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Chemistry, Analytical
Consumers in developed and Western European countries are becoming more aware of the impact of food on their health, and they demand clear, transparent, and reliable information from the food industry about the products they consume. They recognise that food safety risks are often due to the unexpected presence of contaminants throughout the food supply chain. Among these, mycotoxins produced by food-infecting fungi, endogenous toxins from certain plants and organisms, pesticides, and other drugs used excessively during farming and food production, which lead to their contamination and accumulation in foodstuffs, are the main causes of concern.
- food safety
- food control
- contaminants
- toxic compounds
- food alerts
1. Introduction
Regardless of the target contaminants and food matrices analysed, LC is consistently the preferred chromatographic approach to be used and reported in the last five years (2018–2023, as reviewed in [98]). This is often preceded by sample preparation using commercial SPE, QuEChERS, among other procedures [99]. Sample preparation and extraction is an important step that will dictate the success of the chromatographic analysis, and for this reason, specific information about the extraction procedures followed in each of the selected reports is also presented in Table 1. There have been some improvements to these standard protocols for the extraction of the mycotoxin citrinin in cereals, food supplements, and red yeast rice using molecularly imprinted polymers as sorbents in the SPE procedure [75] or the extraction of the toxin okadaic acid in clams using magnetic SPE [100]. Regarding QuEChERS, successful downscale ability to extract tropane alkaloids in leafy vegetables is noteworthy [67]. Deep eutectic solvents (DES) have also been employed in the liquid–liquid microextraction of organophosphorus and pyrethroid pesticides from fruit juices and teas [50,52]. Another interesting report on the analysis of PAHs in nutritional supplements containing omega-3 and fish oil involved fabric sorbent-phase extraction (FPSE) [89]. The application of covalent organic frameworks (COFs) and metal organic frameworks (MOFs) to obtain sorbents with augmented retention capabilities has been successfully explored in recent years, particularly for the extraction of antibiotics from different foodstuffs (reviewed in [101,102]). Overall, from the reports compiled in Table 1, it is clear that, despite the improvements and innovations introduced in the extraction procedure, MS detection is essential to obtain a better analytical performance. However, as observed in the determination of citrinin in red yeast rice, the use of improved extraction protocols (MISPE) partially compensates for the lack of MS detection systems, clearly improving the analytical performance of the methodologies reported using the HPLC-FLD architecture [73,75]. GC-MS is used less frequently than LC for the analysis of food contaminants, because its range of applications is limited to volatile and semi-volatiles compounds. A derivatisation procedure to obtain volatile molecules is sometimes possible; however, this can make the procedure longer and more prone to errors, resulting in poorer analytical performance. Nevertheless, it is worthwhile to refer to the use of GC-MS/MS to detect dioxins and furans in different meats, salmon, and fish oils [92], or more recently, to detect genotoxic carcinogens of vegetable origin in infant formulas and elderly milk powders [87].
Table 1. Toxic molecules reported in foodstuffs and the methodology used to assess their safety found in the literature in the last five years.
