C18 Cartridge Column Research Articles

Antagonistic activities against selected pathogens of a bacteriocin-producing lactic acid bacteria isolated from Balao-balao, a fermented rice-shrimp mixture

Lactic acid bacteria from a fermented rice-shrimp mixture traditionally known in the Philippines as Balao-balao were isolated in the present study. Screening of lactic acidproducing strains revealed that ten isolates showed promising inhibitory activities against test microorganisms namely Staphylococcus aureus BIOTECH 1634, Escherichia coli BIOTECH 1582, Bacillus subtilis BIOTECH 1679 and Vibrio harveyi SEAFDEC 010. Of interest was isolate PL12, a bacteriocin-producing strain which showed the highest inhibitory activity against the pathogens tested. Isolate PL12 was identified as Pediococcus pentosaceus (GenBank accession number MF353992) with 100% similarity by 16S rDNA sequence analyses. Excluding the effects of organic acids and hydrogen peroxide, the cell-free supernatant (CFS) of PL12 isolate exhibited strong antagonistic activities against test pathogens in an agar well diffusion assay. These results confirmed the isolate’s proteinaceous nature and are indicative of typical characteristics of bacteriocins. To further concentrate the proteins present in the CFS, ammonium sulfate precipitation followed by column purification (Sep-Pak C18 cartridge column) was performed. Positive antagonism of PL12 bacteriocin was observed in both Gram-positive and Gram-negative bacteria tested. The highest inhibitory activity was found against E. coli in every purification step. These results suggested that bacteriocin-producing PL12 isolate can be a promising preservative in the food industry and as probiotics in aquaculture since it possesses antagonistic activities against V. harveyi.

Multiplex Immunosuppressant (ISD) Method for the Measurement of Cyclosporine A, Tacrolimus, Sirolimus/Rapamycin, and Everolimus in Whole Blood Using MassTrak™ Kit.

Cyclosporine A, everolimus, sirolimus, and tacrolimus are the most commonly used immunosuppressant drugs in organ transplant and auto-immune patients. The narrow therapeutic window of these immunosuppressant drugs requires close monitoring of drug blood levels to ensure proper therapeutic response. A quick, robust high-throughput liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was introduced for monitoring whole blood levels of these immunosuppressant drugs with the use of the MassTrak™ Immunosuppressant kit. The assay was carried out in 96-well plate format and requires a simple precipitation step; after which, the supernatant is subjected to liquid chromatography separation (2min total run time) using a C18 Cartridge column. Identification and quantitation of cyclosporine A, everolimus, sirolimus, and tacrolimus was achieved by employing multiple reaction monitoring (MRM) in positive mode electrospray ionization (ESI). The method exhibits a linear measuring range from 10 to 1500ng/mL (Cyclosporine A), 1.0-30.0ng/mL (Everolimus), 1.0-26.0ng/mL (Sirolimus), and 1.0-30.0ng/mL (Tacrolimus) and has a within-run and between-run imprecision of <10%.

Simultaneous determination of glyphosate, glufosinate, and their metabolites in honey using liquid chromatography-tandem mass spectrometry and solid-phase extraction.

Here, we developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of residual glyphosate, glufosinate, and their metabolites N-acetylglyphosate (Gly-A), 3-methylphosphinicopropionic acid (MPPA) and N-acetylglufosinate (Glu-A) in honey using a mixed mode column of reversed-phase and anion exchange without derivatization. The target analytes were extracted from honey samples using water, cleaned up on a reverse phase C18 cartridge column and an anion exchange NH2 cartridge column, and quantified using LC-MS/MS. Glyphosate, Glu-A, Gly-A, and MPPA were detected in negative ion mode based on deprotonation, whereas glufosinate was detected in positive ion mode. The coefficients of determination (R2) of the calibration curve, calculated in the range of 1-20µg/kg for glufosinate, Glu-A, and MPPA, and 5-100µg/kg for glyphosate and Gly-A, were higher than 0.993. The developed method was evaluated using honey samples spiked with glyphosate and Gly-A at 25µg/kg and glufosinate, and MPPA and Glu-A at 5µg/kg, based on the maximum residue levels. The validation results show good recoveries (86-106%) and precision (< 10%) for all target compounds. The limit of quantification of the developed method is 5µg/kg for glyphosate, 2µg/kg for Gly-A, and 1µg/kg for glufosinate, MPPA and Glu-A. These results suggest that the developed method is applicable for quantifying residual glyphosate, glufosinate, and their metabolites in honey in compliance with Japanese maximum residue levels. Moreover, the proposed method was applied to the analysis of honey samples and glyphosate, glufosinate, and Glu-A were detected in some samples. The proposed method will be a useful tool for the regulatory monitoring of residual glyphosate, glufosinate, and their metabolites in honey.

