method detection limit
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2021 ◽  
Vol 9 ◽  
Author(s):  
Ivana Kosarac ◽  
Cariton Kubwabo ◽  
Guru Prasad Katuri ◽  
Dora Petraccone ◽  
Trevor K. Mischki

During the summer of 2019, cases of lung injury associated with vaping emerged in North America, including among individuals who reported exclusive use of nicotine vaping liquids. Once vitamin E acetate was identified as a potential causative agent a quantitative method based on a simple sample dilution, separation by gas chromatography and analysis by triple quadrupole mass spectrometry (GC MSMS) was developed. Method detection limit (MDL) and limit of quantification (LOQ) were determined at 0.159 µg/mL and 0.505 µg/mL, respectively. The analysis was performed on a subset of 203 commercially sourced nicotine containing vaping liquids of various flavour profile and nicotine range (nicotine free-59 mg/mL) from an internal inventory. The target analyte, Vitamin E Acetate, was not detected in any samples analyzed, as expected, given the reported detection in literature and high association of the chemical with cannabis and not nicotine containing vaping products.


Author(s):  
Amitesh Malhotra ◽  
Banu Örmeci

Abstract Effective monitoring tools and methods are needed for the early detection and management of cyanobacteria in water bodies to minimize their harmful impacts on the environment and public health. This research investigated changing the cuvette pathlength (10-, 50-, and 100-mm) to improve the detection of cyanobacteria using UV-Vis spectrophotometry with subsequent application of derivative spectrophotometry and Savitzky-Golay (S-G) transformation. A non-toxigenic strain of blue-green cyanobacteria, Microcystis aeruginosa (CPCC 632), and a green algae strain for comparison, Chlorella vulgaris (CPCC 90), were studied in a wide range of concentrations (955,000–1,855 cells/mL). In each concentration range, method detection limits were established with absorbance measurements and S-G first derivative of absorbance using 10-, 50-, and 100-mm cuvette pathlengths. Increasing the cuvette pathlength from 10 to 100 mm resulted in a 15-fold improvement in sensitivity with absorbance and a 13-fold improvement with S-G first derivative of absorbance for M. aeruginosa. Overall, adoption of 100 mm pathlength and application of S-G derivative spectra improved the method detection limit for M. aeruginosa from 337,398 cells/mL to 4,916 cells/mL, which is below the WHO guideline for low probability of adverse health effects (<20,000 cells/mL). Similarly, the detection limit for C. vulgaris was improved from 650,414 cells/mL to 11,661 cells/mL. The results also showed that spectrophotometry could differentiate M. aeruginosa from C. vulgaris based on the variations in their pigment absorbance peaks.


Author(s):  
Fathy Atia Mohamed Atia ◽  
Ahmad Ali Ahmadi ◽  
Mohammed AlSafran

A lowest detection limit with straight linearity was obtained by developing a method to analyze Phenacetin (Phe) in both aqueous and organic extraction by using Liquid chromatography Triple Quoadrpole mass with electrospray ionization (LCMSMS/ESI). The validation of the developed method was carried out according to ICH Harmonized Tripartite guideline. Validation criteria obtained were; the method detection limit MDL is 0.089 ng/ml, method quantification limit MQL is 0.19 ng/ml while the calibration curve linear from 0.1 to 1000 ng/mL with correlation coefficient R2 is 0.9994, Accuracy and precision up to 97% and the repeatability inter and intraday for six replicates of three concentration with RSD 2.1%. Separation occurred using Nova Pack C18 4 um, 150 x 3.9 mm column, using acetonitrile: 0.1% Formic acid 60:40% (v:v) at flow rate 1ml/min. the detector was triple quad mass spectrometry at multi-reaction mode MRM to detect parent mass 180.1 at frag 97 to transition fragments 110 and 138 at collision voltages 16 and 12 respectively.


Author(s):  
Trong Le Van ◽  
Thanh Hang Nguyen Thi ◽  
Huy Do Quang ◽  
Khai Nguyen Manh ◽  
◽  
...  