| Compound | Sample | Extraction Method | Analysis | Results (LODs/Recoveries) |
Ref. |
|---|---|---|---|---|---|
| Pesticides | |||||
| Imidacloprid, acetamiprid, clothianidin, and atrazine | Fruits and vegetables | QuEChERS: 5 g sample, 5 mL ACN; 0.6 g MgSO4, and 0.2 g PSA | LC-MS/MS | 0.08–141 μg/kg/70–110% | [103] |
| Organophosphorus pesticides | Juices, water, tomato, cucumber, and honey samples | 75 mL sample; nanocomposite comprising metal-organic framework MIL-101(Cr), and graphene nanopowder | GC-MS | 0.005–15.0 µg/kg/84–110% | [51] |
| Organophosphorus pesticides | Vegetables | 30 min sonication of 4 g homogenised samples mixed with 8 mL ACN; collect the filtrate; repeat three times; combine and evaporate (50 °C N2 stream); redissolve (1 mL acetone); MSPE: add 25 mg Fe3O4@COF@Zr4+ to the sample solution; 30 min vortex; discard supernatant; elute (1 mL acetone; 8 min US); 0.22 μm filtration | GC-FPD | 0.7–3.0 μg/kg/87–121% | [104] |
| Organophosphorus pesticides (phosalone and chlorpyrifos) | Red grape juice and sour cherry juice | 10 mL sample; DES-UALLME: choline chloride/4-chlorophenol (408 μL) | HPLC-UV | 0.070–0.096 ng/mL/87.3–116.7% | [105] |
| 14 organophosphorous pesticides | Fruits and vegetables | 2 g sample; SPME: N-doped C-(C3N4@MOF) fibre coating | GC–MS | 0.23–7.5 ng/g/82.6–118% | [50] |
| Pyrethroids (transfluthrin, fenpropathrin, fenralerate, ethofenprox, and bifenthrin) | Tea beverages and fruit juices | 5 mL sample; DES-DLLME: Hexafluoro-isopropanol-based hydrophobic DES (0.15 g) | HPLC-DAD | 0.06–0.17 ng/mL | [52] |
| Neonicotinoids | Water | 2 mg MOFs + 1 mL NEOs standards; 5 min incubation; centrifugation (14,000 rpm, 2 min); 500 μL MeOH ultrasonic elution; vacuum evaporator, 100 μL mobile phase solubilisation | LC-MS | 0.02–0.1 ng/mL | [106] |
| Veterinary drug residues | |||||
| 52 veterinary drug residues | Mutton or leg meat | 5 g sample; QuEChERS: modified with reduced graphene oxide-melamine sponge (r-GO@MeS) | UPLC–MS/MS | LOD: 0.02–2.0 μg/kg LOQ: 0.05–5.0 μg/kg/63.7–109.5% |
[107] |
| 103 veterinary drug residues | Milk and dairy products | 5 g liquid milk or 1 g milk powder; QuEChERS with dispersive solid phase: 100 mg C18 and 300 mg anhydrous sodium sulphate | UPLC-MS/MS | LOQ: 0.1–5 μg/kg (milk) and 0.5–25 μg/kg (milk powder)/>60% | [108] |
| Beta-lactams, quinolones, sulphonamides, and tetracyclines | Fish, poultry, and red meat | 1 g sample; SPE: 5 mL ACN | LC-MS/MS | LOD: 0.3–15 µg/kg, LOQ: 0.8–45.3 µg/kg/82–119% | [109] |
| Sulphonamides | Pork, milk, and water | 100 mL sample loaded through the TPB-DMTP-COF column; washing (3 mL water); drying; elution (8 mL MA); drying (N2 flow); eluent re-dissolved (1.0 mL ultrapure water) | LC–MS/MS | 0.5–1.0 ng/L | [110] |
| Malachite green and crystal violet | Hairtail fish | 5 g sample; dSPE: NiO/ZnO-coated carbon microspheres, 3 mL 3:7 MeOH–H2O, 4 mL 9:1 MeOH | UPLC-UV | 0.50 μg/L (malachite green) and 0.35 μg/L (crystal violet) | [57] |
| 8 nitrofurans | Muscle, milk, eggs, honey, and casings | 2 g sample; hydrolysis and derivatisation, followed by ethyl acetate extraction | UHPLC-MS/MS | 93.5–127.5% recovery | [60] |
| Doxycycline | Chicken claws | 2 g sample; extraction with 5 mL 5% TCA | UHPLC−MS/MS | 5 μg/kg/80–110% | [111] |
