Determination of chlorinated methylthiobenzenes and their sulfoxides and sulfones in fish

A procedure was developed to determine chlorinated methylthiobenzenes and their respective sulfur oxidation products in fish. Perch samples fortified at the 0.1 ppm level with 2,4,5-trichloromethylthiobenzene, pentachloromethylthiobenzene, and their sulfoxides and sulfones were extracted and cleaned up using an adaptation of the official AOAC method for multiple residues of organochlorine pesticides. The Florisil column cleanup was modified; 200 mL 6% petroleum etherethyl ether eluted the methylthiobenzenes, 200 mL 50% PE-EE eluted the sulfones, and 200 mL EE eluted the sulfoxides. Recoveries determined by electron capture (ECD) gas chromatography (GC) were 75-101% for the methylthiobenzenes and their sulfones and 63-93% for the sulfoxides. Co-extracted materials in the Florisil eluates that interfered with the ECD/GC quantitation were removed by partitioning the sulfoxides and sulfones into sulfuric acid and by thin layer chromatography on silica gel, using methylene chloride-hexane (50 + 50) as the developing solvent. Seven fish samples containing residues of chlorinated benzenes or polychlorinated biphenyls (PCBs) were examined for chlorinated methylthiobenzenes, methylthio-PCBs, and their oxidation products by matching GC retention times obtained with the EC detector and a flame photometric detector operated in the sulfur mode. These analytes were not found in the fish samples above a detection level equivalent to 0.02 ppm 2,4,5-trichloromethylthiobenzene.     

Gas chromatographic determination of electron capture sensitive volatile industrial chemical residues in foods, using AOAC pesticide multiresidue extraction and cleanup procedures

Electron capture (EC) gas chromatographic (GC) parameters have been developed for determining some of the more volatile industrial chemicals that can be determined by the AOAC multiresidue method for organochlorine and organophosphorus pesticides with modified GC operating conditions. Retention times relative to pentachlorobenzene are reported for 143 industrial chemicals, pesticides, and related compounds on OV-101 GC columns at 130 degrees C. Also reported for most of the compounds are recoveries from fortified samples carried through the AOAC extraction and cleanup procedures for fatty and/or nonfatty foods, Florisil elution characteristics, and GC relative retention times on mixed OV-101 + OV-210 columns at 130 degrees C. Our laboratory has used the modified EC/GC parameters with the AOAC multiresidue extraction/cleanup procedures to determine many volatile halogenated industrial chemical contaminants in foods, chiefly in samples of fresh-water fish. Other modifications of the AOAC method are described to improve the tentative identification and quantitative measurement of these volatile residues.     

大连湾养殖海域有机氯农药污染研究

采用毛细管GC-ECD法测定了大连湾海域表层沉积物及表层、微表层海水中16种有机氯农药(OCP₁₆)的含量。结果表明,毛细管GC-ECD测定OCPs回收率高、响应因子变异系数小、检出限低,适合于海洋环境样品中OCPs测定。在大连湾海域沉积物和水体中对OCPs均有检出,但污染水平相对较低。表层海水中OCPs平均含量为4.52 ng/L,表层沉积物中OCPs平均含量为6.17 ng/g。大连湾各站位微表层海水OCPs含量显著高于表层水,显示微表层海水对OCPs有较强的富集作用,平均富集系数在5.1～15.4之间。     

