 µg kg^?1 in ginseng. The method was applied to the analysis of PCNB and its metabolite residues in commercial ginseng samples.     

SPE of Tanshinones from Salvia miltiorrhiza Bunge by using Imprinted Functionalized Ionic Liquid-Modified Silica

Ionic liquid-modified silica, with functional groups based on imidazole as the cation, was obtained. A molecular imprinting technique was introduced to form the order of functional groups. The selectivity of the obtained ionic liquid-modified silica was successfully used as a special imprinted sorbent in the solid-phase extraction to isolate cryptotanshinone, tanshinone I and tanshinone IIA from Salvia miltiorrhiza Bunge. Several washing and elution solvents with different polarities were evaluated. The ionic liquid-modified silica as the sorbent exhibited a higher selectivity than blank ionic liquid-modified silica, traditional silica and C₁₈ cartridges. A quantitative analysis was conducted by liquid chromatography with a C₁₈ column and methanol/water (75:25, v/v, containing 0.5% acetic acid) as the mobile phase. A good linearity was obtained from 0.5 × 10^?4 to 0.1 mg mL^?1 (r ²  > 0.99) with relative standard deviations that were less than 4.6%.     

Simultaneous Analysis of Hexaconazole, Myclobutanil, and Tebuconazole Residues in Apples and Soil by SPE Clean-Up and GC with Nitrogen–Phosphorus Detection

A facile and sensitive method utilizing capillary gas chromatography with nitrogen phosphorus detection (GC–NPD) has been developed and validated for simultaneous analysis of hexaconazole, myclobutanil, and tebuconazole, three broad-spectrum systemic fungicides, in apples and soil. Two samples were fortified with the three pesticides and subjected to ultrasonic extraction, followed by solid-phase extraction (SPE) to remove coextractives, before analysis by GC–NPD. SPE procedures were performed on PSA cartridges (500 mg, 3 mL), the analytes being eluted with n-hexane–acetone (9:1 v/v, 2 mL). Recovery of three pesticides from the fortified apple and soil samples ranged from 94.5 to 107.3% with relative standard deviations less than 9.7% at the three spike levels (0.01, 0.1, and 0.5 mg kg^?1). Limits of quantification of the method for apple and soil were 0.01 mg kg^?1, sufficiently below the maximum residue limits. Direct confirmation of the analytes in samples was achieved by gas chromatography–mass spectrometry (GC–MS).     

A Rapid Method for the Analysis of Ten Compounds in Psoralea corylifolia L. by UPLC

The objective of this study was to develop a simple, efficient and reliable method for routine quantitative analysis for Psoralea corylifolia L. An ultra performance liquid chromatography with DAD detector system was employed for simultaneous quantification of ten compounds. The chromatographic analysis was performed by UPLC with C₁₈ column and gradient elution of 0.05% formic acid aqueous solution and acetonitrile in 16 min. All calibration curves were linear (R ² ≥ 0.9990) over the tested ranges. The LOD and LOQ were lower to 13.07 and 39.22 ng mL^?1 with 2 μL of injection volume, respectively. The intra- and inter-day precisions as determined from sample solutions were below 4.1 and 4.2%. The average recoveries were ranged from 94.2 to 108.8% with RSDs ≤ 4.6%. This validated method was applied for the analysis of ten analytes in P. corylifolia L. from different origins. The variation of the content of ten compounds was remarkable among the tested samples: psoralenoside increased from 7.42 to 17.04 mg g^?1, isopsoralenoside from 6.05 to 14.34 mg g^?1, psoralen from 2.37 to 3.90 mg g^?1, isopsoralen from 2.53 to 3.65 mg g^?1, neobavaisoflavone from 1.59 to 2.96 mg g^?1, bavachin from 1.02 to 2.35 mg g^?1, psoralidin from 0.45 to 1.91 mg g^?1, isobavachalcone from 1.33 to 4.71 mg g^?1, corylifol A from 1.02 to 2.40 mg g^?1 and bakuchiol from 28.10 to 63.89 mg g^?1.     