| Estrogens | Milk and cosmetics | 5 mL milk + perchloric acid (100 μL, 10% v/v); homogenisation and centrifugation (3 min 10,000 rpm); supernatant pH adjusted to 4 (NaOH, 1 M); 0.45 μm filtration; lotion centrifugation (10 min 10,000 rpm); supernatant pH adjusted to 4 (HCl 1 M); 0.45 μm filtration; add 40 mg MILs + 0.275 g NaCl; 5 min shaken 1500 rpm; recover MILs; 500 µL ACN elution | HPLC-UV | 5–15 ng/mL/98.5–109.3% | [112] |
| Biotoxins | |||||
| Ergot alkaloids and their epimers | Oat-based foods and food supplements (bran, flakes, flour, grass, hydroalcoholic extracts, juices, and tablets) | QuEChERS: 1 g sample; 4 mL ACN and 5 mM ammonium carbonate (85:15, v/v); dSPE: 150 mg C18:Z-Sep+ (1:1); residue reconstituted with 750 µL MeOH 50% (v/v), 0.22 µm nylon membrane filter | UHPLC–MS/MS | LOQ: 3.2 μg/kg/89.7–109% | [78] |
| Lipophilic marine toxins (yessotoxins, dinophysistoxins, okadaic acid, azazspiracids, and spirolides) | Fresh and processed shellfish | 100 g sample; QuEChERS: 2 mL MeOH/ethanol/isopropanol; dSPE: 50 mg graphene oxide/ 100 mg MgSO4 | UPLC-MS/MS | LOD: 0.10–1.47 μg/kg LOQ: 0.32–4.92 μg/kg/85–117.4% |
[113] |
| Staphylococcal enterotoxin type A (SEA) | Cow’s milk | 25 g sample, clean up: pH control (pH 3.5 ± 0.5 + 5 M HCl; pH 7.5 ± 0.1 + 5 M NaOH) and TCA precipitation (20% TCA solution); protein denaturisation (5 mL 100 mM Tris-HCl, pH 8.5, 7 M guanidium hydrochloride + 10 mM EDTA); enzymatic digestion and desalting: trypsin digestion (1:100 (w/w)), 1% formic acid acidification, desalting with a GL–Tip styrene-divinylbenzene | LC–MS/MS | LOQ: 10 µg/kg/70–120% | [114] |
| Okadaic acid | Clams | MSPE: 2 g samples + 9 mL MeOH, mix; clean-up: 3 mg Fe3O4@TaTp dispersed in 200 μL MeOH, extraction (5 mL blank seawater containing okadaic acid) and derivatives incubated with Fe3O4@TaTp; rinse with 200 μL ultrapure H2O, 90% MeOH desorption (50 μL); extraction: 5 mg Fe3O4@TaTp dispersed in 200 μL MeOH, extraction with 1 mL reconstituted solution of shellfish samples spiked with okadaic acid and derivatives incubated with Fe3O4@TaTp; rinse with 200 μL ultrapure H2O, 200 μL ACN desorption; 0.22 μm nylon filtration | LC-MS/MS | 0.5 pg/mL (seawater) and 0.04 µg/kg (shellfish) | [100] |
| Pinnatoxin-G | Mussels | 2 g mussel tissue; 9 mL methanol; 2.5 mL methanolic extract hydrolysed with 313 µL 2.5 M NaOH; neutralised with 313 µL 2.5 M HCl; 0.22 µm filtration | LC–MS/MS | LOD: 0.1 µg/kg LOQ: 0.4 µg/kg/62–110% |
[115] |
| Biocontaminants | |||||
| Tropane alkaloids | Leafy vegetables | 0.1 g sample; µQuEChERS: 150 mg MgSO4, and 25 mg PSA | HPLC-MS/MS | LOQ: 2.2–2.3 ng/g/82–110% | [67] |
| Histamine | Cheese and cured meat products | 10 g sample; 100 mL HNO3 (0.1 mol/L); ultrasonication (15 min, 35 kHz, 40 °C) | IC-PCD | 0.15 mg/kg/91.3–116.9% | [116] |
| Mackerel canned fish | 5 g sample; 20 mL perchloric acid 0.2 M; SPE: 0.5 g cationic exchange resin; column derivatisation: ortho-phthalaldehyde (0.1 mL), and 2-mercaptoethanol | HPLC-UV | LOD: 1.8 mg/kg LOQ: 5 mg/kg/98–99% |
[117] | |
| 7 cannabinoids | Hemp products: seeds, cannabis-infused beer, energy drink, chocolates, roasted coffee and tea | Beer and energy drink (30 mL): SPE (1 mL hydrochloric acid 0.1 M/ 2 mL MeOH); chocolates, hemp seeds, and hemp tea (0.02 g): UAE (10 mL MeOH) | LC-MS | LOD: 2.19 ng/mL LOQ: 6.59 ng/mL/70.0–110% | [63] |