Volatile Compounds in Five Starches

Volatile compounds in commercial wheat, corn, potato, waxy corn, and tapioca starches and in laboratory‐prepared wheat, corn, and potato starches were collected, separated, and identified by a purge and trap concentrator (P&T) interfaced to a gas chromatograph (GC) equipped with a Fourier transform infrared detector (FTIRD) and a mass selective detector (MSD). Hexanal was the most abundant compound in the corn and potato starches and in the laboratory‐prepared wheat starch as determined by total ion chromatogram (TIC) peak areas. Hexanal was the third most abundant compound in commercial wheat starch after 2‐ethyl‐1‐hexanol and benzaldehyde. Among the volatile organics, the level of aldehydes was the highest, followed by alcohols, ketones, benzenes, esters, and terpenes. Specific compounds identified, the majority of which appear to be degradation products of lipid peroxidation, include hexanal, heptanal, octanal, nonanal, decanal, benzaldehyde, 2‐propanone, 2‐propanol, 1‐butanol, 2‐ethyl‐1‐hexanol, methylbenzene, and tetradecane. Waxy corn starch, which released a substantially higher level of total volatiles than all other starches, contained large amounts of pentyl, 2‐methyl‐1‐butyl, benzyl, and isobornyl acetates; and citronella and 1,8‐cineole. Tapioca starch contained few volatiles but did contain an increased level of 2‐propanol. No alcohols occurred in the commercial corn starch. Terpene compounds were detected only in commercial potato, waxy corn, and tapioca starches. Many volatiles detected in wheat and corn starches also were detected in the kernels of their commercial samples.     

Halogenated phenols in water at forty Canadian potable water treatment facilities

Samples of raw and treated water were collected once in each of 3 seasons at 40 potable water treatment plants across Canada and were analyzed for phenol and 33 halogenated phenolic compounds including chlorophenols, bromophenols, bromochlorophenols, and chloroguaiacols. Eighteen of the compounds were not found at any treatment plant; phenol and each of the remaining halogenated phenols were found in at least 1 sample. Pentachlorophenol was the only halogenated phenolic compound found in more than 20% of the raw water samples in the fall and winter samples at levels up to 53 ng/L with mean values of 1.9 and 2.8 ng/L, respectively. No halogenated phenols were detected in raw water summer samples. The halogenated phenols found most frequently in treated water samples were 4-chloro-, 2,4-dichloro-, 2,4,6-trichloro-, and bromodichlorophenols. Mean values were less than 15 ng/L and maximum values seldom exceeded 100 ng/L. Most of the positive values for the treated water samples were found at 8 of the 40 treatment plants but no correlations could be found between halogenated phenol levels and raw water type, treatment process, or chemical dosages.     

Organochlorine pesticides and polychlorinated biphenyls in sediment and fish from Wetlands in the north central United States

Sediment samples collected in 1980-1982 from riverine and pothole wetlands at 17 locations in the north central United States were analyzed for organochlorine pesticides, certain of their metabolites, and polychlorinated biphenyls (PCBs). Concentrations were above minimum detection levels (5 ng/g of organochlorines and 20 ng/g of PCBs) in less than 4% of the samples taken. Fish samples taken at 9 of these 17 locations, and analyzed for the same compounds, showed a higher frequency of detectable contaminants. The most common compound found in fish was DDE, which was found in 51% of the samples at levels up to 512 ng/g. alpha-BHC was present at concentrations of 5 to 27 ng/g in 36% of the fish samples, and DDD was found at levels of 5 to 60 ng/g in 14%. Four other compounds, DDT, dieldrin, PCB, and trans-nonachlor, were detected in fish at relatively low concentrations in less than 10% of the samples. This survey, thus, indicated little contamination by organochlorine pesticides or PCBs in the wetland habitats of this region.     

Gas chromatographic analysis of histamine in mahi-mahi (Coryphaena hippurus)

Several authors have studied histamine using gas chromatography (GC) as a tool for quantitation, but the methods used were not always suitable depending on the kind of food. Problems frequently cited include incomplete histamine elution from the columns and peak tailing. Histamine is of interest because it is the factor common to all cases of scombroid poisoning, it has physiological and biological activity, and it is a chemical indicator of fish quality. In this study a modified GC method was used to quantify histamine in mahi-mahi (Coryphaena hippurus). Mean recovery was 67% for the GC method, compared with 90% for the AOAC fluorometric method. There was a 0.96 correlation of the GC histamine values with those of the AOAC fluorometric method. A temperature program, splitless/split injection, and analyte cleanup were essential for GC properties. Histamine retention time was 8.2 min. The method allowed peak height to be used for quantitation and simultaneous analysis of cadaverine and putrescine.     

