Department of Chemistry and Physics

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Browsing Department of Chemistry and Physics by Subject "Adulteration"

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    Development and validation of LC-MS/MS method for determination of non-opioid analgesics in adulterated herbal medicines
    (Sokoine University of Agriculture, 2022-11) Mpanyakavili, Anna Lucas
    Background: Herbal medicines are increasingly used worldwide despite the increased concern of their adulteration with conventional drugs. Non-opioid analgesics are among of the conventional drugs reported to be used in adulteration of anti-pain herbal medicines. This rise a need for developing reliable analytical method for determination of adulterated conventional drugs in herbal medicines for quality control. This study aimed at developing a high throughput Liquid Chromatography coupled with Tandem Mass Spectrometry for determination of non-opioid analgesics (acetaminophen, caffeine, acetylsalicylic acid, diclofenac, and ibuprofen) in herbal medicines in one run. The study also aimed at optimizing a sample preparation technique to enhance detection of the adulterants in herbal medicine obtained from the Tanzania market. Methodology: Solid Phase Extraction (SPE) and Ultrasonic Assisted Extraction (UAE) methods were compared in respect of recoveries, extraction time, complexity, matrix effects, and expenses for sample preparation. Waters OASIS Hydrophilic-lipophilic balance (HLB) 200 mg 6 mL, a C 18 sorbent was used in Solid Phase Extraction method optimization. The optimized parameters were effects of filters on sample filtration, sample loading pH, selection of suitable solvents for conditioning, washing, and elution. Ultrasonic bath and centrifuge were used for optimization of ultrasonic assisted extraction method parameters including effectives of organic solvent in extraction, extraction solvent content, and sample to extraction solvent volume ratio. Both methods were evaluated by calculating their matrix effects, absolute recoveries, and percentage recovery for sub- steps. The effective sample preparation method was used in development and validation of an advanced hyphenated method using an Agilent Technologies 1100 series Liquid Chromatography coupled with Waters Tandem Mass spectrometry (LC-MS/MS) with electrospray ionization. The LC-MS/MS method was validated for its selectivity, sensitivity, linearity, accuracy, precision, recovery, matrix effects, and stability. It was then used to analyse 132 samples collected from the markets of four regions in Tanzania. Results and Discussion: The Ultrasonic Assisted Extraction method showed to be efficient to Solid Phase Extraction method for extraction of selected non-opioid analgesics. This was clearly evidenced by high recoveries, minimum extraction time, good peak shape, its simplicity in procedures, and use of less expensive consumables. The absolute recoveries for Ultrasonic Assisted Extraction were at acceptable range (> 60%) ranging from 60 % to 107 % while for Solid Phase Extraction method showed poor recovery except for diclofenac and ibuprofen having 83% and 67%, respectively. The matrix effect expressed as signal suppression/enhancement ranged from 70% - 122% for Ultrasonic Assisted Extraction method and 3% to 124% for Solid Phase Extraction method. From the results the Ultrasonic Assisted Extraction method was chosen for sample extraction for analysis of Herbal Samples. The developed LC-MS/MS method was linear with coefficient of determination of R 2 ≥ 0.9931. The Limit of Detection (LOD) and Limit of Quantification (LOQ) for selected non-opioid analgesics were within the range of 0 – 3.7 μg/mL. The intra-precision of the LC-MS/MS method was expressed as Relative Standard deviation and was less than 9.5% with varying matrix effect among analytes. Twenty one percent (21%) of 132 collected herbal medicines were adulterated with caffeine and acetylsalicylic acid. 1,029.22 μg/mL was one of the highest concentration of caffeine detected in one of the analysed herbal medicines. Conclusion and recommendation: This is the first study in Tanzania to report an analytical method for analysis of five (5) non opioid analgesics in herbal medicines in Tanzania. The developed LC-MS/MS method is suitable for the identification and quantification of 5 non opioid analgesics explored adulterants. The method can be adopted by the regulatory authorities for routine analysis of herbal medicines for monitoring its quality and safety. Further studies are recommended for Ultrasonic Assisted Extraction method using additional internal standards.