| 21 pyrrolizidine alkaloids | Oregano samples | 0.2 g sample; QuEChERS: 150 mg MgSO4 and 25 mg PSA | UHPLC-MS/MS | LOD: 0.1–7.5 µg/kg, LOQ: 0.5–25 µg/kg/77–96% | [65] |
| 14 pyrrolizidine alkaloids and pyrrolizidine alkaloid N-oxides | Teas and weeds | 1 g sample; 0.1 M sulphuric acid; SPE: 1% formic acid, and 5 mL MeOH/4 mL MeOH + 0.5% ammonium hydroxide | UHPLC-MS/MS | LOD: 0.001–0.4 μg/kg LOQ: 1–5 μg/kg/ 68.6–110.2% |
[66] |
| Mycotoxins | |||||
| Citrinin | Red yeast rice | LLE: 30 mg sample, 2 mL H2O–acetone 2:3 (V/V) | HPLC-FLD | 4 mg/kg/109.9% | [73] |
| Nutraceutical green tea | SPE: 1 g sample, sorbent zirconia-coated silica and PSA | UHPLC-HRMS | LOQ: 0.2 μg/kg/97% | [74] | |
| Cereals, food supplements and red yeast rice | MISPE: 0.5 g sample, molecularly imprinted polymer | HPLC-FLD | 550–1105 μg/kg/75.6–90.7% | [75] | |
| Alternariol, alternariol monamethyl ether, tenuazonic acid, tentoxin, deoxynivalenol, and patulin | Cherry tomato, lettuce, and pakchoi | SPE: 1 g sample, HLB SPE cartridges (hydrophilic N-vinyl pyrrolidone and lipophilic diethyl benzene) | UHPLC-MS/MS | LOD: 0.05–3.0 μg/kg LOQ: 0.2–10.0 μg/kg 81.1–116% |
[70] |
| 19 mycotoxins | Lotus seeds | QuEChERS: 1 g sample, 5 mL ACN 80% (v/v), 150 mg C18, and 150 mg MgSO4 anhydrous | UHPLC-MS/MS | 0.1–15.0 μg/kg/84.6–96.4% | [76] |
| 17 mycotoxins | Edible nuts | QuEChERS: 5 g sample, 10 mL ACN-formic acid (99.9/0.1 (v/v)); dSPE-EMR-lipid: 0.4 g NaCl, and 1.6 g anhydrous MgSO4 | LC-MS | 0.05–5 μg/kg/ 75–98% |
[118] |
| Chemical and industrial contaminants | |||||
| PAHs | Nutritional supplements containing omega-3 and fish oil | FPSE: sol–gel phenyl/polydimethylsiloxane (PDMS)-coated FPSE membranes back-extracted with ACN | HPLC-UV | LOD: 2.16–2.50 ng/mL LOQ: 6.50–7.50 ng/mL/63.2–102.3% |
[89] |
| Sulphites | Herbal teas | dSPE: ACN and 0.1% acetic acid + 10 mM ammonium acetate | UPLC-MS/MS | 0.51–12.1 μg/kg/83.8–102.7% | [95] |
| Sulphur dioxide | Stir-fried foods, dried fruits, preserved fruits, ginger, and shredded squid | 1 g sample; 25 mL NaOH 0.4 mM; derivatisation: 2 mL sample disodium hydrogen phosphate and potassium dihydrogen phosphate buffer (pH 5.5)/2.50 mL phthalaldehyde and 1.5 mL ammonium acetate | HPLC-FLD | LOD: 0.2 mg/kg LOQ: 0.7 mg/kg/82.32–105.08% |
[97] |
| Acrylamide | French fries, bakery biscuits, and branded biscuits | 1 g defatted sample; 10 mL H2O; 0.5 mL Carrez I and Carrez II solutions; filtration (0.45 μm cellulose acetate syringe filter paper) | HPLC-DAD | LOD: 3.733 ng/μL LOQ: 11.045 ng/μL/98–110% |
[85] |
| Coffee and coffee products | QuEChERS: 0.5 g roasted coffee or 2.5 g ready-to-drink (brewed) + 5 mL dichloromethane; SPE Carb/SCX/PSA cartridge; acrylamide residue transformed to 2,3-dibromoacrylamide (acrylamide-Br2) by KBr derivatisation (1 mL 15% (m/v)) and potassium bromate (100 μL 1.7% (m/v)) at acidic conditions (70 μL 10% (v/v) sulphuric acid); 0.22 μm PTFE filtration | UPLC-MS/MS | Roasted and instant coffees: LOD: 1.2 μg/kg LOQ: 4 μg/kg; Ready-to-drink coffees: LOD: 0.24 μg/kg LOQ: 0.8 μg/kg/ 99.3–102.2% |
[86] | |
| Polychlorinated dibenzo-p-dioxins and furans | Boiled eggs, crab meat, beef, sheep liver, herring, cod liver, salmon, and fish oil | Dichloromethane/n-hexane (1:1, v/v); acidic silica gel (44% sulphuric acid) to remove lipids and polar interfering substances | GC-MS/MS | LOQ: 0.005–0.101 ng/mL (GC-APCI-MS/MS) and 0.006–0.201 ng/mL (GC-EI-MS/MS) | [92] |
