Determination of Cu(II) in Beer by Derivative Potentiometric Stripping Analysis

Derivative Potentiometric‐Stripping Analysis (dPSA) is described as an inexpensive and rapid method for the determination of Cu(II) in beer. Beer samples were analysed directly after degassing and addition of the analytical reagents (hydrochloric acid, mercury(II) chloride, and potassium metabisulfite). It was not necessary to digest the sample. During dPSA the metal ions are deposited on a glassy carbon‐working electrode and then stripped by a suitable oxidant. Quantitative analysis was carried out by the method of standard additions. The recovery of the method was tested by adding 50 μg L^?1, 75 μg L^?1 and 100 μg L^?1 of Cu(II) (as Cu(II) chloride solution) to the beer. The mean recoveries of Cu(II) ranged from 95 ± 5% to 98 ± 2%. The reproducibility was evaluated by three repetitive analyses for each sample and the standard deviation ranged from 0.6 μg L^?1 to 5.5 μg L^?1. The detection limit was 0.8 μg L^?1. The Cu(II) concentration determined in seven beer samples ranged from 28 μg L^?1 to 48 μg L^?1 and the results obtained were not significantly different from those obtained by atomic absorption spectrophotometry (AAS).     

An automated enzymic assay for determining the cyanide content of cassava (Manihot esculenta crantz) and cassava products

An automated enzymic method for the analysis of cyanide in cassava and cassava products is described. A total of 300 analyses a day can be handled easily. A wide range of free (nonglycosidic) or bound (cyano-substituted glycosides) cyanides (0.4–40 μg HCN ml^?1) can be assayed in the extracted solutions. The upper limit of detection for the bound cyanide can easily be increased by another three-fold by assaying it under partial hydrolysis conditions. The two enzymic methods, manual and automated on Technicon's AutoAnalyzer, agreed well for the free and the bound cyanide in the leaf and the peeled storage root samples.     

Trace elements and heavy metals in mineral and bottled drinking waters on the Iranian market

A survey of Iranian waters, sampled from 2010 to 2013, is presented. A total of 128 water samples from 42 different brands of bottled mineral and drinking water were collected and analysed for contamination levels of lead (Pb), cadmium (Cd), copper (Cu), arsenic (As) and mercury (Hg). Determinations were performed using a graphite furnace atomic absorption spectrophotometer for Pb, Cd and Cu, a hydride vapour generation as well as an Arsenator digital kit (Wagtech WTD, Tyne and Wear, UK) for As and a direct mercury analyser for Hg. Arsenic concentration in six bottled gaseous mineral samples was higher than the related limit. Regardless of these, mean concentrations of Pb, Cd, Cu, As and Hg in all types of water samples were 4.50 ± 0.49, 1.08 ± 0.09, 16.11 ± 2.77, 5.80 ± 1.63 and 0.52 ± 0.03 µg L^?1, respectively. Values obtained for analysed heavy metals in all samples were permissible according to the limits of national and international standards.     

Evaluation of the conditions of carotenoids production in a synthetic medium by Sporidiobolus salmonicolor (CBS 2636) in a bioreactor

This work studied the cultivation conditions for the production of carotenoids by Sporidiobolus salmonicolor (CBS 2636) in a bioreactor. A Plackett–Burman design was used for the screening of the most important factors, followed by a complete second order design, to maximise the concentration of total carotenoids. The maximum concentration of 3425.9 μg L^?1 of total carotenoids was obtained in a medium containing 80 g L^?1 glucose, 15 g L^?1 peptone and 5 g L^?1 malt extract, with an aeration rate 1.5 vvm, 180 r.p.m., 25 °C and an initial pH of 4.0. Fermentation kinetics showed that the maximum concentration of total carotenoids was reached after 90 h of fermentation. Carotenoid bio‐production was partially associated with cell growth. The specific carotenoid production (Y_P/X) was 238 μg carotenoids/g cells, whereas Y_P/S (substrate to product yield) was 41.3 μg g^?1. The specific growth rate (μ_x) was 0.045 h^?1. The highest cell and total carotenoid productivity were 0.19 g L^?1 h^?1 and 56.9 μg L^?1 h^?1, respectively.     

