MURAH REZEKI...

Assalamualaikum warahmatullah,

Semua orang impikan rezeki yang banyak, mudah, berkat serta makmur, termasuklah saya. He.. he… Dalam pekerjaan kita seharian mencari rezeki, mestilah sentiasa niatkan dalam hati supaya Allah mengurniakan kita dengan rezeki yang halal, berkat, mudah serta luas. Terdapat amalan-amalan yang boleh menjadi sebab Allah melimpahi hamba-Nya dengan keluasan rezeki dan rasa kaya dengan pemberian-Nya.

Berdasarkan konsep rezeki yang telah diperkatakan, Allah memberi jalan buat setiap hamba-Nya untuk memperolehi rezeki dalam pelbagai bentuk yang boleh menjadi punca kebaikan dunia dan akhirat.

Di antaranya:

1. Menyempatkan diri beribadah

Allah tidak sia-siakan pengabdian diri hamba-Nya, seperti firman-Nya dalam hadis qudsi: “Wahai anak Adam, sempatkanlah untuk menyembah-Ku maka Aku akan membuat hatimu kaya dan menutup kefakiranmu. Jika tidak melakukannya maka Aku akan penuhi tanganmu dengan kesibukan dan Aku tidak menutup kefakiranmu.” (Hadis Riwayat Ahmad, Tirmizi, Ibnu Majah dan al-Hakim dari Abu Hurairah r.a.)

2. Memperbanyak istighfar

Istighfar adalah rintihan dan pengakuan dosa seorang hamba di depan Allah, yang menjadi sebab Allah jatuh kasih dan kasihan pada hamba-Nya lalu Dia berkenan melapangkan jiwa dan kehidupan si hamba. Sabda Rasulullah SAW : “Barang siapa memperbanyak istighfar maka Allah SWT akan menghapuskan segala kedukaannya, menyelesaikan segala masalahnya dan memberinya rezeki dari arah yang tidak disangka.” (Hadis Riwayat Ahmad, Abu Daud, an-Nasa’i, Ibnu Majah dan al-Hakim dari Abdullah bin Abbas r.a.)

3. Tinggalkan perbuatan dosa

Istighfar tidak laku di sisi Allah jika masih buat dosa. Dosa bukan saja membuat hati resah malah menutup pintu rezeki. Sabda Rasulullah SAW : “… dan seorang lelaki akan diharamkan baginya rezeki kerana dosa yang dibuatnya.” (Hadis Riwayat at-Tirmizi)

4. Sentiasa ingat Allah SWT

Banyak ingat Allah SWT buatkan hati tenang dan kehidupan terasa lapang. Ini rezeki yang hanya Allah beri kepada orang beriman. Firman-Nya: “…(iaitu) orang-orang beriman dan hati mereka menjadi tenteram dengan mengingati Allah. Ingatlah, hanya dengan mengingati Allah hati menjadi tenteram.” (Surah Ar-Ra’d, ayat 28)

5. Berbakti dan mendoakan ibu bapa

Dalam hadis riwayat Imam Ahmad, Rasulullah SAW berpesan agar siapa yang ingin panjang umur dan ditambahi rezekinya, hendaklah berbakti kepada ibu bapanya dan menyambung tali kekeluargaan. Rasulullah SAW juga bersabda: “Siapa berbakti kepada ibu bapanya maka kebahagiaanlah buatnya dan Allah akan memanjangkan umurnya.” (Hadis Riwayat Abu Ya’ala, at-Tabrani, al-Asybahani dan al-Hakim)

Mendoakan ibu bapa juga menjadi sebab mengalirnya rezeki, berdasarkan sabda Rasulullah SAW : “Apabila hamba itu meninggalkan berdoa kepada kedua orang tuanya nescaya terputuslah rezeki (Allah) daripadanya.” (Hadis Riwayat al-Hakim dan ad-Dailami)

6. Berbuat baik dan menolong orang yang lemah

Berbuat baik kepada orang yang lemah ini termasuklah menggembirakan dan meraikan orang tua, orang sakit, anak yatim dan fakir miskin, juga isteri dan anak-anak yang masih kecil. Sabda Rasulullah SAW : “Tidaklah kamu diberi pertolongan dan diberi rezeki melainkan kerana orang-orang lemah di kalangan kamu.” (Hadis Riwayat Bukhari)

7. Tunaikan hajat orang lain

Menunaikan hajat orang menjadi sebab Allah lapangkan rezeki dalam bentuk tertunainya hajat sendiri, seperti sabda Rasulullah SAW : “Siapa yang menunaikan hajat saudaranya maka Allah akan menunaikan hajatnya…” (Hadis Riwayat Muslim)

8. Banyak berselawat

Ada hadis yang menganjurkan berselawat jika hajat atau cita-cita tidak tertunai kerana selawat itu dapat menghilangkan kesusahan, kesedihan, dan kesukaran serta meluaskan rezeki dan menyebabkan terlaksananya semua hajat. Wallahu a’lam.