| Glycidyl esters | Infant formulas and elderly milk powders | Transesterification by automation: 0.5 g sample, 2 g anhydrous sodium sulphate, and 2 mL distilled H2O; 10 mL hexane: ethanol (2:1, v/v); residue re-dissolved with 400 μL isooctane | GC-MS/MS | LOD: 0.8 μg/kg/91.7–111.3% | [87] |
| Sodium iron chlorophyllin and sodium copper chlorophyllin | Candies | 0.1 N hydrochloric acid (5 mL), ultrasonication (50 °C, 10 min), dilution to 20 mL (MeOH); vortex mixing, centrifugation (10,000 rpm, 10 min), filter upper layer (0.2 μm)/HPLC-MS | UHPLC-MS | LOD/LOQ: 1.2; 4.1 mg/kg (SIC); 1.4; 4.8 mg/kg (SCC), | [119] |
2. Recent Developments and Future Perspectives in the Control of Food Safety Using Chromatographic Approaches
In recent decades, there has been growing recognition of the adverse effects of human activity on the environment, which has prompted an increase in the search for more environmentally friendly analytical methodologies, including chromatography. Large-scale multiresidue methods that enable the simultaneous analysis of a large number of compounds can reduce the number of necessary analyses. Rizzo et al. [120], for instance, proposed an analytical platform using salting-out-assisted liquid–liquid extraction of aqueous extracts combined with ultra-high-performance liquid chromatography–high-resolution tandem mass spectrometry for the screening of 88 pyrrolizidine alkaloids in food matrices with a high risk of contamination. In turn, Steiner, et al. [121] developed an LC-MS/MS-based multiclass approach for the accurate quantification of >1200 biotoxins, pesticides, and veterinary drugs in complex feeds. This approach was challenged with more than 130 real compound feed samples, providing the first insight into the co-exposure of animal feed to agricultural contaminants. A reliable and efficient method for analysing 302 targeted contaminants in catfish muscle was also developed and validated. This method was designed to detect pesticides and their metabolites at US regulatory levels as well as other lipophilic pesticides and environmental contaminants, including PAHs, PCBs, PBDEs, and other flame retardants. The sample preparation was based on the QuEChERS extraction technique. The extracted sample was divided and analysed using UHPLC-MS/MS for 128 analytes after filtration and low-pressure (LP) GC-MS/MS for 219 analytes after an automated robotic micro-SPE clean-up [122]. Another remarkable example was reported by Fialkov et al. [123], who designed an LP GC-MS system capable of achieving good separation with full analysis cycle times of less than one minute. This was accomplished by combining low-pressure GC-MS with low thermal mass resistive-heating for rapid temperature ramping and cooling of the capillary column. This method was successfully applied to replicate the EPA Method 8270 using a complex mixture of 76 semivolatile compounds, which are typically quantified using conventional GC-MS. This approach has great potential for the rapid analysis of PAHs in food samples [123]. Another methodology using GC-MS/MS has been devised to analyse 209 pesticides and persistent organic pollutants (POPs) in non-target wildlife animal liver tissues. This technique requires only 100 mg of liver tissue and allows for the detection of multiple residues in each sample [124].
