An advanced optic-fiber differential sensing system enhanced by molecularly imprinted polymer for specific sodium benzoate detection.

A molecularly imprinted polymer (MIP) based microfiber differential demodulation sensing system for sodium benzoate (SB) concentration detection is proposed. The specific binding of MIP on the surface of microfibers with SB can lead to changes in local refractive index (RI). RI change induces a drift in the interference wavelength, which can be monitored by the power difference between two fiber Bragg gratings (FBGs). The sensing system can detect SB in the concentration range of 0.1-50 µg/ml, and interference wavelength and FBG power difference sensitivities are 0.55 nm/(µg/ml) and 2.64 dB/(µg/ml) in the low concentration range of 0.1-1 µg/ml, respectively, with a limit of detection (LOD) of 0.1 µg/ml. This microfiber differential demodulation sensing system is not only simple to fabricate, but also simplifies the demodulation equipment to reduce the cost, which providing a simple, reliable and low-cost technique for the quantitative detection of SB concentration in beverages and flavoured foods.

Molecular docking study of frequently used food additives for selected targets depending on the chromosomal abnormalities they cause.

Food additives (FAs) (flavor enhancers, sweeteners, etc.) protect foods during storage and transportation, making them attractive to consumers. Today, while the desire to access natural foods is increasing, the chemicals added to foods have started to be questioned. In this respect, genotoxicity tests have gained importance. Studies show that some food additives may have genotoxic risks. Previous studies carried out in our laboratory also revealed genotoxic effects of Monopotassium glutamate (MPG), Monosodium glutamate (MSG), Magnesium diglutamate (MDG) as flavor enhancers; Potassium benzoate (PB), Potassium sorbate (PS), Sodium benzoate (SB), Sodium sorbate (SS) as preservatives; Acesulfame potassium (ACE-K), Xylitol (XYL) as sweeteners. In this study, we determined the interactions of these food additives with ATM and p53 proteins, which are activated in the cell due to genotoxic effects, and with DNA by employing the molecular docking method for the first time. Among the food additives, SB (-4.307) for ATM, XYL (-4.629) for p53, and XYL (-4.927) for DNA showed the highest affinity. Therefore, flexible docking (IFD) scores were determined for SB, XYL, and MDG from flavor enhancers. The potential binding modes of the food additives to target molecules' possible inhibition mechanisms were determined by molecular docking. Thus, new information was obtained to show how these additives cause chromosomal abnormalities.

Starch-based antifungal edible coatings to control sour rot caused by Geotrichum citri-aurantii and maintain postharvest quality of 'Fino' lemon.

BACKGROUND: Two edible coating (EC) emulsions based on potato starch (F6 and F10) alone or formulated with sodium benzoate (SB, 2% w/w) (F6/SB and F10/SB) were evaluated to maintain postharvest quality of cold-stored 'Fino' lemons and control sour rot on lemons artificially inoculated with Geotrichum citri-aurantii. Previous research showed the potential of these ECs to improve the storability of 'Orri' mandarins and reduce citrus green and blue molds caused by Penicillum digitatum and Penicillium italicum, respectively. RESULTS: The coatings F6/SB and F10/SB significantly reduced sour rot incidence and severity compared to uncoated control samples on lemons incubated at 28 °C for 4 and 7 days. The F6/SB coating reduced weight loss and gas exchange compared to uncoated fruit after 2 and 4 weeks of storage at 12 °C plus a shelf life of 1 week at 20 °C, without adversely affecting the lemon physicochemical quality. CONCLUSION: Overall, the F6/SB coating formulation, composed of pregelatinized potato starch, glyceryl monostearate, glycerol, emulsifiers and SB, with a total solid content of 5.5%, showed the best results in reducing citrus sour rot and maintaining the postharvest quality of cold-stored 'Fino' lemons. Therefore, it showed potential as a new cost-effective postharvest treatment suitable to be included in integrated disease management programs for citrus international markets with zero tolerance to chemical residues. © 2021 Society of Chemical Industry.

Assessment of Concentrated Liquid Coffee Acceptance during Storage: Sensory and Physicochemical Perspective.