9. Buat kebajikan banyak-banyak

Ibnu Abbas berkata: “Sesungguhnya kebajikan itu memberi cahaya kepada hati, kemurahan rezeki, kekuatan jasad dan disayangi oleh makhluk yang lain. Manakala kejahatan pula boleh menggelapkan rupa, menggelapkan hati, melemahkan tubuh, sempit rezeki dan makhluk lain mengutuknya.”

10. Berpagi-pagi

Menurut Rasulullah SAW, berpagi-pagi (memulakan aktiviti harian sebaik-baik selesai solat Subuh berjemaah) adalah amalan yang berkat.

11. Menjalin silaturrahim

Rasulullah SAW bersabda : “Barang siapa ingin dilapangkan rezekinya dan dilambatkan ajalnya maka hendaklah dia menghubungi sanak-saudaranya.” (Hadis Riwayat Bukhari)

12. Melazimi kekal berwuduk

Seorang Arab desa menemui Rasulullah SAW dan meminta pedoman mengenai beberapa perkara termasuk mahu dimurahkan rezeki oleh Allah SWT. Rasulullah SAW bersabda: “Sentiasalah berada dalam keadaan bersih (dari hadas) nescaya Allah akan memurahkan rezeki.” (Diriwayatkan daripada Sayidina Khalid al-Walid)

13. Bersedekah

Sedekah mengundang rahmat Allah dan menjadi sebab Allah buka pintu rezeki. Nabi SAW bersabda kepada Zubair bin al-Awwam: “Hai Zubair, ketahuilah bahawa kunci rezeki hamba itu ditentang Arasy, yang dikirim oleh Allah azza wajalla kepada setiap hamba sekadar nafkahnya. Maka siapa yang membanyakkan pemberian kepada orang lain, nescaya Allah membanyakkan baginya. Dan siapa yang menyedikitkan, nescaya Allah menyedikitkan baginya.” (Riwayat ad-Daruquthni dari Anas r.a.)

14. Melazimi solat malam (tahajud)

Ada keterangan bahawa amalan solat tahajjud memudahkan memperoleh rezeki, menjadi sebab seseorang itu dipercayai dan dihormati orang dan doanya dimakbulkan Allah.

15. Melazimi solat Dhuha

Amalan solat Dhuha yang dibuat waktu orang sedang sibuk dengan urusan dunia (aktiviti harian), juga mempunyai rahsia tersendiri. Firman Allah dalam hadis qudsi: “Wahai anak Adam, jangan sekali-kali engkau malas mengerjakan empat rakaat pada waktu permulaan siang (solat Dhuha), nanti pasti akan Aku cukupkan keperluanmu pada petang harinya.” (Riwayat al-Hakim dan Thabrani)

16. Bersyukur kepada Allah

Syukur ertinya mengakui segala pemberian dan nikmat dari Allah. Lawannya adalah kufur nikmat. Allah berfirman: “Demi sesungguhnya! Jika kamu bersyukur, nescaya Aku tambahi nikmat-Ku kepadamu, dan demi sesungguhnya jika kamu kufur, sesungguhnya azab-Ku amat keras.” (Surah Ibrahim, ayat 7)

Firman-Nya lagi: “… dan Kami akan memberi balasan kepada orang-orang yang bersyukur.” (Surah ali-Imran, ayat 145)

17. Mengamalkan zikir dan bacaan ayat Quran tertentu

Zikir dari ayat-ayat al-Quran atau asma’ul husna selain menenangkan, menjenihkan dan melunakkan hati, ia mengandungi fadilat khusus untuk keluasan ilmu, terbukanya pintu hidayah, dimudahkan faham agama, diberi kemanisan iman dan dilapangkan rezeki.

Misalnya, dua ayat terakhir surah at-Taubah (ayat 128-129) jika dibaca secara konsisten tujuh kali setiap kali lepas solat, dikatakan boleh menjadi sebab Allah lapangkan kehidupan dan murahkan rezeki.

Salah satu nama Allah, al-Fattah (Maha Membukakan) dikatakan dapat menjadi sebab dibukakan pintu rezeki jika diwiridkan selalu; misalnya dibaca “Ya Allah ya Fattah” berulang-ulang, diiringi doa: “Ya Allah, bukalah hati kami untuk mengenali-Mu, bukalah pintu rahmat dan keampunan-Mu, ya Fattah ya ‘Alim.” Ada juga hadis menyebut, siapa amalkan baca surah al-Waqi’ah setiap malam, dia tidak akan ditimpa kepapaan. Wallahu a’lam.

