Ibrahim Hotan Alsohaimi

Quantitative determination of methylene blue in environmental samples by solid-phase extraction and ultra-performance liquid chromatography-tandem mass spectrometry: a green approach

Industrial effluents with dyes may contain appreciable concentrations of materials with high chemical oxygen demand and suspended solids, posing adverse effects to both humans and aquatic life; therefore, these effluents require quantitative monitoring. In the present study, an analytical method based on solid-phase extraction (SPE) and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) has been optimized for the quantitative analysis of methylene blue (MB) in environmental samples. For the extraction of MB, a variety of solvents, including formic acid, were investigated to obtain optimum recovery. MB extraction using the SPE method was best achieved using methanol with 1 M formic acid. Chromatographic separation of MB and methylene violet 3RAX (MV 3RAX, internal standard) was accomplished on an Acquity® BEH C18 column using water (64.99%) with formic acid (0.01%) and acetonitrile (35%) in isocratic elution mode. Chromatographic separation for both MB and MV 3RAX was achieved in 0.999), run-to-run and day-to-day precisions with relative standard deviations of <4%, sensitivity with a low limit of detection (LOD) of 0.1 ng mL−1 and limit of quantification (LOQ) of 0.4 ng mL−1 were obtained. Industrial wastewater samples (paper, textile, laundry and printing press) were analyzed, and an MB level was found in between 0.36 and 1.08 μg mL−1 with excellent recovery rates (95–99%) depending on samples.

Triethylenetetramine modified multiwalled carbon nanotubes for the efficient preconcentration of Pb(II), Cu(II), Ni(II) and Cd(II) before FAAS detection

A novel, accurate and easy separation and preconcentration procedure has been established in the presented work. Triethylenetetramine modified multiwalled carbon nanotubes (TETA-MWCNTs) were prepared and used as an efficient adsorbent for the solid phase extraction of heavy metal ions. This modification of multiwalled carbon nanotubes results in the surfaces of MWCNTs being rich with amino groups, which have a strong interaction with heavy metal ions. The characterization and surface morphology of TETA-MWCNTs were evaluated using FT-IR and SEM. The parameters of the developed solid phase extraction procedure were investigated. The optimum results were obtained at pH 7, and with 8 mL of 3 M nitric acid as the eluent. The LOD values were 3.7 μg L−1, 0.5 μg L−1, 2.4 μg L−1 and 0.3 μg L−1 for Pb(II), Cu(II), Ni(II) and Cd(II), respectively. The relative standard deviations (RSDs) were found to be 1.4%, 4.7%, 2.9% and 4.2% for Pb(II), Cu(II), Ni(II) and Cd(II), respectively. This method was validated by using it for certified reference materials (TMDA-53.3 fortified water and TMDA-64.2 Lake Ontario water). The TETA-MWCNTs were applied for the preconcentration of Pb(II), Cu(II), Ni(II) and Cd(II) from water, cigarette and fertilizer samples.

An ultra performance liquid chromatography-electrospray ionization-mass spectrometry method for the rapid analysis of nitrate in drinking water

Excess of nutrient load can cause water eutrophication and be harmful to humans. While nitrogen is an important nutrient for crops, its introduction into the soil with fertilizers containing nitrate (NO3−) has been a major source of water pollution and monitoring NO3− has become necessary. In the present work, an ultra performance liquid chromatography-mass spectrometry method has been developed for the rapid quantification of NO3− in drinking water with reversed phase chromatography using a Waters Acquity BEH C18 (50 mm × 2.1 mm i.d., 1.7 μm particle size) column and a triple quadrupole mass spectrometer operating in Single Ion Recording mode. The quality parameters of the developed method were established, obtaining a limit of detection of 0.02 μg L−1; linearity (r2 > 0.999) over a concentration range covering 3 orders of magnitude; high precision, with repeatability and reproducibility lower than 3% (n = 5) in terms of relative standard deviation when analyzing a standard (0.05 mg NO3− L−1) and unspiked drinking water samples with levels of NO3− of 1 μg L−1 (metropolitan water) and 3 mg L−1 (bottled water). These quality parameters show that the proposed method improves the performance of conventional analytical methods used for the analysis of NO3−. This method has been applied successfully for determination of NO3− in metropolitan and bottled water from the Kingdom of Saudi Arabia; a total of 25 samples have been analyzed where NO3− was found to be present from levels below the limit of detection to 6.49 mg L−1.