Simultaneous Determination of Ibuprofen and Diphenhydramine Citrate in Tablets by Validated LC

A stability-indicating LC method was developed for the simultaneous determination of ibuprofen and diphenhydramine citrate in pharmaceutical dosage forms. The chromatographic separation was achieved on an Inertsil ODS 3V, 150 × 4.6 mm, 5 μm, column. The mobile phase contained a mixture of 50 mM potassium dihydrogen phosphate buffer:acetonitrile:triethylamine:glacial acetic acid (55:45:0.2:0.2, v/v/v/v). This method allowed the determination of 2.85–9.14 mg mL^?1 of ibuprofen and 0.54–1.73 mg mL^?1 of diphenhydramine citrate, in a diluent consisting of pH 7.2, 50 mM potassium dihydrogen phosphate buffer:acetonitrile (40:60, v/v). The flow rate was 1.2 mL min^?1 and the detection wavelength was 260 nm. The limit of detection for ibuprofen and diphenhydramine citrate was 1.72 and 0.54 μg mL^?1 and the limit of quantification was 5.73 and 1.64 μg mL^?1, respectively. This method was validated for accuracy, precision and linearity. The method was also found to be stability indicating.     

Simultaneous Determination of Zoalene and Its Metabolite in Chicken Muscle and Liver by SPE and UPLC�CMS-MS

This paper presents an analytical method for the simultaneous determination of zoalene and its metabolite 3-amino-5-nitro-o-toluamide (3-ANOT) in chicken muscle and liver by solid phase extraction and UPLC?CMS-MS operated in the positive and negative ionization switching mode. Samples were extracted with phosphate buffer solution and purified with OASIS^? HLB cartridge after pH adjustment. The determination was carried out using UPLC?CMS-MS on a Waters Acquity BEH C₁₈ column with 0.1% formic acid in water/acetonitrile as mobile phase with gradient elution. The linearity of the analytical response across the studied range of concentrations (2.0?C1,000 ??g L^?1) was excellent, obtaining correlation coefficients higher than 0.999. Matrix effects had been investigated for zoalene and 3-ANOT. Recovery studies were carried out on spiked chicken muscle and liver blank samples, at four concentration levels (50, 1,500, 3,000, and 4,500 ??g kg^?1 for chicken muscle and 50, 3,000, 6,000, and 9,000 ??g kg^?1 for chicken liver) performing six replicates at each level. Mean recoveries of 77.9?C94.2% with CVs of 3.2?C8.7% were obtained. The method demonstrated to be suitable for the simultaneous determination of zoalene and 3-ANOT in chicken tissues.     

Determination of Chlorantraniliprole Residues in Corn and Soil by UPLC�CESI�CMS/MS and Its Application to a Pharmacokinetic Study

A rapid, highly sensitive, and selective method was developed for the determination of the insecticide chlorantraniliprole (CAP) in corn and soil using ultra-performance liquid chromatography?Ctandem mass spectrometry (UPLC?CMS/MS). Samples were extracted with acetonitrile, and aliquots were cleaned with solid-phase extraction cartridges. Two precursor-product ion transitions for CAP were measured and evaluated to provide maximum confidence in the results. Average recovery for soil, corn grain, and corn straw at different levels (5 or 10, 40, and 100 ??g kg^?1) ranged from 74.9 to 97.5%, with intra-day relative standard deviation (RSD) values of 1.9?C11.3% and inter-day RSD values of 4.7?C10.4%. Coefficients of determination (R ²) of 0.9988 or higher were achieved for CAP in soil, corn grain, and corn straw matrix calibration curves, from 5 to 1,000 ??g L^?1. The CAP limits of quantitation in soil, corn grain, and straw were determined to be 5, 10, and 10 ??g kg^?1, respectively, which were much lower than the maximum residue levels established by the Environmental Protection Agency of United States. UPLC?CMS/MS was used to determine the CAP residues in real corn and soil for studies on their dissipation. The trial results showed that the half-lives of CAP changed from 12.6 to 23.1 days in soils and ranged from 4.9 to 5.4 days in corn straws in the districts of Henan and Shandong, and the average levels of CAP residues in corn grains were all <0.01 mg kg^?1 with a harvest withholding period of 180 days.     

UPLC a Powerful Tool for the Separation of Imidazolium Ionic Liquid Cations

Ultra-performance liquid chromatography (UPLC) in reversed-phase (RP), ion pair (IP) and hydrophilic interaction chromatography (HILIC) has been investigated for the separation of imidazolium-based ionic liquid (IL) cations. Among the three stationary phases (i.e., C18, C8 and phenyl) studied under RP conditions the phenyl phase provided much stronger retention for the IL cations. Four acids (hydrochloric, methanesulfonic, perchloric and trifluoroacetic) as mobile phase additives were compared in light of their effects on the retention of IL cations. It was shown that the retention of all IL cations decreased upon acidification of the mobile phase, possibly due to suppression of residual silanol ionization. Very fast (~3 min) and efficient RP-UPLC separation of six cations was achieved by gradient elution with acetonitrile?Cwater mobile phase containing 2.5 mmol L^?1 perchloric acid. In IP-UPLC all solutes were well resolved in about 4 min by gradient elution with acetonitrile?Cwater mobile phase containing 1 mmol L^?1 sodium 1-octanesulfonate as ion pairing reagent. Finally, under HILIC conditions by using isocratic elution with acetonitrile?Cwater (85:15, v/v) mobile phase containing 5 mmol L^?1 ammonium formate (pH 3.2) the separation time was reduced to less than 2 min while maintaining excellent peak shapes and sufficient resolution. Compared to current LC systems UPLC allowed considerably faster separations with better peak shapes.     

