Quantitative analysis of iodine and bromine in soil using an energy-dispersive X-ray fluorescence spectrometer with three-dimensional polarized optics

A nondestructive and simple method for the determination of bromine and iodine in soil was investigated using an energy-dispersive X-ray fluorescence spectrometer equipped with three-dimensional polarized optics. Using a gadolinium X-ray tube and Mo and Al2O3 as optimal secondary target materials, K-lines were detected for bromine and iodine. The minimum detection limits for bromine and iodine were calculated using JSAC0411, a certified reference material of soil for metal composition analysis, and were 0.77 mg/kg for bromine and 2.3 mg/kg for iodine at a measurement time of 600 s. The results of the determination of bromine and iodine in soil samples by the standard addition method were 256 ± 8 mg/kg for iodine and 67.9 ± 1.3 mg/kg for bromine with JSAC0411, which were in close agreement with the results measured by inductively coupled plasma mass spectrometry (ICP-MS) after alkaline extraction with tetramethylammonium hydroxide (TMAH) solution. The method developed in this study is an excellent technique for direct analysis of soil by X-ray fluorescence analysis without any pretreatment such as alkaline extraction. It is expected to be a practical analytical method for elucidating the dynamics of bromine and iodine in agricultural land and soil.

Quantification of risperidone and paliperidone by liquid chromatography-tandem mass spectrometry in biological fluids and solid tissues obtained from two deceased using the standard addition method

Risperidone (RIS) is an atypical antipsychotic agent and its 9-hydroxylated metabolite named paliperidone (PAL) also has pharmacological properties similar to that of RIS. Quantifications of RIS and PAL in authentic human biological fluids and solid tissues by liquid chromatography (LC)-tandem mass spectrometry (MS/MS) have not been reported yet although those in plasma (and blood) were reported abundantly. In the present work, a quantification method for RIS and PAL based on the standard addition method was devised and validated for the human fluid and solid tissue specimens. RIS and PAL in biological fluids were quantified only after their dilution and deproteinization. The concentrations of RIS and PAL in the heart whole blood, pericardial fluid, stomach contents, bile, urine, liver, kidney and cerebrum were determined for a deceased who had been treated with RIS therapeutically, and also a deceased who had ingested RIS with other drugs intentionally. To our knowledge, this is the first report on the quantification of RIS and PAL by LC-MS/MS in the authentic human tissues and biological fluids.

Fluorescence-based absolute quantification of near-infrared probes in tissue extracts for biodistribution analyses

In recent years, significant progress has been made in the development of fluorescent contrast agents for clinical applications. For the development of a fluorescent probe, it is crucial to evaluate its safety profile, including biodistribution. Specific methods need to be developed for the absolute quantification of fluorescent probes in tissue specimens from animals administered with test compounds in the framework of biodistribution/efficacy/toxicity studies. Here, we describe a new method for the absolute quantification of fluorescent probes in tissue specimens from animals administered with compounds that have absorption and emission wavelength in the Near-Infrared region (600-800 nm). The protocol is based on the standard addition approach in order to minimize the interference of the matrix on the analyte signal causing inaccuracy in the absolute determination of the concentration. The measurement of the fluorescence intensity is done via a microplate reader. The method has been fully validated and applied for the quantification of a fluorescence-guided surgery targeted contrast agent in a Good Laboratory Practice (GLP) biodistribution study. Results clearly demonstrate that this procedure is fully applicable in a preclinical setting and that it overcomes common issues associated with fluorescence signal quantification in tissue extracts.

Development and validation of HS-SPME-GCMS/MS method for quantification of 2-acetyl-1-pyrroline in rice cultivars

The commercial significance of accurate and simple quantification of 2-Acetyl-1-pyrroline (2-AP) cannot be overstated. Present study was carried out to standardize a method for extraction and accurate quantitation of 2-AP from rice grain using GC-MS/MS equipped with HS-SPME auto sampler. The effect of sample quantity, addition of solvent, grinding process, sample particle size, head space parameters and SPME fiber incubation parameters, were optimized in the developed method. Dehusked rice powder (2 g) prepared under liquid nitrogen, and passed through the 80-mesh sieve, incubated for 40 min at 80 °C in headspace, followed by fiber (DVB/Carbon WR/PDMS) saturation time of 15 min, could produce the maximum response. The recovery of 2-AP from fortified sample ranged between 7.02 and 9.02% at 50-200 ng g-1 fortification irrespective of the grain matrices used. Standard addition method was appropriate to overcome the matrix effect and recovery of 2-AP was more than 90% using this method. The developed method was further utilized for quantification of 2-AP in four Basmati and two non-Basmati aromatic rice samples. The content of 2-AP ranged between 57.17 and 147.10 ng g-1 of rice and varied with geographical location. This fully automated method could improve the work efficiency and reduce error during the volatile extraction and adsorption phase.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05674-7.