18. Berdoa

Berdoa menjadikan seorang hamba dekat dengan Allah, penuh bergantung dan mengharap pada rahmat dan pemberian dari-Nya. Dalam al-Quran, Allah suruh kita meminta kepada-Nya, nescaya Dia akan perkenankan.

19. Berikhtiar sehabisnya

Siapa berusaha, dia akan dapat. Ini sunnatullah. Dalam satu hadis sahih dikatakan bahawa Allah berikan dunia kepada orang yang dicintai-Nya dan yang tidak dicintai-Nya, tapi agama hanya Allah beri kepada orang yang dicintai-Nya saja. (Riwayat Ahmad, Ibnu Abi Syaibah dan al-Hakim)

Bagi orang beriman, tentulah dia perlu mencari sebab-sebab yang boleh membawa kepada murah rezeki dalam skop yang luas. Misalnya, hendak tenang dibacanya Quran, hendak dapat anak yang baik dididiknya sejak anak dalam rahim lagi, hendak sihat dijaganya pemakanan dan makan yang baik dan halal, hendak dapat jiran yang baik dia sendiri berusaha jadi baik, hendak rezeki berkat dijauhinya yang haram, dan sebagainya.

20. Bertawakal

Dengan tawakal, seseorang itu akan direzekikan rasa kaya dengan Allah. Firman-Nya: “Barang siapa bertawakal kepada Allah, nescaya Allah mencukupkan (keperluannya) .” (Surah at-Thalaq, ayat 3)

Nabi SAW bersabda: “Seandainya kamu bertawakal kepada Allah dengan sebenar-benar tawakal, nescaya kamu diberi rezeki seperti burung diberi rezeki, ia pagi hari lapar dan petang hari telah kenyang.” (Riwayat Ahmad, at-Tirmizi, Ibnu Majah, Ibnu Hibban, al-Hakim dari Umar bin al-Khattab r.a.)

Kesemua yang disebut di atas adalah amalan-amalan yang membawa kepada takwa. Dengan takwa, Allah akan beri “jalan keluar (dari segala perkara yang menyusahkan) , dan memberinya rezeki dari jalan yang tidak terlintas di hatinya.” (Surah at-Talaq, ayat 2-3)

Pendek kata, bagi orang Islam, untuk murah rezeki dalam ertikata yang sebenarnya, kuncinya adalah buat amalan-amalan takwa. Amalan-amalan ini menjadi sebab jatuhnya kasih sayang Allah, lalu Allah limpahi hamba-Nya dengan keluasan rezeki dan rasa kaya dengan pemberian-Nya.

Renung-renungkan dan marilah kita sama-sama beramal. Mudah-mudahan Allah SWT melimpah-ruahkan rezeki-Nya kepada kita. Amiin.* sumber dari blog shbt.



aahaa.. dpt tips.. apelagi? jom lakukan Anjakan !!

Let the dust settle

Household dust is one of the principal sources of indoor pollution. Floating dust can be breathed in by the occupants but much settles on floors and surfaces, where it is more of a threat to young children. They spend a great deal of their time on the floor and their frequent hand-to-mouth contact means that they ingest greater amounts of dust.

Settled house dust (SHD) consists of deposited indoor dust, biological material and particles trodden in from outside. It can contain all sorts of chemicals but one group of particular concern is the ubiquitous polycyclic aromatic hydrocarbons (PAHs). Several common PAHs are probable carcinogens and they have been detected in SHD.

Despite a broad knowledge of PAH sources, particularly the incomplete combustion of wood, fossil fuels, tobacco and food, it has been difficult to pinpoint the major source of PAHs in SHD. Now, a new research study carried out in the USA may have come up with the answer and it is all to do with parking lots.

Barbara Mahler and colleagues from the US Geological Survey in Austin and Denver, the Watershed Protection Department of the City of Austin, and Designs4Earth in Manchaca, Texas, were not worried about emissions from vehicles but from the lots themselves. Many parking lots are surfaced with asphalt which is treated after application with a sealant to improve the look and increase the lifetime of the surface.

Of the two common types of sealant used in the USA, one is based on an asphalt emulsion and the other on coal tar. It is known that the two have strikingly different PAH contents. The asphalt-based sealant has relatively low total PAH levels of 50 µg/g but the coal tar-based sealant is far more potent, containing median values of more than 50,000 µg/g PAHs.

