Validation of the standard method EN ISO 19343:2017 for detection and quantification of histamine in different matrices of fish and fishery products using high performance liquid chromatography

Motivation: Histamine, a biogenic amine produced by bacterial decarboxylation of histidine, is the main cause of scombroid fish poisoning and is strictly regulated by the European Union in fish and fishery products [1]. Therefore, an adequate histamine quantification method is necessary in order to assess current regulations and prevent health problems. In this sense, High Performance Liquid Chromatography (HPLC) have been widely used for the detection of histamine as it provides good specificity and sensitivity when coupled with a highly sensitive detector. The standard protocol EN ISO 19343 is the current in use and it was developed to meet with 2073/2005 European Regulation about microbiological criteria for food products. However, there is still room for improvement in terms of resolution, sensitivity and discrimination and the validation of this protocol is a necessary step in laboratories to prove the reliability of results and a previous step to get ISO certification [2].Methods: In this study, we use the HPLC method-based ISO 19343:2017 to compare the results from different samples of raw fish, canned fish, fish sauce and fishery derived products. This method allows the separation of histamine within the set of biogenic amines from fish and fishery products. The sample is extracted by mixing it with perchloric acid. A derivatization is carried out prior passing through a chromatographic column using dansyl chloride to do histamine detectable under UV light. Biogenic amines and components in the solution are separated by HPLC using a chromatographic column, with UV detection. Histamine concentration is calculated from the ratio between the areas of histamine peaks and internal standard, using a calibration curve.In the validation process, veracity of the method is studied, examining parameters such as accuracy, recovery and correction. The work interval is defined between the lower and upper quantification limit. The specificity / selectivity of the method is studied and verified by performing exercises in different matrices with different compositions and checking that the quality criteria are met independently of the matrix composition. In this way, and if the parameters are within the limits established by the standard, the method would be validated [3]

Validation of methods for the determination of pH and phosphates in foods

Nowadays food companies are obliged to produce food that not only covers nutritional needs, but are also safe for consumption, as well as not being a source of disease and infection. This is why there are controls at all points in the production chain for potentially dangerous elements. Regarding chemical hazards, one of the main determinations in food is the content of additives i. e. phosphorus additives, which are those that contain inorganic phosphorus as a main component. The food companies carry out analysis of the content of these additives according to the Regulation (EU) No. 1169/2011 of the European Parliament and of the Council of 25 October 2011 on the provision of food information to consumers. This regulation is focused on the protection of public health and consumers, the prevention of fraud and the protection of industrial and commercial property rights, indications of provenance, registered designations of origin and the prevention of unfair competition.Moreover, food analysis laboratories carry out other types of routine tests as pH due to its high influence on food security. In this study, the validation of phosphorus and pH determinations were carried out separately. The validation of the phosphate analysis was based on the formation of molybdivanadophosphate complex measured spectrophotometrically. The validation of the pH determination was carried out using reference materials of fruit juice, cheese, meat and milk in Laboratorios Vital. In addition, patterns were used to cover the entire pH range between 1,00 and 13,01. In both validations, parameters such as accuracy, repeatability and reproducibility were studied

Comparative study of different methods for determining moisture in differents food matrices

The determination of moisture in food is a very important process because the moisture content affects the processing capacity, the shelf life, and the quality of the product. Therefore, moisture content determination plays a key role in ensuring quality in many industries, such as food, pharmaceutical and chemical.The objective of this study was to evaluate the differences between the internal method used in Laboratorios Vital and different external methods of the Official Association of Analytical Chemists (AOAC) or the International Organization for Standardization (ISO). External methods evaluated were: ISO 662:2016, ISO 3727-1:2001, ISO 665:2001, AOAC 984.25, AOAC 931.04, AOAC 926.08, AOAC 968.11, AOAC 934.01, AOAC 941.08, AOAC 925,45C, ISO 5537:2004, ISO 579:2013 and AOAC 934.06. By means of this study, what is intended is to demonstrate the validity of the internal method being that each external method of the AOAC or ISO has associated the use of a specific temperature and time which would require more time to perform the moisture determination.To carry out this study, 12 different food matrices were introduced in a Dinko D60D stove: butter, oil seeds, frozen chips, chocolate, cheese, roasted coffee, tea, ice cream, honey, milk powder, coke and dried fruit.Moisture analysis were performed for 5 non-consecutive days and every day 2 replicates of each food matrix were analyzed.After carrying out the different tests, the results were compared and it was observed that there were no significant differences in the determination of the percentage of moisture. This allows to confirm that the internal method used by the company is reliable for the determination of this parameter, which has clear economic advantages for the analytical laboratory that reduces the time of delivery of data to customers by almost a week