Role of silver nanoparticles in fluorimetric determination of urea in urine samples

Herein, an economical, analytical and sensitive method was established for the fluorometric determination of urea using freshly prepared silver nanoparticles (Ag-NPs) in real urine samples. The standard addition and second-order derivative methods were selected for the ongoing research work to eliminate the possible effect of interferences in a real environment. In this work, Ag-NPs were prepared by reducing silver nitrate salt in the presence of 1,3-di-(1H-imidazole-1-yl) -2-propanol (DIPO) in an aqueous medium. Urea in the urine samples was successfully determined through the complexation of Ag-NPs with urea molecules. The results revealed high percent recovery with ± RSD of urea in the three different urine samples, where percent recoveries by spectrofluorometric standard addition were 99.77 ± 3.4, 100.24 ± 5.1, 100.93 ± 2.8 and that is by the spectrofluorometric second-order derivative method were 103.57 ± 2.4, 101.8 ± 1.3, 98 ± 3.2, respectively. The successful application of these analytical methods in the spectrofluorometric determination of urea in urine samples can accumulate further addition in the effects and possible role of Ag-NPs in the determination of biological molecules in biological and non-biological samples in the scientific as well as clinical fields.

LC-MS/MS method for rapid and accurate detection of caffeine in a suspected overdose case

Excessive intake of caffeine, otherwise known to be a safe and mild central nervous system stimulant, causes nausea, vomiting, convulsions, tachycardia, and eventually fatal arrhythmias and death. Caffeine intoxication, a global problem, has been increasing in Japan since 2013. Thus, there is a need for rapid and accurate diagnosis of caffeine poisoning in forensic and clinical toxicology investigations. Herein, we demonstrate rapid and accurate caffeine quantitation by liquid chromatography tandem mass spectrometry using the standard addition method in a fatal case. Biological samples were diluted 500-100,000-fold and subjected to a simple pretreatment (adding caffeine standard and internal standard and passing through a lipid removal cartridge). The multiple reaction monitoring transitions were 195 → 138 for quantitation, 195 → 110 for the qualifier ion, and 204 → 144 for the internal standard (caffeine-d9). The standard plots were linear over 0-900 ng/mL (r² = 0.9994-0.9999) for biological samples, and the reproducibility (%RSD) of the method was 1.53-6.97% (intraday) and 1.59-10.4% (interday). Fatal levels of caffeine (332 μg/mL) and toxic to fatal levels of olanzapine (625 ng/mL), along with other pharmaceuticals were detected in the external iliac venous blood. The cause of death was determined to be multi-drug poisoning, predominantly caused by caffeine. Our method is useful for not only forensic cases but also the rapid diagnosis of caffeine overdose in emergency clinical settings.

Postmortem distribution/redistribution of buformin in body fluids and solid tissues in an autopsy case using liquid chromatography-tandem mass spectrometry with QuEChERS extraction method

An autopsy for a suicidal case of a male in his 40s, who had died of poisoning due to ingestion of a large amount of buformin, was performed at our department. Buformin is biganide class agent used for patients of diabetes mellitus, which can occasionally cause severe lactic acidosis. The autopsy was performed about 10 days after his death, and the direct cause of his death was judged as asphyxia due to the aspiration of stomach contents into the airway. The nine body fluids and eight solid tissues specimens were dealt with for investigating postmortem distribution/redistribution of buformin in a whole body; femoral vein blood, right and left heart blood, pericardial fluid, urine, bile, stomach contents, small intestine contents, cerebrospinal fluid, the brain, lung, heart muscle, liver, spleen, kidney and skeletal muscle were examined. For extracting buformin from specimens, a modified QuEChERS method including dispersive solid-phase extraction was employed, followed by the analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS). Buformin in various kinds of human matrices were quantified by the standard addition method in this study, which can overcome the matrix effects and recovery rates without use of blank human matrices. All concentrations of buformin in specimens examined in this case were extremely higher than those of previously reported poisoning cases. The concentrations of buformin in left and right heart blood and femoral vein blood specimens of this case were 399, 216 and 261μg/mL, respectively; although the direct cause of his death was judged as asphyxia due to occlusion of airway with stomach contents, the vomiting was thought to be provoked by buformin poisoning. In this study, marked differences of buformin concentrations between brain tissue and cerebral spiral fluids, and other specimens were observed, which suggested that its distribution was influenced also by blood-brain-barrier. Although a number of buformin poisoning cases were published so far, they gave sporadic data on its concentrations and/or distribution in some limited human specimens. This study is the first to describe detailed distribution/redistribution of buformin in a whole human body quantified by using LC-MS/MS.

