11C-Para-aminobenzoic acid PET imaging of S. aureus and MRSA infection in preclinical models and humans.

Tools for noninvasive detection of bacterial pathogens are needed but are not currently available for clinical use. We have previously shown that para-aminobenzoic acid (PABA) rapidly accumulates in a wide range of pathogenic bacteria, motivating the development of related PET radiotracers. In this study, 11C-PABA PET imaging was used to accurately detect and monitor infections due to pyogenic bacteria in multiple clinically relevant animal models. 11C-PABA PET imaging selectively detected infections in muscle, intervertebral discs, and methicillin-resistant Staphylococcus aureus-infected orthopedic implants. In what we believe to be first-in-human studies in healthy participants, 11C-PABA was safe, well-tolerated, and had a favorable biodistribution, with low background activity in the lungs, muscles, and brain. 11C-PABA has the potential for clinical translation to detect and localize a broad range of bacteria.

Neonatal mice resist Plasmodium yoelii infection until exposed to para-aminobenzoic acid containing diet after weaning.

We developed a newborn (NB) mouse Plasmodium yoelii NL infection model to study malaria in early age. Surprisingly, the onset of parasitemia in P. yoelii challenged NB mice was delayed compared to adults and coincided with the weaning date when weanlings switched from maternal milk to normal chow diet. Also, compared to adult mice, parasitemia resolved much later (48 days vs 20 days post challenge) and the peak parasitemia was twice as high in weanlings. Concurrently, weanlings' germinal center reaction was delayed and diminished compared to adult mice. Maternal milk is deficient in para-aminobenzoic acid (PABA), which is required for de novo folate synthesis by Plasmodium. Suggesting a possible role for the protection afforded by PABA-deficient maternal milk, mice fed with a PABA-deficient diet after the weaning continued to control parasitemia. Despite the reduced parasitemia, these mice developed robust T follicular helper (Tfh) responses and were protected from a second P. yoelii challenge. The NB malaria model provides mechanistic insight into the human infant malaria manifestations where a diet solely based on breast-feeding reduces the incidence of severe malaria in infants. NB mice experiments also support further studies to investigate dietary PABA restriction in the management of severe malaria in infants.

Simple and Robust N-Glycan Analysis Based on Improved 2-Aminobenzoic Acid Labeling for Recombinant Therapeutic Glycoproteins.

N-glycans of therapeutic glycoproteins are critical quality attributes that should be monitored throughout all stages of biopharmaceutical development. To reduce both the time for sample preparation and the variations in analytical results, we have developed an N-glycan analysis method that includes improved 2-aminobenzoic acid (2-AA) labeling to easily remove deglycosylated proteins. Using this analytical method, 15 major 2-AA-labeled N-glycans of Enbrel® were separated into single peaks in hydrophilic interaction chromatography mode and therefore could be quantitated. 2-AA-labeled N-glycans were also highly compatible with in-line quadrupole time-of-flight mass spectrometry (MS) for structural identification. The structures of 15 major and 18 minor N-glycans were identified from their mass values determined by quadrupole time-of-flight MS. Furthermore, the structures of 14 major N-glycans were confirmed by interpreting the MS/MS data of each N-glycan. This analytical method was also successfully applied to neutral N-glycans of Humira® and highly sialylated N-glycans of NESP®. Furthermore, the analysis data of Enbrel® that were accumulated for 2.5 years demonstrated the high-level consistency of this analytical method. Taken together, the results show that a wide repertoire of N-glycans of therapeutic glycoproteins can be analyzed with high efficiency and consistency using the improved 2-AA labeling-based N-glycan analysis method.

Pesticide dispersion by spraying under tropical conditions.