Micellar liquid chromatography is a green chromatographic approach that is notable for its minimal requirement for organic modifiers, such as acetonitrile and methanol, and ease of recycling the mobile phase. This results in a reduction in excess solvents. Micellar liquid chromatography has a wide range of applications, including, but not limited to, the analysis of antibacterial substances, melamine, biogenic amines, plant protection products, flavonoids, and peptides in various biological matrices, such as milk, eggs, tissues, honey, and feed [125]. The assessment of the more environmentally friendly profile of micellar liquid chromatography was further investigated by Mohamed and Fouad [126], who proposed three alternative HPLC methods for determining the levels of sulfadiazine and trimethoprim in bovine meat and chicken muscles. After thorough evaluation using the GAPI, NEMI, and analytical eco-scale, it was concluded that micellar liquid chromatography demonstrated superior environmental performance.
2.1. Multidimensional Chromatography
Methods involving two consecutive chromatographic separations, hereby considered multidimensional (MD) chromatography, have great potential by combining the resolution power of the chromatographic approaches taken individually. However, these formats require sophisticated and expensive instrument configurations and expertise that can be challenging to achieve [127]. Nevertheless, advancements in LC, such as increased orthogonality, separation power, sensitivity, and the ability to hyphenate with more powerful MS detectors, are boosting foodomic investigations, leading to an increase in the number of applications, including food contaminant analyses [128,129]. In this respect, MD-LC has gained significant popularity over the past few years for separating non-volatile analytes from complex matrices. Conventional one-dimensional LC cannot resolve potential co-elutions or minimise matrix effects, which can hinder accurate quantitative analysis. However, coupling MD-LC with MS results in a notable enhancement of the separation power or peak capacity, owing to increased selectivity and sensitivity, making it a valuable tool for many applications, such as the quantification of mycotoxins [127]. Mycotoxins are major contaminants in agricultural products, and several other MD-LC approaches have been developed for their analysis, such as a multi LC-LC coupled with the ESI–MS/MS method for the determination of seven mycotoxins in beer [130], or a 2D-LC HRMS method for the simultaneous monitoring of 70 regulated and emerging mycotoxins in Pu-erh tea [131]. Other notable examples of this approach include enhanced analytical capacities for the analysis of aromatic biogenic amines using 2D heart-cutting sequential injection chromatography [132] and the determination of dangerous compounds in milk and colostrum by coupling MD-LC with HR-MS [128].
Online LC-GC streamlines the sample preparation process, thereby saving time and improving the sensitivity and reliability of analysis. This MD system integrates sample preparation in the first dimension (LC) and analysis in the second dimension (GC). The LC dimension has a high sample capacity, whereas the GC dimension offers a high separation efficiency and the ability to utilise various detectors, including MS. A recent automatised interface, named TOTAD, has been proposed to eliminate manipulation errors and offer different operation modes that enhance analytical performance (e.g., the ability to inject or transfer large volume fractions regardless of the eluent used) [127]. Another promising development in this field is a compact 2D GC system that incorporates microfabricated columns and a nanoelectromechanical system resonator as the detector. This system is eco-friendly, portable, and capable of ultra-fast chromatographic separation, making it suitable for a range of applications where size, weight, power, and speed are critical, including real-time and on-site food safety assays [133].