Characterization of scallop midgut gland certified reference material for quantification of diarrhetic shellfish toxins

A scallop midgut gland certified reference material, NMIJ CRM 7520-a, was developed for validation and quality assurance during the inspection of shellfish for diarrhetic shellfish toxins. The candidate material was prepared by using naturally-toxic and nontoxic boiled midgut glands spiked with okadaic acid (OA). The homogeneity and stability of the material were found to be appropriate. For the characterization of OA and dinophysistoxin-1 (DTX1), nine participants were involved in a co-laboratory study based on the Japanese Official Testing Method, where the compounds were assayed by liquid chromatography-tandem mass spectrometry following alkaline hydrolysis. The analytical values were obtained by the standard addition method with a standard spiking solution calibrated using the standard-solution certified reference materials OA and DTX1. The certified concentrations with expanded uncertainties (coverage factor k = 2, approximate 95% confidence interval) were determined to be (0.205 ± 0.061) mg/kg for OA and (0.45 ± 0.11) mg/kg for DTX1.

A standard addition method to quantify histamine by reductive amination and hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry

Histamine is an organic nitrogenous compound that acts as a neurotransmitter in the uterus, spinal cord, and brain and is involved in local immune responses. In this study, we developed a fast and simple derivatization method based on reductive amination that can be used to quantify histamine by hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry. Histamine isotope analogs were synthesized via reductive amination. Histamine was modified with H₂-formaldehyde to form N-dimethylated histamine to act as a standard or with D₂-formaldehyde to form N-dimethylated histamine-d₄ to act as an internal standard. Using this method, we achieved a limit of detection of 3.6 ng/mL, a limit of quantification of 7.9 ng/mL, and a linear calibration curve with a coefficient of determination (R²) of 0.9987. Furthermore, the intra-day relative standard deviations ranged from 0.9% to 3.7% and the inter-day relative standard deviations ranged from 2.0% to 17.6%. After derivatization, N-dimethylated histamine showed 382.5% signal enhancement compared to unmodified histamine in mass spectrometry detection. To demonstrate the applicability of this method for biological samples, we utilized standard addition method to quantify histamine in fetal bovine serum and achieved a recovery of 86.7%.

Quantification of karrikins in smoke water using ultra-high performance liquid chromatography-tandem mass spectrometry

BACKGROUND

Karrikins (KARs) are plant growth regulators that promote seed germination and the subsequent growth and development of seedlings of many plant species. In nature they are generated and released by combustion of plant material and promote the restoration of burned ecosystems. Smoke water can be artificially prepared as a saturated extract of all substances in smoke produced by burning plants, and it has various horticultural and agricultural applications.

RESULTS

We have developed, validated and applied the first fast, specific and sensitive method, based on ultra-high performance liquid chromatography-tandem mass spectrometry, for quantifying KARs in smoke water. To assist these efforts and further analyses, standards of the main KARs (which are not commercially available) were synthesized. Due to the complex matrix of smoke waters, two quantification approaches (standard dilution with a structural KAR analogue and standard addition) were compared. The standard addition method allowed absolute quantification of KARs in six of eight smoke water samples of diverse origins and ages.

CONCLUSIONS

Our findings reveal differences in both total and relative levels of KARs in smoke water, and indicate that differences in its KAR composition may be linked to variations in its bioactivity.

Postmortem distribution of mepirapim and acetyl fentanyl in biological fluid and solid tissue specimens measured by the standard addition method

Purpose

Mepirapim is a new synthetic cannabinoid. We previously reported that the concentrations of unchanged mepirapim in whole blood and urine were much higher than those of other synthetic cannabinoids. To determine the postmortem distribution of mepirapim and acetyl fentanyl in the deceased individual, we established a standard addition method for detailed analysis by liquid chromatography–mass spectrometry (LC–MS) for quantification of these drugs.

Methods

The LC–MS method was fully validated for linearity, extraction recovery, matrix effect and repeatability.