Pesticide air pollution by spraying was evaluated under different temperature, humidity and wind climatic conditions in Brazil. Field experiments were performed with application towards the soil and in guava orchards, where spray dispersion was monitored by adding p-aminobenzoic acid (PABA), a fluorescent substance, as a tracer to the water contained in the spray tanks. Samples were collected with filter membranes (Whatman 180025), and the PABA was extracted from the filters by shaking with water in a Petri dish and measured in a spectrofluorometer. A spray aimed towards the soil with filters positioned on the ground and hung at different heights did not show different upward dispersion as observed when lateral pulverization was conducted. In this case, a tractor with a sprayer moved through a 3 m high and 6 m wide frame with filter membranes mounted at 60 cm intervals. Spray dispersion patterns were modified by guava leaf resistance. No influence of temperature and humidity was observed in this short-lived spraying process. Nevertheless, wind drift can occur during airborne dispersion and is an important pesticide pollution source which requires control. Droplets with PABA powered by assisted spraying upwards returned to the ground by gravity and, therefore, did not constitute a vertical source of atmospheric pollution.

Fotoprotetores bioativos multifuncionais contendo rutina, octil dimetil PABA e avobenzona: caracterização físico-química, funcional e eficácia clínica / Bioactive sunscreens containing rutin, octyl dimethyl PABA and avobenzone: physicochemical, functional and clinical characterization

A exposição crônica à radiação solar pode contribuir para o aparecimento do câncer de pele, sendo o uso de fotoprotetores um fator primordial na prevenção desses efeitos deletérios. Atualmente, substâncias bioativas tais como a rutina têm sido foco de interesse da comunidade científica graças às suas propriedades fotoprotetoras e antioxidantes, que podem promover aumento dos valores de FPS, além de conferir características multifuncionais às formulações. Achados in vitro recentes indicam que a rutina, quando incorporada em emulsões fotoprotetoras óleo em água, promove aumento da atividade antioxidante e aumento do FPS. No entanto, a realização de estudos clínicos é fundamental para confirmar e quantificar esses resultados, já que a metodologia in vitro possui baixa repetibilidade e ausência de correlação com ensaios in vivo, principalmente quando as formulações analisadas apresentam substâncias antioxidantes em sua composição. O objetivo deste estudo foi avaliar pela primeira vez a atividade da rutina frente ao FPS e sua segurança clínica através da comparação de formulações fotoprotetoras contendo rutina 0.1% (w/w), avobenzona 3.0% (w/w) e octil dimetil PABA 8.0% (w/w) com uma preparação similar sem o composto bioativo. Adicionalmente, hidratação cutânea, FPS in vitro e atividade antioxidante da rutina em associação com outros filtros foram investigados. O perfil de segurança das formulações qualificou as fórmulas para os testes de eficácia clínica. O teste de DPPH confirmou a capacidade antioxidante da rutina, demonstrando cerca de 40% de aumento na capacidade de sequestro de radicais livres na presença do composto bioativo. A rutina em combinação com os filtros UV aumentou o FPS clínico de 7.30 ± 0.60 para 12.37 ± 1.13, o que representa cerca de 70% de aumento. Os resultados encontrados provam que a rutina em combinação com outros filtros pode aumentar significativamente o valor do FPS e que a mesma é segura para uso clínico

Unprotected chronic exposure to solar radiation can contribute to premature skin cancer and sunscreens are a key factor to avoid those detrimental effects. Currently, there is a growing interest in the photoprotector and antioxidant potential of bioactive substances, such as rutin, that could help to increase the SPF value and add multifunctional characteristics to the formulations. Recent in vitro findings indicated that rutin, when incorporated in oil-in-water photoprotective emulsions can provide antioxidant activity and SPF increase. However, clinical studies are fundamental to determine this activity duo to in vitro methodology lack of repeatability and correlation between the in vivo data, especially when the analyzed formulas contain antioxidant substances. The aim of this study was to evaluate for the first time to date the rutin in vivo SPF and clinical safety by comparing sunscreens formulations containing rutin 0.1% (w/w), butyl methoxydibenzoylmethane 3.0% (w/w) and octyl dimethylPABA 8.0% (w/w) with a similar bioactive-free preparation. Additionally, skin hydration, in vitro SPF and in vitro antioxidant activity of rutin, in association with the UV filters were investigated. The safety profile of the formulations under sun-exposed skin conditions qualified the formulas for clinical efficacy assays. DPPH test confirmed rutin antioxidant properties, demonstrating about 40% increase in radical scavenging potential when the bioactive compound was present. Rutin in combination with the UV filters increased the clinical SPF from 7.30 ± 0.60 to 12.37 ± 1.13, representing about 70% growth in the SPF value. The results obtained proved that rutin in combination with UV filters can improve the SPF value significantly and is safe for clinical use

An innovative nano-sorbent for selective solid-phase extraction and spectrophotometric determination of p-amino benzoic acid in cosmetic products.