Levels of 3,3',4,4'-tetrachloroazobenzene in diuron and linuron herbicide formulations

Levels of 3,3',4,4'-tetrachloroazobenzene (TCAB) were determined by capillary gas chromatography (GC) with electron-capture detection (ECD) in 25 samples of diuron and linuron formulations obtained from the Canadian market. Acidic aqueous methanol was used to retain urea herbicide and the neutral TCAB was allowed to partition into hexane. Silica gel was used for cleanup of the hexane extract, followed by GC/ECD determination. Recovery data obtained at 4 different spiking levels (i.e., 0.3, 0.1, 1.0, and 5.0 ppm) in linuron averaged 93, 86, 85, and 97%, respectively. For diuron, spiking was done at 0.5, 1.0, and 5.0 ppm levels and the corresponding average percent recoveries were 95, 101, and 104. The TCAB contamination level observed in diuron on a 100% active ingredient basis ranged from 0.15 to 3.38 ppm, whereas in linuron, it varied from 0.91 to 10.28 ppm.     

Distribution of bromophenols in species of marine algae from eastern Australia

Forty-nine species (87 samples) of marine macroalgae from eastern Australia were analyzed by GC/MS for the key seafood flavor components 2- and 4-bromophenol, 2,4- and 2,6-dibromophenol, and 2,4, 6-tribromophenol. All five bromophenols were found in 62% of samples, four in 32% of samples, and three in the remaining 6% of samples. 2, 4,6-Tribromophenol was found in all samples and, with few exceptions, was present in the highest concentrations. The total bromophenol content determined on a wet-weight basis varied widely across species from 0.9 ng/g in the green alga Codium fragile to 2590 ng/g in the red alga Pterocladiella capillacea. Species with the highest concentrations of bromophenols were all collected from sites exposed at low tide. The study demonstrates the wide occurrence of bromophenols in marine algae and provides a possible source of such compounds in fish that feed predominantly on ocean plants. The possible effect that dietary marine algae has on the flavor of omnivorous ocean fish is discussed.     

Determination of semivolatile compounds in Baltic herring (Clupea harengus membras) by supercritical fluid extraction-supercritical fluid chromatography-gas chromatography-mass spectrometry

The on-line supercritical fluid extraction-supercritical fluid chromatography-gas chromatography method was applied to the determination of volatile compounds of raw and baked Baltic herring (Clupea harengus membras). The analytes were extracted with supercritical carbon dioxide at 45 degrees C and 10 MPa pressure. After extraction, the volatiles and coeluted lipids were separated on-line using supercritical fluid chromatography and the volatile fraction was introduced directly into a gas chromatograph. In all, 30 compounds were identified from fish samples with mass spectrometry. The most abundant compounds in the fresh Baltic herrings were heptadecane and 1-heptadecene. When the fish were stored for 3-6 days at 6 degrees C, the total peak area of the volatiles began to increase and the proportions of short chain acids (acetic, propanoic, 2-methylpropanoic, and 3-methylbutanoic) also increased. After 8-9 days of storage, 3-methylbutanoic acid comprised about 36 and 40% of all volatiles in raw and baked herring, respectively.     