Occurrence of acrylamide carcinogen in Arabic coffee Qahwa , coffee and tea from Saudi Arabian market

The present work describes the outcomes of the assessment on acrylamide contents in a number of thermally treated foods (Arabic coffee Qahwa, coffee and tea) obtained from the Saudi Arabian markets. A total of 56 food samples of different brands and origin were studied, the amounts of acrylamide in Arabic coffee Qahwa, coffee and tea were obtained in the range of 10 to 682 μg kg−1. In comparison to coffee (152–682 μg kg−1), the Arabic coffee Qahwa (73–108 μg kg−1) and tea (10–97 μg kg−1) contain lower amounts of acrylamide. Among the analyzed samples, the green tea contained low amounts of acrylamide ranged from 10 to 18 μg kg−1, and thus the green tea could be considered as a healthier hot drink. A great variation of acrylamide formation has been observed in these food products. This divergence may be due to the initial concentration of amino acids especially asparagines and reducing sugars in food products, in addition to roasting temperature and time, pH and water activity. The obtained data can also be used in epidemiological investigation to estimate the acrylamide exposure from nutritional survey.

Solid phase extraction and ultra performance liquid chromatography-tandem mass spectrometric identification of carcinogenic/mutagenic heterocyclic amines in cooked camel meat

In the present study, three kinds of camel (Mjahim, Mgatir and Humor) from Saudi Arabia have been studied for heterocyclic amines (HAs) contents in their cooked meat. The camel meats were cooked using common cooking practices, such as frying, griddling, stewing and barbequing, under controlled temperature. The investigated HAs were IQ, MeIQ, MeIQx, 4,8-DiMeIQx and PhIP. An analytical method based solid-phase extraction and ultra performance liquid chromatography-tandem mass spectrometry was used for the analysis of HAs in cooked samples. The level of IQ and MeIQ were found either below the limit of quantification or not detected in all of the analyzed samples. The fried samples produced MeIQx, 4,8-DiMeIQx and PhIP, between 2.13 ng g−1 and 5.89 ng g−1, whereas the griddled and barbequed samples generated MeIQx, 4,8-DiMeIQx and PhIP ranging from 0.93 to 4.34 ng g−1. The stewing method applied to meat samples generated only PhIP at concentrations between 0.4 ng g−1 and 0.65 ng g−1, while MeIQx and 4,8-DiMeIQx were found to be below the limit of quantification. The low levels of HAs in stewing method might be explained from the fact that the samples were not directly in contact with the cooking pot or blaze, which influences the formation of HAs. These outcomes suggest that camel meat is a significant dietary source of HAs and can be used in epidemiological studies to approximate HA exposure from dietary questionnaires.

Quantitative analysis of bromate in non-alcoholic beer using ultra performance liquid chromatography-electrospray ionization mass spectrometry

Bromate (BrO3−) is a possible human carcinogen which is formed as a bromide containing source water ozone disinfection by-product. Thus, BrO3− is subject to assess its threat to humans. In the present study, an ultra performance liquid chromatography-electrospray ionization mass spectrometry method has been developed for the quantitative analysis of BrO3− in non-alcoholic beer. The chromatographic separation of both transitions 81BrO3− and 79BrO3− (isotope contributions of 79Br and 81Br) was carried out and achieved in 0.9999), precision (repeatability and reproducibility in terms of relative standard deviation) <1% at 1.0 μg mL−1 standard and <3% in the analysis of sample 1 (classic malt) and sensitivity with a low limit of detection (LOD, 81BrO3−, 0.03 ng mL−1 and 79BrO3−, 0.03 ng mL−1) and limit of quantification (LOQ, 81BrO3−, 0.1 ng mL−1 and 79BrO3−, 0.1 ng mL−1) in the standard. Nevertheless, the LOD and LOQ in sample 1 (classic malt) were obtained only for transition 81BrO3−, 0.05 ng mL−1 and 0.16 ng mL−1, respectively. For transition 79BrO3− the obtained peak was below the limit of detection. A total of 39 non-alcoholic beer samples of different flavors were analyzed and the 81BrO3− level in classic samples was found between 1.20 μg mL−1 and 3.73 μg mL−1, however, in other flavored samples the concentration levels reached up to 14.04 μg mL−1 with excellent recovery rates (96–99%). In most of the analyzed real samples, only transition 81BrO3− was found nevertheless, transition 79BrO3− was either <LOD or completely diminished from the obtained sample chromatogram. This is one of the main findings from the present study and the mechanism of this cause is unknown. The obtained BrO3− levels were much higher than the limits in drinking water (10–25 ng mL−1) recommended by several regulatory agencies.