Concentrated liquid coffees (CLCs) refer to stored extracts stable at environmental temperature, used as ingredients in the retail market. Their low chemical stability affects the sensory profile. This study was performed in two CLCs, one without additives (BIB) and another with a mix of sodium benzoate and potassium sorbate additives (SD), stored at 25 °C for one year. Quantitative-Descriptive (QDA) and discriminant analyses permitted identifying the critical sensory attributes and their evolution over time. The concentrate without additives presented an acceptance limit of 196 days (evaluated at a 50% acceptance ratio), while the additives increased the shelf life up to 226 days (38.9% improvement). The rejection was related to a decreased aroma, increased acidity, and reduced bitterness. A bootstrapped feature selection version of Partial Least Square analysis further demonstrated that reactions of 5-caffeoylquinic acid (5CQA) and 3,5-dicaffeoylquinic acid (3,5diCQA) could cause changes in the aroma at the first degradation stage. In the following stages, changes in fructose and stearic acid contents, a key indicator of acceptance for both extracts possibly related to non-enzymatic reactions involving fructose and other compounds, might affect the bitterness and acidity. These results provided valuable information to understand flavor degradation in CLCs.

Production of the Carboxylate Reductase from Nocardia otitidiscaviarum in a Soluble, Active Form for in†vitro Applications.

Accessing aldehydes from carboxylate moieties is often a challenging task. In this regard, carboxylate reductases (CARs) are promising catalysts provided by nature that are able to accomplish this task in just one step, avoiding over-reduction to the alcohol product. However, the heterologous expression of CARs can be quite difficult due to the excessive formation of insoluble protein, thus hindering further characterization and application of the enzyme. Here, the heterologous production of the carboxylate reductase from Nocardia otitidiscaviarum (NoCAR) was optimized by a combination of i) optimized cultivation conditions, ii) post-translational modification with a phosphopantetheinyl transferase and iii) selection of an appropriate expression strain. Especially, the selection of Escherichia coli tuner cells as host had a strong effect on the final 110-fold increase in the specific activity of NoCAR. This highly active NoCAR was used to reduce sodium benzoate to benzaldehyde, and it was successfully assembled with an in vitro regeneration of ATP and NADPH, being capable of reducing about 30 mM sodium benzoate with high selectivity in only 2 h of reaction.

Effects of a chemical additive on the fermentation, microbial communities, and aerobic stability of corn silage with or without air stress during storage.

We evaluated the effects of a chemical additive on the microbial communities, fermentation profile, and aerobic stability of whole-plant corn silage with or without air stress during storage. Whole-plant corn was either untreated or treated with a chemical additive containing sodium benzoate, potassium sorbate, and sodium nitrite at 2 or 3 liters/t of fresh forage weight. Ten individually treated and replicated silos (7.5 liters) were made for each treatment. Half of the silos remained sealed throughout a 63-d storage period, and the other half was subjected to air stress for 2 h/wk. The composition of the bacterial and fungal communities of fresh forage and silages untreated or treated with 2 liters/t of fresh forage weight was analyzed by Illumina Miseq sequencing. Treated silage had greater (P < 0.05) aerobic stability than untreated, even when subjected to air stress during storage, but the numbers of yeasts culturable on selective agar were not affected. However, the additive reduced the relative abundance (RA) of the lactating-assimilating yeast Candida tropicalis (P < 0.01). In air-stressed silages, untreated silage had a greater (P < 0.05) RA of Pichia kudriavzevii (also a lactate assimilator) than treated silage, whereas treated silage was dominated by Candida humilis, which is usually unable to assimilate lactate or assimilates it slowly. The additive improved the aerobic stability by specifically preventing the dominance of yeast species that can consume lactate and initiate aerobic spoilage. To the best of our knowledge, this is the first work that identifies the specific action of this additive on shifting the microbial communities in corn silage.

Effect of sodium benzoate and chlorhexidine gluconate on a bio-thermoplastic elastomer made from thermoplastic starch-chitosan blended with epoxidized natural rubber.

Thermoplastic elastomer (TPE) was developed by blending thermoplastic starch (TPS) with rubber. Thermoplastic starch-chitosan (TPSC) was prepared by the solution mixing of cassava starch, chitosan (CTS) and glycerol in acidified water (lactic acid 1 wt%) at 80 °C follow by melt mixing at 130 °C. Sodium benzoate (BEN) and chlorhexidine gluconate (Cl) were added during the solution mixing as additives for antimicrobial properties. TPSC was melt-mixed with epoxidized natural rubber (ENR) (70/30 wt/wt). The tensile strength and elongation at break of the TPSC/ENR increased with the additive content. Elastic recovery was improved by the addition of Cl. A new peak in the FTIR data confirmed the reaction between the reactive functional groups of the CTS and the additives with the epoxy groups of ENR. These reactions and miscibility of the TPSC/ENR/additives blends improved the mechanical properties, elasticity, morphology, and antimicrobial properties of the blends.