This discrepancy is reflected in the PAH contents of dust swept up from parking lots, which contains typically 2.1 and 2200 µg/g PAHs, respectively. So, this is where the researchers focussed their efforts. They analysed dust collected from apartment parking lots with various surfaces and compared the results with SHD from the ground floor apartments adjacent to the lots. Dust collection took place in Austin, Texas, and more than 50% of the parking lots examined were coated with the coal tar-based sealant before it had been banned in 2006.

The dust was extracted for PAH analysis by GC/MS with electron ionisation in full-scan and SIM modes. The contents of the 16 PAHs defined in the US EPA priority pollutants lists were summed, as well as those of 7 PAHs recognised as probable carcinogens.

Dust from coal tar-sealed lots contained median concentrations of total PAHs of 4760 µg/g, about 530-fold higher than any other type of lot tested, in agreement with published work. The asphalt-coated, asphalt-uncoated and concrete-uncoated surfaces had statistically similar low PAHs contents.

The SHD from apartments adjacent to coal tar-coated parking lots had a median total PAH content of 129 µg/g. This value was about 25 times higher than SHD from apartments adjacent to the other types of lot and exceeded reported values for total PAHs in most other studies.

In previous work, some researchers have recognised the high PAH levels in SHD but have been unable to figure out their sources. Mahler and the team thought that coal tar sealcoat "might be that source."

In support of that prediction, a statistical analysis revealed that the absence or presence of an associated coal tar-sealed parking lot accounted for 48% of the variance in total PAHs in SHD. A number of other factors were examined to try and make up the difference and a second factor explained 60% of the difference when considered with the coal tar sealant. This was the intensity of urban land use that considered the contribution of residential buildings, commercial premises, offices, warehouses, streets and roads.

Other factors such as the vehicle emissions, the frequency of vacuuming, indoor fires, the amount of carpets, and the presence of PCs appeared to have insignificant contributions.

The 7 PAHs that are probably carcinogenic also had relatively high median concentrations of 47 µg/g in SHD from apartments beside coal tar-sealed lots. This has serious health implications.

Published work on the non-dietary exposure of preschool children to these PAHs in the USA was based on levels of 1-2 µg/g in SHD, far lower than this new data, greatly under-estimating exposure levels. PAHs in settled household dust represent the greatest source for infants living in apartments in these particular locations and should be taken into account in future models.

Related Links:

*
Environmental Science and Technology 2010, 44, 894-900: "Coal-tar-based parking lot sealcoat: An unrecognized source of PAH to settled house dust"

Ionic liquids for the GC of biodiesel blends

Biodiesel was the first advanced biofuel to make it to market, where it is generally sold as blends with petroleum distillates. It has already become a significant alternative fuel due to three main factors: its sources, lack of toxic content, and combustion characteristics.

The fuel is produced from domestic renewable resources such as vegetable oils, recycled cooking oils, animal fats and, lately, algae. Contrary to one of the most common criticisms, biodiesel production does not contribute to land clearage for new crops because it is produced from co-products of existing crops. So, rather than contributing to greenhouse gas emissions, it reduces lifecycle carbon emissions by 60-80%. This makes it "the best carbon reduction tool of any liquid fuel commercially available" according to the US National Biodiesel Board.

Apart from assuring its biodegradability, the biological sources ensure that there are no toxic sulphur or nitrogen compounds present. In diesel engines, a blend of 20% biodiesel in petroleum (B20) showed similar fuel consumption, horsepower, torque and haulage rates as conventional diesel fuel over 50 million miles of tests. Biodiesel also has superior lubricity as well as the highest BTU content of any alternative fuel.

Biodiesel consists of mixtures of fatty acid methyl esters (FAMEs) and their quantities in blends is gauged by one of two official methods. ASTM D7371 uses mid-IR spectroscopy to assess FAME levels of 1-20% whereas the European UNI EN 14331 procedure measures the FAME profile using HPLC fractionation followed by GC. The latter procedure has been used for middle distillates containing up to 5% FAMEs but it is relatively complex and time consuming.

Italian scientists have developed an alternative method for measuring FAMEs in biodiesel blends that is quicker and simpler and can be applied to blends containing up to 40% esters. Luigi Mondello, Carla Ragonese, Peter Quinto Tranchida and Danilo Sciarrone from the University of Messina and University Campus Biomedico of Rome used GC-FID in a procedure that required no pre-fractionation of the fuel blend.

Their method relies on an ionic liquid as stationary phase. This is not a novel concept for GC, with reports of ionic liquids being used for the separation of PAHs, essential oils and chlorinated pesticides. Their low volatility, good wetting properties, high thermal stability and selectivity towards particular classes enhance their suitability.