The use of experimental design for the development and validation of an HPLC-ECD method for the quantitation of efavirenz.

A high performance liquid chromatography with electrochemical detection (HPLC-ECD) method for the quantitation of efavirenz (EFV) was developed, since traditional HPLC-UV methods may be inappropriate, given that EFV undergoes photolytic degradation following exposure to UV light. This work describes the use of response surface methodology (RSM) based on a central composite design (CCD) to develop a stability-indicating HPLC method with pulsed ECD in direct current (DC) mode at an applied potential difference and current of +1400 mV and 1.0 μA for the analysis of EFV. Separation of EFV and imipramine was achieved using a Nova-Pak®C18 cartridge column and a mobile phase of phosphate buffer (pH 4.5): acetonitrile (ACN) (55:45 v/v). Mobile phase pH, buffer molarity, ACN concentration and applied potential difference were investigated. The optimized method produced sharp well resolved peaks for imipramine and EFV with retention times of 3.70 and 8.89 minutes. The calibration curve was linear (R2 = 0.9979) over the range 5-70 μg/mL. Repeatability and intermediate precision ranged between 3.37 and 4.34 % RSD and 1.31 and 4.29 % RSD and accuracy between -0.80 and 4.71 % bias. The LOQ and LOD were 5.0 and 1.5 μg/mL. The method was specific for EFV and was used to analyse EFV in commercially available tablets. The HPLC-ECD method is more suitable for quantitative analysis of EFV than HPLC-UV.

GPC-HPLC-MS/MS测定植物组织中IAA与ABA的方法

植物激素检测的有效性和高效性是开展植物研究的前提。本试验采用净化-定量-浓缩多联机系统(GPC)纯化样品、利用HPLC-MS/MS检测以及内标法定量测定植物组织内源IAA和ABA含量。通过正交试验设计优化适于激素提取和纯化的条件，结果表明：取样量0.5 g、80%甲醇提取液、浓缩温度35℃和C18 SPE柱为最优组合。IAA和ABA的含量分别为20.34 ng/g和789.93 ng/g；最低检出限分别为2.36 ng/g和31.95 ng/g；回收率为70.43%和80.17%；变异系数分别为1.87%和2.26%。 The effectiveness and efficiency of the plant hormone detection is a prerequisite for plant research. The sample was purified with the GPC system, and the method employed HPLC-MS/MS for multiple reaction monitoring of concentrations of IAA, ABA, and deuterated IAA and ABA analogs. The condition of extraction and purification of hormones were optimized by orthogonal design. The results show that the composite of 0.5 g samples, 80% methanol extraction solvent, concentration temperature 35˚C and C18 cartridge column for solid-phase extraction (SPE), were optimal extraction procedure for each type of plant tissue. The contents of IAA and ABA as high as 20.34 ng/g and 789.3 ng/g were achieved by this method, respectively; the detectable limits were 2.36 ng/g and 31.95 ng/g; the recoveries were 70.43% and 80.17%; the RSD were 1.87% and 2.26%.

Determination of Diphenylamine in Agricultural Products by HPLC-FL.

A method for the determination of diphenylamine in agricultural products was developed. Diphenylamine was extracted with acetonitrile from a sample under an acidic condition, passed through a C18 cartridge column, re-extracted with n-hexane, cleaned up on a PSA cartridge column, determined by HPLC with fluorescence detector and confirmed by liquid chromatography with tandem mass spectrometry. Average recoveries (n=5) from brown rice, corn, soybeans, potato, cabbage, eggplant, spinach, orange, apple and green tea were in the range from 76.7 to 94.9%, and the relative standard deviations were from 0.6 to 5.8% at concentrations equal to the maximum residue limits (MRLs). The quantification limits were 0.01 mg/kg, which is the uniform limit in the positive list system for agricultural chemical residues in food in Japan.