Pharmaceutical excipient salts effect on micellization and drug solubilization of PEO-PPO-ph-PPO-PEO block copolymer.

Hydrophobic modification PEO-PPO copolymer BP123 was synthesized, with two aromatic rings in the centre linked to PEO-PPO blocks, and the identical PEO and PPO block numbers were possessed with commercial copolymer P123. The influence of three common pharmaceutical excipient salts sodium chloride (NaCl), sodium citrate (NaCA) and sodium benzoate (NaBZ) on self-assembly behaviors of BP123 and P123 was investigated via cloud point, surface tension, pyrene fluorescence and dynamic light scattering. Solubilization for hydrophobic drug simvastatin (SV) and in vitro drug release behavior were assessed accordingly. In the presence of NaCl or NaCA, cloud point and critical micellization concentration (CMC) decreased, micelles became more hydrophobic, micellar size and drug solubilization increased, drug release rate slowed, and the impact of NaCA was more significant than NaCl. Oppositely, cloud point and CMC increased with the addition of NaBZ. NaBZ could participate in the formation of micelles by hydrophobic aromatic ring, which greatly raised solubilization of SV. Moreover, a different performance occurred when NaBZ was added to BP123 or P123, due to the hydrophobic benzene rings in BP123, which prominently enhanced the interaction with hydrophobic drug, leading to obvious delay of drug release for BP123. This work is conducive to turning copolymer property in diverse pharmaceutical applications and in drug delivery systems as drug carriers.

Octadecyltrichlorosilane Incorporated Alginate Micro-granules as Sustained-Release Carriers for Small Hydrophilic Molecules.

BACKGROUND: Hydrogels are excellent drug carriers, but their inability to retain hydrophilic drugs for a prolonged period of time has greatly limited their usage. Research has mostly focused on intricate designs and manipulations of hydrogels to expand their applications in drug delivery. OBJECTIVE: In this study, a simple approach by incorporating a hydrophobic agent, octadecyltrichlorosilane (OTS), to alginate hydrogel micro-granules (Alg-Ms), was investigated as an effective technique to prolong the release of small hydrophilic drugs. METHODS: Sodium Benzoate (SB), a highly water-soluble antimicrobial and anti-inflammatory compound, was used as a model drug. The presence of hydrophobic OTS impeded swelling of these OTS incorporated Alg-Ms (OTS-Alg-Ms), hence sustaining the release of SB. RESULT: The release data was fitted with Ritger-Peppas and Peppas-Sahlin models and the results showed that SB released from OTS-Alg-Ms with higher OTS content was mainly controlled by Fickian diffusion; with a lower OTS content, OTS-Alg-Ms swelled more easily, the combined diffusion and swelling led to a faster SB release. CONCLUSION: Thus, by simply tuning the OTS concentration in the solution where Alg-Ms were briefly submerged in a predefined release period, from hours to a few days, small hydrophilic drugs from these OTS-Alg-Ms could be successfully achieved.

Development of a new stability indicating method for the simultaneous separation of voriconazole from its impurities along with sodium benzoate used as a preservative in a powder for oral suspension.