OBJECTIVE: A novel nano-sorbent was developed for selective extraction and pre-concentration of p-amino benzoic acid (PABA) prior to determination by spectrophotometry. METHODS: Selective extraction of PABA from aqueous solutions was performed using a solid-phase extraction column packed with 200 mg of nickel-zinc-aluminium layered double hydroxide (Ni-Zn-Al LDH) as a nano-sorbent. Extraction procedure is based on the adsorption of p-amino benzoate ions on the Ni-Zn-Al-nitrate LDH and/or their exchanging with LDH interlayer nitrate ions. After elution of extracted analyte by 2.5 mL of 2 mol L(-1) NaCl solution, its concentration was determined spectrophotometrically at λmax = 268 nm. RESULTS: The spectrophotometry method gave a linear response for PABA within the range of 12.5-425.0 µg L(-1) with a correlation coefficient of 0.9994. In the optimum experimental conditions, the limit of detection and sorption capacity were 3.78 µg L(-1) and 21.25 mg g(-1) , respectively. CONCLUSION: The presented method uses mild separation conditions and is a sensitive, reproducible, simple, low-cost and environment-friendly technique that could be used for the extraction and determination of PABA in various cosmetic samples.

Evaluation of a simple in-house test to presumptively differentiate Mycobacterium tuberculosis complex from nontuberculous mycobacteria by detection of p-nitrobenzoic acid metabolites.

The timely differentiation of Mycobacterium tuberculosis complex (MTC) and non-tubercular mycobacterium (NTM) species is urgently needed in patient care since the routine laboratory method is time consuming and cumbersome. An easy and cheap method which can successfully distinguish MTC from NTM was established and evaluated. 38 mycobacterial type and reference strains and 65 clinical isolates representing 10 species of mycobacterium were included in this study. Metabolites of p-nitrobenzoic acid (PNB) reduction were identified using liquid chromatography and tandem mass spectrometry (LC/MS/MS). A spectrophotometric method was developed to detect these metabolites, which was evaluated on a number of MTC and NTM species. All of the tested NTM species and strains reduced PNB to p-aminobenzoic acid (PABA), while none of the MTC strains showed a similar activity. Spectrophotometric detection of PABA had 100% sensitivity and specificity for MTC and NTM differentiation among the type strains and the clinical isolates tested. PABA was identified as one of the metabolites of PNB reduction. All the tested NTM species metabolized PNB to PABA whereas the MTC members lacked this activity. A simple, specific and cost-effective method based on PABA production was established in order to discriminate MTC from NTM from cultured organisms.

Differential pulsed amperometry coupled to microchip capillary electrophoresis.

In this work, we describe a novel electrochemical detection method, differential pulsed amperometry (DPA) on microchip capillary electrophoresis (MCE). In a pulse period, a sequential two-step sampling is executed at two different potentials (E1 and E2). Differential current signal of the duplex sampling events is recorded that functions as time domain. The performance of this detection scheme was evaluated by separating and detecting three model analytes including tyramine (Tym), tryptophan (Trp), and p-aminobenzoic acid (PABA). Multiple parameters that would affect electrochemical response and peak shape, such as sampling potential, sampling time, and electrode cleaning time, were investigated. This pulse technique exhibits better sensitivity over constant potential amperometry (CPA), nearly equal to triple pulsed amperometry (TPA). More importantly, DPA can generate more stable baseline than TPA, primarily due to the background subtraction through the two-step sampling, which is beneficial to further improve analytical sensitivity. In the optimal condition, the limits of detection for Tym, Trp and PABA, were down to 0.27µM, 0.32µM and 1.1µM, respectively. DPA detection opens up a new avenue for microchip electrochemistry, and can be virtually extended to other fluid analysis techniques.