Improved Method for the Determination of Cyanuric Acid in Animal Feed by GC–MS

A specific and sensitive analytical method for the quantitative determination of cyanuric acid in animal feed was developed. Sample preparation involved the diethylamine/acetonitrile/water extraction of feed using sonication and shaking. The extract was subjected to clean-up by dual solid phase extraction using mixed mode anionic and cationic extraction cartridges. After removal of clean-up solvent, cyanuric acid was converted to a tert-butyldimethylsilyl derivative and was determined by gas chromatography–mass spectrometry in the selected ion monitoring mode. ¹³C ₃ ¹⁵ N₃-cyanuric acid was employed as the internal standard. The calibration curve was found to be linear up to 4 mg kg^?1. LOD and LOQ were determined to be 0.06 to 0.4 mg kg^?1 for fish and chicken feed. The mean recovery of cyanuric acid was 96 to 98% with relative pooled standard deviation of 1.8–7.4% in the range of 0.5 to 100 mg kg^?1 for fish and chicken feed. The validated method was applicable for analysing cyanuric acid in animal feed.     

Quantification of Tricyclic and Nontricyclic Antidepressants in Spiked Plasma and Urine Samples Using Microextraction in Packed Syringe and Analysis by LC and GC-MS

In this paper, a highly selective Sudan IV molecularly imprinted polymer was synthesized by surface molecular imprinting technique in combination with a sol?Cgel process using ??-aminopropyl triethoxysilane as functional monomer, tetraethoxysilane as cross-linker and activated silica gel as support material. The imprinted polymer was characterized by FT-IR spectra, scanning electron micrograph and adsorption experiments and it was exhibited good recognition and selective ability, offered a faster rate for the adsorption of Sudan IV. Using the imprinted material as sorbent, a solid-phase extraction coupled with high-performance liquid chromatography method for determination of trace Sudan IV was presented. The detection limit (S/N = 3) was 25.2 ng L^?1, and the RSD for five replicate was 2.86%. With a loading flow rate of 2.5 mL min^?1 for loading 30 mL, an enrichment factor of 104 was achieved. This method was applied for extraction and determination of chilli powder and duck egg samples with good recoveries ranging from 85.3 to 98.1%.     

Biodegradation of imidacloprid in sandy loam soil by Bacillus aerophilus

A study of the biodegradation of imidacloprid in soil was carried out under laboratory conditions. Sandy soil samples were fortified with imidacloprid at 50, 100 and 150 mg kg^?1 along with 45 x 10⁷ colony forming units (cfus) of Bacillus aerophilus and the samples were compared with unamended soil. The samples were extracted with acetonitrile, cleaned up by treatment with primary secondary amine sorbent and graphitised carbon black. The residues of imidacloprid and its metabolites were analysed by high performance liquid chromatography. The parent compound, imidacloprid, was found to be more persistent in both the treatments. Among metabolites, the highest values were obtained for urea and olefin while 5-hydroxy, 6-chloronicotinic acid (6-CNA), nitrosimine and nitroguanidine (NTG) were also observed in all the treatments in amended soil. In case of unamended (control) soil, 6-CNA was found to be the most persistent metabolite followed by olefin, urea, 5-hydroxy, nitrosimine and NTG metabolites. Total imidacloprid residues for control soil samples followed first-order kinetics at 50 and 150 mg kg^?1 but in case of control imidacloprid fortified at 100 mg kg^?1, the total residues of imidacloprid and its metabolites followed pseudo-first-order kinetics. The respective half-life value for 50 mg kg^?1 was 25.08 days and 30.10 days for both 100 and 150 mg kg^?1. However, total imidacloprid residues followed pseudo-first-order kinetics for its applications at 50, 100 and 150 mg kg^?1 in sandy loam soil amended with B. aerophilus. The half-life values for 50, 100 and 150 mg kg^?1 were worked out to be 14.33, 15.05 and 18.81 days, respectively. With the use of B. aerophilus, the reduction percentage of initial applied dose imidacloprid in sandy loam soil was found to be higher in all the three doses as compared to that of the control samples.