Mondello and colleagues used a commercial column containing 1,9-di(3-vinylimidazolium)nonane bis(trifluoromethyl)sulphonylimidate (SLB-IL100). In initial experiments using a 30 m column, it performed better on a mixture of C4-C24 FAMEs than a conventional 100% polyethylene glycol (PEG) stationary phase under the same conditions.

Resolution was good for both columns but the ionic liquid column accomplished the separation in a quicker time, the C24 methyl ester eluting after 48 minutes, compared with 65 minutes on the PEG column. In addition, plots of the elution temperatures versus the carbon number revealed that the ionic liquid column should elute the C32 methyl ester at its highest operating temperature (230°C) compared with the C28 ester for the PEG column at its maximum temperature of 280°C.

The polarity of the IL100 column was calculated to be 4437, almost double that of the PEG column and even greater than that of the highly polar tris(2-cyanoethoxy)propane stationary phase.

For the analysis of B20 blends, each FAME eluted separately on a 30 m IL100 column without interference from the other more polar diesel components such as PAHs. In contrast, the PEG column brought about coelution of some components.

The same good separation was achieved with a 12 m IL100 column, but in a fraction of the time, taking just 2.5 minutes to elute the FAMEs.

The FAME contents in a soybean B20 blend were measured on the 12 and 30 m columns from calibration curves, based on the peak areas of each component corrected for detector response. The calibrations curves were linear for both columns up to 40% (by volume) of FAMES.

Both columns gave low coefficients of variation for retention time and concentration and very similar contents for each of 6 FAMEs. The methyl esters of linoleic, oleic, palmitic, linolenic, stearic and eicosanoic acid were present at 55.4-56.1, 21.5-21.8, 12.7-11.8, 6.3-6.6, 3.3-3.0 and 0.7%, respectively.

The ionic liquid GC stationary phase gave excellent performance in short and long GC columns, its high polarity ensuring complete separation of the target FAMEs from each other and the diesel hydrocarbons in a faster time than conventional GC columns. Combined with the absence of a pre-fractionation step, the method should be useful for the routine quality control of biodiesel blends.

Related Links:

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Journal of Chromatography A 2009, 1216, 8992-8997: "Conventional and fast gas chromatography analysis of biodiesel blends using an ionic liquid stationary phase"

Cobalt dispersive extraction with ionic liquids

Cobalt is an essential element for humans, being part of vitamin B12, one of the few natural compounds that possess a carbon-metal bond. It is also an important industrial chemical and finds its way into the environment via effluents, where it can pose a danger to wildlife and humans. Cobalt is a suspected carcinogen and some of its compounds are toxic.

The conventional method for measuring levels of cobalt in environmental and biological samples is electrothermal atomic absorption spectrometry (ETAAS), which has good sensitivity and relatively low cost. It is a routine and well-established technique but sometimes needs a little help when cobalt levels are very low. Preconcentration and sample clean up of trace cobalt is often required before analysis can proceed.

One extraction technique for cobalt that has found favour recently involves the use of room temperature ionic liquids (RTILs). They have been used in single drop microextraction, where a complexing agent traps the metal ions before transfer to the extraction drop. However, the limited reproducibility encountered in published methods, combined with break-up of the drops led some research groups to examine the use of ionic liquids in the larger-volume dispersive liquid-liquid microextraction (DLLME).

One complexing agent used to trap cobalt ions was 1-(2-pyridylazo)-2-naphthol but it showed limited sensitivity towards metals, despite having favourable stability constants. An alternative naphthol has now been tested by researchers in Argentina, who found that 1-nitroso-2-naphthol (1N2N) has excellent selectivity and sensitivity.

Rodolfo Wuilloud and Paula Berton from the Laboratory of Environmental Research and Services of Mendoza (LISAMEN), part of the National Scientific and Technical Research Council (CONICET), and the National University of Cuyo, Mendoza, optimised the extraction of cobalt for subsequent analysis by ETAAS.

The RTIL was selected from three candidates on the basis of its viscosity and solubility in water. 1-Hexyl-3-methylimidazolium hexafluorophosphate was preferred over the butyl and octyl analogues.

For method optimisation, cobalt(II) standard solutions were mixed with 1N2N, acetate buffer (pH 4.0), sodium nitrate and surfactant to form the Co-1N2N complex. The solution was cooled over ice and adjusted to pH 2 with hydrochloric acid before addition of the ionic liquid as extractant and methanol as dispersant for DLLME. Dispersion of the RTIL into the aqueous sample expanded the contact area between the two phases.

