Development of validated LC-MS/MS method for imidacloprid and acetamiprid in parsley and rocket and evaluation of their dissipation dynamics

Alamer

Alrasheed

2018

A sensitive, simple and rapid QuEChERS extraction method and liquid chromatography equipped with triple quadrupole mass spectrometry (LC-MS/MS) were used to determine 42 pesticides in dates. Acidified acetonitrile and citrate buffer salts were used to extract re-hydrated samples. Acceptable validation performances were achieved, i.e. recovery range of 70-120% and RSD values ≤20% for 42 analytes at three different concentrations:100, 50 and 10 μg/kg. This method was used to analyse 200 date fruit samples (var. Sukkari) collected from different large markets in the Al-Qassim region in Saudi Arabia. Pesticide residues were detected in 36 (18%) of the date fruits samples, and 15 samples (7.5%) exceeded the maximum residue levels. The ruggedness test results showed that this method is robust and suitable for the determination of pesticide residues in dates. Additionally, the results showed that the monitored dates did not have a health impact on consumers in Saudi Arabia during the study period.

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Market Sample Monitoringmentioning

confidence: 99%

mentioning

confidence: 99%

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Monitoring pesticide residues in dates marketed in Al‐Qassim, Saudi Arabia using a QuEChERS methodology and liquid chromatography–tandem mass spectrometry

Alamer

Alrasheed

2018

“…The slope of the matrix‐matched calibration curve (sets two and three) was compared with the slope of the solvent curve (first set) equation. (Abdallah, Abdel Ghani, & Hrouzková, ; Malhat et al, ; Matuszewski, Constanzer, & Chavez‐Eng, ). The matrix effect is considered nonsignificant, moderate or significant if the value is 0–20, 20–50% and >50%, respectively (Keller, Suj, Young, & Whittal, ).…”

Section: Methodsmentioning

confidence: 99%

Buprofezin dissipation and safety assessment in open field cabbage and cauliflower using GC/ITMS employing an analyte protectant

Agamy

Abdelraheem

et al. 2019

Self Cite

An analytical method for the determination of buprofezin residues in cabbage and cauliflower was developed and validated using gas chromatography with ion trap mass spectrometry. The analyte protectant D-sorbitol was used at a concentration level of 0.5 mg mL −1 in acetonitrile instead of in matrix for constructing the calibration curves of the buprofezin standard. The average recoveries ranged from 91.3 to 96.8%, with an RSD of ≤2.7%. The limits of detection and quantitation of the method in cabbage and cauliflower were 1.3, 1.7 and 4.3, 6.2 μg kg −1 , respectively. The residual levels and dissipation kinetics of buprofezin 25% wettabe powder in cabbage and cauliflower cultivated under open field conditions was investigated at the single (T1) and double (T2) recommended rates of application. Half-life periods were found to be 1.73 and 2.1 days in cabbage, whereas in cauliflower, these values were 1.85 and 2.36 days at T1 and T2, respectively. Based on the dissipation study, and the maximum residue limit value of 0.05 mg kg −1 , the proposed pre-harvest interval of buprofezin in cabbage was 3-6 days and that in cauliflower was 4-10 days. The results showed that buprofezin is safe for application at both recommended application rates. KEYWORDSanalyte protectant, Brassica oleracea, buprofezin, GC/ITMS, QuEChERS

Levels of residues and dietary risk assessment of the fungicides myclobutanil, penconazole, tebuconazole, and triadimenol in squash

Alrasheed

Al-Mundarij

et al. 2021

Triazole fungicides may potentially harm human health. The 'quick, easy, cheap, effective, rugged, and safe' approach has become popular for extraction and cleanup during pesticide residue analysis. We aimed to (a) validate a method for the simultaneous determination of myclobutanil, penconazole, tebuconazole, and triadimenol in squash using LC-MS/MS and (b) determine the pre-harvest intervals (PHIs) and assess the related risk of consuming squash cultivated under open-field conditions in Saudi Arabia. Using acetonitrile as the extraction solvent and fourfold dilution in deionized water led to weak signal suppression (<À6.1%). The limits of quantitation ranged from 10 to 40 μg/kg. Mean recovery and relative standard deviation ranged from 81.7 to 96.3% and from 3.6 to 11.4%. The half-lives ranged from 2.22 to 3.83 days, and the dissipation followed first-order kinetics. The terminal residues of myclobutanil, penconazole, tebuconazole, and triadimenol were <0.771, <0.307, <0.459, and <0.954 mg/kg, respectively, 7 days after two or three applications of recommended dosages. The PHIs of 7. 1-11.4, 8.7-13.1, 3.8-5.3, and 11.3-14.3 days are suggested after the application of the recommended dose and double the recommended dose. A consumer risk assessment based on estimated dietary intake indicated that the consumption of squash treated with the recommended doses does not pose a significant health risk. K E Y W O R D S dissipation kinetics, LC-MS/MS, risk assessment, squash, triazole fungicides 1 | INTRODUCTION Squash (Cucurbita sp.)-a rich source of nutrients such as carbohydrates, vitamins, and minerals (Roura et al., 2004)-is a major crop in Saudi Arabia, where the plants are cultivated under open-field and greenhouse conditions (FAOSTAT, 2018). Squash and other cucurbit plants are susceptible to powdery mildew disease, which is mainly caused by the fungus Podosphaera xanthii. In severe cases, powdery mildew can cause premature death of the leaves and reduce squash production over the long term (Velkov & Masheva, 2002).At present, powdery mildew infections of squash leaves are routinely treated with the triazole fungicides myclobutanil, penconazole, tebuconazole, and triadimenol (Figure 1). Triazoles are inhibitors of demethylation that disrupt the biosynthesis of fungal cell