Remodeling of Marrow Hematopoietic Stem and Progenitor Cells by Non-self ST6Gal-1 Sialyltransferase

Glycans occupy the critical cell surface interface between hematopoietic cells and their marrow niches. Typically, glycosyltransferases reside within the intracellular secretory apparatus, and each cell autonomously generates its own cell surface glycans. In this study, we report an alternate pathway to generate cell surface glycans where remotely produced glycosyltransferases remodel surfaces of target cells and for which endogenous expression of the cognate enzymes is not required. Our data show that extracellular ST6Gal-1 sialyltransferase, originating mostly from the liver and released into circulation, targets marrow hematopoietic stem and progenitor cells (HSPCs) and mediates the formation of cell surface α2,6-linked sialic acids on HSPCs as assessed by binding to the specific lectins Sambucus nigra agglutinin and Polysporus squamosus lectin and confirmed by mass spectrometry. Marrow HSPCs, operationally defined as the Lin-c-Kit+ and Lin-Sca-1+c-Kit+ populations, express negligible endogenous ST6Gal-1. Animals with reduced circulatory ST6Gal-1 have marrow Lin-Sca-1+c-Kit+ cells with reduced S. nigra agglutinin reactivity. Bone marrow chimeras demonstrated that α2,6-sialylation of HSPCs is profoundly dependent on circulatory ST6Gal-1 status of the recipients and independent of the ability of HSPCs to express endogenous ST6Gal-1. Biologically, HSPC abundance in the marrow is inversely related to circulatory ST6Gal-1 status, and this relationship is recapitulated in the bone marrow chimeras. We propose that remotely produced, rather than the endogenously expressed, ST6Gal-1 is the principal modifier of HSPC glycans for α2,6-sialic acids. In so doing, liver-produced ST6Gal-1 may be a potent systemic regulator of hematopoiesis.

Application of LC-MS/MS in Identification of Toxin in the Causative Gastropod and Victim Samples

Food paralytic poisoning incident was detected in the gastropod Nassariidae Niotha clathrata and Zeuxis scalaris occurred in December 2012 in Kaohsiung, Taiwan. The toxin was purified from each remain of cooked gastropod and victim tissues by ultrafiltration using a YM-3 membrane, followed by C18 cartridge column purification. Based on analyses by LC-MS/MS, the causative agent of gastropod food poisoning was identified as tetrodotoxin. The toxicity of remain of cooked sample was 245 MU/g (1MU = 0.178 μg TTX) for N. clathrata and 203 MU/g for Z. scalaris. The blood and excrements of victim was shown to contain TTX of 0.13 and 0.18 μg/g, respectively. There was positive between results from LC-MS/MS and mouse bioassay in the causative gastropod. The LC-MS/MS method is suitable for rapid screening of TTX.

Therapeutic drug monitoring of tacrolimus by liquid chromatography–tandem mass spectrometry: Is it truly a routine test?

Therapeutic drug monitoring of tacrolimus by high-performance liquid chromatography–tandem mass spectrometry has become standard practice. We report on the long-term (4.5 years) use of one such method. Whole blood samples (25μL) were treated with zinc sulphate (100μL) and acetonitrile containing ascomycin (internal standard, 250μL). A high-performance liquid chromatography–tandem mass spectrometer operating in positive ion mode with an electrospray interface was used. Chromatography was performed on a TDM C18 cartridge column (10mm×2.1mm, 10μm, Waters) using a switch gradient. A total of 4029 batches were analyzed for tacrolimus; this comprised of 81950 analyses of which 61027 were patient samples. Calibration curves (1.0–50μg/L) were run on 1765 occasions (mean r2=0.999; range r2=0.988–0.999). Inter-batch accuracy and imprecision of the method (2.5, 12.5 and 30.0μg/L), when in routine use, was 97.6–98.5% and <8.0%, respectively (n=4031). Evaluation of the method against other methods in an external quality control scheme revealed good agreement by linear regression analysis (y=0.924x+0.196, r2=0.985). The percentage difference between our results and that of all methods revealed a mean bias of −6.3% and a range of −33.3% to 11.1%. During the evaluation period, four batch failures occurred (0.1% failure rate) and greater than 1000 samples per analytical column was achieved. In conclusion, the described method is ideally suited as a routine test for tacrolimus in the clinical setting.