Voltammetric analysis of DL‐α‐tocopherol with a paste electrode

BACKGROUND: A voltammetric study of vitamin E (DL‐ α‐tocopherol) detection using square wave stripping and cyclic voltammetry is discussed in this paper. The working sensor was made by mixing carbon nanotube powder with DNA (double‐stranded calf thymus DNA) and mineral oil. In this electrode, the anodic peak was obtained for ? 0.6 V in a 0.1 mol L^?1 phosphate electrolyte solution. RESULTS: Under optimized stripping conditions, analytical linear working ranges of 0.5–4.0 µg L^?1 and 40.0–160.0 µg L^?1 were obtained. The RSD precision was pegged at 0.105% with seven points using an 80 µg L^?1 spike. The detection limit (S/N) was found to be 0.056 µg L^?1 (1.30 × 10^?10 mol L^?1). CONCLUSION: The developed method was found to be applicable to quality control analysis in the food, pharmaceutical and other manufacturing sectors. Copyright © 2008 Society of Chemical Industry     

Natural deep eutectic solvent-based ultrasound-assisted-microextraction for extraction,pre-concentration and analysis of methylmercury and total mercury in fish and environmental waters by spectrophotometry

ABSTRACT

In this study, a simple, pH-controlled, and natural deep eutectic solvent-based microextraction (NADES-ME) procedure is proposed before the spectrophotometric analysis of methylmercury (MeHg) and total mercury in fish and environmental waters. The method is based on charge-transfer sensitive ion-pair formation between MeHg and 3-(dimethylamino)-7-(methylamino)phenothiazin-5-ium chloride (Azure B – AzB) in the presence of chelating citrate-phosphate buffer at pH 6.0, and then extraction of the formed ion-pair complex with the NADES. The important variables affecting extraction efficiency were evaluated and optimised. At optimal conditions (300 µL of 1.0 × 10^?3 mol L^?1 AzB, 600 µL NADES (betaine-sorbitol, 1:3) containing 10% water (v/v) as extractant, 375 µL acetonitrile as aprotic solvent for sonication of 7 min at power of 300 W/40 kHz, and centrifugation at 4000 rpm for 3 min, respectively), the figures of merit for MeHg include a good linearity in the concentration range of 0.7–340 µg L^?1, limits of detection and quantification of 0.25 and 0.83 µg L^?1, and pre-concentration and sensitivity enhancement factors of 120 and 95, respectively. Figures of merit for total Hg (iHg, where Hg₂²⁺ ions are predominantly present in natural oxygen-rich waters such as freshwaters and seawater as well as elemental Hg and Hg²⁺ ions at very low amounts) after pre-oxidation at pH 5.0 include linearity range of 3–270 µg L^?1 with limits of detection and quantification of 0.92 and 3.10 µg L^?1, and pre-concentration and sensitivity enhancement factors of 120 and 35, respectively. The reliability (with recovery of 92–98.7% and RSD of 1.9–5.5%) was statistically validated by analysis of two standard reference materials (SRMs) with and without spiking. The method was successfully applied to the speciation analysis of total Hg, iHg and MeHg in fish and environmental waters.     

Rapid on‐site determination of melamine in raw milk by an immunochromatographic strip

A rapid and simple method was established based on gold nanoparticle‐labelled monoclonal antibody probes for the detection of melamine pollution in raw milk. The conditions for conjugation between the antibody and gold nanoparticles were optimised (pH 8.0, antibody concentration 5 μg mL^?1). It gives a single proportional to melamine concentration with a performance time of only 3 min. A practical calibration curve was established with a reader system with limit of detection calculated as 4.47 and 8.34 μg L^?1 with naked eyes. Three structural analogues, atrazine, desethyl‐desisopropyl‐atrazine and cyromazine, were used to test the specificity of the immunochromatographic strip, and small colour changes on the strip test line were found even at the 500 ng mL^?1 spiked level. Fifty raw milk samples were detected with this strip method, and the resulting data coincided well with results from gas chromatography tandem mass spectrometry. The above‐mentioned results showed that this test strip can be used for melamine screening in the daily monitoring of milk.     