2.2. Miniaturisation of Chromatographic Architectures
The scaling down of traditional macroscale systems, including conventional chromatographic architectures, offers several advantages, including a substantial reduction in the consumption of reagents, samples, and energy, as well as faster and more cost-effective analytical processes, resulting in shorter analysis times. Furthermore, such systems are more prone to efficient automation, resulting in higher throughput and multiplexing [134]. The miniaturisation of GC methodologies involves less energy consumption, whereas the same strategy applied to LC results in a reduction in solvent consumption [135]. One example of these approaches is the bubble-in-drop (BID) microextraction of carbamate pesticides followed by GC-MS analysis. This method utilises only 1.00 μL of the extraction solvent and an air bubble volume of 0.40 μL to determine carbamates in water with good recovery rates, low limits of detection, and high enrichment factors [136].
Another path involves the development of new architectures, such as that proposed by Liao et al. [137], employing a cellular design that simultaneously performs the partial separation of analytes during the sampling process. The authors assayed this promising progressive cellular architecture in microscale GC using a range of polar and nonpolar analytes with wide molecular weights and vapour pressure variations, including alkanes, alcohols, aromatics, and phosphonate esters. Under these conditions, separations within 12 min at a column temperature of 63–68 °C and resolutions greater than two for any two homologues that differ by one methyl group were achieved [137].
Regarding LC developments in this field, nano-LC offers several advantages that align with green chemistry principles, such as reduced flow rate and solvent consumption, resulting in a lower environmental impact and cost of analysis. Common HPLC stationary phases, including C18 sorbents with particle sizes of 3–5 µm or smaller, can be used in nano-LC methods. Additionally, nano-LC methods have been found to have several advantages when applied to pesticide analysis compared to other types of LC, including requiring fewer sample preparation steps and achieving greater sensitivity. Given the increasing regulatory requirements for detecting contaminants, there is a strong demand for more capable analytical methods, and nano-LC has the potential to provide better analytical performance than other chromatographic methods [138]. Moreno-González et al. [139] reported a remarkable example of the nano-LC potential for determining pesticide residues in specific parts of bee specimens. The method developed allows for the extraction of useful information from specific bee parts of individual specimens and provides pseudo spatially resolved chemical information about pesticide contamination [139]. The presence of pyrrolizidine alkaloids in honey, tea, herbal tinctures, and milk was also determined with increased sensitivity and reduced solvent consumption using nano-LC-MS with high-resolution Orbitrap mass spectrometry [140].
2.3. Portable Chromatography Solutions and Chromatography-on-Chip
Polycyclic aromatic hydrocarbons (PAHs) are classified as priority hazardous substances because of their carcinogenic properties and potential threats to public health. There are strict regulations in place to prevent their release into the environment, but these regulations are not consistently enforced due to the lack of a reliable field-testing procedure. To address this challenge, Chatzimichail et al. [141] developed a hand-portable system capable of separating, identifying, and quantifying PAHs. The developed system incorporates an HPLC and a spectrally wide absorption detector, which can identify all 24 PAHs on the priority pollutant list of the United States Environmental Protection Agency [141]. In addition, an alternative chipHLPC device using fluorescence and electrospray mass spectrometry (ESI-MS) was used to obtain a rapid and on-site separation of four PAHs [142]. Another microfluidic chromatography detection system was used to measure the concentrations of saccharin sodium (SAC) and acesulfame potassium (Ace-K) in 16 commercial food samples, providing rapid detection of artificial sweeteners in food [143].
Unconventional print and media technologies have also been applied in the field of chromatography, resulting in the creation of a compact, all-in-one LabToGo system. This emerging field, referred to as office chromatography (OC), employs additive manufacturing for the 3D printing of functional components, as well as open-source hardware and software. For example, the analysis of steviol glycosides in Stevia leaves yielded results comparable to those obtained through traditional methods, while the bioanalytical screening of water samples enabled the evaluation of potential health and environmental risks [144].
This entry is adapted from the peer-reviewed paper 10.3390/molecules29030579
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