After a suitable extraction period in the region of 7 minutes, the solutions were centrifuged to separate the phases and the RTIL was withdrawn, dissolved in methanol and analysed.

The amount of the RTIL required for 100% extraction efficiency was minimised to avoid the possibility of interfering in the ETAAS assay. For 40-80 mg cobalt and 0.5 ml methanol, recoveries of 100% were achieved with 60 mg of the ionic liquid.

The other extraction conditions were also optimised for the extraction of cobalt, including the sample volume (7.5 ml), the pH for complex formation (4.0) and the temperature for complex formation (50°C). The pH for extraction of the cobalt-1N2N complex was set to 2.0 to eliminate the co-extraction of other metal species that might form complexes with 1N2N.

Under these conditions, the cobalt detection limit in ETAAS was 3.8 ng/l with a r.s.d. value of 3.4%.

The optimised procedure was used to extract cobalt from domestic tap water, river water, human saliva and, following digestion with peroxide under UV light, human urine. Saliva is an important and non-invasive medium for monitoring cobalt that has leached out from dental cast alloys and devices such as orthodontic wires.

Recoveries over the whole range of samples were 97-103% and cobalt was found in all cases apart from two saliva samples. For 4 samples of each type, cobalt levels were 0.45-0.57 (tap water), 0.53-0.65 (river water), 0-0.15 (saliva) and 0.32-0.92 µg/l (urine).

The DLLME method for extracting cobalt from aqueous samples following complexation with 1-nitroso-2-naphthol presents a new, green procedure that provides high efficiency with short extraction times. It is suitable for ETAAS, the standard technique for measuring trace levels of metals in biological samples.

Related links:

* Analytica Chimica Acta 2010, 662, 155-162: "Highly selective ionic liquid-based microextraction method for sensitive trace cobalt determination in environmental and biological samples"

Tobacco acids reacted in syringe

One of the recently developed microextraction techniques that have been designed to replace large-volume solvent extractions is single drop microextraction (SDME). By definition, it uses one drop of solvent to accomplish the extraction of volatile compounds, by holding the drop in the headspace above the sample, or by immersing the drop in the liquid sample. In the latter case, the drop and the sample should be immiscible liquids, or the drop will be lost.

The drop is generally held at the end of a microsyringe during extraction, then withdrawn into the syringe when extraction is completed. SDME has the advantage of requiring very small volumes of organic solvent, reducing the environmental impact compared with liquid-liquid extractions, and cutting the cost of the procedure.

Since the compounds extracted from the headspace are volatile, one of the commonly used analytical techniques is GC/MS. With judicial selection of the solvent, the drop can be injected directly from the syringe into the inlet. However, not all volatile compounds are suitable for immediate analysis by GC/MS, due to their polar nature, so a derivatisation step may be required.

One solution devised by a group of Chinese scientists is in-drop derivatisation, in which the derivatising agent is dissolved in the extraction solvent before SDME begins. As soon as the compounds are adsorbed into the drop, their derivatisation begins, removing the need for a separate derivatisation step. Once reaction is deemed to be complete, the contents can be injected into the GC/MS system.

The same team began to study the content of volatile organic acids in cigarette tobacco, using SDME for extraction. These straight-chain and branched acids, such as formic, acetic and butyric acid up to heptanoic acid, would need to be derivatised for subsequent GC/MS analysis. The researchers chose the standard, highly efficient agent, bis(trimethylsilyl)trifluoroacetamide (BSTFA), but it is too volatile to remain in the drop for in-drop derivatisation SDME.

So, they adopted a recently developed technique called in-syringe derivatisation in which the reagents could be held in a controlled space. Following SDME, the drop is withdrawn into the microsyringe before a small volume of BSTFA is also drawn in. The plunger is moved gently up and down to encourage mixing and reaction within the syringe.

Optimisation of the method using standard solutions of the acids was described in the Journal of Separation Science by Da Wu, Yunfei Sha and Yichun Zhang from the Shanghai Tobacco (Group) Corporation Technical Center and Jiaoran Meng and Chunhui Deng from Fudan University, Shanghai. The acids were analysed by GC/MS in selected ion monitoring mode.

Of the three preferred solvents for SDME, decane was selected because dodecane and heptadecane interfered with the organic acid derivatives. Using an extraction volume of 1 µL, equilibrium was achieved within 30 s. The optimal conditions for in-syringe derivatisation were a BSTFA volume of 0.8 µL and a reaction time of 3 min at room temperature.

The recoveries of 10 organic acids were 92.2-108.1% and the detection limits ranged from 0.10-3.37 µg/g. Linear calibration curves were obtained and the repeatabilities were less than 15.2%.