Antibiotics are contaminants at low concentrations and found in water with the range of ng/L. Determination of antibiotics at trace concentrations requires modern and high accuracy equipment. Liquid chromatography mass tandem spectrometry (LC-MS/MS) able to determine contaminants at ppt and ppb levels, which is suitable for quantification of the macrolide and tetracycline group in water. The Analytical method using Agilent Triple Quard 6460 LC-MS/MS system with positive ion mode. Agilent XDB C18 column (1.8 µm × 2.1 × 100 mm) and Agilent Eclipse SDB C18 pre-column (2.1 × 5 mm × 1.8 µm) were used. Mobile phase was acetonitrile and HCOOH 0.1%. Samples were cleaned with Oasis PRiME HLB 3cc SPE column (150 mg). The method was evaluated based on specificity, recovery, repeatability and estimation of the uncertainty. The method detection limit (MDL) for the analytes is 0.03 µg/L. Recovery ranges from 85.23 -117.70%; repeatability (RSDr) is between 2.20% and 12.45%.


2020 ◽  
Vol 103 (6) ◽  
pp. 1521-1527
Author(s):  
Koichi Saito ◽  
Junki Ishii ◽  
Misaki Naniwa ◽  
Rie Ishii ◽  
Mihoko Kato ◽  
...  

Abstract Background Aflatoxins (AFs) are carcinogenic mycotoxins. A simple, quick, and accurate method for the micro-analysis of AFs in foodstuffs, especially spices, is needed. Objective A sophisticated pretreatment method that combines solid-phase dispersive extraction (SPDE) and solid-phase fluorescence derivatization using immunoaffinity (IA) gel as the solid phase was developed to analyze AFs in spices simply, quickly, and sensitively by liquid chromatography with fluorescence detection. Method White and black pepper samples were extracted with a mixed solution of methanol/water (4:1) and then diluted with 7% aqueous solution of Triton-X. The solution was subjected to cleanup by SPDE using IA gel. Trifluoroacetic acid was added to the IA gel for on-site solid-phase fluorescence derivatization. Results Chromatograms containing well-separated peaks and few interference peaks from contaminants were obtained. The method detection limit of AFs in white and black pepper was 0.15–0.29 ng/g. Repeatability and intermediate precision were <10% and <15%, respectively, and accuracy was 61.7–87.8%. In addition, inter-laboratory precision was <29% and mean recovery was 61.5–76.7%. A favorable z-score of |Z| ≦ 1 was obtained in seven laboratories, although one laboratory gave 2 < |Z| < 3. Conclusions The validity, reliability, practicality, and robustness of the developed method were verified. Highlights By using SPDE and solid-phase fluorescence derivatization in combination for AF analysis, fluorescence derivatization during cleanup was realized, leading to simplification of the pretreatment operation.


Foods ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 746
Author(s):  
Kunho An ◽  
Inhwan Kim ◽  
Chan Lee ◽  
Joon-Kwan Moon ◽  
Hee-Jae Suh ◽  
...  

Morpholine salts of fatty acids have been used in wax coatings on the surfaces of fruit and vegetable commodities in China and the United States, etc. However, morpholine usage was prohibited in many other countries because of safety concerns. We optimized analytical methods to determine morpholine in the peel and pulp of fruits and vegetables by gas chromatography-mass spectrometry (GC-MS). This morpholine analysis method was applied to real samples of apples, citrus fruits, and vegetables from Korea, China, and the U.S. The method was validated using apple and citrus fruit peels and pulp. The method detection limit (MDL) was 1.3–3.3 µg/kg. The recovery rates of morpholine were 88.6–107.2% over a fortified level of 10–400 µg/kg. Intra-day and inter-day precisions were 1.4–9.4% and 1.5–2.8%, respectively. The morpholine concentrations were n.d. (not detected)–11.19 and n.d. (not detected)–12.82 µg/kg in apple and citrus peels, respectively. Morpholine was not detected in citrus or apple pulp samples or in vegetable samples.