Production of aromatics in Saccharomyces cerevisiae--a feasibility study.

Aromatics are amongst the most important bulk feedstocks for the chemical industry, however, no viable bioprocess exists today and production is still dependent on petro-chemistry. In this article the production of aromatic precursors such as p-hydroxybenzoic acid (PHBA) and p-amino benzoic acid (PABA) in Saccharomyces cerevisiae was evaluated using metabolic network analysis. Theoretical mass yields for PHBA and for PABA obtained by metabolic network analysis were 0.58 and 0.53 g g(glucose)⁻¹, respectively. A major setback for microbial production of aromatics is the high toxicity of the products. Therefore, PHBA and PABA toxicity was evaluated in S. cerevisiae. Minimal inhibitory concentrations of 38.3 g L⁻¹ for PHBA and 0.62 g L⁻¹ for PABA were observed. However, PABA toxicity could be alleviated in adaptation experiments. Finally, metabolic engineering was used to create proof of principle first generation strains of S. cerevisiae. Overall accumulation of 650 µM PHBA and 250 µM PABA could be achieved.

UV filters, ethylhexyl methoxycinnamate, octocrylene and ethylhexyl dimethyl PABA from untreated wastewater in sediment from eastern Mediterranean river transition and coastal zones.

UVF may occur in the aquatic environment through two principal sources: direct inputs from recreational activities and indirect wastewater- and river-borne inputs. The aim of this study was to obtain a first overview of levels of three UVF (EHMC, OC and OD-PABA) in coastal areas subjected to river inputs, untreated wastewater discharges and dumpsite leachates. We selected three eastern Mediterranean rivers that have been impacted for decades by untreated wastewater release and collected sediment in the coastal zone during the hot and humid seasons. Western Mediterranean sites receiving treated wastewaters were analyzed for comparison. The results gave an overview of sediment contamination under these two contrasted situations representative of Mediterranean coastal areas without bathing activities. The analysis of the three UVF revealed the ubiquity and high point source contamination by EHMC and OC in transition and coastal zones, with levels as high as 128 ng g(-1)d.w. OD-PABA was also frequently detected, but at lower concentrations (

Neutral desorption extractive electrospray ionization mass spectrometry for fast screening sunscreen agents in cream cosmetic products.

High throughput analysis of sunscreen agents present in cream cosmetic has been demonstrated, typically 2 samples per minute, using neutral desorption extractive electrospray ionization mass spectrometry (ND-EESI-MS) without sample pretreatment. For the targeted compounds such as 4-Aminobenzoic acid and oxybenzone, ND-EESI-MS method provided linear signal responses in the range of 1-100 ppb. Limits of detection (LOD) of the method were estimated at sub-ppb levels for the analytes tested. Reasonable relative standard deviation (RSD=8.4-16.0%) was obtained as a result of 10 independent measurements for commercial cosmetics samples spiked with each individual sunscreen agents at 1-10 ppb. Acceptable recoveries were achieved in the range of 87-116% for direct analysis of commercial cream cosmetic samples. The experimental data demonstrate that ND-EESI-MS is a useful tool for high throughput screening of sunscreen agents in highly viscous cream cosmetic products, with the capability to obtain quantitative information of the analytes.

Bioaccumulation assessment of the sunscreen agent 2-ethylhexyl 4-(N,N-dimethylamino)benzoate in human semen by automated online SPE-LC-MS/MS.

The proven endocrine disruption nature of the sunscreen ingredient 2-ethylhexyl 4-(N,N-dimethylamino)benzoate (EDP) calls for research to understand its distribution and bioaccumulation in the human body. A sensitive analytical method to determine EDP and its metabolites in human semen based on online SPE-LC-MS/MS is described. The method has been fully validated and a standard addition calibration has been used for quantification to correct the observed matrix effects. The on-column detection limits of the analytes are between 0.2 and 0.6 ng, depending on the analyte and the sample. The repeatability of the method, expressed as relative standard deviation, was in the range 4.6-9.4%. The method was satisfactorily applied to semen samples from male volunteers who were subjected to single and repeated whole-body applications of an EDP-containing sunscreen product. EDP metabolites were found at different concentrations in semen samples from the repeated application study, thus showing evidences of bioaccumulation in humans.