Analytical Method of Clofencet in Animal Fishery Products by LC/MS

A method for the determination of clofencet in animal and fishery products was developed, using liquid chromatography with electrospray ionization mass spectrometry (LC/ESI-MS). The sample was homogenized with water and hexane, and the homogenate was extracted with acetonitrile, then acetonitrile-water (4 : 1). An aliquot of the crude extract was passed through a C18 cartridge column (1,000 mg), and the eluate was concentrated. A solution of 10% sodium chloride and 1% sodium hydrogen carbonate, and ethyl acetate were added to the residue, and the mixture was shaken. After shaking, the aqueous phase was recovered and acidified with hydrochloric acid, and then clofencet was extracted with ethyl acetate. The extract was evaporated to dryness and the residue was dissolved in methanol-water (3 : 7). Clofencet was analyzed by LC/MS. The recoveries of clofencet from ten kinds of animal and fishery products were 77.8-97.8%, and the relative standard deviations were 0.6-5.8% (n=5). S/N of the peak of clofencet was >10 and no interfering peak was found in animal and fishery products fortified at 0.01 mg/kg.

Bacillus horikoshii, a tetrodotoxin-producing bacterium isolated from the liver of puffer fish

A bacterium S184 isolated from the liver of puffer fish was found to produce tetrodotoxin (TTX). The toxin was purified from the cultures by activated charcoal column and C18 cartridge column after being cultured at 28 °C in broth medium. The results of toxicity mouse bioassay, liquid chromatography/fluorescent detection (LC/FLD), liquid chromatography/mass spectrometry (LC/MS), liquid chromatography/tandem mass spectrometry (LC/MS/MS) suggested that the strain could produce TTX during cultivation. The strain was identified asBacillus horikoshii according to its physiological-biochemical characteristics and phylogenetic analysis based on 16S rDNA sequences.

Simple Multiresidue Method for Monitoring of Trimethoprim and Sulfonamide Residues in Buffalo Meat by High-Performance Liquid Chromatography

A simple, specific, and rapid analytical method for the determination of trimethoprim (TMP) and three sulfonamide (SA) antimicrobial drug residues in buffalo meat is developed and validated. This method is based on a solid-phase extraction technique followed by high-performance liquid chromatography (HPLC)-photodiode array (PDA) detection. Target compounds were extracted from the meat by acetonitrile and water, cleaned up on a Bond Elute C 18 cartridge column, and separated on a RP-C 18 column during HPLC analysis. Acetonitrile along with water appears to be an excellent extractant as recovery of the analytes at maximum residues levels (MRLs) in spiked sample was in the range of 75-108%, with coefficient of variations (CVs) ranging between 1.34 and 22%. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.031 and 0.062 microg/g, respectively, for all of the compounds. Intra- and interday assay precisions of the method at 0.125 microg/g concentrations for any drug ranged between 3 and 4%. The linearities of the TMP, sulfadimidine (SDM), sulfadoxine (SDO), and sulfamethoxazole (SMX) were 0.9989, 0.9999, 0.9998, and 0.9997, respectively. For robustness, the analytical method was applied to 122 buffalo meat samples obtained from export meat processing plants.

Determination of Theaflavins Including Methylated Theaflavins in Black Tea Leaves by Solid-Phase Extraction and HPLC Analysis

A quantitative method for four theaflavins and two methylated theaflavin derivatives in black tea leaves was developed by solid-phase extraction and a high-performance liquid chromatographic method with photodiode array detection. The theaflavins in black tea leaves were extracted three times with 40 vol 50% aqueous ethanol (mg dry tea powder/mL) containing 2% ascorbic acid. The ethanol extracts were diluted 4-fold with distilled water. All diluted extracts were directly applied to the solid-phase C18 cartridge column without concentration. The fraction of theaflavins was obtained by 40% ethanol extraction after rinsing with water followed with 15% ethanol extraction. An aliquot of theaflavins after concentration was injected onto an ODS C18 reversed-phase column, and four theaflavins and two methylated theaflavins were sufficiently separated by a linear gradient system using distilled water and acetonitrile with 0.5% acetic acid. This analytical method is sensitive for the determination of a small amount of methylated theaflavins, since various interfering substances produced during the fermentation process were eliminated in advance by solid-phase extraction. Using this analytical method, we also demonstrated that methylated theaflavins were easily produced during the manufacture of black tea.