Determination of CO2 origin (natural or industrial) in sparkling bottled waters by 13C/12C isotope ratio analysis

This paper describes an isotope control method designed to identify the origin of CO₂ in sparkling bottled waters. The method is based on the analysis of the ¹³C/¹²C ratio in the dissolved inorganic carbon (DIC) of carbonated bottled water. Natural carbonated natural water has δ¹³C_PDB (DIC) values between −8‰ and +7‰. Generally, the industrial carbon dioxide injected into mineral bottled water is produced from hydrocarbons by burning or chemical processing. Hydrocarbons, and their derived CO₂, are characterised by a low ¹³C/¹²C ratio. Thus, a single analysis distinguishes the carbon dioxide in the bottled water (i.e. either from a natural source or added exogenous CO₂ of industrial origin). Rarely, CO₂ can be obtained from other industrial sources, mainly as a by-product of fermentation plants. Nevertheless, the carbon isotope fingerprint allows detection of the industrial gas injected in most of these cases.     

Batch kinetics and modelling of ethanolic fermentation of whey

The fermentation of whey by Kluyveromyces marxianus strain MTCC 1288 was studied using varying lactose concentrations at constant temperature and pH. The increase in substrate concentration up to a certain limit was accompanied by an increase in ethanol formation, for example, at a substrate concentration of 10 g L^?1, the production of ethanol was 0.618 g L^?1 whereas at 50 g L^?1 it was 3.98 g L^?1. However, an increase in lactose concentration to 100 g L^?1 led to a drastic decrease in product formation and substrate utilization. The maximum ethanol yield was obtained with an initial lactose concentration of 50 g L^?1. A method of batch kinetics was utilized to formulate a mathematical model using substrate and product inhibition constants. The model successfully simulated the batch kinetics observed at S₀ = 10 and 50 g L^?1 but failed in case of S₀ = 100 g L^?1 because of strong substrate inhibition.     

Occurrence of 3-MCPD fatty acid esters in human breast milk

A series of twelve breast milk samples were analysed by gas chromatography-mass spectrometry (GC/MS) operated in selected ion monitoring mode for 3-chloropropane-1,2-diol (3-MCPD). Whilst none of the samples contained 3-MCPD above the limit of detection of 3 μg kg^?1 milk, all contained high amounts of 3-MCPD esterified with higher fatty acids. The levels of 3-MCPD released by hydrolysis of these esters (bound 3-MCPD) ranged from the limit of detection (300 μg kg^?1, expressed on a fat basis) to 2195 μg kg^?1; with a mean level of bound 3-MCPD of 1014 μg kg^?1, which corresponded to 35.5 μg kg^?1 milk. The presence of bound 3-MCPD was confirmed using orthogonal gas chromatography coupled with high-speed time-of-flight mass spectrometry analysis for four randomly selected breast milk samples. Six breast milks collected from one of the nursing mothers 14–76 days after childbirth contained bound 3-MCPD within the range of 328–2078 μg kg^?1 fat (mean 930 μg kg^?1 fat). The calculated bound 3-MCPD content of these samples was within the range of 6 and 19 μg kg^?1 milk (mean of 12 μg kg^?1 milk). The major types of 3-MCPD esters were the symmetric diesters with lauric, palmitic, and oleic acids, and asymmetric diesters with palmitic acid/oleic acid among which 3-chloro-1,2-propanediol 1,2-dioleate prevailed.     

Evolution of some physicochemical parameters of iodine fortified sunflower oil and margarine

Experimental research were effectuated to establish the modalities of incorporation of the molecular iodine in sunflower oil double refined and deodorised of autochthon production. It was established that the iodisation of sunflower oil may be considered as an admissible method, which allows the incorporation of a considerable amount of iodine (1–100 μg mL^?1) without modifying the physicochemical properties of the product. It should be noted that iodine value varied a little, even in the sample with a maximum content of iodine (1000 μg mL^?1), its values did not exceed permitted limit. Research of quality indices variation of iodised oil during product storage (3 months), demonstrated that only in the case of maximum concentration of iodine (1000 μg mL^?1) it was manifested a slight overcome of the maximum permitted limit caused by the free iodine presence. Iodised oil was used for the manufacture of iodised margarine in order to fortificate this product with iodine (1 μg iodine g^?1 margarine). Physicochemical indices (moisture and volatile substances, melting point, free fatty acids content) of iodised margarine did not differ from the characteristics of the product without iodine.     