Results

Good linearities, extraction recoveries, matrix effects and repeatabilities were shown for both target compounds in all specimens. The concentrations of mepirapim and acetyl fentanyl in three body fluid specimens and 12 solid tissue specimens were measured. For mepirapim, the highest concentrations were found in the liver and kidney, and the concentrations in the blood and urine specimens were one order of magnitude lower than the high concentrations in the solid tissues except the psoas major muscle. For acetyl fentanyl, the highest concentrations were found in the myocardium, spleen and kidney, and the concentrations in the body fluid specimens were also one order of magnitude lower than the highest concentrations in the solid tissues. There were concentration differences of mepirapim and acetyl fentanyl among the regions of the brain.

Conclusions

The concentration of unchanged mepirapim in urine was much higher than those of other synthetic cannabinoids; the higher dosage, urinary excretion, metabolisms and/or pharmacokinetics of mepirapim may be quite different from those of other synthetic cannabinoids.

Surface-enhanced Raman spectroscopy and MCR-ALS for the selective sensing of urinary adenosine on filter paper

Adenosine is a purine nucleoside that is present in all human cells and is essential for regulating certain physiological activities in tissues and organs. Since adenosine is considered to be a potential cancer biomarker in urine, its determination may be crucial for the early diagnosis and non-invasive monitoring of cancer. Herein, we present a label-free method to quantify urinary adenosine using surface-enhanced Raman spectroscopy (SERS) and multivariate curve resolution-alternating least squares (MCR-ALS). Ring-oven preconcentration and direct deposition of monodisperse gold nanoparticles on filter paper were employed to improve the sampling efficiency. Further, MCR-ALS (assessed with and without a correlation constraint), the standard addition method and pH controls were combined to compensate for the matrix effect and to address overlapping bands in the analysis of human urine samples. As a result, the proposed method showed to be sensitive (LOD varying between 3.8 and 4.9 µmol L^-1, S/R = 3), reproducible (RSD less than ± 15%), and selective over other nucleosides (guanosine, cytidine, thymidine and uridine) and unknown interferences (second-order advantage). This is the first report of a SERS-chemometric method applied to urinary adenosine sensing at physiologically relevant concentrations, with minimal sample preparation, and has strong potential to be a valuable tool in cancer research.

Spectrophotometric methods for the determination of urea in real samples using silver nanoparticles by standard addition and 2nd order derivative methods

In this work, we have developed simple, sensitive and inexpensive methods for the spectrophotometric determination of urea in urine samples using silver nanoparticles (AgNPs). The standard addition and 2nd order derivative methods were adopted for this purpose. AgNPs were prepared by chemical reduction of AgNO₃ with hydrazine using 1,3-di-(1H-imidazol-1-yl)-2-propanol (DIPO) as a stabilizing agent in aqueous medium. The proposed methods were based on the complexation of AgNPs with urea. Using this concept, urea in the urine samples was successfully determined spectrophotometric methods. The results showed high percent recovery with ±RSD. The recoveries of urea in the three urine samples by spectrophotometric standard addition were 99.2%±5.37, 96.3%±4.49, 104.88%±4.99 and that of spectrophotometric 2nd order derivative method were 115.3%±5.2, 103.4%±2.6, 105.93%±0.76. The results show that these methods can open doors for a potential role of AgNPs in the clinical determination of urea in urine, blood, biological, non-biological fluids.

Alternate injections coupled with flow-gated capillary electrophoresis for rapid and accurate quantitative analysis of urine samples

Capillary electrophoresis (CE) is a powerful separation technique with advantages over HPLC in terms of separation efficiency, speed, and cost. However, CE suffers in poor reproducibility in quantitative chemical analysis, which is one of major drawbacks preventing its widespread use in routine analytical laboratories. Here we report a novel strategy to enhance the quantitative capability of flow-gated CE. The platform integrated dual flow branches to respectively supply a sample and its standard additions that were then alternately injected into a single capillary for rapid separations (typically 20-90 s). A micro-fabricated switch was used to enable the alternate injections. It was assumed that the analytical system maintained constant conditions during neighboring injections that served as external self-standards for quantitation. This strategy was expected to reduce uncertainties caused by the fluctuation in capillary conditions and the drift of detection systems. Experimental results demonstrated that the dual-branch flow-gated CE coupled with alternate injections significantly improved the reproducibility with respect to peak height ratios under deliberate variations in injection volumes, separation voltages, optical focusing, and laser power; and thus the interday precision was ensured. To demonstrate its applicability, cyanide and amino acids in human urine were quantified rapidly with the one-point standard addition method after fluorogenic derivatization with naphthalene-2,3-dicarboxaldehyde (NDA), and the measurement accuracy was validated by determining the recovery of standard cyanide added to a urinary matrix. This strategy would be valuable to enable the quantitative capability of flow-gated CE in the measurements of a broad range of analytes, especially those lacking suited internal standards.