Antihyperglycemic Effect of Polyphenols from Acerola (Malpighia emarginataDC.) Fruit

A crude acerola polyphenol fraction (C-AP) was prepared by subjecting an acerola extract to a C18 cartridge column, and eluting the adsorbed fraction with ethanol containing 10% of acetic acid. C-AP appeared in a previous study to have an inhibitory effect on alpha-glucosidase and particularly on maltase activities. To elucidate the antihyperglycemic effect of C-AP further, we examined the regulation by C-AP of glucose uptake in Caco-2 cell; this resulted in the inhibition of glucose uptake. We next conducted single administration tests of glucose and maltose to ICR mice to investigate whether C-AP really controlled the intestinal glucose absorption in an animal body. The results showed that C-AP significantly suppressed the plasma glucose level after administering both glucose and maltose, suggesting that C-AP had a preventive effect on hyperglycemia in the postprandial state. The mechanism for this effect is considered to have been both suppression of the intestinal glucose transport and the inhibition of alpha-glucosidase. Despite such a preventive effect, the therapeutic effect of C-AP on hyperglycemia appeared to be low from the experiment with KKAy mice.

Determination of Glycoalcaloids in Hungarian Potatoes by HPLC

In this work potato genotypes originated from an intensive resistance breeding programme that includes unique combination of resistance to several pathogens and consumer response were analysed for glycoalcaloid content by reversed phase high performance liquid chromatographic method. The glycoalcaloids were concentrated from potato samples by solid-phase extraction with a disposable C18 cartridge column. Nucleosil 100-5 C-18-AB column was used with 50% acetonitrile in phosphate buffer as the mobile phase. The method was validated according to calibration curve, precision and recovery tests, limit of detection and quantitation. The results indicated that as low as 0.27 µg mL−1 can be quantitatively determined by this method with 94–98% and 99% for recovery and precision, respectively. Hungarian potatoes were analysed by the adapted procedure for their glycoalcaloid content. The result showed that the tested Hungarian potato varieties contain glycoalcaloids between 0.09 and 15 mg 100 g−1. The content of glycoalcaloids in the new varieties of potato was lower than the limit of the Official Food Regulations.

Determination of tetrodotoxin in human urine and blood using C18 cartridge column, ultrafiltration and LC–MS

Six fishermen were victims (including one death) of food poisoning from unknown fish on their boat in central Taiwan Strait, in April 2001. The symptoms were like those of tetrodotoxin (TTX) poisoning. As there was no remaining fish, a new protocol was developed to determine TTX in the urine and blood of the victims. The urine and blood samples were cleansed using a C18 Sep-Pak cartridge column, and the toxin was extracted by methanol. The eluate was filtered through a microcentrifuge filter. The filtrate was freeze-dried, dissolved in distilled water, and determined by LC-MS. The recovery was more than 88.9%. The detection limit was 15.6 nM. A linear relationship between response and concentration was obtained between 93.75 and 9375 nM of TTX. It was shown that the urine and blood of the victims contained TTX. The range of TTX was 4.5-40.6 nM in blood and 47-344 nM in urine. Judging from the symptoms of the victims and the experimental data, the causative agent of the food poisoning was identified as TTX.

酵素分解を用いたα‐グルコシルトランスフェラーゼ処理ステビア（酵素処理ステビア）製品の成分分析法

We have developed an analytical method for components of alpha-glucosyltransferase-treated stevia, a food additive product. Suitable conditions to separate additional sugar from alpha-glucosyltransferase-treated stevia by using glucoamylase were found (55 degrees C for 3 hr with 250 U of glucoamylase in 10 mL of reaction solution). By solid-phase extraction using a C18 cartridge column, polysaccharides were excluded from the sample, and the glycosides and sugar obtained after hydrolysis with glucoamylase were separated on another C18 cartridge column. The glycosides and sugar contents were determined by HPLC. By this method, additional sugar was detected in all of three product samples tested and the sugar was glucose. The contents of glucose and total glycosides (minus unreacted glycoside) were 25-42% and 35.7-52.5%, respectively. In alpha-glucosyltransferase-treated stevia, the sum of total glycosides and glucose amounted to 77.5-80.4% of the total and their recoveries from samples from which polysaccharide had been excluded by C18 cartridge column processing were over 85%. The contents of alpha-glucosyltransferase-treated stevia obtained by multiplying the sugar content by the coefficient (0.9) for hydrolysis and converting on dry weight basis were all over 80.0% and met the standard set by the Japan Food Additives Association.