Determination of atrazine and degradation products in Luxembourgish drinking water: origin and fate of potential endocrine-disrupting pesticides

Several pesticides have been hypothesized to act as endocrine-disrupting compounds, exhibiting hormonal activity and perturbing normal physiological functions. Among these, especially s-triazine herbicides have received increased attention. Despite being banned in many countries, including the European Union, atrazine is still the world's most widely used herbicide. Despite its discontinued use, considerable concentrations of atrazine and its degradation products, mainly desethylatrazine (DEA) and deisopropylatrazine (DIA), are still found in the environment, including drinking water sources. The aim of this investigation was to study concentrations of especially s-triazine herbicides and major degradation products in drinking water, including spring water, tap water and bottled water in Luxembourg. Spring water (2007/2008/2009, n?=?69/69/69), tap water (2008/2009, n?=?19/26), and bottled water (2007/2008/2009, n?=?5/13/7) were sampled at locations in Luxembourg and investigated for pesticides by LC-ESI-MS/MS. Atrazine was the predominant triazine, detectable in many spring water locations, tap and bottled water, ranging (mean) from 0–57 (9), 0–44 (4), and 0–4 (1) ng?l^?1, respectively. DEA and DIA in spring water ranged (mean) from 0–120 (19) and 0–27 (3) ng?l^?1, with higher concentrations from agricultural areas and low molar ratios of DEA:atrazine <0.5 and high ratios of atrazine:nitrate suggesting point-source contamination. Levels (mean) of DEA and DIA in tap water were 0–62 (14) and 0–6 (<1) ng?l^?1 and in bottled water 0–11 (2) and 0–7 (2) ng?l^?1. Simazine and other triazines were detected in traces (<5?ng?l^?1). Thus, the conducted monitoring suggested the presence of low concentrations of s-triazines in raw and finished water, presumably partly due to non-agricultural contamination, with concentrations being below thresholds advocated by the European Union Directive 98/83/EC.     

Sensitive Determination of Bromate in Water Samples by Capillary Electrophoresis Coupled with Electromembrane Extraction

Electromembrane extraction (EME) as a novel sample preparation technique was firstly applied for the purification and enrichment of bromate (BrO₃ ^?) in drinking water prior to capillary zone electrophoresis with capacitively coupled contactless conductivity detection (CZE-C⁴D). BrO₃ ^?, as the primary disinfection by-product of ozonation, could be well separated with the major inorganic anions coexisting in water samples using a 300 mmol L^?1 acetic acid solution as the running buffer. Under the optimum conditions, the calibration curve showed good linearity (r ²?=?0.996), and the limit of detection was down to 0.12 ng mL^?1 with the enrichment factor at 267. The relative standard deviation (RSD) values for peak area and migration time at a spiked concentration of 10 ng mL^?1 of bromate were below 8.8 and 2.5 %, respectively. This proposed EME-CZE-C⁴D method has been successfully applied to analyze bottled drinking water and tap water samples with recoveries in the range of 85~98 %, providing an alternative to the determination of bromate in drinking water.     

Detoxification of Aflatoxin B1 and M1 by Lactobacillus acidophilus and prebiotics in whole cow's milk

The detoxification ability of Lactobacillus acidophilus and prebiotics was evaluated by a Plackett‐Burman Design to examine the reduction of concentration and bioaccessibility of aflatoxin B₁ (AFB₁) and M₁ (AFM₁) in artificially contaminated whole cow's milk. Six variables were evaluated: AFB₁ (3.25–6.0 μg L^?1) or AFM₁ (1.0–2.0 μg L^?1) concentration; incubation time (0–6 h); and inulin, oligofructose, β‐glucan, and polydextrose concentrations (each between 0.00 and 0.75%). All runs achieved reductions of AFB₁ (13.53–35.53%) and AFM₁ (17.65–71.52%). Comparing with the positive control, the AFB₁ bioaccessibility ranged from 23.68 to 72.67% and for AFM₁ was 0%. The probiotic, isolated or combined with prebiotics, was efficient in mycotoxin reduction, while the combination of the two reduced the mycotoxin bioaccessibility. The best experimental condition was the highest concentration of AFB₁ (6.5 μg L^?1) and AFM₁ (2.0 μg L^?1), incubation time of 0 h and the addition of probiotic and inulin (0.75%).     