Voriconazole is a second-generation triazole derived from fluconazole, having an enhanced antifungal spectrum, compared with older triazoles. It is the drug of choice for treatment of invasive aspergillosis and many Scedosporium/Pseudallescheria Fusarium infections. Voriconazole is available in both intravenous and oral formulations. Since there is much interest in pharmaceutical quality control, separation of impurities from the main drug substances and accurate assay quantification, and since there is no reference or monograph until nowadays reported for the simultaneous separation of voriconazole from its specified and unspecified impurities along with sodium benzoate used as an antimicrobial preservative, our aim of this work is to develop a new simple, sensitive and stability indicating assay method allowing thus separation by high-performance liquid chromatography. The development of our method consisted in optimizing the following analytical parameters: nature and composition of the mobile phase, its pH, buffer concentration, nature of the stationary phase, column temperature and detection wavelength. After optimisation, separation was achieved on a stainless steel column NOVAPACK C18 (3.9mm×150mm; 4µm particle size) using a gradient mode with methanol, acetonitrile R and an aqueous solution acidified by acetic acid at 1% and adjusted to pH 2.77. The eluted compounds were monitored at 254nm. The flow rate was set at 1.0mL/min, the injection volume at 10µL, and the column oven temperature was maintained at 35°C. Under these conditions, separation was achieved with good resolution and symmetrical peaks' shape. The developed method was validated according to the International Conference on Harmonization (ICH) guidelines, and then it was successfully applied to establish inherent stability of the pharmaceutical formulation subjected to different ICH prescribed stress conditions. The developed method was proved to be simple, specific and precise. Hence, it can be considered as a method for stability study and for routine quality control analysis of voriconazole and sodium benzoate in a powder for oral suspension.

Molecular and technical aspects on the interaction of serum albumin with multifunctional food preservatives.

Synthetic food preservatives like sodium acetate (SA), sodium benzoate (SB), potassium sorbate (PS) and Butyl paraben (BP) have been widely used in food and pharmacy industries. One of the toxicological aspects of food additives is evaluation of their interaction with serum proteins such as albumin. These additives interaction with human serum albumin (HSA) can exert considerable effect on the absorption, distribution, metabolism and toxicity of chemical compounds. It should be noticed that the aforementioned food preservatives intake increase mainly in the presence of glucose may lead to complex formation of SA, SB, PS and BP with HSA and accelerate the development of variety disease such as cancer, diabetes, multiple sclerosis, brain damage, nausea and cardiac disease. Therefore, to understand the mechanisms of aforementioned food additives interaction and conformational changes of proteins, we aim to review various studies that investigated albumin interaction with these additives using several procedures.

Oxidation of cystatin imparted by riboflavin generated free radicals: Spectral analysis.

Thiol Protease inhibitors (cystatins) are endogenous natural inhibitors of cysteine proteases. They are present in all mammalians cells and body fluids. Cystatin are allocated into three major families. Family -I stefins, family -II cystatins and family -III kininogens, according to their amino acid sequence, molecular weight, carbohydrate content and disulphide bonds. It has been investigated that thiol proteases (cathepsin) and their endogenous inhibitor, cystatins have been closely associated with diseases like Alzheimer's, Prions, neurodegenerative diseases, cancer and diabetes. Photodynamic effect of various sensitizers' have long been applied to delineate structural and functional properties of biologically active proteins. Flavins are well known to photo oxidize amino acids which effects conformation of proteins. Riboflavin (Vit B2) with a recommended daily requirement of approximately 2-3 mg is a yellow pigment, It is widely distributed in human tissues and blood, in both free and conjugated forms. In the present Study it has been shown that cystatin purified from buffalo brain (BC) is susceptible to reactive oxygen species generated by photo activation of riboflavin. It was observed that Photo activated riboflavin leads to inactivation of BC. Major Loss of tryptophan intensity was observed in the presence of purified thiol protease inhibitor upon incubation with 50 µM of riboflavin. In order to inspect the type of reactive oxygen species involved in inactivation of the inhibitor, different scavenger's were used namely glucose, potassium Iodide, sodium azide, manitol, thiourea, sodium benzoate, curcumin, quercetin, ascorbic acid and uric acid. It was found that Glucose, Potassium Iodide and sodium azide, have preventive effect on photo inactivation of the purified cystatin whilst other scavengers illustrated diminutive defensive effect.

Stability of Extemporaneously Prepared Sodium Benzoate Oral Suspension.

The stability of extemporaneously prepared sodium benzoate oral suspension in cherry syrup and Ora-Sweet was studied. Oral solutions of 250-mg/mL sodium benzoate were prepared in either cherry syrup or Ora-Sweet. To a beaker, 50 grams of Sodium Benzoate Powder USP was dissolved and filtered, the solution was divided equally into two parts, and each aliquot was added into two separate calibrated 100-mL amber vials. In the first vial, cherry syrup was added to make a final volume of 100 mL. In the second vial, Ora-Sweet was added to give a final volume of 100 mL. This process was repeated to prepare three solutions of each kind and all were stored at room temperature. A 250-µL sample was withdrawn immediately after preparation and again at 7, 14, 28, 60, and 90 days for each sample. At each time point, further dilution was made to an expected concentration of 0.25 mg/mL with sample diluent, and the samples were assayed in triplicate by stability-indicating high-performance liquid chromatography. Stability was defined as the retention of at least 90% of the initial concentration. At least 92% of the initial concentration of sodium benzoate in cherry syrup and at least 96% of the sodium benzoate in Ora-Sweet remained throughout the 90-day study period. There were no detectable changes in color and no visible microbial growth in any sample. Extemporaneously compounded suspensions of sodium benzoate in cherry syrup or Ora-Sweet were stable for at least 90 days when stored in a 4-oz amber plastic bottle at room temperature in reduced lighting.