Mass transfer ways of ultraviolet printing ink ingredients into foodstuffs.

The case of isopropylthioxanthone (ITX) showed conclusively that the ingredients of ultraviolet printing inks may migrate into packaged foodstuffs. For multilayered materials like beverage cartons, the only way that mass transfer can occur is by the so-called set-off effect. In contrast, in the case of rigid plastics like yoghurt cups, two other methods of mass transfer, permeation and gas phase, have to be considered. In cooperation with producers of ink, plastic cups and yoghurt, a project was conducted in order to elucidate the mass transfer of ink ingredients. In addition, the influence of storage time and the age of ultraviolet lamps on the migration level was examined. The suitability of 50% ethanol as a simulant for yoghurt was also tested. ITX was chosen as a model migrant, as it is easily detectable. Furthermore, the migration of two other substances, the photo-initiator 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (MTMP) and the amine synergist ethyl-4-(dimethylamino)benzoate (EDAB), which may be used in combination with ITX, was studied. Before being filled with yoghurt or 50% ethanol, the printed cups were stored under different contact conditions, with and without contact between the inner layer and the printed surfaces, in order to distinguish between the possible mass transfer ways. All analyses were performed by means of high performance liquid chromatography with diode array and fluorescence detection (HPLC-DAD/FLD). It was shown that contamination with ITX and EDAB occurs via set-off and that the degree of migration increases with lamp age and storage time of the unfilled cups. Migration of MTMP was not detectable. The results show that besides the careful selection of the appropriate raw materials for printing ink, a close monitoring of the process also plays a major role in migration control. In addition, the results proved that 50% ethanol is a suitable simulant for yoghurt.

Quantitative determination of TEGDMA, BHT, and DMABEE in eluates from polymerized resin-based dental restorative materials by use of GC/MS.

This study investigated the leaching of ingredients from several commercial dental composite resins cured with LED, and immersed in methanol or water for 24 h, respectively. The composites used were: Admira Dentin (VOCO), Artemis Schmelz (Enamel) (Ivoclar Vivadent), Els extra low shrinkage (Saremco Dental), Filtek Supreme XT Dentin (3 M ESPE), Gradia Direct (GC), Venus & Venus flow (Heraeus Kulzer), and XRV Herculite Prodigy Enamel (Kerr). From each dental composite four specimens with defined structure and 100-mg net weight were made. After the polymerization process, according to manufacturer's instructions, the specimens were immersed in either 1 ml water or 1 ml methanol and incubated at 37 degrees C for 24 h. Eluted ingredients triethyleneglycoldimethacrylate (TEGDMA), 2,6-di-tert-butyl-4-methylphenol (BHT), and 4-N,N-dimethylaminobenzoicacidethylester (DMABEE) were detected and quantified using gas chromatography-mass spectrometry (GC-MS). The amounts of the detected analytes from 100 mg polymerized composites ranged between the following values: TEGDMA: 0-0.5 mg (water), 0-1.6 mg (methanol); BHT: 0-0.03 µg (water), 0-0.11 mg (methanol); and DMABEE: 0-0.11 mg (water), 0-1.4 mg (methanol). We conclude from the results that the elution rates into methanol and water differ significantly. Furthermore, it is concluded that all the determined amounts eluting from the composites are far below toxic-relevant concentrations.

Determination of the optimal photoinitiator concentration in dental composites based on essential material properties.