Extension of the measurement range method for histamine determination by HPLC

Motivation: Histamine is a biogenic amine, produced post-mortem in the muscle of scombroid fish by bacterial or tissue enzymes during decarboxylation of the amino acid histidine. It is associated with food poisoning after ingestion of some fish species rich in histidine, such as tuna, mackerel, sardine, herring and anchovy [1]. Therefore, the level of histamine produced in scombroid or other histidine-containing fish can be used to assess the degree of fish spoilage and it is often considered one of the best biomarkers for quality control during food production, transportation, and marketing [2].Methods: Commission Regulation (EC) No. 2073/2005 [3] provides for food safety criteria for histamine and sampling plans for fishery products from fish species associated with a high amount of histidine. Also indicates that High Performance Liquid Chromatography (HPLC) is the analytical reference method for its determination. In this study, we modified the analytical method used by Kose et al., [4] in order to reduce the limit of quantification in the histamine calibration curve from 25 to 10 ppm to quantify more selectively and more accurately the presence of histamine after the extraction, derivatization and chromatographic separation process. This would allow us to evaluate the degree of decomposition of the fish through the histamine content in a range of 5 to 500 ppm

A search for ultra-high-energy photons at the Pierre Auger Observatory exploiting air-shower universality

The Pierre Auger Observatory is the most sensitive detector to primary photons with energies above ∼0.2 EeV. It measures extensive air showers using a hybrid technique that combines a fluorescence detector (FD) with a ground array of particle detectors (SD). The signatures of a photon-induced air shower are a larger atmospheric depth at the shower maximum (X$_{max}$) and a steeper lateral distribution function, along with a lower number of muons with respect to the bulk of hadron-induced background. Using observables measured by the FD and SD, three photon searches in different energy bands are performed. In particular, between threshold energies of 1-10 EeV, a new analysis technique has been developed by combining the FD-based measurement of X$_{max}$ with the SD signal through a parameter related to its muon content, derived from the universality of the air showers. This technique has led to a better photon/hadron separation and, consequently, to a higher search sensitivity, resulting in a tighter upper limit than before. The outcome of this new analysis is presented here, along with previous results in the energy ranges below 1 EeV and above 10 EeV. From the data collected by the Pierre Auger Observatory in about 15 years of operation, the most stringent constraints on the fraction of photons in the cosmic flux are set over almost three decades in energy

Study on multi-ELVES in the Pierre Auger Observatory

Since 2013, the four sites of the Fluorescence Detector (FD) of the Pierre Auger Observatory record ELVES with a dedicated trigger. These UV light emissions are correlated to distant lightning strikes. The length of recorded traces has been increased from 100 μs (2013), to 300 μs (2014-16), to 900 μs (2017-present), to progressively extend the observation of the light emission towards the vertical of the causative lightning and beyond. A large fraction of the observed events shows double ELVES within the time window, and, in some cases, even more complex structures are observed. The nature of the multi-ELVES is not completely understood but may be related to the different types of lightning in which they are originated. For example, it is known that Narrow Bipolar Events can produce double ELVES, and Energetic In-cloud Pulses, occurring between the main negative and upper positive charge layer of clouds, can induce double and even quadruple ELVES in the ionosphere. This report shows the seasonal and daily dependence of the time gap, amplitude ratio, and correlation between the pulse widths of the peaks in a sample of 1000+ multi-ELVES events recorded during the period 2014-20. The events have been compared with data from other satellite and ground-based sensing devices to study the correlation of their properties with lightning observables such as altitude and polarity