Assessment of the Target Engagement and D-Serine Biomarker Profiles of the D-Amino Acid Oxidase Inhibitors Sodium Benzoate and PGM030756.

Irregular N-methyl-D-aspartate receptor (NMDAR) function is one of the main hypotheses employed to facilitate understanding of the underlying disease state of schizophrenia. Although direct agonism of the NMDAR has not yielded promising therapeutics, advances have been made by modulating the NMDAR co-agonist site which is activated by glycine and D-serine. One approach to activate the co-agonist site is to increase synaptic D-serine levels through inhibition of D-amino acid oxidase (DAO), the major catabolic clearance pathway for this and other D-amino acids. A number of DAO inhibitors have been developed but most have not entered clinical trials. One exception to this is sodium benzoate which has demonstrated efficacy in small trials of schizophrenia and Alzheimer's disease. Herein we provide data on the effect of sodium benzoate and an optimised Takeda compound, PGM030756 on ex vivo DAO enzyme occupancy and cerebellar D-serine levels in mice. Both compounds achieve high levels of enzyme occupancy; although lower doses of PGM030756 (1, 3 and 10 mg/kg) were required to achieve this compared to sodium benzoate (300, 1000 mg/kg). Cerebellar D-serine levels were increased by both agents with a delay of approximately 6 h after dosing before the peak effect was achieved. Our data and methods may be useful in understanding the effects of sodium benzoate that have been seen in clinical trials of schizophrenia and Alzheimer's disease and to support the potential clinical assessment of other DAO inhibitors, such as PGM030756, which demonstrate good enzyme occupancy and D-serine increases following administration of low oral doses.

Pediatric drug formulation of sodium benzoate extended-release granules.

Urea cycle disorders are a group of inherited orphan diseases leading to hyperammonemia. Current therapeutic strategy includes high doses of sodium benzoate leading to three or four oral intakes per day. As this drug is currently available in capsules or in solution, children are either unable to swallow the capsule or reluctant to take the drug due to its strong bitter taste. The objective of the present study was to develop solid, multiparticulate formulations of sodium benzoate, which are suitable for pediatric patients (i.e. flavor-masked, easy to swallow and with a dosing system). Drug layering and coating in a fluidized bed were applied for preparing sustained-release granules. Two types of inert cores (GalenIQ® and Suglets®) and three different polymers (Kollicoat®, Aquacoat® and Eudragit®) were tested in order to select the most appropriate polymer and starter core for our purpose. Physical characteristics and drug release profiles of the pellets were evaluated. A Suglets® core associated with a Kollicoat® coating seems to be the best combination for an extended release of sodium benzoate. A curing period of 8 h was necessary to complete film formation and the resulting drug release pattern was found to be dependent of the acidity of the release medium.

Changes induced by UV radiation in the presence of sodium benzoate in films formulated with polyvinyl alcohol and carboxymethyl cellulose.

This work was focused on: i) developing single and blend films based on carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVOH) studying their properties, ii) analyzing the interactions between CMC and PVOH and their modifications UV-induced in the presence of sodium benzoate (SB), and iii) evaluating the antimicrobial capacity of blend films containing SB with and without UV treatment. Once the blend films with SB were exposed to UV radiation, they exhibited lower moisture content as well as a greater elongation at break and rougher surfaces compared to those without treatment. Considering oxygen barrier properties, the low values obtained would allow their application as packaging with selective oxygen permeability. Moreover, the characteristics of the amorphous phase of the matrix prevailed with a rearrangement of the structure of the polymer chain, causing a decrease of the crystallinity degree. These results were supported by X-rays and DSC analysis. FT-IR spectra reflected some degree of polymer-polymer interaction at a molecular level in the amorphous regions. The incorporation of sodium benzoate combined with UV treatment in blend films was positive from the microbial point of view because of the growth inhibition of a wide spectrum of microorganisms. From a physicochemical perspective, the UV treatment of films also changed their morphology rendering them more insoluble in water, turning the functionalized blend films into a potential material to be applied as food packaging.