OBJECTIVES: The aim of this study was to determine the concentrations of the photosensitizer (camphoroquinone, CQ) and coinitiator (ethyl-4-dimethylaminobenzoate, EDMAB) that resulted in maximum conversion but generated minimum contraction stress in experimental composites. METHODS: Experimental composites were prepared with an identical resin formulation [TEGDMA:UDMA:bis-GMA of 30.25:33.65:33.65]. Five groups of resin were prepared at varied CQ concentrations (0.1, 0.2, 0.4, 0.8 and 1.6wt% of the resin). Five subgroups of resin were prepared at each level of CQ concentration, by adding EDMAB at 0.05, 0.1, 0.2, 0.4 and 0.8wt% of the resin, resulting in 25 experimental resins. Finally, strontium glass ( approximately 3microm) and silica (0.04microm) were added at 71.5 and 12.6wt% of the composite, respectively. Samples (n=3) were then evaluated for Knoop hardness (KHN), degree of conversion (DC), depth of cure (DoC) and contraction stress (CS). RESULTS: There was an optimal CQ and EDMAB concentration that resulted in maximum DC and KHN, beyond which increased concentration resulted in a decline in those properties. KHN testing identified two regions of maxima with best overlaps occurring at CQ:EDMAB ratio of 1.44:0.42 and 1.05:1.65mol%. DC evaluation showed one region of maximum, the best overlap occurring at CQ:EDMAB ratio of 2.40:0.83mol%. DoC was 4mm. Overall, maximum CS was attained before the system reached the maximum possible conversion and hardness. SIGNIFICANCE: (1) Selection of optimal photoinitiator/amine concentration is critical to materials' formulation, for excessive amounts can compromise materials' properties. (2) There was no sufficient evidence to suggest that contraction stress can be reduced by lowering CQ/EDMAB concentration without compromising DC and KHN.

Use of liquid chromatography with electrochemical detection for the determination of antioxidants in less common fruits.

Neurodegenerative disorders (NDD) have become the common global health burden over the last several decades. According to World Health Organization (WHO), a staggering 30 million people will be affected by Alzheimer's disease in Europe and the USA by 2050. Effective therapies in this complex field considering the multitude of symptoms associated with NDD indications, have not been found yet. Based on the results of NDD related studies, prevention appears to be the promise alternative. Antioxidative and anti-inflammatory properties are hypothesized for natural phenolics, a group of plant secondary products that may positively impact neurodegenerative diseases. In these studies, phenolic-rich extracts from less common fruit species: Blue honeysuckle (Lonicera edulis, Turcz. ex. Freyn), Saskatoon berry (Amelanchier alnifolia Nutt.), and Chinese hawthorn (Crateagus pinnatifida Bunge) were obtained and analyzed to detect neuroprotective substances content and establish a potential therapeutic value. High performance liquid chromatography with electrochemical detection was optimized and further applied on analysis of the extracts of less common fruit species. It was observed that Chinese hawthorn and Blue honeysuckle extracts are potent source of neuroprotective phenolic antioxidants. In accordance the results, it appears that the fruit or formulated products may have the potential for the prevention of neurodegenerative diseases.

Simultaneous trace determination of nine organic UV-absorbing compounds (UV filters) in environmental samples.

A new sensitive method has been successfully developed and validated for the simultaneous determination and quantification of nine estrogenic UV filters (benzophenone-1, benzophenone-2, benzophenone-3, benzophenone-4, 4,4-dihydroxybenzophenone, ethyl-4-aminobenzoate, 2-ethyl-hexyl-4-trimethoxycinnamate, 3-(4-methylbenzylidene)-camphor, 3-benzylidene-camphor) in different environmental matrices. After optimisation of extraction conditions for the best recovery of polar to lipophilic compounds from fish tissue and a subsequent lipid clean-up in HPLC, fish extraction recoveries exceeded 72% for all nine UV filters. Identification and quantification of compounds was performed for lipophilic UV filters with gas chromatography-electroionisation-mass spectrometry and for polar and mid-polar compounds with liquid chromatography coupled to electrospray ionisation mass spectrometry. Instrumental detection limits (IDL) varied between 5 and 260 pg injected and method detection limits (MDL) were in the low ng/g lipids range for all test compounds. The described analytical methods are shown to be useful to screen for estrogenic UV filters in environmental samples such as fish and polar organic chemical integrative samplers.

Determination of ink photoinitiators in packaged beverages by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry.