Zearalenone occurrence in surface waters in central Illinois,USA

Zearalenone (ZEN) is an estrogenic secondary metabolite produced by certain fungi that commonly infest important cereal crops. The ability of ZEN to move from contaminated crops to surface waters has been demonstrated previously. This article reports the development and application of a method for the measurement of ZEN in surface waters from the central part of Illinois, USA. The method uses a cleanup procedure based on tandem reverse-phase disks and immunoaffinity columns, separation by liquid chromatography and detection by a combination of absorbance and fluorescence. ZEN was frequently found in samples of waters from lakes, streams and a field ditch. Although the frequency of detection was high (32% above the limit of detection, 0.4?ng?L^?1), the levels found were low, with the highest sample having 5.7?ng?L^?1. Therefore, although fungi can contribute to the exposure to environmental estrogens, the contribution from zearalenone in water is likely small.     

Survey of bottled waters for perchlorate by electrospray ionization mass spectrometry (ESI‐MS) and ion chromatography (IC)

Perchlorate has been identified in ground and surface waters around the USA including some that serve as supplies for drinking water. Because perchlorate salts are used as solid oxidants in rockets and ordnance, water contamination may occur near military or aerospace installations or defense industry manufacturing facilities. This ion has been added to the Environmental Protection Agency's Contaminant Candidate List and the Unregulated Contaminant Monitoring Rule. Concern over perchlorate has prompted many residents in affected areas to switch to bottled water; however, bottled waters have not previously been examined for perchlorate contamination. Should the EPA promulgate a regulation for municipal water systems, US law requires the Food and Drug Administration to take action on bottled water. Methods will therefore be required to determine perchlorate concentrations not only in tap water, but also in bottled waters. Ion chromatography (IC) is the primary technique used for its analysis in drinking water, but it does not provide a unique identification. Confirmation by electrospray ionization mass spectrometry (ESI‐MS) can serve in this capacity. The ESI‐MS method can be applied to these products, but it requires an understanding of matrix effects, especially of high ionic strength that can suppress electrospray. When using methyl isobutyl ketone (MIBK) as the extraction solvent, the ESI‐MS method can reach lower limits of detection of 6 ng ml ⁻¹ for some bottled waters. However, dilution required to negate ionic strength effects in mineral waters can raise this by a factor of 10 or more, depending on the sample. Decyltrimethylammonium cation (added as the bromide salt) is used to produce an ion pair that is extracted into MIBK. After extraction, the sum of the peak areas of the ions C₁₀H₂₁NMe₃(Br)(ClO₄)⁻ (m/z = 380) and C₁₀H₂₁NMe₃(ClO₄)₂⁻ (m/z = 400) is used to quantitate perchlorate. Standard additions are used to account for most of the matrix effects. In this work, eight domestic brands and eight imported brands of bottled water were comparatively analyzed by the two techniques. For comparison, a finished potable water known to contain perchlorate was also tested. None of the bottled waters were found to contain any perchlorate within the lower limit of detection for the IC method. Recoveries on spiked samples subjected to the IC method were ≥98%. Published in 2000 for SCI by John Wiley & Sons, Ltd     

Simple Voltammetric Determination of Rhodamine B by Using the Glassy Carbon Electrode in Fruit Juice and Preserved Fruit

This paper reported an innovative simple voltammetric approach for determination of rhodamine B based on a glassy carbon electrode. Cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical behavior of rhodamine B. After optimizing the experimental conditions, the anodic peak current of rhodamine B was linear to its concentration in the range of 4.78–956.1 μg?L^?1, and the limit of detection was 2.93 μg?L^?1 in pH 4.0 buffer solution. The electrode showed good repeatability and acceptable selectivity. This method was successfully applied to the detection of rhodamine B in preserved fruit and fruit juice samples, which has shown good reliability.     