Edible Active Coatings Based on Pectin, Pullulan, and Chitosan Increase Quality and Shelf Life of Strawberries (Fragaria ananassa).

Edible active coatings (EACs) based on pectin, pullulan, and chitosan incorporated with sodium benzoate and potassium sorbate were employed to improve the quality and shelf life of strawberries. Fruits were washed, disinfected, coated by dipping, packed, and stored at 4 °C for 15 d. Application of EACs reduced (P < 0.05) weight loss and fruit softening and delayed alteration of color (redness) and total soluble solids content. In contrast, pH and titratable acidity were not affected (P > 0.05) throughout storage, and ascorbic acid content was maintained in pectin-EAC coated strawberries. Microbiological analyses showed that application of EACs reduced (P < 0.05) microbial growth (total aerobic counts, molds, and yeasts) on strawberries. Chitosan-EAC coated strawberries presented the best results in microbial growth assays. Sensory quality (color, flavor, texture, and acceptance) improved and decay rate decreased (P < 0.05) in pectin-EAC, pullulan-EAC, and chitosan-EAC coated strawberries. In conclusion, EACs based on polysaccharides improved the physicochemical, microbiological, and sensory characteristics, increasing the shelf life of strawberries from 6 (control) to 15 d (coated fruits).

Investigation on sodium benzoate release from poly(butylene adipate-co-terephthalate)/organoclay/sodium benzoate based nanocomposite film and their antimicrobial activity.

Polymeric nanocomposites embedded with nontoxic antimicrobial agents have recently gained potential industrial significance, mainly for their applicability to preserve food quality and ensure safety. In this study, a poly(butylene adipate-co-terephthalate) (PBAT)/organoclay (CMMT) based nanocomposite film doped with sodium benzoate (SB) as antimicrobial agent was prepared by a solution mixing process. A homogenous dispersion of organoclay (cetyltrimethylammonium-modified montmorillonite [CMMT]) in PBAT matrix was observed by X-ray diffraction and transmission electron microscopy. PBAT/CMMT nanocomposite film showed higher barrier properties against water and methanol vapor compared to the PBAT film. The release of SB from PBAT and its nanocomposite film was measured and the relevant data were fitted to the Weibull model. The higher values of Weibull's shape factor and scale parameter as corroborated by experimental findings indicated faster rate of SB release from PBAT/CMMT/SB nanocomposite film, when compared to the pristine PBAT film. Bacterial inhibition studies were accomplished against 2 food pathogenic bacteria, Bacillus subtilis and Staphylococcus aureus, by determining the zone of inhibition and corresponding growth profiles. Both bacterial inhibition studies and growth profiles established that PBAT/CMMT/SB demonstrated better antimicrobial activity than PBAT/SB film. Therefore, PBAT/CMMT/SB nanocomposite film can be used for food packaging application as it showed good barrier properties and antimicrobial activity against food pathogenic bacteria.

HPLC and LC-MS/MS methods for determination of sodium benzoate and potassium sorbate in food and beverages: performances of local accredited laboratories via proficiency tests in Turkey.

High Performance Liquid Chromatography LC-UV and LC-MS/MS methods were developed and validated for quantitative analyses of sodium benzoate and potassium sorbate in foods and beverages. HPLC-UV and LC-MS/MS methods were compared for quantitative analyses of sodium benzoate and potassium sorbate in a representative ketchup sample. Optimisation of the methods enabled the chromatographic separation of the analytes in less than 4 min. A correlation coefficient of 0.999 was achieved over the measured calibration range for both compounds and methods (HPLC and LC-MS/MS). The uncertainty values of sodium benzoate and potassium sorbate were found as 0.199 and 0.150 mg/L by HPLC and 0.072 and 0.044 mg/L by LC-MS/MS, respectively. Proficiency testing performance of Turkish accredited laboratories between the years 2005 and 2013 was evaluated and reported herein. The aim of the proficiency testing scheme was to evaluate the performance of the laboratories, analysing benzoate and sorbate in tomato ketchup.