Determination of Dicyandiamide in Powdered Milk Using Direct Analysis in Real Time Quadrupole Time-of-Flight Tandem Mass Spectrometry

Rapid and sensitive approaches for detecting food fraud: A review on prospects and challenges

Precise and reliable analytical techniques are required to guarantee food quality in light of the expanding concerns regarding food safety and quality. Because traditional procedures are expensive and time-consuming, quick food control techniques are required to ensure product quality. Various analytical techniques are used to identify and detect food fraud, including spectroscopy, chromatography, DNA barcoding, and inotrope ratio mass spectrometry (IRMS). Due to its quick findings, simplicity of use, high throughput, affordability, and non-destructive evaluations of numerous food matrices, NI spectroscopy and hyperspectral imaging are financially preferred in the food business. The applicability of this technology has increased with the development of chemometric techniques and near-infrared spectroscopy-based instruments. The current research also discusses the use of several multivariate analytical techniques in identifying food fraud, such as principal component analysis, partial least squares, cluster analysis, multivariate curve resolutions, and artificial intelligence.

Detection of nitrification inhibitor dicyandiamide: A direct electrochemical approach

A single run approach for rapid detection of nitrification inhibitor, dicyandiamide (DCD) using electrogenerated chlorine assisted polymerization through azo bond, under acidic conditions and at a preanodized screen printed carbon electrode (SPCE*) is presented. The role of chloride containing support electrolyte in acidic medium along with oxygen functionalities/edge sites are found to be crucial for the successful oxidative polymerization and subsequent adsorption of oxidized products on the electrode surface. The SEM, cyclic voltammetry and X-ray photoelectron spectroscopy studies were used to characterize the polymer film formation. The system exhibited a linear range between 20 and 170 μM with a detection limit of 3 μM (S/N = 3). The method was successfully tested for the detection of DCD in dairy and water samples. Simultaneous detection of DCD in the presence of melamine has also been demonstrated.

A Novel Integrated APCI and MPT Ionization Technique as Online Sensor for Trace Pesticides Detection

The misuse of pesticides poses a tremendous threat to human health. Excessive pesticide residues have been shown to cause many diseases. Many sensor detection methods have been developed, but most of them suffer from problems such as slow detection speed or narrow detection range. So, the development of rapid, direct and sensitive means of detecting trace amounts of pesticide residues is always necessary. A novel online sensor technique was developed for direct analysis of pesticides in complex matrices with no sample pretreatment. The portable sensor ion source consists of an MPT (microwave plasma torch) with desolventizing capability and an APCI (atmosphere pressure chemical ionization), which provides abundant precursor ions and a strong electric field. The performance which improves the ionization efficiency and suppresses the background signal was verified by using pesticide standard solution and pesticide pear juice solution measurements with an Orbitrap mass spectrometer. The limit of detection (LOD) and the limit of quantization (LOQ) of the method were measured by pear juice solutions that were obtained in the ranges of 0.034-0.79 μg/L and 0.14-1 μg/L. Quantitative curves were obtained ranging from 0.5 to 100 μg/L that showed excellent semi-quantitative ability with correlation coefficients of 0.985-0.997. The recoveries (%) of atrazine, imidacloprid, dimethoate, profenofos, chlorpyrifos, and dichlorvos were 96.6%, 112.7%, 88.1%, 85.5%, 89.2%, and 101.9% with the RSDs ranging from 5.89-14.87%, respectively. The results show that the method has excellent sensitivity and quantification capability for rapid and direct detection of trace pesticide.

Identification of milk from different animal and plant sources by desorption electrospray ionisation high-resolution mass spectrometry (DESI-MS)

This study used desorption electrospray ionisation mass spectrometry (DESI-MS) to analyse and detect and classify biomarkers in five different animal and plant sources of milk for the first time. A range of differences in terms of features was observed in the spectra of cow milk, goat milk, camel milk, soya milk, and oat milk. Chemometric modelling was then used to classify the mass spectra data, enabling unique or significant markers for each milk source to be identified. The classification of different milk sources was achieved with a cross-validation percentage rate of 100% through linear discriminate analysis (LDA) with high sensitivity to adulteration (0.1-5% v/v). The DESI-MS results from the milk samples analysed show the methodology to have high classification accuracy, and in the absence of complex sample clean-up which is often associated with authenticity testing, to be a rapid and efficient approach for milk fraud control.

Applications of direct analysis in real time mass spectrometry in food analysis: A review

RATIONALE

Direct analysis in real time (DART) combined with mass spectrometry (MS) detection has become one of the most broadly used analytical approaches for the direct molecular characterization of food samples with regard to their chemical quality, safety, origin, and authentication. The major advantages of DART-MS for food analysis include high chemical sensitivity and specificity, high speed and throughput of analysis, simplicity, and the obviation of tedious sample preparation and solvents.

METHODS

The recent applications of DART coupled with different mass analyzers, including quadrupole, ion trap, Orbitrap, and time of flight, are discussed. In addition, sample pretreatment methods that have been coupled with DART-MS are discussed.

RESULTS

We summarize the applications of DART-MS in food science and industry published in the period from 2005 to this date. The applications and analytical characteristics are systematically categorized across the three major types of foods: solid foods, liquid foods, and viscous foods.

CONCLUSIONS

DART-MS has proved its high suitability for the direct, rapid, and high-throughput molecular analysis of very different food samples with minimal or no sample preparation, thus offering a high-speed alternative to liquid chromatography/mass spectrometry (LC/MS) and gas chromatography/mass spectrometry (GC/MS) approaches that are traditionally employed in food analysis.

