BSA BSTFA

Hydroxyl groups in alcohols and phenols Silylation BSA, BSTFA, BSTFA + TMCS, HMDS, MSTFA, MSTFA + TMCS Most often used derivatives Good thermal stability... 

BSA, BSTFA and Tri-Sil , a soln. of hexamethyldisilazane and trimethylchlorosilane in pyridine Carrier gas... 

For low molecular weight aliphatic acids, try TMSDEA reagent. Otherwise, use MSTFA, BSTFA, or TRI-SIL BSA (Formula P). For analysis of the keto acids, methoxime derivatives should be prepared first, followed by the preparation of the trimethylsilane (TMS) derivatives using BSTFA reagent. This results in the meth-oxime-TMS derivatives. 

MTBSTFA is the recommended reagent for silylating the amine functionality because it forms a more stable derivative than MSTFA. BSTFA, or BSA. Because amines can be difficult to silylate, the solvent used is important. 

Derivatives Add 0.25 ml of methoxime hydrochloride in pyridine and let stand at room temperature for 2 hr. Evaporate to dryness with clean, dry nitrogen. Add 0.25 ml of BSTFA, MSTFA, or BSA reagent and let stand for 2 hr at room temperature. 

Alternative silylating reagents such as N,0-bis(trimethylsilyl)acetamide 22a (BSA) [39-43], N,0-bis(trimethylsilyl)trifluoracetamide 22b (BSTFA) [44], or N,N-bis(trimethylsilyl)formamide 22c (BSF) [41, 46], in which the N- and O-trimethyl-silyl groups are in equilibrium [45] (Scheme 2.4), are much more powerful silylating reagents [40, 45] but are more expensive than FIMDS 2, because they are usually prepared by heating formamides or acetamides with TCS 14/triethylamine... 

BSTFA or BSA Reagents of choice for the formation of N-TMS derivatives. May promote the formation of enol-TMS ethers unless ketone groups are protected. 

BSTFA Produces volatile byproducts which do not interfere with the GC analysis of low molecular weight compounds. Reactivity is similar to BSA and is generally preferred to BSA for most applications. 

BSTFA provided the highest yield of product in comparison to other silylating agents. BSA [bis(trimethylsilyl)acetamide] reacted with DDQ. TMSOTf with luti-dine or collidine in toluene offered the best alternative but the yield was lower than the yield achieved with BSTFA. 

Silylation of AN with BSA and BSTFA produces as by-products A-trimethyl-silylacetamide (bp 70°C/35mm Hg) and A-trimethylsilyltrifluoroacetamide (bp 60°C/35mm Hg), respectively. Owing to high volatility typical of fluorinated hydrocarbons, distillation of BSTFA from the reaction mixture seems to be more favorable, although their high casts should also be taken into account. 

N,0-Bis( trimethylsilyljacetamide (BSA), as silylating agent, 22 693t, 694, 695 A,0-Bis(trimethylsilyl)trifiuoroacetamide (BSTFA), as silylating agent, 22 693t, 694... 

Another approach consists of an in-situ acetylation and extraction of NPEOs and further analysis of the acetyl derivatives. The method has been applied to analyse effluent water and sewage sludges [102,103], sediments [104] and river waters [105]. Silylated derivatives [106] using BSA or BSTFA have also been used to determine NPEO (n < 6) in seawater [107] and wastewater [107,108], sediments [109] and sludges from wool scour effluents [110]. Halogenated derivatives of alkylphenols (AP) can also be formed as a result of chlorination practices in water treatment or wastewater if bromide is present. Brominated OPs and NPs (BrAPEOs) have been identified by GC-MS in sewage [111] and tap water [89], respectively. 

HFAA, heptafluorobutyric acid anyhydride BSTFA, N,O-bis(trimethylsilyl)tnfluoroacetamide 3 -hydroxysteroid dehydrogenase BSA, N,O-bis(trimethylsilyl)acetamide MSTFA, N-methyl-N-(trimethylsily)trifluoroacetamide TMS, trimethylsilane SEA, supercritical-fluid extraction PFBCMO, pentafluorobenzylcarboxymethoxime. 

NBD-CI, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole MSTFA, N-methyl-N-(trimethylsilyl)trifluoroacetamide BSA, N, O-bis(trimethylsily-l)acetamide MTBSTFA, N-methyl-N-(tetr.-butyldimethylsily)trifluoroacetamide BSTFA, N,0-bis(trimethylsilyl)trifluoroacetamide HFB, heptafluorobutyric acid SFE, supercritical-fluid extraction. 

Bromo-2,6-xylenol, b270 BSA, b207 BSTFA, b212 BTMS A, b208 Busulfan, b 88... 

Among the more important trimethylsilylation reagents are trimethylchloro-silane (TMCS) hexamethyldisilazane [(Me3Si)2NH, (HMDS)] iV-trimethyl-silylimidazole (TMSI) (1) AT,0-bis(trimethylsilyl)acetamide (BSA) (2) AT,0-bis(trimethylsilyl)trifluoroacetamide (BSTFA) (3) and A-methyl-A-(t-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) (4). 

Family of reagents forming derivatives that have stabilities similarto those produced by TMSIM, BSA, MSTFA, and BSTFA, with additional electron capture detection R = ch3 sensitivity enhancement usually... 

On the day of analysis the samples were dried under nitrogen and dissolved in 25 yl dry acetonitrile, mixed with 10 yl silylating agent BSA—N,0,bis-tri-methylsilyl)-acetamide—or BSTFA—N,0-bis-(trimethyl-silyl)-triflouroacetamide—and kept at 50-60° for 10 minutes. The solutions were evaporated to dryness under a stream of nitrogen and redissolved in 10 yl dry acetonitrile and 2 yl was subjected to mass fragmentography. ... 

TMSIM > BSTFA > BSA > MSTFA > TMSDMA > TMSDEA > MSTA > TMCS > HMDS... 

This procedure is reputedly more suitable than silylation with BSTFA under the same conditions or with BSA—pyridine at room temperature. Other workers [272] accomplished the silylation of thiohydantoins with the aid of BSTFA-pyridine (1 1) at 50°C for 10 min. Gly and Thr, however, provide two products which are not stable. A good separation of silylated 2-thiohydantoins was obtained on a 4 ft. X 2 mm I.D. column packed with 10% of SP-400 on Chromosorb W HP with temperature programming (145— 260°C). The analysis was also performed on 1% of Dexsil 300 GC and 5% of OV-17 with identification by means of mass spectrometry. A number of mass spectra of thiodantoins and their TMS derivatives have been published [271]. 

---