Cooking decreases observed perfluorinated compound concentrations in fish

Dietary intake is a major route of exposure to perfluorinated compounds (PFCs). Although fish and seafood contribute significantly to total dietary exposure to these compounds, there is uncertainty with respect to the effect of cooking on PFC concentrations in these foods. Eighteen fish species purchased from markets in Toronto, Mississauga, and Ottawa, Canada were analyzed for perfluorooctanesulfonamide (PFOSAs)-based fluorochemicals and perfluorinated acids (PFAs) in raw and cooked (baked, boiled, fried) samples. Of 17 analytes, perfluorooctanesulfonic acid (PFOS) was detected most frequently; concentrations ranged from 0.21 to 1.68 ng/g ww in raw and cooked samples. PFOSAs were detected only in scallops at concentrations ranging from 0.20 ng/g ww to 0.76 ng/g ww. Total concentrations of PFAs in samples were 0.21 to 9.20 ng/g ww, respectively, consistent with previous studies. All cooking methods reduced PFA concentrations. Baking appeared to be the most effective cooking method; after baking samples for 15 min at 163 C (325 degrees F), PFAs were not detected in any of the samples. The margin of exposures (MOE) between the toxicological points of reference and the dietary intake of perfluorocarboxylates (PFCAs) and PFOS in fish and seafood muscle tissue were greater than 4 orders of magnitude. This indicates that reducing consumption of fish muscle tissue is not warranted on the basis of PFC exposure concerns at the reported levels of contamination, even for high fish consuming populations.     

Identification of O,O-dialkyl-S-methylphosphorodithioate residues in fish

O,O-Dialkyl-S-methylphosphorodithioates were found in Mississippi River buffalo fish caught near several chemical plants and oil refineries in Hartford and Wood River, IL. These chemicals, which have not been previously recognized as environmental or food contaminants, were identified and quantitated by a procedure similar to the AOAC multiresidue method for organochlorine and organophosphorus pesticides, using gas chromatography (GC) with flame photometric detection (FPD). The key to their identification was a GC/FPD retention time pattern that was virtually the same as that for the diazomethane reaction products of a commercial zinc dialkyl dithiophosphate motor oil additive. GC/mass spectrometry (MS) showed that the compound producing the largest GC/FPD peak contained butoxy groups. The identification of this compound as O,O-di(2-methylpropyl)-S-methyl-phosphorodithioate (Compound C) was confirmed by GC/MS analysis by comparison with the authentic material. The buffalo fish contained 0.15 ppm Compound C and 0.5 ppm total O,O-dialkyl-S-methylphosphorodithioates. Subsequent analyses of fish from other areas showed that these contaminants were not limited to the Hartford-Wood River area. Lower residue levels of Compound C, ranging from 0.01 to 0.05 ppm, were found in fish from the Mississippi River at Sauget, IL, and from the Delaware River and Newark Bay in NJ.     

白洋淀鱼类体内多氯联苯积累特征及其毒性评价

针对持久性有机污染物在水生生物体内易于积累的特性,利用气相色谱与质谱联用技术（GC-MS）,检测了白洋淀8种鱼类体内多氯联苯（PCBs）含量,并分析了同系物组成特征。根据白洋淀鱼类检测到同系物情况,计算毒性当量（TEQ）并进行评价。白洋淀8种鱼类体内PCBs平均含量范围是55.85~1 485.74 ng.g-1脂肪重,从高到低的顺序依次为黄颡〉黄鳝〉乌鳢〉泥鳅〉鲤鱼〉鳙鱼〉鲫鱼〉鲇鱼。在8种鱼类PCB同系物组成中,四氯联苯和五氯联苯是主要的同系物,其相对百分含量为52.0%~84.3%。这种组成模式反映了白洋淀地区有多氯联苯工业品的使用历史。8种鱼类体内PCBs的毒性当量（TEQ）范围是0.09~1 412.87 pg TEQ.g-1脂肪重,其大小顺序依次为鳙鱼〉鲫鱼〉鲇鱼〉黄颡〉黄鳝〉鲤鱼〉乌鳢〉泥鳅。结果表明,白洋淀淀区部分鱼类已经受到PCBs一定程度的污染,应引起重视。     

Matrix solid-phase dispersion extraction and gas chromatographic determination of chloramphenicol in muscle tissue