Ambient (desorption/ionization) mass spectrometry methods for pesticide testing in food: a review

Ambient mass spectrometry refers to the family of techniques that allows ions to be generated from condensed phase samples under ambient conditions and then, collected and analysed by mass spectrometry. One of their key advantages relies on their ability to allow the analysis of samples with minimal to no sample workup. This feature maps well to the requirements of food safety testing, in particular, those related to the fast determination of pesticide residues in foods. This review discusses the application of different ambient ionization methods for the qualitative and (semi)quantitative determination of pesticides in foods, with the focus on different specific methods used and their ionization mechanisms. More popular techniques used are those commercially available including desorption electrospray ionization (DESI-MS), direct analysis on real time (DART-MS), paper spray (PS-MS) and low-temperature plasma (LTP-MS). Several applications described with ambient MS have reported limits of quantitation approaching those of reference methods, typically based on LC-MS and generic sample extraction procedures. Some of them have been combined with portable mass spectrometers thus allowing "in situ" analysis. In addition, these techniques have the ability to map surfaces (ambient MS imaging) to unravel the distribution of agrochemicals on crops.

High-throughput quantification of drugs of abuse in biofluids via 96-solid-phase microextraction-transmission mode and direct analysis in real time mass spectrometry

RATIONALE

The workload of clinical laboratories has been steadily increasing over the last few years. High-throughput (HT) sample processing allows scientists to spend more time undertaking matters of critical thinking rather than laborious sample processing. Herein we introduce a HT 96-solid-phase microextraction (SPME) transmission mode (TM) system coupled to direct analysis in real time (DART) mass spectrometry (MS).

METHODS

Model compounds (opioids) were extracted from urine and plasma samples using a 96-SPME-TM device. A standard voltage and pressure (SVP) DART source was used for all experiments. Examination of SPME-TM performance was done using high-resolution mass spectrometry (HRMS) in full scan mode (100-500 m/z), whereas quantitation of opioids was performed using triple quadrupole MS in multiple reaction monitoring mode and by using a matrix-matched internal standard correction method.

RESULTS

Thirteen points (0.5 to 200 ng mL^-1 ) were used to establish a calibration curve. Low limits of quantitation (LOQ) were obtained (0.5 to 25 ng mL^-1 ) for matrices used. Acceptable accuracy (71.4-129.4%) and repeatability (1.1-24%) were obtained for validation levels tested (0.5, 30 and 90 ng mL^-1 ). In less than 1.5 hours, 96 samples were extracted, desorbed and processed using the 96-SPME-TM system coupled to DART-MS.

CONCLUSIONS

A rapid HT method for detection of opioids in urine and plasma samples was developed. This study demonstrated that ambient ionization mass spectrometry coupled to robust sample preparation methods such as SPME-TM can rapidly and efficiently screen/quantify target analytes in a HT context.

A validated method for the quantification of mitragynine in sixteen commercially available Kratom (Mitragyna speciosa) products

The recent rise in the recreational use of plant-based "legal highs" has prompted the development of methods for the identification of the bulk material, and quantification of their psychoactive components. One of these plants is Mitragyna speciosa, commonly referred to as Kratom. While traditional use of this plant was primarily for medicinal purposes, there has been a rise in its recreational use, and as a self-prescribed medication for opioid withdrawal. Although Kratom contains many alkaloids, mitragynine and 7-hydroxymitragynine are unique psychoactive biomarkers of the species, and are responsible for its psychoactive effects. A rapid validated method for the quantification of mitragynine in Kratom plant materials by direct analysis in real time-high-resolution mass spectrometry (DART-HRMS) is presented. It has a linear range of 5-100 μg mL^-1, and a lower limit of quantification of 5 μg mL^-1. The protocol was applied to determination of the mitragynine content of 16 commercially available Kratom plant products purchased online. The mitragynine amounts in these materials ranged from 2.76 to 20.05 mg g^-1 of dried plant material. The utilization of DART-HRMS affords a mechanism not only for the preliminary identification of bulk plant material as being M. speciosa-derived (with no sample preparation required), but also provides the opportunity to quantify its psychoactive components using the same technique.

Clinical Application of Ambient Ionization Mass Spectrometry

Ambient ionization allows mass spectrometry analysis directly on the sample surface under atmospheric pressure with almost zero sample pretreatment. Since the development of desorption electrospray ionization (DESI) in 2004, many other ambient ionization techniques were developed. Due to their simplicity and low operation cost, rapid and on-site clinical mass spectrometry analysis becomes real. In this review, we will highlight some of the most widely used ambient ionization mass spectrometry approaches and their applications in clinical study.

Detection of polydimethylsiloxanes transferred from silicone-coated parchment paper to baked goods using direct analysis in real time mass spectrometry

The non-stick properties of parchment papers are achieved by polydimethylsiloxane (PDMS) coatings. During baking, PDMS can thus be extracted from the silicone-coated parchment into the baked goods. Positive-ion direct analysis in real time (DART) mass spectrometry (MS) is highly efficient for the analysis of PDMS. A DART-SVP source was coupled to a quadrupole-time-of-flight mass spectrometer to detect PDMS on the contact surface of baked goods after use of silicone-coated parchment papers. DART spectra from the bottom surface of baked cookies and pizzas exhibited signals because of PDMS ions of the general formula [(C2H6SiO)n  + NH4 ](+) in the m/z 800-1900 range.