Evaluation of acrylamide and selected parameters in some Turkish coffee brands from the Turkish market

The purpose of this study was to measure acrylamide (AA) levels and selected parameters of different traditional Turkish coffees. AA, 5-hydroxymethylfurfural (HMF), total reducing sugar, protein, pH, moisture, dry matter (DM) as well as ash, caffeine and soluble solids content (SSC) in DM, L*, a*, b* colour parameters of coffee samples were determined and the correlation between AA level and these parameters were investigated. A total of 36 coffee samples (20 Turkish, 8 Dibek and 8 Terebinth coffee) from the Turkish market were examined. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was validated for the detection and quantitation of AA in coffee samples. The calibration curve was linear (R² ≥ 0.999) over the range of 30–1000 μg kg^?1. The limit of detection (LOD) and limit of quantification (LOQ) were found as 4.6 μg kg^?1 and 15.5 μg kg^?1, respectively. The amounts of AA in analysed coffee samples were in the range 31.1 ± 0.6 to 323.4 ± 5.4 µg kg^?1. The highest mean AA levels were found in Terebinth coffees (240.3 μg kg^?1) followed by Turkish coffees (204.3 µg kg^?1) and then Dibek coffees (78.6 µg kg^?1). No tested Turkish coffee samples had an AA concentration above the indicative value (450 µg kg^?1) for roast coffee recommended by the European Commission (EC) in 2011. In addition, a strong positive correlation was found between HMF values and AA amounts of selected coffee types.     

BTES and aldehydes analysis in PET-bottled water in Lebanon

The aim of this study was to determine benzene, toluene, ethylbenzene, styrene (BTES), formaldehyde, acetaldehyde and benzaldehyde in Lebanese polyethylene terephthalate (PET)-bottled water. Aldehydes were analysed by high-performance liquid chromatography with ultraviolet–visible detection (HPLC/UV-vis) after 2,4-dinitrophenylhydrazine (DNPH) derivatisation and solid phase extraction (SPE) concentration, whereas headspace trap gas chromatograph–flame ionisation detector (GC/FID) was used for BTES determination. Both methods were validated according to the NF XP 90-210 and showed good linearity ranging from 3 (limit of quantification [LOQ]) to 15?µg?L^?1 for BTES and from 20 (LOQ) to 900?µg?L^?1 for aldehydes. No quantified contamination with BTES, acetaldehyde and benzaldehyde was determined in all analysed fresh Lebanese PET-bottled waters. Formaldehyde was quantified in 3 of the 15 samples at concentrations lower than the maximum contaminant level set by the US Environmental Protection Agency and the World Health Organisation. The samples' exposure to sunlight during 5 months increases the migration of formaldehyde and acetaldehyde. Similar migration increase was observed when the samples were incubated at 40°C during 10 days.     

Improvement of Procedure for HAV Detection in Bottled Water

Hepatitis A virus (HAV) is responsible for around half of the total number of hepatitis infections diagnosed worldwide. HAV infection is mainly propagated via the fecal–oral route, and as a consequence of globalization, foodborne outbreaks are reported with increasing frequency. A future standard (CEN/TC 275/WG6/TAG4) for norovirus and HAV detection in food will consider bottled water as a food product; therefore, a validated method for routine monitoring of HAV in bottled water is required. In this study, we describe the validation of a procedure to monitor and quantify HAV in bottled water samples by real-time RT-PCR. Initial experiments focused on evaluating the elution conditions suitable for HAV release from positively charged membrane. Finally, elution with 50 mM glycine and 1 % beef extract (pH 9.5), using an ultrasound cleaning bath, and concentration by ultrafiltration were the methods selected to evaluate HAV detection limit in different types of bottled waters. The HAV detection limit was determined between 0.2 and 20 TCID₅₀/L of bottled water depending on the composition of the bottled water, which highlights the importance of evaluating different types of bottled waters when a method has to be standardized.