Enhancement of human plasma glucosylceramide assay sensitivity using delipidized plasma

Glucosylceramide (GL-1) level in human has been considered as a surrogate biomarker for enzyme replacement and substrate reduction therapies (ERT and SRT) for Gaucher and Fabry patients. Due to the high endogenous level of GL-1 in human plasma, it is difficult to achieve the analytical sensitivity of plasma GL-1 below the normal endogenous level (1.7 μg/mL to 6.6 μg/mL) when using the standard addition method and regular plasma matrix for standard curve. A high sensitivity plasma GL-1 assay with LLOQ at 0.1 μg/mL was developed and validated using delipidized plasma so that patient plasma concentrations that are below normal reference range can be measured accurately. The normal reference range was established from 120 healthy donors using this developed new method. Twenty-three Fabry patient plasma samples including baseline and post-investigation drug treatment samples were measured. All post-treatment samples showed GL-1 concentration below 2.0 μg/mL, indicating the utility of the reported high sensitivity assay using delipidized plasma for monitoring the plasma GL-1 biomarker level in patients.

A Simple Spectrofluorimetric Method Based on Quenching of a Nickel(II)-Phthalocyanine Complex to Determine Iron (III)

A new nickel(II)-phthalocyanine complex (NiPc) was synthesized and used as a fluorescent ligand in determination of iron in real samples. The NiPc compound, when excited at 350 nm, decreases of emission with increases of the iron(III) concentration at 425 nm were used analytical response in a modified standard addition method. The method was validated by analyzing two certified reference materials (CRM-SA-C Sandy Soil C and Mixed Polish Herbs (INCT-MPH-2). Food and drug samples were digested in a closed microwave system using nitric acid and hydrogen peroxide. Therefore, all iron in the samples converted to iron(III) ion. These solutions were used directly in determination of iron(III) ion. No cleanup or enrichment of the solutions was required. The calibration graph was linear until 14.00 μg mL(-1). Detection limit and quantification limit were 1.29 μg mL(-1) and 3.88 μg mL(-1), respectively. The method provided accurate results for the majority of the food samples tested, including spanich, dill, mint, purslane, rocket, red lentils, dry beans and two iron medicinal tablets. Also, the high recovery (95.6 %) was obtained for a fortified stream water sample. The simple and cost-effective method is suitable for monitoring total iron concentration in foods and drug samples.

Quantitative mass spectrometric analysis of dipeptides in protein hydrolysate by a TNBS derivatization-aided standard addition method

The aim of this study was to establish, through a standard addition method, a convenient quantification assay for dipeptides (GY, YG, SY, YS, and IY) in soybean hydrolysate using 2,4,6-trinitrobenzene sulfonate (TNBS) derivatization-aided LC-TOF-MS. Soybean hydrolysate samples (25.0 mg mL(-1)) spiked with target standards were subjected to TNBS derivatization. Under the optimal LC-MS conditions, five target dipeptides derivatized with TNBS were successfully detected. Examination of the standard addition curves, with a correlation coefficient of r(2) > 0.979, provided a reliable quantification of the target dipeptides, GY, YG, SY, YS, and IY, in soybean hydrolysate to be 424 ± 20, 184 ± 9, 2188 ± 199, 327 ± 16, and 2211 ± 133 μg g(-1) of hydrolysate, respectively. The proposed LC-MS assay is a reliable and convenient assay method, with no interference from matrix effects in hydrolysate, and with no requirement for the use of an isotope labeled internal standard.

Direct determination of acrylamide in food by gas chromatography with nitrogen chemiluminescence detection

A method of gas chromatography with nitrogen chemiluminescence detection and using standard addition is described for the determination of acrylamide in heat-processed foods. Using a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation method removes the acrylamide precursors completely, and the risk of overestimating acrylamide concentration due to additional analyte formation in the hot gas chromatograph inlet is also avoided. Sample preparation is rapid and inexpensive. A Deans switch device is utilized to heart-cut acrylamide and to prevent interferences from the solvent and matrix from reaching the detector. The pre-column is backflushed at high temperature to maintain a clean baseline and shorten the cycle time compared to baking out the column. Quantitation using standard addition is employed for compensation of potential variability in the acrylamide extraction efficiency in acetonitrile. The limit of detection and the limit of the quantification obtained for this method are 27 and 81 μg/kg, respectively, in food samples (equivalent to 3.5 and 10.6 μg/L in acetonitrile, respectively), and the linear range is 76-9697 μg/kg in food samples (equivalent to 10-1280 μg/L in acetonitrile) with an R(2) value of 0.9999.