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    Optimization of HPLC–MS/MS method for determination of antimalarial adulterants in herbal products
    (SPRINGER, 2023-01-12) Mwankuna Christopher J.; Kiros Feven; Mariki Eliapenda E.; Mabiki Faith P.; Malebo Hamisi M.; Mdegela Robinson H.; Styrishave Bjarne
    The use of herbal products is booming all over the world because of being believed as safer than conventional drugs and free of side effects. However, there are untrustworthy manufacturers who adulterate herbal products by adding conventional drugs which might eventually lead to microbial resistance and herb-to-drug interactions. There is a need to develop methods for detecting adulterants in herbal products. A high performance liquid chromatography-tandem mass spectrometry (HPLC– MS/MS) method for simultaneous identification and determination of conventional antimalarials (chloroquine, quinine, sulfadoxine, pyrimethamine, mefloquine, lumefantrine, amodiaquine, artemisinin, dihydroartemisinin, artesunate and artemether) in herbal products was developed. Stable isotopically labelled compounds (artemether-d3, quindine-d3, and sulfadoxine-d3) were used as internal standards (ISs) for quantitative analysis. Extraction of analytes was performed using methanol: water: formic acid (90:10:0.1, v/v) and chromatographic separation was done in a gradient mode using mobile phase A: Ultrapure water containing 0.1% formic acid and 1 mM ammonium formate and mobile phase B: Acetonitrile/ methanol (50:50) containing 0.1% formic acid and 1 mM ammonium formate. The calibration curves were linear (r2 ≥ 0.991) over the range of 0.001–0.3 μg ­mL−1 for all compounds. The limit of detection (LOD) ranged from 0.002 to 0.02 μg ­mL−1 while the limit of quantification (LOQ) ranged from 0.006 to 0.08 μg ­mL−1. Accuracy, expressed as recovery of spiked herbal products ranged from 52 to 128%. The precision, expressed as percent relative standard deviation (%RSD) at two concentration levels, ranged from 1.0 to 13.8%. The matrix effect expressed as the matrix factor (MF) ranged from 0.77 to 0.97. The developed method was used to identify and quantify conventional antimalarials in herbal product samples from Tanzania. Ten out of 50 herbal products were found to contain amodiaquine, sulfadoxine, pyrimethamine, mefloquine, dihydroartemisinin, artemether and lumefantrine. The developed method is considered a valuable tool for getting a better understanding of the adulteration of conventional antimalarials in herbal products.
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    Thin layer chromatographic method for detection of conventional drug adulterants in herbal products
    (MDPI, 2022) Mwankuna, Christopher Johnson; Mariki, Eliapenda Elisante; Mabiki, Faith Philemon; Malebo, Hamisi Masanja; Styrishave, Bjarne; Mdegela, Robinson Hammerton
    Commercially available conventional drugs have been used to adulterate herbal products. Considering the rapid growth of herbal products’ market, it is essential to screen herbal products for the presence of conventional drugs. Simple analytical methods are needed for the rapid screening of conventional drugs that are likely to be adulterated in herbal products. Thin layer chromatography (TLC) methods for screening twelve conventional drugs in herbal products have been developed and applied. The analytes were extracted from herbal products using acetonitrile:methanol:acetic acid:water (4:4:1:1, v/v). Solvent mixture of dichloromethane:ethyl acetate:methanol (75:15:10, v/v) separated well trimethoprim, sildenafil, paracetamol, and sulfamethoxazole while pyrimethamine, metronidazole, and sulfadoxine were well separated by dichloromethane:ethyl acetate:methanol (77.5:12.5:10, v/v). In addition, acetyl salicylic acid, ibuprofen, diclofenac, quinine, and lumefantrine were well separated by ethyl acetate:methanol:30% ammonia (75:22.5:2.5, v/v). Chromatographic separations were found to be highly reproducible, and more than 10 samples can be analysed in one run. The method was applied in the screening of 229 herbal products. Consequently, 24.0% of the samples contained one adulterant, while 21.4% contained at least two adulterants. All conventional drugs detected in herbal products were not mentioned on the labels and therefore the consumers are kept unaware of their side effects and health problems. Further studies for confirming and quantitatively determining the adulterants in a wide range of products as well as a systematic toxicological analysis of the adulterants in herbal products are recommended.
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    Thin layer chromatographic method for detection of conventional drug adulterants in herbal products
    (MDPI, 2022-12-31) Mwankuna Christopher Johnson; Mariki Eliapenda Elisante; Malebo Hamisi Masanja; Styrishave Bjarne; Mdegela Robinson Hammerton
    Commercially available conventional drugs have been used to adulterate herbal products. Considering the rapid growth of herbal products’ market, it is essential to screen herbal products for the presence of conventional drugs. Simple analytical methods are needed for the rapid screening of conventional drugs that are likely to be adulterated in herbal products. Thin layer chromatography (TLC) methods for screening twelve conventional drugs in herbal products have been developed and applied. The analytes were extracted from herbal products using acetonitrile:methanol:acetic acid:water (4:4:1:1, v/v). Solvent mixture of dichloromethane:ethyl acetate:methanol (75:15:10, v/v) separated well trimethoprim, sildenafil, paracetamol, and sulfamethoxazole while pyrimethamine, metronidazole, and sulfadoxine were well separated by dichloromethane:ethyl acetate:methanol (77.5:12.5:10, v/v). In addition, acetyl salicylic acid, ibuprofen, diclofenac, quinine, and lumefantrine were well separated by ethyl acetate:methanol:30% ammonia (75:22.5:2.5, v/v). Chromatographic separations were found to be highly reproducible, and more than 10 samples can be analysed in one run. The method was applied in the screening of 229 herbal products. Consequently, 24.0% of the samples contained one adulterant, while 21.4% contained at least two adulterants. All conventional drugs detected in herbal products were not mentioned on the labels and therefore the consumers are kept unaware of their side effects and health problems. Further studies for confirming and quantitatively determining the adulterants in a wide range of products as well as a systematic toxicological analysis of the adulterants in herbal products are recommended.