A new analytical method, using gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-mass spectrometry (LC/MS) techniques, was developed for the determination in packaged food beverages of five ink photoinitiator residues: 2-isopropylthioxanthone (ITX), benzophenone, 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB), 1-hydroxycyclohexyl-1-phenyl ketone (IRGACURE 184) and ethyl-4-dimethylaminobenzoate (EDAB). Samples were extracted from selected beverages (milk, fruit juices and wine) and relative packagings, using n-hexane and dichloromethane, respectively, purified on solid-phase extraction (SPE) silica gel cartridges, and then analyzed in GC/MS and LC/MS. The recovery percentages, obtained spiking the beverage samples at concentrations of 4 and 10 microgl(-1) with a standard mixture of photoinitiators, were in the range 42-108% (milk), 50-84% (wine), and 48-109% (fruit juices). The repeatability of the method was assessed in all cases by the % of correlation value, that was lower than 19%. The lowest limits of detection (LODs) and limits of quantification (LOQs), obtained using GC/MS, were in the range 0.2-1 and 1-5 microgl(-1), respectively. The method was applied to the analysis of forty packaged food beverages (milk, fruit juices and wine samples). The most significant contamination was that of benzophenone, found in all samples in a concentration range of 5-217mugl(-1). Its presence was confirmed by an LC/Atmospheric-Pressure PhotoIonization (APPI)/MS/MS analysis. The photoinitiator (EHDAB) was found in eleven out of forty beverages in a concentration range of 0.13-0.8 microgl(-1). Less important was the ITX contamination, found in three out of forty samples in a range 0.2-0.24 microgl(-1). The work proposes a new method to analyze ink photoinitiator residues in polycoupled carton packaging and in contained food beverages.

Rapid and sensitive HPLC assay for simultaneous determination of procaine and para-aminobenzoic acid from human and rat liver tissue extracts.

A sensitive and rapid high-performance liquid chromatography method has been developed for simultaneous determination of procaine and its metabolite p-aminobenzoic acid (PABA) from human and rat liver tissue extracts. The method has been validated according to ICH guidelines in terms of selectivity, linearity, lower limit of detection, lower limit of quantitation, accuracy, precision and recovery from human and rat liver tissue extracts. Chromatography was carried out on a Discovery C(18) column using 10mM ammonium acetate at pH 4.0 and acetonitrile as mobile phase. Retention times for procaine and PABA were 6.6 and 5.3 min, respectively. Linearity for each calibration curve in both tissue extracts was observed across a range from 10 microM to 750 microM for procaine and PABA. The lower limit of detection for both procaine and PABA was 5 microM and the lower limit of quantitation was 10 microM in both tissue extracts. The intra- and inter-day relative standard deviations (R.S.D.) for both procaine and PABA were <6%. Recoveries of procaine and PABA from human and rat liver tissue extracts were determined by two different methods with a single-step protein precipitation technique being employed in both methods. Recoveries for both procaine and PABA were greater than 80% from both human and rat liver tissue extracts.

Multiway partial least-squares coupled to residual trilinearization: a genuine multidimensional tool for the study of third-order data. Simultaneous analysis of procaine and its metabolite p-aminobenzoic acid in equine serum.

A new third-order multivariate calibration approach, based on the combination of multiway-partial least-squares with a separate procedure called residual trilinearization (N-PLS/RTL), is presented and applied to multicomponent analysis using third-order data. The proposed chemometric algorithm is able to predict analyte concentrations in the presence of unexpected sample components, which require strict adherence to the second-order advantage. Results for the determination of procaine and its metabolite p-aminobenzoic acid in equine serum are discussed, based on kinetic fluorescence excitation-emission four-way measurements and application of the newly developed multiway methodology. Since the analytes are also the reagent and product of the hydrolysis reaction followed by fast-scanning fluorescence spectroscopy, the classical approach based on parallel factor analysis is challenged by strong linear dependencies and multilinearity losses. In comparison, N-PLS/RTL appears an appealing genuine multiway alternative that avoids the latter complications, yielding analytical results that are statistically comparable to those rendered by related unfolded algorithms, which are also able to process four-way data. Prediction was made on validation samples with a qualitative composition similar to the calibration set and also on test samples containing unexpected equine serum components.