Quantification of Indole-3-Acetic Acid and Amino Acid Conjugates in Rice by Liquid Chromatography–Electrospray Ionization–Tandem Mass Spectrometry

A method for quantifying indole-3-acetic acid (IAA) and its conjugates with the six amino acids, Ala, -Asp, -Ile, -Glu, -Phe and -Val, in rice (Oryza sativa) by using high-performance liquid chromatography coupled with electrospray ionization and tandem mass spectrometry (HPLC-ESI-MS/MS) is described. Samples from the rice plant or callus were treated with 80% acetone in water containing 2.5 mM diethyl dithiocarbamate. Each extract was partially purified in C18 cartridge column for solid-phase extraction (SPE) and subjected to HPLC-ESI-MS/MS without converting the product. The detection limit was 3.8 fmol for IAA, and 0.4-2.9 fmol for the IAA amino acid conjugates. The method was applied to the analysis of IAA and its conjugates in rice seedlings, dehulled rice and calli, using 20-100 mg tissue samples.

Development of hemolymph prostaglandins assay systems and their concentration variations during ovarian maturation in the kuruma prawn, Penaeus japonicus

Abstract Hemolymph prostaglandin (PGF2α and PGE2) measurement systems for the kuruma prawn Penaeus japonicus were developed and validated. In these systems, both PGF2α and PGE2 in hemolymph obtained from a single prawn were measured. PGs were extracted through reverse-phase C18 cartridge column, separated for isomers of each PG by high-performance liquid chromatography (HPLC), and quantified with a radioimmunoassay (RIA). Detectable range was 6.5–200 and 26–400 pg/tube for the PGF2α and PGE2 assays, respectively. Serial dilution of extracted and separated hemolymph PGs (RIA sample) produced a curve parallel to the standard curves in both assays. These assays were able to measure PGs in the RIA samples spiked with the authentic standard. Overall, results indicate that the presently established assay systems can accurately measure hemolymph PGs in female kuruma prawns. When hemolymph PGF2α and PGE2 levels were determined and plotted against the gonado-somatic index (GSI), no correlation was found in either PGs. In terms of ovarian developmental stages, however, the concentration of PGF2α significantly increased from 66.7 pg/ml at stage I (previtellogenic stage) to 303 pg/ml at stage II (primary vitellogenic stage) and decreased gradually thereafter. The concentration of PGE2 also increased markedly (4037.7 pg/ml) at stage II and decreased at stage III (secondary vitellogenesis stage). These results indicate that PGs vary in concentration during ovarian development in kuruma prawns.

Determination of bisphenol A in foods using GC/MS

An analytical method using GC/MS was developed for bisphenol A (BPA) in foods and BPA was determined in canned foods and fresh foods such as vegetables, fruit and meat. BPA was extracted with acetone from the samples and the extract was concentrated at under 40 degrees C in vacuo to afford an aqueous solution, which was washed with hexane after alkalization and extracted with 50% diethyl ether-hexane after acidification. Extracts were cleaned up on a PSA and/or a C18 cartridge column, and BPA was derivatized with heptafluorobutyric anhydride and determined by GC/MS (SIM). This method was applicable to the detection and determination of BPA residues in food samples at the level of 1 ng/g. Among canned foods, BPA was found in 6 corned beef, 1 chicken, 9 sweet corn and 3 bean samples at the levels of 17-602 ng/g, 212 ng/g, 2.3-75 ng/g and 3.5-26 ng/g, respectively. BPA was also detected in 1 retort soup and 1 retort pack product at the levels of 11 ng/g and 86 ng/g, respectively. As for dairy products, BPA was not detected in butter and milk. Among fresh foods, BPA was detected in 2 fish and 3 liver samples at the levels of trace (tr)-6.2 ng/g and tr-2.2 ng/g, respectively. In vegetables, fruits and chocolates, a trace level of BPA was detected in only 1 chocolate. Traces of BPA were also detected in 3 samples of 6 boxed lunches.