The optimised method was applied to the organic acids in cigarette tobacco removed from 7 commercial brands, using hexanoic acid-d11 as an internal standard. All 10 acids were found: formic, acetic, propionic, butyric, isobutyric, isovaleric, valeric, isocaproic, caproic and heptanoic acid.

The proportions of the acids differed from brand to brand but the two most abundant in all cases were formic and acetic acid. The third most abundant acid varied between propionic, butyric, isobutyric and isovaleric acid. The C2-C7 organic acids are important flavour components of tobacco, so this data is important in assessing the odour and flavour of the individual brands.

SDME with in-syringe derivatisation proved to be a simple, rapid and low-cost method using minimal solvent for the extraction and derivatisation of volatile organic acids for subsequent GC/MS analysis. It provides an alternative to in-drop derivatisation for reagents such as BSTFA that are too volatile.

Related links:

* Journal of Separation Science 2010, 33, 212-217: "Determination of volatile organic acids in tobacco by single-drop microextraction with in-syringe derivatization followed by GC-MS"

Chiral separation of fruity flavonoids

Citrus fruits are promoted as one of the healthy eating options. In the UK, they are options within the five-a-day programme of the Department of Health in which people are encouraged to eat at least five portions of fruit and vegetables a day to "help reduce the risk of some cancers, heart disease and many other chronic conditions."

Like other types of healthy food, the active components in citrus are flavonoids which have been recognised to impart many health benefits. Bioflavonoids are also referred to collectively as vitamin P, although they are not actually vitamins, probably due to their health-promoting properties.

The predominant flavonoid in lemons and oranges is a compound called hesperidin. It is concentrated in the white, membranous parts and the peel and has been credited with antioxidant, antibacterial, antifungal, antiviral, anticancer and analgesic properties, among others.

Chemically, hesperidin consists of a flavanone component joined to a sugar group through the oxygen atom at the 7-position to give the rhamnoglucoside. After ingestion, the sugar group is removed in the gut to leave the parent flavanone, 3',5,7-trihydroxy-4'-methoxyflavanone, also known as hesperetin.

In order to study the actions and effects of hesperidin in the human body, scientists need to study hesperetin, the active metabolite. There are a number of reported studies on its bioactivity but they fail to take into account the chiral nature of the compound. Hesperetin exists as two enantiomers, the (R)- and (S)-forms, which will have different properties, so should be considered independently.

Scientists from Italy and Algeria recently succeeded in separating the enantiomers of several flavanones and their glycosides, including hesperetin and hesperidin, using nano-LC. They used a specially prepared chiral column, based on phenylcarbamate-modified propyl-beta-cyclodextrin, which provided baseline resolution of most of the enantiomeric pairs.

By switching from the conventional HPLC column with an internal diameter of 4.6 mm, to a nano column with an internal diameter of 100 µm, the sensitivity was increased by about 2000-fold. In addition, the switch rendered the procedure more environmentally friendly, due to the reduced volumes of the stationary phase and phases.

Now, the team has applied the column to determine the enantiomers of hesperetin in human urine after the consumption of orange juice. Salvatore Fanali and colleagues from the Institute of Chemical Methodologies of the Italian National Council of Research in Rome and the University of Science and Technology Houari Boumediene in Algiers transferred the optimised conditions from their previous work.

The mobile phase consisted of triethylamine acetate buffer (pH 4.5) in 70% aqueous methanol at room temperature. The retention times of the (R)- and (S)-isomers were 9 and 12 minutes, respectively, and no interfering peaks were observed from orange juice or urine. The LC instrument was fitted with a UV detector operating at 205 nm.

7-Ethoxycoumarin was added as an internal standard, eluting after 7 minutes. The detection limits were 0.1 µg/L for each enantiomer and linear calibration curves were obtained over 0.25-25 µg/mL. Recoveries were higher than 82%.

Under these conditions, the (R)- and (S)-enantiomers of hesperetin and hesperidin were first measured in a high quality commercial blood orange juice. Hesperetin was not detected, confirming that the flavanone exits in orange juice in its conjugated form only. The concentrations of (R)- and (S)-hesperidin were found to be high, at 112.81 and 599.55 mg/L, respectively.

A volunteer drank 1 L of the orange juice and urine was collected at intervals over 24 hours for analysis after hydrolysis. Both enantiomers appeared in urine after about 2 hours, maximised after 7 hours then fell back sharply, returning to zero after 24 hours.

The total amounts of (R)- and (S)-hesperetin excreted corresponded to 6.44 and 3.55% of the original orange juice content and most of this, 87 and 91% respectively, was excreted in the busy period from 4-8 hours.