A method based on matrix solid-phase dispersion (MSPD) was developed for the gas chromatographic (GC) determination of chloramphenicol (CAP) residues in animal muscle tissue. Muscle tissue was blended with octadecylsilyl-derivatized silica (C(18)). A column made from the C(18)/muscle tissue matrix was washed with n-hexane and acetonitrile/water (5 + 95), after which CAP was eluted with acetonitrile/water (50 + 50) and partitioned into ethyl acetate. The final extract was evaporated, and a trimethylsilyl derivative of CAP was prepared with Sylon HTP and detected by GC with an electron capture detector (ECD) and a mass spectrometer. For quantitation, the internal standard used was the meta isomer of CAP (m-CAP) for GC-ECD. Muscle tissue samples were fortified at three concentration levels. At 5, 10, and 15 microg/kg levels the respective mean recoveries were 93, 96, and 98%, and the repeatabilities were 13, 11, and 3%. The detection and quantitation limits with ECD were 1.6 and 4.0 microg/kg, respectively. No statistically significant difference was observed in the efficiency of CAP extraction from muscle tissue of various animals (bovine, porcine, and poultry) by the MSPD technique.     

Polycyclic Musks in Water, Sediment, and Fishes from the Upper Hudson River, New York, USA

Synthetic musks are used in many consumer products for their pleasant odor and their binding affinity for fabrics. In the early 1990s, polycyclic musks were reported to occur in air, water, sediment, wildlife, and humans from many European countries. Concentrations of polycyclic musks, particularly 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta-[??]-2-benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronapthalene (AHTN), have been reported to increase over time in the environment. In this study, concentrations of musks in water, sediment, fish, and mussel were determined from three locations along the upper Hudson River. HHCB and AHTN were detected in water (n?=?5; 3.95?C25.8 and 5.09?C22.8 ng/L, respectively), sediment (n?=?3; 72.8?C388 and 113?C544 ng/g, dry weight), fish (n?=?30; <1?C125 and <1?C32.8 ng/g, lipid weight), and zebra mussel (n?=?4; 10.3?C19.3 and 42.2?C65.9 ng/g, lipid weight) samples. Bioaccumulation factors of HHCB calculated for white perch, catfish, smallmouth bass, and largemouth bass were in the range of 18 to 371, when the concentrations in fish were expressed on a wet weight basis; the factors were in the range of 261 to 12,900, when the concentrations in fish were expressed on a lipid weight basis.     

Comparative Study on Trace Metal Accumulation in Liver of Mediterranean Deep-Sea Fish and Their Selenium/Mercury Molar Ratios

The objectives of this study were to determine and compare the concentrations of Hg, Cd, Pb, Zn, Cu, Ni and Se in the liver of macrourid fish as Trachyrinchus scabrus, Nezumia sclerorhynchus and Coelorhynchus coelorhynchus from the Mediterranean Sea, Italy. It was also carried out to evaluate the relationship between metal concentration and fish size and to explore selenium/mercury molar ratio. The highest concentrations were in T. scabrus, followed by N. sclerorhynchus and C. coelorhynchus. In all species, any element displayed significant correlation between metal body burden and fish size, except Hg. The mean selenium/mercury ratios were greater than one in all fish species indicating that Se antidotal effect in counteracting Hg occurred. This report represents one of the few surveys providing information on trace metal in deep-sea fish from Mediterranean Sea constituting, thus, an essential baseline work with which future levels may be compared.     

Changes of Heavy Metal and PCB Contents in Surficial Sediments of the Barcelona Harbour after the Opening of a New Entrance

Water, Air, & Soil Pollution - The Barcelona harbour is one of the biggest and most important in commercial and passenger traffic in the Mediterranean Sea. In 2003, construction works for the...     