Postmortem distribution of α-pyrrolidinobutiophenone in body fluids and solid tissues of a human cadaver

We experienced an autopsy case of a 21-year-old male Caucasian, in which the direct cause of his death was judged as subarachnoid hemorrhage. There was cerebral arteriovenous malformation, which seemed related to the subarachnoid hemorrhage. The postmortem interval was estimated to be about 2days. By our drug screening test using gas chromatography-mass spectrometry, we could identify α-pyrrolidinobutiophenone (α-PBP) in his urine specimen, which led us to investigate the postmortem distribution of α-PBP in this deceased. The specimens dealt with were right heart blood, left heart blood, femoral vein blood, cerebrospinal fluid, urine, stomach contents and five solid tissues. The extraction of α-PBP and α-pyrrolidinovalerophenone (α-PVP, internal standard) was performed by a modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method, followed by the analysis by liquid chromatography-tandem mass spectrometry. Because this study included various kinds of human matrices, we used the standard addition method to overcome the matrix effects. The highest concentration was found in urine, followed by stomach contents, the kidney, lung, spleen, pancreas and liver. The blood concentrations were about halves of those of the solid tissues. The high concentrations of α-PBP in urine and the kidney suggest that the drug tends to be rapidly excreted into urine via the kidney after its absorption into the blood stream. The urine specimen is of the best choice for analysis. This is the first report describing the postmortem distribution of α-PBP in a human to our knowledge.

Qualitative and quantitative electroanalysis of synthetic phenolic antioxidant mixtures in edible oils based on their acid-base properties

A simple electroanalytical method using square wave voltammetry at a Pt band ultramicroelectrode to perform a qualitative and quantitative analysis of different synthetic antioxidant mixtures permitted by official regulations in edible oils is proposed. The methodology was based on the comparison of voltammetric signals obtained in acetonitrile+0.1M (C4H9)4NF6P with those recorded in the same reaction medium when different aliquots of (C4H9)4NOH were added to allow a qualitative differentiation between antioxidants. Firstly, studies on solutions prepared from commercial reagents were carried out. Then, the results obtained were transferred to the analysis of a real matrix, i.e., an edible olive oil. From real samples spiked with a known amount of different synthetic antioxidant mixtures, we could deduce the presence of these antioxidants by comparing results obtained in the neutral medium with those obtained after the successive addition of base. The standard addition method was used to quantify the individually spiked synthetic antioxidants in the real sample. Recovery percentages were between 88% and 118%. The reproducibility was 1.5%, 3.1%, 4.1% and 4.1% in ACN+0.1M TBAHFP and 1.5%, 4.6%, 6.6% and 2.5% in Bz/EtOH (1:2)+0.1M H2SO4 for TBHQ, BHA, BHT and PG, respectively. The repeatability was 1% for PG in both media. These parameters show a good system performance.

Application of the standard addition method for the determination of acrylamide in heat-processed starchy foods by gas chromatography with electron capture detector

A gas chromatography electron capture detector (GC-ECD) using the standard addition method was developed for the determination of acrylamide in heat-processed foods. The method entails extraction of acrylamide with water, filtration, defatting with n-hexane, derivatization with hydrobromic acid and saturated bromine-water, and liquid-liquid extraction with ethyl acetate. The sample pretreatment required no SPE clean-up and concentration steps prior to injection. The final extract was analyzed by GC-ECD. The chromatographic analysis was performed on polar columns, e.g. Supelcowax-10 capillary column, and good retention and peak response of the analyte were achieved under the optimal conditions. The qualification of the analyte was by identifying the peak with same retention time as standard compound 2,3-DBPA and confirmed by GC-MS. GC-MS analysis confirmed that 2,3-DBPA was converted to 2-BPA nearly completely on the polar capillary column, whether or not treated with triethylamine. A four-point standard addition protocol was used to quantify acrylamide in food samples. The limit of detection (LOD) was estimated to be 0.6μg/kg on the basis of ECD technique. Validation and quantification results demonstrated that the method should be regarded as a low-cost, convenient, and reliable alternative for conventional investigation of acrylamide.