Author(s):  
Sani Rachman Soleman ◽  
Tomoko Fujitani ◽  
Yukiko Fujii ◽  
Kouji H. Harada

Persistent organic pollutants can accumulate inside the human body, including in mothers’ milk, which may affect infant development. This cross-sectional study aimed to examine selected persistent organic pollutants in the milk of 100 mothers in Sendai city, Miyagi Prefecture, Japan. We used gas-chromatography-electron capture negative chemical ionization-mass spectrometry to check for octachlorostyrene, dechlorane (Dec) plus, Dec 602, Dec 603, and Dec 604. Octachlorostyrene was detected in 86 samples at more than the method detection limit (84 pg g-lipid−1) but no dechloranes were above the method detection limit (1 ng mL−1 for dechlorane plus, Dec 602, and Dec 603; 20 ng mL−1 for Dec 604). The mean octachlorostyrene concentration was 461 pg g-lipid−1, the median was 337 pg g-lipid−1, and the standard deviation 450 pg g-lipid−1. No baseline characteristics were associated with octachlorostyrene level except for mother’s occupation (stay-at-home mother, 353 ± 327 pg g-lipid−1; others, 531 ± 509 pg g-lipid−1). Octachlorostyrene was also significantly negatively correlated with lipid content (r = −0.35, p = 0.0004). However, the maximum intake of octachlorostyrene among infants in this study (3.5 ng/kg/day) was under the acceptable daily intake (30 ng/kg/day, derived from 12−month study in rats), and is therefore unlikely to pose a health risk.


2020 ◽  
Vol 984 ◽  
pp. 58-63
Author(s):  
Guang Bao Ye

The determination of the migration of 11 organotin compounds in food contact materials by GC-MS was established. The gastric acid was simulated with 0.07 mol/L hydrochloric acid solution, and the sample was soaked and extracted, and then derivatized with sodium tetraethylborate, extracted with n-hexane liquid solution, detected by GC-MS, and quantified by internal standard method. The linear range of the method is 5~600 μg/L, the correlation coefficient is greater than 0.997, and the method detection limit is 0.014 mg/kg. The recoveries of the three concentration levels ranged from 83.6% to 105.6% with a relative standard deviation of less than 11.4%. The method is simple and sensitive, and can be used for detecting the migration of organotin compounds in food contact materials.


2020 ◽  
Vol 83 (4) ◽  
pp. 710-714
Author(s):  
KADINE WILLIAMS ◽  
ELISABETH MOHAMMED ◽  
DEVIKA MAHARAJ ◽  
TERRY MOHAMMED ◽  
AZAD MOHAMMED

ABSTRACT Arsenic contamination in chicken is a cause of concern because of the potential health problems that may arise. In Trinidad and Tobago, chicken consumption averages about 53.8 kg per person per year, and chicken accounts for 85% of all the meat consumed locally. Fourteen chicken samples of imported, locally grown, and local organically farmed chickens were obtained from poultry depots and local supermarkets and were analyzed in triplicate. The concentration of total arsenic in the imported chicken ranged from below the method detection limit (MDL) to 512.50 μg/kg, and the concentration in the locally produced chicken ranged between <MDL and 516.44 μg/kg. The estimated concentration of inorganic arsenic (iAs) in the imported chickens ranged between <MDL and 333.12 μg/kg, whereas in local chicken it ranged between <MDL and 335.68 μg/kg. The estimated daily intake (EDI) of iAs varies between 0 and 0.72 μg/kg/day. Five of the samples evaluated exceeded the tolerable limit of 0.3 μg/kg of body weight per day as set by the U.S. Environmental Protection Agency. HIGHLIGHTS


Molecules ◽  
2019 ◽  
Vol 24 (22) ◽  
pp. 4089 ◽  
Author(s):  
J. Jiménez-López ◽  
E.J. Llorent-Martínez ◽  
S. Martínez-Soliño ◽  
A. Ruiz-Medina

In this work, we present an automated luminescence sensor for the quantitation of the insecticide thiacloprid, one of the main neonicotinoids, in lettuce samples. A simple and automated manifold was constructed, using multicommutated solenoid valves to handle all solutions. The analyte was online irradiated with UV light to produce a highly fluorescent photoproduct (λexc/λem = 305/370 nm/nm) that was then retained on a solid support placed in the flow cell. In this way, the pre-concentration of the photoproduct was achieved in the detection area, increasing the sensitivity of the analytical method. A method-detection limit of 0.24 mg kg−1 was achieved in real samples, fulfilling the Maximum Residue Limit (MRL) of The European Union for thiacloprid in lettuce (1 mg kg−1). A sample throughput of eight samples per hour was obtained. Recovery experiments were carried out at values close to the MRL, obtaining recovery yields close to 100% and relative standard deviations lower than 5%. Hence, this method would be suitable for routine analyses in quality control, as an alternative to other existing methods.


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