Based on the speed, simplicity, accuracy and relatively low cost of the method, the researchers proposed the use of hesperetin as a biomarker for citrus juice uptake. It could be used in clinical studies of the bioactivity of hesperetin and could be extended to other flavanones, once their separation on the chiral column has been confirmed.

Related links:

* Journal of Pharmaceutical and Biomedical Analysis 2010, 51, 225-229: "Analysis of hesperetin enantiomers in human urine after ingestion of blood orange juice by using nano-liquid chromatography"

Barbecue with toxins on the side

Rain, sleet, snow and freezing temperatures. This time of year seems a lifetime away from the balmy summer evenings when we were lounging outside enjoying the delights of a barbecue. The smell of grilled meat and smoky charcoal wafting through the air is the essence of summer to many people.

The best position at an outdoor barbecue is a few feet upwind, so that the smoke is drifting away but odours of the cooking food still manage to percolate the area. The macho position in control over the barbecue is reckoned by some to be the worst of all, as it is accompanied by a surplus of heat from the equipment and frequent lungsful of smoke.

These considerations are not without foundation. Not only are the smoke particles a health hazard, but they are accompanied by harmful series of compounds originating from the cooking food and the charcoal itself. Outdoors, these will quickly disperse after they have blown over the chef but indoors, they can accumulate in the air and reach dangerous concentrations.

The indoor problem is not as odd as it sounds. In Asia, there are special barbecue-style restaurants where the customers cook their own food at their tables. It is likely that any volatile compounds will remain in the restaurant and be inhaled by the patrons. Carbon monoxide, toxic carbonyl compounds and aromatic hydrocarbons are some of the potential pollutants.

The emission of these groups of compounds from charcoal has been investigated by scientists from Sejong University and Korea University in Seoul and was described by senior reporter Ki-Hyun Kim in the Journal of Hazardous Materials. The team studied 16 barbecue charcoals originating from Korea, Indonesia, China and Malaysia, all of which are commonly available in Korea.

Samples of each charcoal were burned in a combustor and the emissions were collected in a Tedlar bag. For volatile hydrocarbons, the trapped gases were passed to a cold trap before thermal desorption and GC-FID analysis. The levels of benzene, toluene, ethylbenzene, m/p-xylene and styrene were measured.

For carbonyl compounds, the gases were passed through a dinitrophenylhydrazine cartridge to convert them to hydrazones, before elution with acetonitrile. The mixtures were analysed by HPLC with UV detection at 360 nm. A C18 column was used to separate the hydrazones with an isocratic mobile phase of aqueous acetonitrile and they were quantified from calibration curves. The detection limits ranged from 0.92 to 1.16 ppb for formaldehyde, acetaldehyde, acrolein, acetone, propionaldehyde, crotonaldehyde, butyraldehyde, benzaldehyde and valeraldehyde.

Smokes from all of the charcoals contained large amounts of aromatic hydrocarbons. The amounts varied with the country of origin with Korean charcoal the highest emitter, having a total of all C6-C16 hydrocarbons of 7160 ppb, compared with 3270, 510 and 315 ppb for Indonesian, Chinese and Malaysian charcoal. Toluene and benzene were the most abundant hydrocarbons at mean levels of 116 and 98.7 ppb.

With the carbonyl compounds, formaldehyde, acetaldehyde and acetone were consistently above the detection limit for all samples, the other carbonyls being present in some, but not all, samples. Formaldehyde and acetaldehyde, at mean levels of 275 and 126 ppb, were the most abundant. The pattern of emissions differed to that of the hydrocarbons, with Chinese charcoal the worst emitter.

The mean levels of nearly all of the compounds tested were below the permissible exposure levels (PELs) for short-term exposure set by the US Occupational Safety and Health Administration (OHSA). The exception was formaldehyde, for which 11 of the 16 samples exceeded the PEL.

The VOC and carbonyl content will be dependent upon the type of wood used to manufacture the charcoal and the presence of other constituents. For instance, vegetable wastes, paper mill residues and scrap wood from furniture or wood flooring are often employed. In addition, coal dust is added as a heat source, along with sodium nitrate to improve ignition and lighter fuel in quick-light brands.

Bearing in mind the acute irritation caused by low levels of formaldehyde and acetaldehyde, and the carcinogenicity of aldehyde, the researchers recommended the introduction of controls on the use of barbecue charcoal to reduce potential health risks. This is especially the case for charcoals produced from improper materials, such as furniture or wood panelling, which may have been painted or lacquered and will release extra pollutants upon combustion.

Related links:

* Journal of Hazardous Materials 2010, 174, 492-499: "Barbecue charcoal combustion as a potential source of aromatic volatile organic compounds and carbonyls"