Detection of hexabromocyclododecane and its metabolite pentabromocyclododecene in chicken egg and fish from the official food control

During routine gas chromatography with electron capture detection (GC/ECD) analysis of chicken eggs, we observed that the most prominent peak in some samples did not match the retention time of any of the food contaminants screened. Subsequent GC coupled with mass spectrometry (GC/MS) studies clarified that the mass spectrum of the peak was very similar to hexabromocyclododecane (HBCD), which was also identified by GC/MS in the egg. The unknown compound was positively identified as pentabromocyclododecene (PBCDE), a metabolite of HBCD detected for the first time in foodstuffs. Studies of the analytical method used for the analysis of pesticides and contaminants showed that this cleanup method was suitable for the determination of HBCD and PBCDE, but storage of sample extracts resulted in the loss of HBCD when the sample extracts were not sufficiently purified. The concentrations of HBCD and PBCDE in the high polluted sample were 2.0 and 3.6 mg/kg egg fat. HBCD and PBCDE were also detected in two additional eggs at lower levels (<0.15 mg/kg), whereas 75 eggs did not contain these compounds (<0.02 mg/kg). We also detected HBCD and PBCDE in two samples of whitefish (Coregonus sp.), while an eel sample (Anguilla anguilla) positively tested for HBCD did not contain PBCDE. Surprisingly, the potential metabolite of HBCD, PBCDE, has not been detected before in any food or environmental sample. The present results indicate that more attention should be paid to the detection of HBCD and its metabolite PBCDE in chicken eggs.     

Fatty acid composition and antioxidant levels in muscle tissue of different Mediterranean marine species of fish and shellfish

The levels of hydrophilic, lipophilic, and enzymatic antioxidants, as well as the fatty acids composition, of triglyceride and phospholipid fractions were determined in the muscle tissue of 21 species of teleosts, 3 species of cephalopods, and 6 species of crustaceans, just caught from the central Tyrrhenian Sea (Mediterranean Sea). The enzymatic activities and the levels of low-molecular-weight antioxidants, and the percentages of fatty acids, showed marked interspecies differences. Our results showed that total polyunsaturated fatty acids (21.7-61.5%) were the highest, followed by saturated (16.9-41.3%) and monounsaturated (9.1-42.8%) fatty acids. The total n-3 fatty acids content (16.6-57.1%) was found to be higher than the total n-6 fatty acids content (4.1-10.6%). All of the species studied had an n-3/n-6 ratio of more than 1, confirming the great importance of fish and shellfish as a significant dietary source of n-3 polyunsaturated fatty acids and their beneficial role in the Mediterranean type of diet.     

Determinations of residual furazolidone and its metabolite, 3-amino-2-oxazolidinone (AOZ), in fish feeds by HPLC-UV and LC-MS/MS, respectively

The antibacterial drug furazolidone belonging to the group of nitrofuran antibacterial agents has been widely used as an antibacterial and antiprotozoal feed additive for poultry, cattle, and farmed fish in China. During application a large proportion of the administered drug may reach the environment directly or via feces. Although the use of furazolidone is prohibited in numerous countries, there are indications of its illegal use. It is known that furazolidone can be rapidly metabolized to 3-amino-2-oxazolidinone (AOZ) in the body of the target organism. In this study, a total of 21 fish feed samples, including 17 commercial fish feeds from local markets in China (representing 15 different formulations) and 4 fish feeds obtained from Germany and Turkey, respectively, are analyzed to determine whether the drug is still illegally used or commercially available feeds are contaminated by this drug. High-performance liquid chromatography (HPLC) and liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) methods have been implemented to determine furazolidone and its metabolite AOZ in fish feeds containing animal protein, respectively. An efficient and convenient cleanup method for the determination of furazolidone in fish feeds is developed, and a simple cleanup method for the determination of AOZ is used. Method recoveries for samples used were determined as 87.7-98.3% for furazolidone at two spike levels of 2.0 and 5.0 ng g-1 and as 95.6-102.8% for AOZ at spike levels of 0.4 and 0.8 ng g-1. Limits of detections were 0.4 ng g-1 for furazolidone and 0.05 ng g-1 for AOZ. The established methods are therefore suitable for the determination of furazolidone and its metabolite AOZ in fish feeds at trace contamination levels. Using the established methods, all fish feed samples have been proved to be furazolidone negative; however, AOZ is tested in 16 of 17 fish feeds obtained from local markets in the Hubei province of China, with a positive rate as high as 94.1%.